F16 crash yesterday

[eagl]

I suspect that the backup mode mentioned in the article is the engine controller's secondary mode, a mechanical engine management system that uses conservative vane, fuel, and pressure settings to keep the engine running when it's suffering a malfunction or is damaged.  The primary engine control is typically a complex digital controller that boosts efficiency and thrust by quite a bit, but if the engine goes outside it's programmed parameters for whatever reason, the whole thing might shut down.  That's where the secondary controller comes in.

If the hydrazine-fueled emergency power system hadn't come online, they probably wouldn't have been able to level off to eject or even make a controlled glide.

[Dago]

I would think they would have as a last ditch power source battery power with a static inverter to supply sufficient A/C to control the aircraft, while shedding off all equipment not absolutely necessary for aircraft control.

At least the fly-by-wire airliners do it that way as a final last ditch control option.

dago

[Cobra412]

There's multiple reasons the engine could have gone to SEC mode. Typically the DEEC (Digital Electronic Engine Control) does just as Eagl has stated previously. If a failure occurs the DEEC will no longer control the motor it will only monitor it. If they can't cycle the light out they will rtb.

Seems whatever happenend here was more than just a basic EEC light. You can get an EEC light and the aircrews won't know anything is wrong except for the light and a master caution. They can attempt to cycle the EEC but that may or may not help.

As far as the hydrazine goes. I'd have to get more details from our 16 guys. From what I understand is they can fire off the hydrazine to give them more time to land in the event of an electrical system failure. Jaxxo is or was a 16 guy if I remember right he may be able to tell you more. If not I'm working in a 16 squadron at the moment and I can ask them on Monday about the ins and outs.