robbreid
23rd Jan 2021, 17:49
Report states after major engine malfunction .. CVR stopped, and pilots shut down good engine ..
Question: especially for Global Drivers .. how does this report sit with you 🤷♂️
https://www.airforcemag.com/app/uploads/2021/01/27-Jan-2020-ACC-Bagram-Airfield-E-11-AIB-Narrative.pdf?fbclid=IwAR3NyBAMk2vWwpM7LdYLFTSOnW6p9I2efSICO qqt-36YVoBRkbt_KDGpMVM
rippey
24th Jan 2021, 01:25
I would agree with report. Unfortunately it was survivable situation but the IMHO the crew was dealt more than their share of bad luck. First with the way the failure presented itself, and then the ditches during the forced landing. I would guess two things caught their eye after the bang and vibrations. The L FADEC FAIL master caution, which if they actioned the QRH would have told them to monitor instruments (with subsequent notes that EPR to N1 reversion may occur, Engine may reduce to idle, engine may shut down). If they monitored the instruments, which probably was a challenge in itself given the description of the vibrations they were experiencing) they might have seen the fan vibs indication for both engines (note that these are not normally seen on the EICAS, unless there is excessive vibration in which case vibs for BOTH engines appear). Unfortunately the affected engine had two amber dashes instead of a number, so they have then focused on the right engine which displayed a value for fan vib. I am assuming at this point the L fadec was in the process of shutting down the engine so when they manipulated the thrust lever it made no change to the vibrations, and then they got very unlucky when they reduced thrust on the right engine and for whatever reason the vibration reduced, leading them to believe it was the right engine that was the problem. QRH for fan vibs (although that should give you a cas message) is to reduce thrust until vibrations reduce, and if you are unable to control the vibrations and it is accompanied by airframe buffet you shut it down. And of course if you shut down an engine you suspect is damaged the QRH of course tells you not to attempt a relight under any circumstance. We’ll never know if they attempted to relight the right engine, but my guess is no, as I can’t really see a scenario where it would not have been successful. The left of course would have been locked out by the fadec so no chance of starting that one. I am also guessing that they didn’t know that they tossed a blade either, because you shouldn’t start the APU with a suspected rotor burst, although if the alternative is a forced landing somewhere in the hills of Afghanistan they maybe felt they had nothing to lose. This is possible as APU start is available at FL370 and they didn’t start it until under 290, so it’s possible they attempted a windmill start first and then started the APU for an ATS start as a last ditch effort.
Anyways, the report made sense to me, but it was a hard read because I really feel like those guys had the deck stacked against them. Yeah, ideally they would have sat on their hands for a minute or two, but I think most pilots would underestimate just how hard that is to do when the airplane feels like it’s shaking itself apart.
tdracer
24th Jan 2021, 03:00
Already being discussed in the Military forum.
https://www.pprune.org/military-aviation/629216-aircraft-destroyed-afghanistan-usaf-e-11a-bacn-5.html#post10974620