Maintenance Human Factors Training EASA 145 & 66
Maintenance Human Factors This training is based on EASA 145, which requires… That maintenance organizations put in place a maintenance Human Factors program that addresses ten (10) maintenance Human Factors issues, and where… One (1) of the issues is the need to train maintenance staff to be competent in maintenance Human Factors knowledge and skills 2
EASA 145 Maintenance Human Factors Training Requirements 1. General / Introduction to human factors 2. Safety Culture 3. Human Error 4. Human Performance & Limitations 5. Environment 6. Procedures, Information, Tools and Practices 7. Communication 8. Teamwork 9. Professionalism and integrity 10. Organization’s HF Program 3
I. General Introduction to Human Factors
Definition Human Factors is a technical discipline aimed at optimizing human performance within a system by contributing to the planning, design, and evaluation of tasks, jobs, products, organizations, environments and systems in order to make them compatible with the needs, abilities, and limitations of people.
This
Not This
5
Where Can Human Factors Be Applied in Maintenance?
Manuals & Procedures
Training
Operational Controls & Displays
Human/Computer Interaction
Design for Maintainability
Work Group Procedures 6
SHELL Model
Liveware • Variations in Performance & limitations – Physical size & shape – Physical needs (sustenance, sleep etc)
– Input/Output Characteristics – Information processing – Environmental tolerances (temp, pressure, humidity, enclosed space, stress & boredom)
8
Liveware – Hardware • Ergonomics – – – –
Tool design & operation Instrument interpretation Work space & access GSE reliability
9
Liveware – Software Non-physical aspects of systems such as: • Document design & layout e.g. maintenance manual • Symbology and computer programmes • Procedures • Training manuals i.e. content and design • Rules and regulations i.e. company and authority
10
Liveware – Environment • Extremes of temperature affects thought processes • Excess noise and vibration affects concentration • Shift work causes fatigue making error prone
11
Liveware – Liveware • Leadership, co-operation, teamwork, personality interactions • Staff/management relationships, corporate culture & climate, company operating pressures • Domestic Pressure 12
Causes of Accidents
Source : FSF , 2000
13
Causes of Accidents 100%
~80% of accidents are now due to human error
90% 80% 70% 60% 50% 40% 30% 20%
~20% of accidents are now due to machine causes
10% 0% 1903
TIME
Today 14
Maintenance-Related Accidents
Maintenance system failures, due to errors and/or violations, can affect safety of flight in two different ways: 1. Primary Cause of an accident. Accident is due to the maintenance/inspection failure. Accident is not in any way due to flight crew action.
2. Contributing Factor to an accident. Accident chain begins with a maintenance/inspection failure that is incorrectly handled by the flight crew, ultimately ending up as an accident (Primary Cause is pilot error). 15
Accident Where Maintenance Is the Primary Cause Kahului, Hawaii, U.S.A. 1988
Upper fuselage separation 737-200
16
Kahului 737 Event Post incident inspection revealed that there were at least 240 cracks present at the last inspection prior to incident. Among the contributing factors to the error of not seeing the cracks… Lack of resources–No proper platform or inspection lights. Fatigue–Inspection carried out late at night. Lack of technical knowledge–Not enough inspection training. Complacency–Done other aircraft and had not find any cracks. 17
Maintenance as a Primary Cause Data provided in a recent Advance-Notice of Proposed Amendment No xx/2007 from EASA*. Primary Cause of HF-Related Accidents Design Production Operations (flight crew related) Maintenance ATM Dispatch Loading TOTAL HF-Related Accidents Non-HF-Related Accidents TOTAL
# of Accidents 135 101 3038 416 66 18 129 3903 1320 5223
% of Total 3% 2 58 8 1 0 2 75 25 100
*Data obtained from EASA Safety Analysis & Research. It is based on airliner accidents only, covering the period 1990 to January 2006. Only reports where causal factors have been positively identified are included in the analysis. 18
Accident Where Maintenance Is a Contributing Factor Lima, Peru 1996
Tape left on static ports 757-200
19
Lima 757 Event The aircraft's three static ports on the left side were obstructed by masking tape. The tape had been applied before washing and polishing of the aircraft the day before the accident flight. Work was begun on one shift and handed over to next morning’s shift. Poor shift handover log was a contributing factor. Mechanics and pilots both missed tape during walk around. 20
Safety Costs of Maintenance Events 2003 The International Air Transport Association (IATA) Safety Report 2003 found that in 26% of the accidents a maintenance-caused event started the accident chain. IATA Safety Report 2006—40% IATA Safety Report 2007—20% IATA Safety Report 2008—15% Note: IATA did not distinguish between maintenance as a Primary Cause vs. a Contributing Factor. 21
Monetary Costs of Maintenance Error Maintenance error caused… 20% to 30% of in-flight shutdowns (IFSDs) at a cost of US $500,000 per IFSD 50% of flight delays due to engine problems at a cost of US $9,000 per hour. 50% of flight cancellations due to engine problems at a cost of US $66,000 per cancellation.
22
Murphy’s Law
23
Summary About 80% of aircraft accidents today are caused by human errors. Maintenance and inspection errors are the primary cause of 8% of the accidents. Maintenance and inspection errors are a link in the accident chain in an additional 20% - 30% of the accidents. Maintenance and inspection errors can also be very costly. The whole industry (manufacturers, vendors, aviation authorities, airlines, and maintenance providers) must work together to reduce the risk from these errors.
24
II. Safety Culture/ Organisational factors
Safety Culture EASA 145 requires that a maintenance organization develop a Safety Culture within the organization. One way to begin development of a Safety Culture is to put the elements of a Safety Management System into place. 26
Safety Culture Safety Management System Definition of culture/safety culture Importance of a good safety culture Elements of a good safety culture Safety Management System (SMS) International Civil Aviation Organization (ICAO) General characteristics and functions of an SMS 27
Definition of Culture Culture = Customary beliefs, behavior patterns, and traits of a racial, religious, or social group Any organization has a culture of its own Management style Morale Acceptable behaviors Norms 28
Definition of Safety Culture What is a “safety culture” as it applies to an aircraft maintenance organization? A “safety culture” is a (maintenance organization) culture in which safety plays a major role.
29
Importance of a Good Safety Culture Safety, as it applies to maintenance, has three components 1. Maintenance actions (e.g., an installation error) can lead to safety of flight issues 2. Mechanic actions can lead to personal safety issues (e.g., cuts, puncture wounds, and broken bones) 3. Maintenance actions can lead to environmental degradation.
A good safety culture will reduce the instances of all three of these events, reducing the accident rate and, thus, saving lives and money. 30
J. Reason—The Elements of a Good Safety Culture Informed Culture—A culture in which those who manage and operate the system have current knowledge about the human, technical, organizational and environmental factors that determine the safety of the system as a whole. Reporting Culture—A culture in which people are willing to report errors and near misses. Learning Culture—A culture in which people have the willingness and competence to draw the right conclusions from its safety information system, and the will to implement major reforms when the need is indicated. 31
J. Reason—The Elements of a Good Safety Culture Just Culture—A just culture where an atmosphere of trust is present and people are encouraged or even rewarded for providing essential safety-related information, but where there is also a clear line between acceptable and unacceptable behavior. Flexible Culture—A culture that has organizational flexibility typically characterized as shifting from the conventional hierarchical structure to a flatter professional structure. 32
Achieving a Safety Culture A Safety Culture is achieved over time, requiring: A commitment to safety from the Senior Management down through every worker in the organization. A process for achieving safety. This process often is called a Safety Management System.
33
III. Human Performance & Limitations
Human Performance & Limitations Normal curve Human strengths and weaknesses Vision Hearing Information processing Attention and perception Memory Speed/accuracy tradeoff
Physical work Fatigue and sleep Claustrophobia and physical access Fitness and health Alcohol, medication, and drugs Repetitive tasks/ complacency
35
Introduction to Human Performance Human beings have strengths and weaknesses Tasks that do not account for human limitations result in:
Vision
Cognition
Hearing Strength
Errors Injuries
If you review a task or work station, do not ask: Can it be done? Ask: Can it be done safely and correctly by the people who do the job?
