ANA 787 Engines shutdown during landing
 

System Manuals
 

Where can you get the entire systems manual for the 787?

30 years in system design (non avionics) and really interested in how these systems work.

Is it possible that this is related to the issues identified in a recent Boeing release ""Uncommanded Engine Shutdown during Landing Roll Bulletin""

Samchui.com comment:

"It’s worth noting that a bulletin was released by Boeing not so long ago to pilots and maintenance crew about the Thrust Control Malfunction Accommodation (TCMA) system, which prevents risk in an uncommanded high-thrust situation, stating that errors in the landing sequence could cause the system to activate. The errors include a combination of selecting full reverse too quickly before the aircraft has transitioned to ground mode followed by a quick deactivation of reverse thrust. Boeing advises not to apply full reverse too quickly in the bulletin."

A quote from https://thepointsguy.com/news/boeing...re-on-landing/ :

May be of interest:
https://patents.google.com/patent/US6704630B2/en

Assuming the (now deleted post) was correct, and this is an issue with TCMA when combined with an unusual T/R application, it has nothing to do with reverse before being on the ground.
TCMA - Thrust Control Malfunction Accommodation - is something Boeing came up with to address an FAA (and later EASA) concern with Uncontrollable High Thrust (UHT) on the ground. UHT is nothing new - although uncommon (probability of occurance is somewhere between 1/10 million and 1/100 million flight hours), all turbine engine installations have failures that can cause the fuel metering valve to go wide open uncommanded. FADEC has made it less likely, but the potential failure is still there.
UHT was always assumed to be something the flight crew could address by shutting down the affected engine - but then there was an event on a 737-200. Going from memory here, but I think it was 1997, it was either in Egypt or an Egyptian operator (fuzzy memory on that part). Anyway, there was an issue with the JT8D fuel control where the splined shaft that fed N2 speed to the fuel control could wear excessively and start slipping. During takeoff power set, that spline started slipping - the fuel control thought the dropping N2 meant the engine was spooling down and opened the fuel metering valve wide open. The crew saw EGT spike over redlline and aborted the takeoff, but the fuel control didn't respond when they retarded the throttles. The went off the side at low speed - no one was seriously injured or killed, but it was a hull loss.
The FAA (and later EASA) decided this meant that UHT on the ground was catastrophic and therefore every aircraft/engine combination ever built didn't comply with the regulations (25.901(c) - no single failure shall result in an unsafe condition).
It become a long and quite messy story - the FAA ended up issuing partial exemptions for aircraft then in production, but dictated that we needed to address UHT on the ground for future aircraft certs. So starting with the 777-300ER/GE90-115B, Boeing came up with TCMA. In short, when on the ground, if the FADEC determines that the engine is at high power with the throttles at/near idle, and not decelerating, TCMA will shut the engine down. For what should be obvious reasons, TCMA is only active on ground, with quite robust air/ground logic that will default to air if it's not sure.

I wonder what the FAA and EASA will make of the recent Lion Air 737 Max event resulting from the failure of a single AoA sensor in the light of 25.901(c)

I think that is already known. They consider that if the actions for a stab trim runaway had been taken there would have been no problem, just switch off the stab trim with the switches provided for just that purpose. Therefore, more than a single failure was required,

@Ian,
the possible non-conformity of the Lion Air B737 Max with Part 25 is more related to 14 CFR 25.672 than 25.901.
Part 25.672 is specifically for stability augmentation systems.
The issue is not so much single or double point of failure but rather dedicated warning.
In the Lion Air accident, the second failure, i.e. not shutting off the electric trim, is linked to the ability of understanding the nature of the problem at stake and understanding that the stability augmentation system is failing.

Luc

AVweb report.https://www.avweb.com/eletter/archiv...4235-full.html

To add a bit to what Luc Lion posted, 25.901(c) is specific to propulsion systems - not flight controls (which have their own set of applicable regulations).
No question if TCMA was the cause of the dual shutdown then there is an issue that needs to addressed in the software. There is a quite comprehensive review of the TCMA limits during the flight test program (at least on the 747-8, we had TCMA deactivated for much of the flight test program, until we had enough real engine data to verify we had adequate margins between the TMCA limits and what a normally functioning engine would really do). However it's really hard to anticipate every possible scenario - and it appears that perhaps the pilots on this flight managed to come up with an unanticipated scenario for the Trent engine.

Is it not possible that a fault occurred in the fuel delivery system during TR deployment and then TCMA performes as designed?

@Smdts : on both engines, simultaneously ?

I dont know hence the question. Does tcma only shutdown the affected engine or both if it is trying to prevent thrust assymetry?

TCMA only shuts down the engine with the problem. Boeing makes of point of not cross talking information between engines to help protect engine-to-engine isolation.
The intent is not to override anything the pilots are doing, but to deal with an engine that's not responding when the thrust lever is moved to idle.

