Jet Fuel Starter (JFS)
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).
|- Compressor Blades|
- Engine Mounting Links
- Titanium Skin Panelling
- Fire Extinguisher Container
- Engine Bay Dividing Firewall
- Corrugated Inner Skin Doubler
- Afterburner Ducting
- Main Engine Mounting Frame
|- Afterburner Nozzle Actuators|
- Nozzle Shroud Fairing
- Nozzle Actuating Rods
- Afterburner Exit Nozzles
- Jet Pipe Central Tail Fairing
- AMAD Gearbox
- 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 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.
The JFS is activated via a handle and a switch on the pilot's right hand console. See the illustration below.
|- JFS Starter Switch|
- JFS Control Handle
|3||- JFS Ready Light|
The JFS starter switch (1) has positions of ON and OFF. For the JFS to be engaged this switch has to be put into ON position. Although the JFS shuts itself down automatically, it can be manually shut down by placing the switch to OFF position at any time during operation.
The JFS control handle (2) is used to discharge the hydraulic accumulator(s) to actually start the JFS. Pulling the handle straight out discharges one accumulator. Rotating the handle 45 degrees counterclockwise and pulling discharges both accumulators (or the remaining one if one has been already discharged). The handle is spring loaded to return to its normal position.
The JFS ready light (3) indicates if the JFS is ready to be engaged. The light goes out when the JFS is shut down.
A 'JFS LOW' caution appears on the caution display on MPD/MPCD if either JFS accumulator pressure is too low.
|Photos: The central gearbox (left) and the jet fuel starter (right).|
JFS - Engine Start
The engine startup sequence is roughly the following (respective controls are referenced by their numbers on the illustration above):
The JFS automatically shuts down when the second engine reaches approx. 50% rpm. Note that on aircraft 86-0183 thru 87-0200 a manual JFS shutdown may result in the CAS and MPDP temporarily dropping off the line.
The JFS may be used during flight to perform a JFS assisted restart (special operating procedures apply to this).
JFS - 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:
JFS - Limitations
There are certain limitations regarding JFS usage. These can be summarized as follows:
|More Reference Photos|
|Text © 2007 Szabolcs Serflek|
Illustrations © 2007 Lutz Gretschel, Szabolcs Serflek, Mike Badrocke
Photos © 2004 US Air Force
|Sources: Steve Davies: "Boeing F-15E Strike Eagle All-Weather Attack Aircraft" (Airlife, 2003)|
Dennis R. Jenkins: McDonnell Douglas F-15 Eagle (Aerofax, 1998)
F-15E Flight Manual TO 1F-15E-1 (courtesy of eFlightManuals.com)
Special thanks to USAF Capt. Randall 'Hacker' Haskin