Reach
36
Humans Are Better than Machines in… Detecting small amount of visual and acoustic energy. Perceiving patterns of light or sound. Improvising and using flexible procedures. Reacting to unusual or unexpected events. Storing very large amounts of information for long periods and recalling relevant facts at the appropriate time. Applying originality at solving problems. Reasoning inductively. Exercising judgment. Learning from experience.
“Use a human operator when a system component is needed that can think on its feet, process information in ways that could not be predicted, and can then act effectively using the result.” 37
Machines Are Better than Humans in… Responding quickly to control signals. Applying great force smoothly and precisely. Performing repetitive, routine tasks. Storing information briefly and then erasing it completely. Reasoning deductively, including computational ability. Handling highly complex operations—doing many different things at once. 38
Other Major Differences Machines can be modified, redesigned, and retrofit—humans cannot. Humans are born with innate, genetically determined differences that are shaped by the environment. Innate aptitudes or abilities are developed through education and training.
Machines can be manufactured to be identical— with (nearly) identical output or performance. Humans are not identical and vary across all sensory, cognitive, physical, and performance characteristics. Specific aspects of human performance can be made more equal through education and training. 39
Vision Performance Issues Being able to see clearly is vital in aircraft maintenance and inspection. •Vision requirements are task based. •Illumination requirements are task based. •Technicians must recognize their individual visual limitations and capabilities. 40
The Normal Visual Field Provide visual access to work area... Without excessive bending For both short and tall people
Visual access is critical to... Doing the task Visual validation of the task
Examples of problems due to poor visual access: Incorrect attachment Inspection errors Increased task time 41
Colorblindness Complete color blindness is quite rare. Most people are actually color deficient and have problems seeing red and green.
No Red receptors
About 10%-15% of males and 1% of females are color deficient. No Green receptors
Most do not even know. They learn to compensate with degrees of brightness and texture. If you find you have it, avoid errors by asking other people when you are unsure.
No Blue receptors
An estimation of what the spectrum looks like for different types of colorblindness. 42
A Quick Colorblindness Test
This is a demonstration. You should see the number 12.
43
What Numbers Do You See?
44
Recommended Illumination Levels* Illumination Levels in Lux
Tasks
Light Source
Recommend
Minimum
Perceiving small details with low contrast for prolonged times, or where speed and accuracy are essential, such as repairing small components, inspecting dark materials
1650
1075
General service plus supplementary
Perceiving small details with fair contrast where speed and accuracy are not so essential, such as electronic assembly
1075
540
General service and/or supplementary
Prolonged reading, desk or bench work, general office and laboratory work, such as assembly work and filing records
755
540
General service and/or supplementary
Occasional reading, recreation, reading signs where visual tasks are not prolonged, such as reading a bulletin board
540
325
General service and/or supplementary
Perceiving large objects with good contrast, such as locating objects in a bulk supply warehouse
215
110
General service
Passing through walkways and handling large objects, such as loading from a platform
215
110
General service
*Illumination requirements for representative tasks (MIL-HDBK-759A)
45
The Human Auditory System The outer ear collects sound The middle ear channels sound to the ear drum The inner ear converts sound to nerve impulses Tiny hair cells (cilia) in the Cochlea vibrate with different sounds Excessively loud noise can result in the hair cells stretching too far and breaking Listening to the same frequency or pitch for a long time can also damage the hair cells Listening to loud noise for a long period can also cause fatigue
Cochlea
Ear Drum
Outer Ear Middle Ear
Inner Ear
46
Protect Your Hearing!! Types of Hearing Protection Disposable plugs Reusable plugs Custom-fitted plugs Ear muffs
Wearing Hearing Protection Properly Follow package directions when putting protection on. Make sure the selected protection fits properly. Maintain hearing protective devices in a sanitary condition. Make sure nothing interferes with the use of hearing protectors (e.g., eyeglass frames). 47
Sound Intensity Levels Db Level Example Dangerous Time Exposure 0 Lowest sound audible to ear None 30 Quiet library, soft whisper None 40 Quiet office, living room None 50 Light traffic at a distance, refrigerator None 60 Air conditioner at 6 m., conversation None 70 Busy traffic, noisy restaurant Critical level begins 80 Subway, heavy city traffic, alarm clock More than 8 hours 90 Truck traffic, lawn mower, shop tools Less than 8 hours 100 Chain saw, boiler shop, pneumatic drill Less than 2 hours 120 Rock concert in front of speakers, Immediate danger sandblasting, thunderclap 140 Gunshot blast, jet plane @ 15 m. Any exposure is bad 180 Rocket launching pad Hearing loss inevitable American Academy of Otolaryngology, Washington, DC 48
Information Processing/ Attention and Perception/ Memory
A Model of Human Information Processing.
Attention (concentration) is a limited Three types of memory resource, which must be shared between Sensory memory Observing the situation Deciding on a response Executing the response
Working or short-term memory Long-term memory
(Adapted from Wickens, C.D. Engineering Psychology and Human Performance. Columbus, Ohio: Charles E. Merrill Publishing Co., 1984.)
50
Attention and Selection The first process of memory is attention. There is much more information in your environment than you can process at any one time. You must make choices (conscious & unconscious) regarding the stimuli to which you will attend. Early theory was that we could only attend to one thing at a time. That theory is still believed to be true. However, we can switch our attention quickly, especially if the information comes from different “channels” (e.g., hearing and vision). 51
Working (Short-Term) Memory This is the memory that we use, for example, when some one gives us a phone number to call or gives us directions on how to find an office in a building Working memory lasts only about 20 seconds, although you can make the memory last longer by “repeating” the information to yourself “in your head” Working memory can hold about 7 + 2 (5 to 9) “chunks” of information. For example, you will remember the name “ Steven” as one “chunk” of information, not as six separate letters. 52
Moving Information from Short-Term Memory into Long-Term Memory All verbal information goes first into the short-term memory. When it is rehearsed (recited), part of it goes into long-term memory. The rest of it, usually the part we are least interested in, returns to short-term memory and is then forgotten. Whether new information is "stored" or "dumped" depends, then, on our reciting it out loud and on our interest in the information. 53
Accessing Long-Term Memory Two ways to access your memory: Recall—coming up with the information from memory Fill-in-the-blank exams Coming up with a person’s name.
Recognition—recognizing the correct information Multiple choice tests True/false tests Recognizing someone that you know.
Recognition is easier than Recall. Often need to recall information we learned long ago. How quickly/reliably we recall it depends on: Activation: How long since we last used the information. Strength: How well we have practiced it. 54
Why Do We Forget?
Three possibilities 1. The memory fades away (decays) over time 2. Interference (overlaying new information over the old) 3. Lack of retrieval cues.
Data now suggest that we forget because of 2 and 3 above. In other words, once we have stored something in long-term memory, it is always there…we just have trouble retrieving the information. 55
Negative Transfer of Training When you learn new material, old material that you learned before is still in long-term memory. If the new material is similar to the old material but with some small differences, you can become confused. Example: Mechanic knows how to replace a hydraulic pump on airplane A. The airline buys a newer model--airplane B. The pump bolts on airplane A must be torqued to 50 ft lbs The pump bolts on airplane B must be torqued to 60 ft lbs Later, the mechanic makes an error by: Replacing a pump on airplane A and tightening the bolts to 60 ft lbs, or Replacing a pump on airplane B and tightening the bolts to 50 ft lbs.
MESSAGE: Be sure to check details when things are almost, but not quite the same.
56
Physical Work
Bio-Mechanics This image cannot currently be displayed.
