Ice Crystal Icing

Ice Crystal Icing Bill McKenzie, 757/767 Technical Pilot Boeing Training & Flight Services

Jeanne Mason, Senior Specialist Engineer Boeing Propulsion Systems Division Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 730-774). An export license may be required before it is used for development, production or use by foreign persons from specific countries. The controller of this data has the individual responsibility to abide by all export laws. Copyright © 2011 Boeing. All rights reserved.

Ice Crystal Icing – View From the Flight Deck

Weather radar

Copyright © 2011 Boeing. All rights reserved.

“I did not fly through a Mesoscale Convective System” Ice Crystal Icing_McKenzie-Mason.2

Agenda • What is Ice Crystal Icing – Engine effects – Weather – Reports from the Flight Deck • Statistics and Example Event • Industry Activity • Boeing Activity • Flight Crew Inputs


Ice Crystal Icing_McKenzie-Mason.3

What Is Ice Crystal Icing? The physics: • Crystals can form ice on engine surfaces warmer than freezing • These warm engine surfaces are in the compressor aft of the fan

Fan

Core air travels downstream to the combustor

Potential ice crystal accretion areas

Ice shed from compressor surfaces can cause engine instability such as surge, flameout, or engine damage Copyright © 2011 Boeing. All rights reserved.


What is Ice Crystal Icing? (continued) • Frozen ice crystals impinging on a warm surface in the engine • Some crystals melt, wetting the surface • Crystals impinging on wetted surface stick, cool the surface to 0°C • Ice begins to form • At high altitude, ice can form deep in the engine core



What is Ice Crystal Icing? It can also clog probes like the Total Aircraft Temperature (TAT) probe, (some airplanes) and the engine inlet temperature probe (some engines)

TAT probe



Weather



What’s New – Ice Crystals! • Convective clouds which cause engine power loss range from isolated CBs to tropical storms and hurricanes

>50K ft High concentrations of ice crystals

• Common factors – water lifted to very high altitude • Ice crystals form just above the freezing level to cloud top • Ice crystal mass can be 4x the certification standard for supercooled drops for engines

Freezing level

Mixed-phase icing

Supercooled water (airframe icing)

Upwind side: supercooled • Away from the core of the storm, liquid sometimes in the anvil, ice crystals have Heavy Rain goes higher been measured to be very tiny – size of baking flour Convective / Cumulonimbus cloud Copyright © 2011 Boeing. All rights reserved.


Ice Crystals are Hard to Recognize and Avoid • 80% of all events - little or no returns at flight level • Amber and red returns below the aircraft • Low updraft velocity, light to moderate turbulence • Aircraft in deepest (tallest) part of the cloud • Clouds can spread out hundreds of miles Tropopause

Freezing level


Many engine events occur without flight-level weather radar returns


RED

Not Visible on Pilot’s Radar

AMBER

Tallest cloud region – clouds above the tropopause – directly below = amber & red on normal radar

GREEN

Hurricane Michael, K-band Radar on Instrumented Aircraft

23,000 ft. 19,250 ft

11,800 ft. Freezing Level

Test aircraft flight path – image from upward and downward looking K-band radar Image courtesy of Walter Strapp, Environment Canada.

Canada Copyright © 2011 Boeing. All rights reserved.

Reference: Abraham, J., J. W. Strapp, C. Fogarty, and M. Wolde, 2004: Extratropical transition of hurricane Michael. Bull. Amer. Met. Soc., 85, 1323-1339. Ice Crystal Icing_McKenzie-Mason.10

RED

Not Visible on Pilot’s Radar

AMBER

On board weather radar would only see green ahead. At freezing level it would also see amber and red

GREEN

Hurricane Michael, K-band Radar on Instrumented Aircraft

23,000 ft. 19,250 ft

11,800 ft. Freezing Level

Canada Copyright © 2011 Boeing. All rights reserved.

Image courtesy of Walter Strapp, Environment Canada Ice Crystal Icing_McKenzie-Mason.11

Aggressive Down Tilt Needed to See Amber at Freezing Level At Cruise on a tropical ISA+15 Day, 6 degrees down-tilt needed at 40 nm

36000 ft

6 degrees 15000 ft Freezing level



“Satellite” Weather Analysis: A Recent Event 1.5

30

1.4

25 Moderate Turbulence

1.3

Ta re lles gi t c on lo ud

e

Potential damage

Light Turbulence

1.1

10 5

1.0 0 0.9

-5

0.8

-10

0.7

-15

0.6

-20

0.5 15000

Temperature (Celsius)

15

1.2 Vertical Accel (g's)

Tu rb ul en c

20

16000

17000

18000

Time (seconds)

-25 20000

19000 Start TAT Anomaly

End

• Traversed 195 km/ 105 mi through tallest cloud region • Pilots reported no radar returns at flight level • Moderate turbulence at onset of TAT anomaly • Engine performance shift: potential damage location

Typically, clouds which cause events are about 100 nmi/185km in diameter Copyright © 2011 Boeing. All rights reserved.


Ice Crystal Icing Reports from the Flight Deck Conditions “Sometimes” Reported • Speckled green on weather radar • Rain on the windscreen • Small collection of ice particles on wiper post

IMC (always)

Rain effect

• “Shhh” sound • TAT near zero • Humid cockpit • Ozone smell • No engine changes Copyright © 2011 Boeing. All rights reserved.


Statistics and Example Event



Industry Awareness is Increasing Engine Events Per Year (5 engine types)

• Since 2003, increased: – Identification of events – Awareness and reporting • Since 2008: – 2 new engines affected – Vibration symptom added

• GE90-94B • CF6-80C2 • RB211-535E4 • PW2000 • JT8D/MD-80 Copyright © 2011 Boeing. All rights reserved.


