Jet Fuel Starter

Jet Fuel Starter Written by Sabc - Last Updated Saturday, 07 November 2009

The Jet Fuel Starter (JFS) is a simple, scaled down jet engine (often called as APU - Auxuliary Power Unit - in civilian aviation) fitted centrally between the two engines - see (15) on the figure below. It is used to start the two engines (in fact it's the only way of starting them).

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3 4 5 6 7 8 - Compressor Blades - Engine Mounting Links - Titanium Skin Panelling - Fire Extinguisher Container - Engine Bay Dividing Firewall - Corrugated Inner Skin Doubler - Afterburner Ducting 9 - Main Engine Mounting Frame 10 11 12 13 14 15 16-- Afterburner Nozzle Actuators 16 - Nozzle Shroud Fairing - Nozzle Actuating Rods - Afterburner Exit Nozzles - Jet Pipe Central Tail Fairing - Central Gearbox (CGB) - Jet Fuel Starter - Engine Bleed Air Ducting

The JFS can start either engine, but not both simultaneously. The JFS itself is started by accumulated hydraulic pressure. There are two hydraulic accumulators which are automatically charged during flight by the utility hydraulic system or manually by a hand pump. Fuel is provided by the aircraft's main fuel system, ignition and electrical power are provided by the JFS generator (permanent (permanent magnet). The JFS has its exhaust on the bottom fuselage of the aircraft, behind the central external hardpoint (SUU-73/A pylon). The location of the JFS intake and exhausts are illustrated on the following figure.

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Pilot Controls

The JFS is activated via a handle and a switch on the pilot's right hand console. See the illustration below.

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1 -2JFS -JFS. JFS Starter Handle Switch -'JFS JFS Ready Light The starter switch (1) has manually to be shut put into down ONhandle by position. placing has Although positions the the oftoON OFF and shuts position OFF. itself For at down any the JFS automatically, to during be engaged operation. itaccumulator can be switch control handle (2)and degrees the one has been counterclockwise countercloc Pulling already the kwise discharged). straight is3used pulling to The out discharge discharges discharges handle isthe spring both one hydraulic accumulators accumulator. loaded accumulator(s) totime return (or the to its remaining to the normal actually handle position. one start 45if the JFS ready light (3) JFS is Control shut down. indicates if switch the JFS isJFS ready to engaged. The light goes outthis when pressure A LOW' is too caution low. appears on the caution display onbe MPD/MPCD ifRotating either JFS

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Photos: The central gearbox (left) and the jet fuel starter (right). {rt}

Engine Start

The engine startup sequence is roughly the following (respective controls are referenced by their numbers on the illustration above):

- Turn the JFS starter switch on. - Pull the JFS control handle. - Engage the first engine by pulling its respective fingerlift fingerlift on the the throttle (see article on throttles in the 'Cockpit' section in the left menu). As a standard operating procedure, procedure, the right engine should be started first so that a hydraulic pump operated by the right engine can be checked. The fingerlift on the front of the throttle engages the JFS connection to the engines. - Wait until the the JFS spins the right engine engine to 20% rpm. Engine rpm rpm can be monitored monitored on the Engine Monitoring Display (EMD) on the front dashboard above the right knee of the pilot (see article on the engines in the 'Engines' section in the left menu). - Push the throttle throttle forward forward out of NULL and into IDLE. The digital electronic electronic engine control control (DEEC) takes over from there. - Monitor the rpm and FTIT FTIT (Fan Turbine Turbine Inlet Temperature) Temperature) on the EMD during during the process process to ensure there is not a hot start or other malfunction. PW-220 hot-start FTIT limit is 680

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Celsius, while the same limit for PW-229 is 800 Celsius. - As the engine engine spins up past past 56% rpm the right generator generator comes comes on-line and and the right engine intake ramp, which has been locked in the full-up position, slams to the full down position (this scares a lot of first-time passengers in the back seat!) - Test fire sensor loops (see article on the Fire Warning/Extinguishing Warning/Extinguishing System System in the 'Engines' section in the left menu). - Repeat the same same process process for the left left engine. engine.

Since the JFS is a jet engine in itself, extra care should be taken not to be within the reach of its air intake and its hot exhaust gases when the JFS is running. The 'danger' zone is a 4 feet circle around the intake and two 20 degree cones from the JFS exhausts to the engine tail cones (see illustration below).

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that temporarily JFSaircraft automatically dropping 86-0183 off shuts thru the line. 87-0200 down when a manual the second engine reaches may result approx. in the 50% CAS rpm. and Note MPDP The procedures may apply be used to this). during flight to perform aJFS JFSshutdown assisted restart (special operat operating ing {rt} on

Engine Shutdown

Complete engine shutdown can be accomplished from the front cockpit only. However if over the left wing access door is used for engine shutdown, the engines can be positioned to IDLE from the rear cockpit as well to reduce danger of intake suction. The engine shutdown procedure is the following:

- Depress the the left and right right engine fire fire extinguisher extinguisher buttons. This action closes the engine engine fuel shutoff and bleed air. Note, that the JFS should be running to provide 28 volt DC power for operation of the AMAD fire extinguisher system.

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- If the JFS JFS is running, push the AMAD AMAD fire button button to close the JFS fuel fuel shut-off relay. - Raise fingerlifts fingerlifts on throttle and pull back back throttles throttles to below IDLE. - Release fingerlifts and pull pull throttle throttle back back to OFF. {rt} Limitations

There are certain limitations regarding JFS usage. These can be summarized as follows:

- Maximum 10 seconds seconds (15 seconds seconds if temperature temperature is below 0 Fahrenheit) Fahrenheit) between between JFS start initiation and ready light. - Starter engagement engagement time shall not exceed exceed 90 seconds, seconds, except if a hot-start hot-start occurs, occurs, when this time may be extended to 150 seconds. - Minimum 10 seconds seconds between first engine at idle speed and engagement for second engine start. If the engine engagement time exceeds 90 seconds, wait 20 seconds before again engaging or shutting down the JFS. {rt} Sources -

Steve Davies: Davies: "Boeing F-15E F-15E Strike Eagle Eagle All-Weather All-Weather Attack Aircraft" Aircraft" (Airlife, (Airlife, 2003) Dennis R. Jenkins: McDonnell Douglas Douglas F-15 F-15 Eagle (Aerofax, 1998) F-15E Flight Flight Manual Manual TO 1F-15E-1 (courtesy of eFlightManuals.com) eFlightManuals.com) Special thanks to USAF USAF Capt. Capt. Randall Randall 'Hacker' 'Hacker' Haskin

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Jet Fuel Starter

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