Human Force Application
Work Posture
Spine Geometry
58
Occupational Risk Factors for Cumulative Trauma Disorders
Posture Force
Vibration Frequency
59
Neutral Position of Hand and Wrist
60
Work Posture - Hand and Wrist
OK
Avoid 61
Work Posture - Arm and Shoulder
OK Avoid 62
Work Posture - Arm and Shoulder
OK
Avoid
63
Neck Flexion
Neck flexion greater than 30 degrees 64
Back Flexion
Back flexion greater than 30 degrees 65
Squatting
> 2 Hours per Shift 66
Kneeling
> 2 Hours per Shift 67
Hands Above Head or Elbows Above Shoulders
> 2 Hours per Shift 68
Repetitively Raise Hands Above Head or Elbows Above Shoulders
> 4 Times/Minute 69
Highly Repetitive Motion – Neck, Shoulders, Elbows, Hands
> 4 Times/Minute 70
Highly Repetitive Motion and Forceful Exertions with Hands
30
o
Greater than 30 degrees 71
Pinch Grip
Objects weighing > 1 kg per hand or force > 2 kg per hand
72
Pinch Grip Plus Repetitive Motion
> 4 times/minute 73
Pinch Grip Plus Wrist Deviation
o
30
Greater than 30 degrees 74
Power Grip
Objects weighing > 5 kg per hand or force > 5 kg per hand
75
Power Grip Plus Repetitive Motion
> 4 times/minute
76
Power Grip Plus Wrist Deviation
Greater than 30 degrees 77
Repeated Impact - Hands
> 10 times/hour 78
Repeated Impact - Knees
> 10 times/hour 79
Intensive Keying and Mousing
> 40 words per minute 80
Lifting
> 11 kg or > 5 kg more than two times/minute
81
Pushing/Pulling
> 16 kg of initial force
82
Use of Vibratory Tools
83
Workstation Design Principle
Example
Design work stations for a range of Boeing airplanes are designed for people, not for the average person people from 157 cm to 193 cm Permit several different working positions
A drill which allows the user to change grip positions
Design should start from the point A component work bench which holds the component in the center where the hands spend most of and the tools around it their time Getting a ladder so that you are Work should be conducted between shoulder and waist height not working over your head Raise the work surface for work that requires precision, so it is closer to your eyes
Raising a manual to see detail or a component work bench which moves up and down.
A component work bench which Lower the work surface for work holds a hydraulic pump at about that requires more force so your arms are in a more neutral position waist high 84
Fatigue and Sleep
Fatigue EASA-145 requires the organisation’s planning procedures to take into account the limitations of human performance, focusing on fatigue.
86
Definitions Fatigue—A feeling of lack of energy, weariness or tiredness. Also called tiredness, weariness, exhaustion, or lethargy. Fatigue is a normal response to physical exertion, emotional stress, and lack of sleep. Alertness—Vigilantly attentive and watchful; mentally responsive and perceptive. 87
Effects of Fatigue More than 100,000 car accidents annually in the US are fatigue-related Disasters such as: Chernobyl (Russian nuclear power plant) Three Mile Island (US nuclear power plant) Bhopal (chemical release in India) Exxon Valdez (oil supertanker accident in Alaska)
were officially attributed to errors in judgment induced by fatigue. 88
Effects of Fatigue Overall performance gets worse Loss of motivation Slowed reactions Forgetful Poor cognitive functioning Thinking Reasoning/judgment Problem solving/ decision making
Loss of creativity Withdrawal from social situations Mood changes Increase alcohol use Long term health can degrade Quality of life degrades
89
Our Circadian Sleep Wake Clock
Alertness
High
Low 6 am
Noon
3-5 am and pm = sleepy 9-11 am and pm = alert
6 pm
Midnight
6 am
Time of Day 90
Sleep Sleep is defined as a state of partial or full unconsciousness during which voluntary functions are suspended and the body rests and restores itself. Lying down Little movement Do not respond as readily to disturbances Reversible—can wake up
Observed in all mammals, all birds, and many reptiles, amphibians, and fish. 91
Sleep Still not totally sure why we need sleep, but there are two theories… Energy conservation—sleep to conserve energy (old theory) Restoration (new theory) Neural circuits in the brain are “rewired” Memory is consolidated and strengthened Short-term memory items move into long-term memory Growth hormone levels are restored Blood pressure drops The cells in your organs are strengthened by protein synthesis Sleep breaks your stress pattern.
Also, we know that bad things happen if we do not sleep. 92
Effects of Missing Sleep A person who loses one night’s sleep will generally be irritable and clumsy during the next day and will either become tired easily or speed up because of adrenalin. After missing two night’s sleep, a person will have problems concentrating and will begin to make mistakes on normal tasks. Three missed nights and a person will start to visually hallucinate and lose grasp of reality. 93
How Much Sleep Do You Need? Depends on… Age Health Circadian rhythm Body metabolism Physical exercise level The quality of the sleep Amount of recent sleep Body temperature Personal differences.
“Magic number” of 8 hours of sleep is an average. Short sleepers—Need around 6 hrs of sleep. Long sleepers—Need around 9 hrs of sleep. 1 in 25 people need more than 10 or less than 5 hrs of sleep. 94
Avoiding Fatigue—No Shift Rotation Getting a Good Night’s Sleep Get up and go to bed at the same time. If you are tired, go to bed early. Use your bed only to sleep—no reading, eating, etc. Keep the bedroom dark, quiet, and cool (58ºF/15ºC). Exercise in the morning or early afternoon, not evening. Do not eat a heavy meal before bed--a light snack at most. No alcohol before bedtime, no caffeine after early afternoon, and avoid nicotine. Quit worrying about falling asleep—it keeps you from falling asleep! Stop looking at that clock! Get up if you are not sleeping. 95
Avoiding Errors While Fatigued Admit you are tired! Remain physical to remain alert. Exercise/stretch at frequent intervals. Talk to people. Drink plenty of liquids. Take a nap. Avoid tedious, boring work. Work with somebody else so you can catch each other’s errors. Go back over and check your work. 96
Drugs and Diet Using drugs to get to sleep should be a last resort, because these drugs decrease REM and deep sleep. But, remember, there are “drugs” in food, also (like caffeine in coffee, tea, soft drinks, and chocolate). Thus, it makes sense to approach food and drugs together. Food and drugs release chemical that interact with our basic body rhythms. This interaction is one cause of the varied effects they produce. One step in controlling the bad effects of foods and certain drugs is to control when we consume them. If you are a “morning person,” the use of “uppers” like coffee and sugar-coated cereal in the morning makes no sense.
Another control strategy is to avoid the combined consumption of food and drugs that have similar effects. For example, combining “downers,” such as alcohol, sleeping pills, and pain medication can be particularly dangerous. 97
Drugs and Diet Food in the stomach causes the stomach walls to stretch. The more the stretch, the stronger the signal to the body to send blood to the stomach to aid digestion. Diverting too much blood to the stomach by overeating can create a shortage of blood elsewhere, like your brain, which causes you to feel sluggish following a big meal. Eating frequent, smaller meals is preferable to eating a few large meals before and during work.
Eating smaller meals in the hours prior to heavy physical work is a key dietary strategy for shift workers. 98
Physical Fitness The Drug and Diet control strategies that we have discussed are meant to decrease the build up of stress resulting from shift work. However, some stress will still occur. One factor that clearly improves our ability to cope with stress is physical fitness. Shift work tends to drain your energy levels; fitness tends to build up your energy levels. Physical activity can burn off excess energy and start the cycle leading to a relaxed state that leads to good deep (non-REM) sleep. Regular physical activity can help stabilize body rhythms and is helpful in speeding the resettling of body rhythms in the first few days of a shift change. 99
“Putting It All Together” to Get a Good Sleep after Your Night Shift Determine how much sleep you need and try to get it every day. Use naps, as necessary. Mental relaxation before bed Physical relaxation before bed Control your drugs and diet Get physically fit Deal with any sleep-related medical problems Keep the bedroom dark, quiet, and cool (15ºC) Use sun-blocking shades Work with family and neighbors for bedroom quiet
Wear sunglasses on the drive home to “fool” your brain Take a nap before the night shift starts in addition to your after-shift sleep. 100
Repetitive Tasks Complacency
Complacency Complacency = Self-satisfaction accompanied by unawareness of actual dangers or deficiencies. Mechanics can become complacent when they have done a task over and over again without making an error. Inspectors can become complacent when they have done an inspection many times before without finding a problem. We must fight complacency! 102
Complacency One of the Dirty Dozen
103
Environment Stress and anxiety Definition Why worry? Symptoms Stressors Physical Psychological
Conditions of the work environment Cold Heat Illumination Noise level
104
What Are Stress and Anxiety? Stress is a physiological reaction to physical and psychological factors (stressors) in our environment. Anxiety (also called angst or worry)… Is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. It is the displeasing feeling of fear and concern in either presence or absence of psychological stress. Anxiety can create feelings of fear, worry, uneasiness, and dread. Anxiety is also considered to be a normal reaction to a stressor.