7 Engine Flameouts on a Single Descent Three events involving multiple engine flameouts (7 flameouts total) • Convective storm near Manila • Aircraft was descending through turbulent weather • Avoiding strong radar returns • 26000 ft: engines 3 and 4 flamed out and recover • 24000 ft: engines 1 and 2 flameout and recover High-altitude ice crystals indicated as the cause of engine power loss Copyright © 2011 Boeing. All rights reserved.

• 18000 ft: engines 1, 2 and 4 flameout and recover

Boeing and Engine Company Proprietary Data


Flight Data Review Recorder Data for Event 1

Flameout

Aural Bank Warning Max A/P Wheel ~18 seconds Rudder Input



Event Analysis • To date, all large transport engines have recovered and operated at commanded thrust for remainder of the flight • In this event, thrust asymmetry exceeded autopilot authority, requiring flight crew input, even though engines recovered • Confusion factors included – Weather – Turbulence – Re-route / diversion – Thrust changes Copyright © 2011 Boeing. All rights reserved.


Industry Activity



New Regulations Coming Research Projects are Underway • New regulation for ice crystals will be published in 2012 • Four areas of research underway: – Instruments for measuring ice crystal icing in the atmosphere – Experimental data characterizing the ice crystal environment – Research on engine ice crystal accretion and shedding – Engine test facilities representative of flight environment This work will take time to complete before practical problem solving can begin Copyright © 2011 Boeing. All rights reserved.


Atmospheric Research Is Still Planned NASA/FAA/Boeing/Environment Canada/Airbus

• Flight program for High Ice Water Content (HIWC) Atmospheric Characterization goal: definition of convective atmosphere containing ice crystals to use as engineering standard • Flight Program planned for 2012, 2013 – focused on the weather that produces engine events



Boeing Activity



Boeing Publication Activity

Pilot Reports and Event Analysis


• Technical Bulletin • Symposiums • Aero magazine articles • MyBoeingFleet (web site) • Flight Crew Training Manual • Supplementary Procedure • QRH Checklists


Key Message In All Publications: Avoid Avoid ice crystal icing weather • During flight in IMC, avoid flying directly over significant amber or red radar returns, even if there are no returns at airplane altitude • Use the weather radar controls to assess weather radar reflectivity below the airplane flight path. Refer to weather radar operating instructions for additional information • Deviations of up to 50 nm may be needed to follow the guidance • We know this is not always practical Specific model/engine checklist steps will be covered in the breakout sessions Copyright © 2011 Boeing. All rights reserved.


Technical Bulletin Table of Contents 1. A New Threat 2. Pilot Reports 3. Indications of Ice Crystal Icing 4. Industry Efforts 5. Research 6. Key Points for Flight Crews 7. More Information 8. Frequently Asked Questions 9. Pilot Questionnaire 10. Information for Dispatchers Copyright © 2011 Boeing. All rights reserved.


Background Published Aero Magazine Articles

4th quarter 2007 Copyright © 2011 Boeing. All rights reserved.

1st quarter 2010 Ice Crystal Icing_McKenzie-Mason.27

Background Information on ‘MyBoeingFleet’ Events, Training and Resources\Safety Tools and Training Aids\Ice Crystals at High Altitude

Also available on CD-ROM Copyright © 2011 Boeing. All rights reserved.


Flight Crew Training Manual

Released July 2011 Copyright © 2011 Boeing. All rights reserved.


Supplementary Procedure (SP.16) FCOM Volume 1 1. General description and avoidance recommendation 2. Refers to the new QRH non-normal checklist 3. Will be published at the same time as the QRH non-normal checklist (Available at the breakouts)



New Ice Crystal Icing Checklist 767 Example Condition statements are airplane dependent First Actions: Set thrust manually, exit weather

4. Engine related steps added as needed Copyright © 2011 Boeing. All rights reserved.


Boeing Publications

 

All Model Tech Bulletin April 2011

MyBoeingFleet Jan 2011 Training Video & Articles





Flt Ops Conf. Sept 2011 Presentation

Flight Crew Training Manual July 2011

Non-normal Checklists (not 737) 2011/2012

MyBoeingFleet 4th qtr 2011 Additional presentations & Articles

Supplementary Procedures 2011/2012

Published at the same time Copyright © 2011 Boeing. All rights reserved.


Project End Vision Airline line pilots are: • Familiar with ICI phenomenon • Aware there is a non-normal checklist • Aware of the need for more event data Airline management pilots: • Have materials available to help them educate their line pilots



Summary • Ice Crystal Icing Events are occurring on many engines • Industry is working to better understand the meteorology and the engine icing phenomenon • Boeing is focused on providing the best information to crews • New material is being published by Boeing (Bulletins, Training, Supplementary Procedure, Checklists)



Flight Crew Input Is Needed! • Most of what we understand is based on pilot reports and flight recorder data • More flight crew reports of ice crystal encounters (with or without engine power loss) would be valuable to: – Develop flight crew cues – Validate current Boeing and industry understanding – Better understand the process of ice crystal accretion inside engines



Flight Crew Input Is Needed! Please use the questionnaire 1. Fill out now or 2. Put in flight bag or 3. Fill out the form on ‘MyBoeingFleet’

Your pilot report will help Jeanne Mason PO Box 3707 MC 9U-UU Seattle, WA 98124-2207 [email protected] Copyright © 2011 Boeing. All rights reserved.


Questions?



Ice Crystal Icing

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