The JFS (Jet Fuel Starter) on an F-16 allows for two attempts to start the engine.


However, if this fails, there is a manual pump that can be operated:

Where is this pump? Inside the cockpit? Hidden in some hatch outside? How is it operated? How long does it take to build up enough pressure for one more attempt to start the engine?

As a bonus question: Surely the JFS system can be charged with external equipment rather than this hand pump? What is that procedure called?


2 Answers 2


I used to be a crew chief on F-16s in the Air Force. Our pilots usually jump both bottles at once during a start up to ensure a proper start, if it fails it's most likely because there wasn't enough pressure accumulated. It's part of our launch procedures before they take off to check to see if it's within limits, if not you have to get the "T handle" and go manually pump it up to pressure. This is done in the left hand wheel well there's a big slot for the handle to be inserted and pinned into to keep it in there while you pump. There's a gauge on the opposite side under a quick access panel to check the gauge. Usually if we do have to pump it you'll pump for awhile and take a look at the gauge and keep going back and forth to check it. We rarely hook anything up to automatically charge it, it's manual 9/10. Actually, it usually takes 15 min to charge however some people are slower or even faster, it's more on the person to determine how fast it charges. It's very tiring to do it.


Meower68 left a comment on this answer explaining how it worked:

WRT comments about the F-16 JFS. Hydraulic pressure from accumulators, not compressed gas, starts it spinning. You have two such accumulators; you can dump one and, if it fails, dump the other and try again. You can dump both at once, providing more time for the JFS to engage. If you've dumped both, without success, you can put a t-shaped handle on an double-acting hydraulic pump in the port wheelwell and MANUALLY repressurize the accumulators and try again. Doing so is roughly equivalent to 150 or so push-ups; extremely exhausting. Ask me how I know :-) – Meower68 Jun 22 '17 at 20:58

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    $\begingroup$ I'll be damned, that's almost exactly the drill on a CH-46 APU start but only one accumulator tank. $\endgroup$ Jun 18, 2019 at 22:09

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