In other words, stress and anxiety are about the same thing. Positive
Stressors
Stress/anxiety
Adaptations Negative 105
Stress/Anxiety and Performance
Time Magazine December 5, 2011 106
Physical & Psychological Stressors Physical stressors Illness Acute Chronic
Environment Temperature Vibration Noise Fumes
Fatigue Shift work High work load.
Psychological stressors Unpredictability Uncertainty Uncontrollability Bereavement/tragedy Daily annoyances Time pressure Peer pressure Management pressure
Chronic stressors Home environment Work place pressures. 107
Why Worry About Threat Stress/Anxiety? Human Error
Reduced Productivity
Injury Illness 108
Conditions of the Work Environment
Another Effect of Heat and Cold on Work Performance Some airlines have noted an increase in maintenance errors in line maintenance during the summer. Why? It is so hot outside or on the aircraft that the mechanic works quickly so that he can get back to the airconditioned building. Speed/accuracy trade-off applies, so errors increase.
Similar thing happens during winter Work quickly to get in out of cold. Have to wear heavy gloves and clothing, so that it is harder to do the work. Thus, errors increase. 110
V. Procedures, Information, Tools, and Practices
Procedures, Information, Tools, and Practices Visual inspection Task inspections/duplicate inspections Planning Work logging and recording Procedure—practice mismatch Technical documentation—access and quality. 112
Visual Inspection Outline Definitions Visual inspection—search and decision Factors affecting visual inspection Task Factors Subject Factors Equipment Factors Environment Factors Social Factors
Concept of Damage Tolerance Systems, Structural, and Zonal Inspections 113
Visual Inspection Over 80% of inspections on aircraft are visual inspections. Visual inspection is often the most economical and fastest way to find defects on an aircraft. Airframe manufacturers and airlines depend on regular visual inspections to ensure the continued airworthiness of their aircraft.
114
Definition of Visual Inspection Visual Inspection means inspection using either or all of human senses such as vision, hearing, touch and smell. Visual Inspection typically means inspection using raw human senses and/or any non-specialized inspection equipment.
115
Types of Inspection General visual inspection (GVI) Detailed inspection (DET) Special detailed inspection (SDI)
116
Definition of General Visual Inspection (GVI) A visual examination of an interior or exterior area, installation or assembly to detect obvious damage, failure or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may require removal or opening of access panels or doors. Stands, ladders or platforms may be required to gain proximity to the area being checked. 117
Definition of a Detailed Inspection (DET) An intensive visual examination of a specific structural area, system, installation or assembly to detect damage, failure or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate by the inspector. Inspection aids, such as mirrors, magnifying lenses, etc. may be used. Surface cleaning and elaborate access procedures may be required.
118
Some of the “Operating Rules” Normal cleanup procedures are to be used prior to conducting general visual or detailed inspections. Specified cleanup procedures are to be used for special detailed inspections, if necessary. Sealant and corrosion protection finishes should only be removed when specified and restored in accordance with the Corrosion Prevention Manual after the task is completed. Excessive dust, debris, or overspray of corrosion inhibiting compounds found during any inspection are considered to be an unsatisfactory condition possibly reducing the fire resistance of the airplane design. Cleanup of these materials should be a standard part of maintenance activity. 119
Definition of a Special Detailed Inspection (SDI) An intensive examination of a specific item(s), installation or assembly to detect damage, failure or irregularity. The examination is likely to make extensive use of specialized inspection techniques and/or equipment. Special detailed inspections are to be used when specified for inspecting hidden details or may be used as alternatives to detailed inspections. NDT Borescope 120
Typical Aircraft Defects Found by Visual Inspection Typical airframe defects that can be found by visual inspection include… Cracks Corrosion Disbonding
Other defects that can be found by visual inspection include… System and component wear Accidental damage Environmental damage from long-term storage, sunlight, etc. 121
Factors Influencing Visual Inspection
Task Factors Subject Factors Equipment Factors Environment Factors Social Factors
122
Task Factors Size/complexity of the object searched—in general, search time is linearly related to either search field area or number of inspectable items in the field. Number of different types of defects—the greater the number of types of defects, the slower the search performance and/or the lower the “hit” rate. Defect/background contrast—higher defect/background contrast produces faster and more accurate searches. 123
Task Factors contd. Defect size—larger defects are generally found more accurately and faster than smaller defects.
Probability that the item contains a defect— the a priori probability that there will be a defect is positively related to hit rate and false alarm rate. Timing/pacing—in general, a self-paced inspection task is more effective than an externallypaced task.
124
Task Factor—Company Inspection Instructions Before certifying any work, you must be satisfied that all components, parts and materials utilized have been obtained from approved sources, are of the correct specification, and are completely serviceable. You must also ensure that all work are performed in accordance with current and approved Maintenance Schedules, Maintenance Manuals, Overhauls Manuals, Repair Test Schedules/Capabilities List, Drawings or any other relevant technical publications, and that all applicable Mandatory Modifications, Inspections or any other special requirements have been duly carried out. In the case of repairs not covered by the approved technical publication, all work performed must be in accordance with the approved instructions of the equipment owner, e.g., Engineering Notes issued by the Engineering Department. 125
Subject Factors Inspector demographics—age, experience, and gender (no affect)
Training—not the same as experience.
Even experienced inspectors can improve their performance (often dramatically) with a well-designed training program, which is based on a task analysis and which provides Knowledge of Results to the trainees.
Visual performance—not related to visual acuity as measured by a Snellen Chart. The size of the visual lobe is a predictor of inspector performance. However, studies done by the US FAA found that 20/20 vision or correctable to 20/20 should be required for inspectors.
Cognitive performance—people with the ability to dis-embed objects from a complex/confusing background make better inspectors. 126
Hidden Figure Example
127
Hidden Figure Example
128
Inattentional Blindness and Human Errors/Accidents Someone performing a task simply fails to see what should have been plainly visible and cannot explain the lapse afterwards. Inattentional blindness causes accidents when attention mistakenly filters away important information, due to a combination of factors: low conspicuity, divided attention, high expectation, low arousal. People are unaware of the blindness. Training mainly affect conscious, voluntary behavior.
Equipment Factors Magnification—increasing magnification may only change the speed-accuracy trade-off with higher magnification improving target detection at the expense of speed. Field integration—using a “known perfect item” for comparison during the inspection. Visual enhancement—specific to NDI.
Human/machine function allocation—specific to NDI. Typically shows that a hybrid of human and machine functions work better than either alone. 130
Environment Factors Visual environment—correct lighting is important both for physical inspection and to avoid glare in computer-based inspection.
Auditory environment—no necessarily clear affects, although some studies show that noise >90 Db worsened inspection performance.
Thermal environment—some data to suggest that really hot and really cold environments have a negative affect on inspection.
