Main Checklist - Engine Shutdown
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…bleed air? That’s even worse, IMO…ever seen the damage a bleed air leak can do?
Yeah - I was thinking mostly about ground ops, though. That’s probably where a mistake is most likely to happen. Unless you secure the feed knob airborne for some reason - I can’t think of one…other than in flight fire, maybe?..
There are a LOT of things working optimistically in BMS…which surprises me. A bit. Probably my own fault - I think I’ve over-hyped it to myself before actually working with it extensively. BMS still rocks, though.
Actually, no on the bleed air leak. Got any good videos?
For an in flight fire, there is no mention of moving the feed knob at all. For a ground fire, its mentioned to turn it to OFF if external power is applied.
BMS rocks, but there is always room for improvement. Fuel systems being a little less (not a lot less) optimistic would be one of those areas. I have to admit, I am still very impressed with how many of the things I thought needed improvement in 4.32, are implemented/improved in 4.33. I guess I didnt really look at the fuel system as being something in need of improvement back with 4.32.
So, with both reservoirs full, and the engine feed knob off, negative G should not present much of an issue (short term). With a reservoir less than full, it (along with maneuvering flight) should present engine starvation problems. High fuel flow with reservoirs less than full should probably present similar issues.
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Yes. Usually there is some sort of restriction on duration for negative G, and this is why - that, and limitations on the engine oil sumps. I rather suspect that at high fuel flow the Viper’s reservoirs may tend to stay full as long as pumps are doing their job. Interruptions in that flow can be catastrophic too - I spent my initial stint in AB Controls investigating a pressure spike that blew the main fuel inlet off the engine in F-16XL (F110DFE at the time) during a throttle transient from idle to max…that happened because the AB boost pump would scavenge dry at part power, and at turn on the demand spike re-filling the cavity was strong enough to back-flow through the whole system and blow the fuel inlet elbow off the engine…jet landed on the lake bed, my boss at the time had the broken elbow on a plaque over his desk…
No…no videos, but some personal experience with a couple jets that have had to divert for bleed air leaks - I think pilots fear bleed air leaks second only to flight control failures or actual developed fire. In general a bleed air leak will result in a fire (something like 700C+ degree air usually)…and depending on just what the air impinges and/or how soon the crew take action the fire can do less visible damage…one such jet that I know of that had a leak that appeared to have not done a lot of damage was recently struck from inventory after it was learned that the heat warped the spine of the structure. Brand new jet, too.
One of the worst things I’ve seen happen to an engine is a titanium fire - usually due to a case rub. When I was working at a GE ASO I used to see CF6-50s that came in with such; at one time those engines had steel compressor blades and titanium cases. Blade would rub the case and the case would catch and burn like magnesium. Looked like someone poured molten lead down the intake of the engine. They stopped that by changing materials from Ti.
I sort of skipped BMS 4.32 because I figured 4.33 was coming as I began my pit project…in my transition from FAF to BMS and because I’m building a pit and PC for BMS I really don’t want to spend a lot of time on it just yet. It does do a LOT of things really, really well…which is another reason I get surprised when it falls short in places. Like I mentioned, I think I over-hype it to myself…but it does really impress me.