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Jet Fuel Starter Print E-mail
(24 votes, average 3.42 out of 5)
Written by Sabc   
Article Index
Pilot Controls
Engine Start
Engine Shutdown
Limitations
Sources
Forum Discussion
Related Articles

jfs_imageThe 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).

argaiv1825

engines_cutaway

1
2
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
- Main Engine Mounting Frame
9
10
11
12
13
14
15
16
- Afterburner Nozzle Actuators
- 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 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.

jfs_intake_exhaust

Pilot Controls

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

jfs_controls

1
2
- 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.

jfs_central_gearbox jfs_jet_fuel_starter

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 on the throttle (see article on throttles in the 'Cockpit' section in the left menu). As a standard operating 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 JFS spins the right engine to 20% rpm. Engine rpm can be 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 forward out of NULL and into IDLE. The digital electronic engine control ( DEEC) takes over from there.
  • Monitor the rpm and FTIT (Fan Turbine Inlet Temperature) on the EMD during the process to ensure there is not a hot start or other malfunction. PW-220 hot-start FTIT limit is 680 Celsius, while the same limit for PW-229 is 800 Celsius.
  • As the engine spins up past 56% rpm the right generator comes on-line 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 System in the 'Engines' section in the left menu).
  • Repeat the same process for the left 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).

jfs_danger_areas

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).

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 left and right engine fire extinguisher buttons. This action closes the 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.
  • If the JFS is running, push the AMAD fire button to close the JFS fuel shut-off relay.
  • Raise fingerlifts on throttle and pull back throttles to below IDLE.
  • Release fingerlifts and pull throttle back to OFF.

Limitations

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

  • Maximum 10 seconds (15 seconds if temperature is below 0 Fahrenheit) between JFS start initiation and ready light.
  • Starter engagement time shall not exceed 90 seconds, except if a hot-start occurs, when this time may be extended to 150 seconds.
  • Minimum 10 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.

Sources

Steve Davies:

Boeing F-15E Strike Eagle - All-Weather Attack Aircraft

2003, Airlife Books, ISBN 1840 373 784

Hardcover, 7.7" x 10" (19.5 cm x 25 cm), 208 pages, over 250 images

It has taken over 18 months to research and write, and the author estimates that as much as 70% of the text is new information that has yet to reach the public domain. It is, without question, the most detailed, well-researched and authoritative analysis of the F-15E Strike Eagle ever written. It is an absolute must-have for all F-15E enthusiasts, many info within this site comes from this book.

F-15E.info rating: HIGHLY RECOMMENDED


Dennis R. Jenkins:

McDonnell-Douglas F-15 Eagle - Supreme Heavy Weight Fighter

1998, Aerofax, ISBN 1 857800 81 8

Paperback, 8.5" x 11" (21.5 cm x 28 cm), 112 pages, over 250 images

Without a doubt the finest air fighter in service with western air forces, the F-15, still in production (now under the Boeing name) is meeting export orders for Israel and Saudi Arabia with interdictor variants. This book includes in-depth coverage of systems, engines, weapons, development usage and all 20 test aircraft. Recommended for F-15 enthusiasts.

F-15E.info rating: HIGHLY RECOMMENDED


  • F-15E Flight Manual TO 1F-15E-1 (courtesy of eFlightManuals.com)
  • Special thanks to USAF Capt. Randall 'Hacker' Haskin

Forum Discussion

You can discuss this article in the Strike Eagle Forum with the latest posts appearing here below as well. Clicking on the 'Discuss' button takes you to the SEF, while clicking on the 'Quick Post' text enables you to make a post here right away.

Article discussions are available for registered users only!

Last Updated on Monday, 30 May 2011
 


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Discuss...
Discuss (8 posts)
Jet Fuel Starter
Nov 04 2010 16:13:01
Not sure if anyone would be interested, but I have a JFS190-18 we are trying to get rid of. Pictures of the unit can be downloaded from the following link. www.dakotaairparts.com/images/attachments/JFS190/JFS190.pdf
The unit is clean! Please let me know if you have any questions. Thanks, Mitch 701-297-9999 mitch@dakotaairparts.com
#251
Jet Fuel Starter
Feb 09 2011 18:09:54
The photos of the JFS and CGB are backwards. You have the CGB listed as the JFS and the JFS listed as the CGB.
#317
Re:Jet Fuel Starter
Feb 09 2011 18:40:27
Got it fixed. Thanks for pointing out!
#318
Re:Jet Fuel Starter
Feb 09 2011 20:25:52
I also have something else to add. If I remember right you do a FIRE BIT TEST after the JFS is online. Then you go for the engine start. Your emer gen comes online at 20% so that you have power to the gages. Then a +- 50% the AMAD 50% cut out switch disengages the JFS and the engine continues to spool up till idle.

The thing with the 50% cut out switch, not sure if the 15E's were like this but the 15A-D's were. Before 2005 or 2006 the switch would cut out at +- 40%. They reason for this was to but less strain on the JFS, but with the old 100 and 220 cores they were getting a lot of hung starts. That is when they pushed the switch back up to +-50%. Just so information that you might like to know. Again I'm not sure if this was the same for the 15E's and the 229's.
#321
Re:Jet Fuel Starter
Feb 09 2011 20:32:46
Thanks! Sounds like a word of experience here. Were/are you an Eagle keeper?
#322
Re:Jet Fuel Starter
Feb 09 2011 20:38:06
Yes 18 years on the Eagle as a Engine Mechanic. Never worked the F15E just 15A-D's and with the old F100-PW-100's.
#323
Re:Jet Fuel Starter
Feb 09 2011 20:42:30
That's a lot of time...

BTW if you browse our pages here and find some mistakes, mistypes, etc. just let me know and I'll gladly correct it. And check back often
#324
Re:Jet Fuel Starter
Feb 09 2011 20:44:26
Plus another thing I seen, your engine shutdown is what would be used for a emergence. For a normal shutdown you would not push the fire buttons to shut off the fuel. You would use the engine master switch. Then thing is that you did not turn the engine master switch off till the engine RPM was below ~40%, well that is the way we did it. By the book you would only turn the master switch off after the engines had spooled down. The reason for doing it before the EMER GEN went off online is so that you did not need to use Exteranl power to close the fuel shutoff valve.
#325

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