Workplace comfort—no data. However, the myth that comfortable inspectors lose vigilance has been refuted. 131
Social Factors Working period—detection performance decreases rapidly over the first 20-30 minutes of a vigilance task (e.g., watching radar), although this phenomenon is hard to replicate in typical visual inspection tasks. Job design—rest periods have been shown to improve performance. Supervision, instruction and other pressures—from signal detection theory, we know that criterion used by an inspector for reporting defects is influenced by the sum of all biases on the inspector. These biases are affected by a priori probability of a defect and also by the perceived costs of misses and false alarms, which can be affected by supervisory instructions/reprimands. Information environment—both feedback of inspection performance (knowledge of results) and feed forward information (where to look for a defect) have been shown to improve inspection performance. 132
Summary Over 80% of inspections on aircraft are visual inspections, which are often the most economical and fastest way to find defects on an aircraft. Visual Inspection means inspection using either or all of human senses such as vision, hearing, touch and smell. A visual inspection includes a search and a decision. The decision criteria can be influenced by outside factors, such as management pressure. Common aircraft visual inspections include system inspections, structural inspections, and zonal inspections. 133
Error Capturing/ Task Inspections and Duplicate Inspections
Error Capturing Error capturing = Adding a task to find a mistake. Common error capturing tasks Operational/functional checks Mechanic/pilot pre-flight walk around checks Task inspections/duplicate inspections.
135
Task Inspection Task (Job) cards typically have two types of signoff: Worked by (Discussed later under “Norms.”) Checked by
What does SIAEC’s GMM say the “checked by” person is supposed to do in order to feel comfortable in signing off the task or sub-task? Supposed to watch the whole task, or the critical parts of the task, being performed? Must have a “high degree of confidence that the work has been carried out correctly.” 136
What Standard Do You Inspect To? Many are found in the Aircraft Maintenance Manual (AMM)… Chapter 20 Airframe Standard Practices Chapter 51 Standard Practices and Structures Chapter 70 Engine Standard Practices
137
Planning of Tasks, Equipment, and Spares
Planning of Tasks, Equipment, and Spares Planning of Tasks, Equipment and Spares •EASA 145 does not require a procedure on the planning of work. •EASA 145 and AMC material clarifies the objective of good planning and includes the elements to consider when establishing the planning procedure.
139
Planning of Tasks, Equipment, and Spares Planning is critical to ensure that there are adequate… Appropriately qualified and alert maintenance staff Tools Equipment Material Maintenance data Facilities
for scheduled and un-scheduled maintenance. Long-term planning. Short-term planning. 140
Planning of Tasks, Equipment & Spares Planning consideration should be given to… Logistics. Inventory control. Space availability (hangar and floor space). Man-hours estimation. Man-hours availability. Preparation of work. Co-ordination with internal and external suppliers. Scheduling of safety-critical tasks during periods when staff are likely to be most alert, and avoiding periods when alertness is likely to very low, such as early morning or night shift. 141
Work Logging and Recording Importance of proper work logging/recording All work on an aircraft should be documented. Work sign-offs should occur soon after the subtask is completed. Do not wait until the end of the task to sign off all “worked by” blocks. Any work done on the aircraft that is not covered in the maintenance manual (e.g., loosening a clamp on a wire bundle in order to get access to a part) should be recorded, typically with a “non-routine” card. 142
Technical Documentation EASA 145 addresses technical documentation (poor maintenance data) Inaccurate, ambiguous, incomplete maintenance procedures, practices, information or maintenance instructions contained in the maintenance data used by personnel must be reported to the author of the data. 143
Technical Documentation The US Federal Aviation Administration recently did a study of aircraft maintenance manuals (AMMs). They found that: The manuals rarely had technical errors in them, but… The manuals were “not written by mechanics,” meaning that the order of the tasks typically does not follow the way in which a mechanic would actually do the task.
144
Documentation and Maintenance Errors MEDA investigations have found that documentation is the most frequent contributing factor to maintenance error. Problems include Not used (50% in MEDA investigations) Not understandable Incorrect step Conflicting information No illustration. Poor illustration 145
VI. Teamwork
Team Behavior
Team Behavior - The way people behave when part of a team.
147
Overview What Affects Team Behavior? Responsibility Motivation Norms Culture
Effective Team Behaviors Communication Assertiveness Situation Awareness Leadership 148
Responsibility Responsibility is... Recognizing that you can affect the team’s success. Choosing to act to help that success.
In a team, we tend to feel less responsible. “Someone else will do it.” “The whole team agreed.” “Nobody saw me, it could be anyone.”“ 149
Social Influence How behavior is influenced by the social environment and the presence of other people Obedience to authority Conformity to group/team.
150
Examples of Taking Responsibility Admitting and fixing errors. Saying something about a situation when you know there is something wrong. Addressing non-critical problems
Picking up debris from the ramp Finding the safety wire you dropped.
Maintaining professional responsibility. Maintaining technical currency. 151
Professionalism—Some Examples of “Unprofessional” Behaviors in Maintenance Memorizing tasks instead of using manuals/cards. Not using torque wrenches or other calibrated tooling. Troubleshooting through experience, instead of using the Fault Isolation Manual (FIM). Deviating from maintenance manual procedures. Failing to attach “Do Not Use” tags when pulling circuit breakers and switches. Skipping operational or functional tests. Signing off for tasks neither seen nor checked. Providing minimum information in task handover log. Failing to document work not specified in the manual (e.g., loosening a clamp on a wire bundle). 152
Why Do We See “Unprofessional” Behavior? Behavior starts to “stray” from the professional standard for various reasons (uncomfortable, time constraints, calibrated equipment unavailable). Supervisor does not intervene. Staff believe that supervisor does not care. Behavior is seen as low risk. Unprofessional behavior becomes the norm. Existing workers put peer pressure on new hires to conform to these behaviors.
153
Why Do We See “Unprofessional” Behavior? Supervisor actually rewards unprofessional behavior. “We’ve got 4 days of work to do in 2 days. I don’t care what you do, just get it done. I am going into my office and closing the door. [After meeting the 2-day deadline.] Way to go guys!! Pizza for everybody.”
Supervisor threatens punishment for carrying out professional behavior. “What do you mean you don’t feel qualified to do the job? You’re trained. You’re certified. Go out there and do that work. You want to keep your job, don’t you?” 154
Then How Do We Move Back to Professional Behaviors? What not to do… Pick out an offender and punish him/her in front of their work group. Threaten staff.
155
Then How Do We Move Back to Professional Behaviors? What you should do… Management decides what behaviors are desired. Management and labor meet to agree on the new behaviors. Address issues brought up by labor, e.g., Time it will take Availability of equipment, calibrated tools, parts, etc.
Supervisors are provided training on new expectations No threats to staff if they are doing correct behavior. Reward correct behavior and model correct behavior.
Labor told of progressive punishment for failure to exhibit new behaviors Verbal warning Letter to file Time off without pay. 156
Motivation Motivation = A process within a person that causes the person to move toward a goal that is rewarding. Two types of motivation: Intrinsic—We move toward a goal because of rewards that are internal to ourselves (e.g., feelings of satisfaction or accomplishment). Extrinsic—We move toward a goal because of rewards that are external to ourselves (e.g., praise, a good grade on a test, or money). 157
Motivation Affected by Beliefs Motivation is determined both by… The intrinsic or extrinsic reward, and The belief that effort will result in achieving the reward. Example: Someone who does not believe they can win a race will not be motivated to try hard to prepare for and win the race, no matter how badly they want the $100K prize money. 158
Performance = Skill X Motivation Performance is determined by BOTH: Skill & Motivation Example: Someone with medium skills and high motivation can out perform someone of high skills and no motivation. 159
Implications for Management Management must not only provide hygiene factors to avoid employee dissatisfaction, but must provide motivation factors intrinsic to the work itself in order for employees to be satisfied with their jobs. The job should have sufficient challenge to use the full abilities/skills of the employee. Employees who demonstrate increasing levels of ability/ skill should be given increasing levels of responsibility. If a job cannot be designed to use an employee’s full abilities/skills, then the organization should consider replacing the employee with one who has fewer abilities/skills. If an employee’s abilities/skills cannot be fully used, then there will be a motivation problem. 160
Norms Definition: Typical behavior in a social group or organization. Norms are simply the state of actual conditions They can be effective or ineffective in the performance of quality work
Tagging connections
Following check lists and procedures
Wearing appropriate safety equipment 161
Some Ineffective Norms We Have Seen at Airlines Memorizing tasks instead of using manuals/cards Not using torque wrenches Troubleshooting through experience, instead of using the Fault Isolation Manual (FIM) Deviating from maintenance manual procedures Failing to attach “Do Not Use” tags when pulling circuit breakers and switches Skipping functional or operational tests Signing off for tasks not seen nor checked Providing minimum information in shift handover log Failing to document work not specified in the manual (e.g., loosening a clamp on a wire bundle) 162
Norms The Asch studies suggest that new staff will quickly pick up the existing norms in their work group. If these are norms like Memorizing tasks instead of using manuals/cards Not using torque wrenches,
then new staff will quickly learn these behaviors.
163
Procedural Non-Compliance EASA 145 requires that procedural noncompliance be addressed. Very important! There is an assumption that people will follow the procedure as written. When this assumption is broken, the whole basis of the safety system is put at risk. Maintenance requirements, therefore safety, are based almost solely on an assumption that people will follow the procedures.
Therefore, maintenance organizations should: Not allow procedural non-compliance to become a normal behavior (norm), and Make sure written procedures are easy to follow so that they will be used. 164
Signing Tasks Not Seen Nor Checked EASA 145 requirement to address this issue. New Alternate Means of Compliance material elaborates on the meaning of “sign-off” and the need to check or inspect the task before signing off.
165
Signing Off Tasks A “sign-off” is a statement by the competent person performing or supervising the work that the task or group of tasks has been correctly performed. This is a “worked by” sign-off, not a QC inspection signoff nor a release to service sign-off. Research has shown that many maintenance tasks, which are carried out by workers who are not competent to sign off on their own work (e.g., temporary staff or trainees), are signed-off unseen by the person supervising the work.
166
Signing Off Tasks Some airlines have one sign-off for each task card. Other airlines have sign-offs for each sub-task within a task card. Signing off small groups of tasks (sub-tasks)… Will help prevent situations where a technician is called away from a task (to do another task or at shift end), and the person picking up the previous task has no record of what has been completed on the task, and Will encourage a mechanic to continue with the task up to the next break point before leaving the task (e.g., either to take a break or end the shift).
Sign-off points would be determined by M&E as appropriate to the nature of the work.
167
Signing Off Tasks CAP 716 states… Sign-offs should be considered as a mechanism for ensuring that all steps in the task have been carried out correctly Not a method for knowing whom to blame if the task is not done correctly. It is expected that the person signing off another’s work view or inspect the work before signing off. However, CAP 716 states, “It is understood that, in some cases, the person signing-off the task…will be unable to view or inspect, in detail, the work which has been carried out, but it is important that that person has a high degree of confidence that the work has been carried out correctly.”
168
Effective Team Behaviors
Communication Assertiveness Situation Awareness Leadership.
169
Communication
Communication - The ability to clearly and accurately send and acknowledge information and to provide useful feedback. 170
Basic Communications Model
Sender
Feedback
Message
Receiver
ENVIRONMENT
171
Communication Model in the U.S. Nuclear Industry
3. Feedback
Sender
2. Feedback 1. Message
Receiver
ENVIRONMENT
172
Sender’s Responsibility Communicating information clearly. Covering timely information accurately. Requesting verification of feedback. Verbalizing plans. 173
Receiver’s Responsibility Acknowledge communications. Repeat information. Paraphrase information. Clarify information. Provide useful feedback. 174
Barriers to Effective Communication Passive listening No feedback Poor feedback.
Not using the right words. Inappropriate method. Vague or late information. 175
Active Listening DO NOT
DO
Argue about things.
Ask good questions.
Bring up things that are not Make eye contact. important. Plan out your words while Use positive body the other person is talking. language. Think about other things while the other person is talking.
Repeat back using your own words to make sure you understand. 176
Written Communication Written communication can be hard. No visual feedback to tell you if the reader understands. The reader cannot ask questions.
Make sure that your writing is: Correct Complete Clear.
Use computer spell checker. 177
Shift and Task Handover EASA and the FAA require a shift and task handover procedure acceptable to the National Aviation Authority. Incident investigation data shows that task handovers are one of the major contributing factors to error-caused events.
178
Shift and Task Handover
The primary objective of handovers is to ensure that all necessary information is communicated between the outgoing and in-coming personnel. Effective handovers depend on three basic elements: 1. The outgoing person’s ability to understand and communicate the important elements of the job or task being passed over to the incoming person. 2. The incoming person’s ability to understand this information. 3. A formalized process for exchanging information between outgoing and incoming persons and a place and time for such exchanges to take place. 179
Shift and Task Handover Organizations should have a recognized procedure for task and shift handovers which all staff understand and adhere to. This procedure should be listed in the GMM. The procedure should provide for sufficient time to be made available by way of a shift overlap— 20 to 30 minutes is considered good practice.
180
Aids to Effective Communication at Shift Handover If only one communication method is used there is a risk of erroneous transmission. For this reason information should be repeated using more than one method. While all essential information (especially the detailed status of tasks) should be recorded in written form, it is also important to pass this information verbally in order to reinforce it. Then feedback/questioning can be used to test one’s understanding of the handover, which increases accuracy. The ability for two-way communication to take place is, therefore, important at shift handover. 181
Aids to Effective Communication at Shift Handover A part of the shift handover process is to help develop a shared “mental picture” of the maintenance system, aircraft configuration, tasks in work etc. This is particularly true when deviations from normal working has occurred, such as Having the aircraft in the flight mode at a point in a maintenance check when this is not normally done. When people have returned following a lengthy absence (the state of things could have changed considerably during this time) and When handovers are carried out between experienced and inexperienced personnel.
In all these cases handovers can be expected to take longer.
182
Aids to Effective Communication at Shift Handover Written communication is helped by the design of the documents, like the handover log, which consider the information needs of those people who are expected to use it. Involve the people who conduct shift handovers Ask them what key information should be included and What format it should be in.
This helps accurate communication and gets their ‘buy-in,’ which contributes to its use and acceptance of the process. 183
Handing Over a Task Directly to Another Person When the task is being directly handed over to someone who is present, the task handover should be done face to face using verbal and written communication. In these cases the written element is normally the task card or non-routine process sheets. These should be accurately completed and clearly identify where in the task the work ended. Any deviations from normal working practices or procedures must be clearly highlighted with the non-routine sheets. 184
Handing Over a Task for Somebody to Complete Later It is common that a job is left incomplete during a shift. In these cases it is often not known who will eventually pick up the job of completing and certifying the release to service. These situations present a far greater risk and challenge to effectively communicate the stage of task accomplishment and what is required to complete the job. Face to face communication is not possible. Therefore, total reliance has to be placed on written communication. This provides no redundancy or an opportunity to question and test a true understanding by the person expected to finish the job. 185
Handing Over Non-Scheduled Tasks Complex or lengthy non-scheduled tasks should always be broken down into a number of discrete steps using stage sheets or process sheets. Many incidents have occurred when people have started a nonscheduled task, but had to leave before it was finished without anybody to handover to. These situations are normally associated with time pressure or emergency situations. It is vital that time is taken by the person leaving the job to record in detail what activities have taken place and what is required to complete the job. Record this on stage sheets and emphasize any deviations from the maintenance manual. Management and supervisors have a responsibility to ensure that adequate time is given to maintenance staff to record their work, if the task is not completed for any reason. 186
Cultural Differences in Communication Culture = Customary beliefs, behavior patterns, and material traits of a group (organization). Some of these beliefs deal with communication issues. Do not admit to mistakes. Indirect (not straightforward) communications. Pilots will not talk to maintenance staff, etc.
Discuss how the participants’ national/ organizational cultures affect communication. 187
Assertiveness
Assertiveness - The willingness to actively participate, and the ability to state and maintain individual position.
188
What Is Assertiveness? Providing relevant information without being asked. Making suggestions. Asking questions as necessary. Confronting ambiguities. Willingness to make decisions. Maintaining position when challenged until convinced by the facts. Clearly stating positions on decisions and procedures. Refusing an unreasonable request.
If a disagreement exists, take the most conservative action until more information is available. 189
Situation Awareness
Situation Awareness - The ability to maintain awareness of what is happening on the ramp or the hangar, as well as what is happening on the task. 190
Situation Awareness Is the Ability to... See elements (e.g., people and equipment) in the work environment. Where they are now. Whether they are moving or stationary.
Understand the importance of what you see, especially with regard to hazards/problems. Project the status of the elements for the near future (i.e., determine future implications) in order to detect situations requiring action. 191
Barriers to Situation Awareness Insufficient communication Fatigue/stress Task overload/underload “Groupthink” mindset “Press-on” mentality Degraded operating conditions.
192
Overcoming Barriers to Situation Awareness Actively question/evaluate. Use assertive behavior when necessary. Analyze/monitor situation continuously.
193
Leadership
Leadership - The use of influence to direct and coordinate the activities of the members of a group toward the accomplishment of group objectives.194
Types of Leadership Designated - Leadership by authority, position, rank, or title. Formal/permanent.
Functional - Leadership by knowledge or experience. Informal/temporary.
195
Designated Leadership Behaviors Company Level Inspire a shared vision, develop a mission, and establish standards that help the organization achieve its next stage of development. Foster teamwork, collaboration, and ownership and motive team members by recognizing/rewarding individual and team contributions. Plan and manage change efficiently and nurture the strengths of followers to facilitate goal directive activities. Serve as a symbol of the group and influence others beyond the group to achieve mutually workable arrangements. Establish an environment that is conducive to learning. 196
Functional Leadership Behaviors Crew Level
Direct and coordinate crew activities. Delegate tasks to crew members. Ensure crew understands expectations. Focus attention on critical aspects of situations. Keep crew informed of task/shift information. Ask crew members for relevant task/shift information. Provide feedback to crew on their performance. Create and maintain a professional atmosphere. 197
Effective Functional Leadership Make suggestions; do not dictate. Encourage crew to participate. Lead by inspiration. Provide feedback to the crew.
198
Barriers To Effective Leadership Micro-management - failure to delegate Poor interpersonal skills Easily frustrated Pressures crew members to perform Unable to adapt to new situations Rigidity. 199
Summary Effective team Factors that affect the way that people behave behaviors include… Good communication, when part of a team including active listening include… Obedience to authority Conformance to team Amount of responsibility Motivation to do a good job Work group norms Work group and national culture.
Assertiveness Situation awareness Leadership.
200
VII. Human Error/ Incident Investigation
Human Error/Incident Investigation Errors and violations Types of errors Error models and theories Reason’s “Swiss Cheese” model Boeing Maintenance Error Decision Aid (MEDA) contributing factors model
Incident Investigation Practice 202
Definitions of Error and Violation An error is a human action (behavior) that unintentionally departs from the expected action (behavior). A violation is a human action (behavior) that intentionally departs from the expected action (behavior).
203
Violations Violations are often made by wellintentioned staff trying to finish a job, not staff who are trying to increase comfort or reduce their work load. There are several types of violations Routine Situational Exceptional 204
Violation Definitions Routine—These are “common practice.” Often occur with such regularity that they are automatic. Violating this rule has become a group norm. Often occur when the existing procedure does not lead to the intended outcome. Condoned by management.
205
Violation Definitions (contd.) Situational—Occur as a result of factors dictated by the employee’s immediate work area or environment. Due to such things as… Time pressure Unavailability of equipment, tools, or parts Insufficient staff Lack of supervisor/degreed engineer to ask questions to. 206
Violation Definitions (contd.) Exceptional—Mechanic/inspector willfully breaks standing rules while disregarding the consequences. These are very rare in our business!
207
Errors and Violations Errors have been the focus of research, so we have more theories of why errors occur than theories of why violations occur. However, errors and violations often occur together to produce an unwanted outcome. Data from the U.S. Navy suggest that… ~20% of the events are caused by a violation only ~20% of the events are caused by an error and a violation, and ~60% of the events are caused by an error only. 208
Types of Maintenance Error Maintenance Error = Error by a mechanic/engineer/inspector that leads to problems on the aircraft. Installation errors Servicing errors Repair errors Fault isolation/inspection/testing errors Errors causing foreign object damage (FOD) Errors causing equipment damage Errors causing personal injury. 209
Human Error in Aircraft Maintenance: UK CAA 1992 1. Incorrect installation of components. 2. Fitting of wrong parts. 3. Electrical wiring discrepancies. 4. Loose objects left in aircraft. 5. Inadequate lubrication. 6. Access panels/fairings/cowlings not secured. 7. Fuel/oil caps and fuel panels not secured. 8. Gear pins not removed before departure. 210
UK Flight Safety Committee 2004 Top 10 Causes of Maintenance Mishaps 1. Failure to follow published technical data or local instructions. 2. Using an unauthorized procedure not referenced in the technical data. 3. Supervisors accepting non-use of technical data or failure to follow maintenance instructions. 4. Failure to document maintenance properly in maintenance records, work package. 5. Inattention to detail/complacency. 6. Incorrectly installed hardware on an aircraft/engine. 7. Performing an unauthorized modification to the aircraft. 8. Failure to conduct a tool inventory after task completion. 9. Personnel not trained or certified to perform the task. 10. Ground support equipment improperly positioned for the task. 211
Why Are Technicians Such a Valuable Asset in Reducing Mx Errors/Violations?
212
Error Models and Theories
Error Theories Now we will focus on the theories of error. Reason’s “Swiss Cheese” model MEDA contributing factors model.
214
Reason’s “Swiss Cheese” Model
Reason’s Model of Accident Causation Defenses Functional Tests Checklists
A maintenance organization has Productive Activities many barriers to error. Repairs, Servicing Fault Isolation
Errors can happen at any level.
Pre-Conditions Off work activities Physical size Facilities Schedule
Line Management Delegation Prioritization Planning
Active And Latent Failures Active Failures
Decision Makers Policies, procedures, corporate culture
Latent Failures Latent Failures Latent Failures
Latent Failures
216
Reason’s Model of Accident Causation Defenses Functional Tests Checklists
In most cases, errors are Productive Activities caught before an Repairs, Servicing Fault Isolation accident occurs. Pre-Conditions Off work activities Physical size Facilities Schedule Line Management Delegation Prioritization Planning
Active And Latent Failures
Decision Makers Policies, procedures, corporate culture
Active Failures Latent Failures Latent Failures
Latent Failures
Latent Failures
217
Reason’s Model of Accident Causation Defenses Functional Tests Checklists
An accident only occurs Productive Activities when a failure occurs Repairs, Servicing Fault Isolation in all of the Pre-Conditions Off work activities barriers. Physical size
Accident
Facilities Schedule Line Management Delegation Prioritization Planning
Active And Latent Failures
Decision Makers Policies, procedures, corporate culture
Active Failures Latent Failures Latent Failures
Latent Failures
Latent Failures
218
Three Types of Error SLIP: An error in EXECUTING the steps of a task Example: The mechanic knows how to install a pump, but turns the wrench too hard and breaks a fitting. Also called an error of commission LAPSE: An error in RETRIEVING information about a task Example: A mechanic is called to help on a different task after torquing 3 of 5 bolts. When he comes back to his original job he forgets that he had two bolts left to torque and moves on to the next task. Also called an error of omission MISTAKE: An error in PLANNING a task Example: “I do not need to do the fault isolation, because I have seen this problem before! I will replace this box.” Based on Reason, James; Human Error, New Your: Cambridge University Press, 1997
219
HF Programs in AMO Occurrence Reporting and Recording Process: Incidents, occurrences, errors and potential safety hazards may be identified as a result of an event (an incident, air turnback, rework, etc) or by a report submitted by a staff member (e.g. reporting an error made by themselves or a colleague which was detected and did not result in an event).
Investigation of Occurrences. Data Analysis and Review. Managing Identified Hazards. Feedbacks. HF training: initial & Recurrent.
220
The Maintenance Error Decision Aid (MEDA) Contributing Factors Model
What Is MEDA? MEDA is a process that is used to investigate events caused by mechanic/inspector performance. A maintenance-related event can be caused by an error, by not following company policies, processes, and procedures (violation), or by an error/violation combination. Maintenance errors are not made on purpose. Errors result from a series of contributing factors in the workplace. Violations, while intentional, are also caused by contributing factors. Most of the contributing factors to errors and/or violations are under management control. Therefore, improvements can be made so that these contributing factors do not contribute to future events. 222
MEDA Contributing Factors Things that affect human performance are called contributing factors Best understood using a maintenance system model
Mechanic
Immediate Work Environment
Overall Supervision Maintenance & Engineering Organization
223
Contributing Factors to Maintenance Error
Mechanic Knowledge Skills Abilities Other characteristics
Immediate Environment Facilities Weather Aircraft design/configuration Component design Equipment/tools/parts Maintenance manuals Tasks Time pressure Teamwork On-the-Job training Communication
Supervision Planning Organizing Prioritizing Delegating Instructing Feedback Performance Management Team Building
Organization Philosophy Other M & E Organizations Policies Procedures Processes Selection Training Continuous Quality Improvement
224
Levels of Causation Two levels of causation Cause-in-Fact: If “A” exists (occurred), then “B” will occur. Probabilistic: If “A” exists (occurred), then the likelihood of “B” increases. The most common level of causation in error investigation is probabilistic
225
MEDA Error Model Probability
Contributing Factors
Lead to
•Poor lighting •Missing step •Poor hand over report •Lack of skill •Hard to reach •Miscalibrated tool •Wrong part from Spares •Understaffed •Poor supervision
Probability
Error
Leads to
•Incomplete installation •Wrong part installed •Incorrectly serviced •Not repaired correctly •Incorrect troubleshooting •Missed during inspection
Event •Flight cancellation •Gate return •In-flight shut down •Diversion •Equipment damage •Personal injury
226
MEDA Error Model Probability
Probability
CF CF
Error
Event
CF
Experience has shown that there is an average of 3 to 4 contributing factors to each error. 227
MEDA Error Model Probability Probability
CF
CF
CF
CF
CF
CF
CF
Probability
Probability
Error
Event
Also, there are contributing factors to the contributing factors.
228
Errors and Violations We now know that errors and violations often occur together to produce an event. Data from the U.S. Navy suggest that: ~20% of the events are caused only by a violation ~20% of the events are caused by both an error and a violation, and ~60% of the events are caused only by an error.
Let us look at the ways that violations can contribute to errors and events. 229
Error and Violation Model 1 Probability
Contributing Factors
Probability
Violation
System Failure
Probability
Event
•Mechanic does not use a torque wrench (violation), •which contributes to an incorrect installation (system failure) because of an under torqued bolt. •This leads to an in-flight shutdown (event). •There are reasons why (contributing factors) the violation occurred (e.g., torque wrench not available in time to do task or work group norm is not to use a torque wrench).
230
Error and Violation Model 2 Probability
Probability
Contributing Factors
System Failure
Contributing Factors
Violation
Event
•The mechanic mistakenly misses a step in the maintenance manual (contributing factor), •which leads to an incomplete installation (system failure). •The mechanic decides not to carry out the operational check (violation), thereby missing the fact that the task was not done correctly. •Because an error was made and this was not caught by the operational check, an in-flight shutdown (event) occurs. 231
Incident Investigation/ MEDA Results Form
Incident Investigation The EASA 145 organizations are now required to investigate, evaluate, collect reports, analyse, identify trends and apply corrective actions. Those that were, or could have been, a serious hazard to the aircraft are submitted to the NAA. Those of a lesser threat to safety are still required to be investigated, evaluated, and analysed. Corrective actions to make the system resistant to similar maintenance errors. 233
MEDA Results Form I. General Information II. Events III. Maintenance System Failure IV. Contributing Factors V. Error Prevention Strategies 234
Results Form - General Information
Boeing provides Results Form on a diskette for airline to modify 235
Results Form Event
Process loss Aircraft damage
Personal injury Rework Airworthiness control
236
The “Event Iceberg” Serious Events
Present level of investigation
Costly Events In-flight shutdowns, turn backs, delays/cancellations, equipment damage, and personal injuries
Other Events
Where MEDA should start Where MEDA should go
Rework--Maintenance tasks done incorrectly but caught by inspection or functional test
All events are due to similar contributing factors. Therefore, responding to lower level events will prevent higher level events.
237
Results Form Maintenance System Failure
238
Results Form - Contributing Factors Information
Individual Factors
Equipment/Tools/Safety Equipment
Environment/Facilities
Aircraft Design/ Configuration/Parts Job/Task
Organizational Factors Leadership/Supervision Communication
Knowledge/Skills
239
Information Information is a contributing factor when it is... Hard to read or understand Incorrect Not used because it is Unavailable Inaccessible Simply not used
Out of date Not modified to meet the current configuration 240
Equipment /Tools/Safety Equipment Equipment or tools may be a contributing factor when they are. . . Unsafe Hard to use Not used Unavailable Mis-calibrated Inappropriate for the task Cannot be used in intended environment No Instructions 241
Aircraft Design/Configuration/Parts Aircraft design is a contributing factor when. . . Design contributes to access problems A part is difficult to reach and remove Aircraft configuration varies A part is easy to replace incorrectly A part is unavailable A part is incorrectly labeled 242
Job/Task The job or task is a contributing factor when it is. . . Repetitive / monotonous Complex / confusing Different from other, similar tasks New task or task changed. 243
Knowledge/Skills Knowledge or skills may be a contributing factor when . . . Technical skills are inadequate Mechanic’s task planning is inadequate Technical knowledge is lacking in... Maintenance organization process Aircraft system Job / task
Other skills may be lacking English language proficiency Teamwork skills Computing skills. 244
Individual Factors Examples of individual contributing factors include: Physical health Senses (eyesight, hearing, etc.) Physical conditions / illnesses
Fatigue Time pressure Peer pressure Body size and strength Task distraction/interruption Memory lapse (forgot) Stress. 245
Environment / Facilities This image cannot currently be displayed.
Examples of the environment or facilities being contributing factors include: Environment Noise Temperature Weather
Facilities Hazards Air quality Lighting Markings Labels/placards/signage.
246
Organizational Factors Examples of organizational contributing factors: Quality of support from technical departments Lack of parts Uncalibrated tools
Company policies Shift work and overtime Staffing levels
Company work processes Not a good process—error inducing Good process, but not followed No documented process Company norm not to follow process. 247
Leadership/Supervision Leadership or supervision may be a contributing factor when. . . There is poor planning or organizing of work. Work is assigned to mechanics who are poorly suited for the job. Supervision has an inaccurate belief about how long it takes to do a task. There is inadequate supervision. 248
Communication Poor written and verbal communication between . . . Mechanics Mechanics / lead Lead / management Flight crew / maintenance Across shifts Departments. 249
Results Form Contributing Factors
Must describe how factor contributes to the system failure N/A = Not applicable 250
The Dirty Dozen
251
Summary We have provided information about the key maintenance Human Factors requirements from EASA 145. These requirements were put into place in order “…to increase safety, quality, and efficiency in aircraft maintenance operations by reducing human error and its impact on maintenance activities.” We hope that you are able to use the information that we have provided in order to enjoy these benefits at your airline. 252
Questions?
253