(ANA) has concluded there was no engine failure following a Jan. 17 incident in which both engines on a Boeing 787-8 shut down after it landed at Japan’s Osaka International Airport.

ANA flight NH985 was arriving from Tokyo Haneda Airport with 109 passengers and nine crew members on board. After touching down on the runway and deploying the thrust reversers to slow the aircraft, pilots noticed that both Rolls-Royce Trent 1000 engines had shut down. The 787 completed rolling out and came to a stop about 8,000 ft. down the runway, according to media reports.

The carrier said it conducted a thorough investigation of the aircraft and found no engine failure. It did not assign responsibility for the cause of the shutdown.

“Following a safe landing in Osaka, an appropriate safeguard system on the 787 was activated properly on both engines, triggering the discontinuation of the thrust,” ANA said in a statement. “This system is meant to prevent the aircraft from becoming unstable after landing when thrust is shifted again from reverse to forward. This safeguard system will not be ready for activation unless it detects that the landing gear is on the ground, and an instrument measuring the altitude will not allow maneuver of the thrust reverser during flight.”

Engine manufacturer Rolls-Royce did not immediately respond to a request for information, and Boeing declined to comment.

https://atwonline.com/engines/ana-fi...e5fb9afefca4d2

Sure sounds like a 'nuisance' TCMA trip on both engines - guessing that the pilots did something very unusual with the thrust levers when transitioning out of reverse.

There is also this more recent incident from 2010
https://www.cad.gov.hk/reports/AB-01-2010e.pdf
where small hard particles contaminating the fuel jammed the fuel metering valve at 74% N1 on a Cathay Pacific A330-300 while in flight. The engine only stopped when shut down on the ground.

It's definitely not impossible even today.

They are not independent when it comes to a common fuel supply as a causal factor

Well, if that is the case, I would have thought the authorities should be treating this as seriously as an accident. :hmm:

OAP

Our company sent out a memo talking about this incident stating that it was a TCMA issue with reverse selected just prior to touchdown(if possible), reversers activating upon touchdown with full reverse selected followed a quick cancellation of reverse thrust selection.

On this topic I thought it was an AMC design criteria for airplane engines to run from their onside WING tank during takeoff and landing. Not on the 787 aparrently. They can be drawing from centre tanks right on rotation.

Perhaps lomapaseo is referring to things such as fuel contamination, incorrect fuel loads, and large-scale fuel leaks that can affect both engines?

Some pilots have a very bad habit of lifting the reverse levers prior to touchdown - depending on the air/ground logic to prevent deployment until they actual land. The good news is that, since Lauda, the air/ground protection is good enough that the probability of the reversers actually deploying prior to touchdown is very remote - the bad news is that if there is some sort of latent fault that allows a reverser to deploy, they'll probably crash :eek:.
We did a big investigation of this on the 757 years back, where lifting the reverse levers was causing a rash of nuisance fault messages. We instrumented a couple in-service 757s and sure enough, about 1% of the landings they were lifting the reverse levers prior to touchdown - sometimes by as much as 10 seconds :ugh:

All that being said, I'd be hard pressed to come up a scenario for how doing that could cause a nuisance TCMA trip...

On the NG you can select reverse thrust from 10 ft above the runway. Limitations forbids this, but it is possible. Going back 20 years, some of our guys did this on short runways. It works if you know what you are doing, but it’s very easy to end up with a firm landing.
You you manage to select reverse 10 seconds before touchdown, you will hit very hard. 😳

SLF here, but I still remember being in reverse thrust for so long on the old/short runway at Edinburgh Turnhouse that I was convinced I must have missed a very sweet touch down, THEN we finally did touch down, quite gently, very far down the runway, and with max braking. Fortunately, the runway was dry! Must have been either a Trident or 111.

FWIW, as a tentative technical contribution to the discussion, my Prentice suffered what I now realise was a rollback and shutdown on rollout after an excellent wheelie landing. Exhaustive investigation by the owner established that the flight crew's fuel management had erred to the extent that when the tail went down the gallon or two remaining fuel sloshed to the back of the tank in use, while the pickup was near the front. If the mods feel that this sorry tale does not help this serious discussion, I won't be offended.

What’s the advantage to being able to select reverse before you’re on the ground? Without checking my FCOM, I’m almost positive you can’t do that on the A320.

I could be wrong, but I believe on the Trident, the centre engine could not only be selected to reverse while airborne, but it actually went into reverse. Always worth watching the Trident land at Aldergrove.

I recall reading somewhere that one of the early jets (DC8?) could reverse two engines for descent control.

Unlike the 727, the Trident didn't have a thrust reverser on the centre engine.

The Trident could use reverse thrust for emergency descent, 10,000 ft/min, and before touchdown. The C17 can use reverse thrust on all engines for tactical descents at 15,000 ft/min

Thanks. My question was targetted to the 737. Any practical reason to select reverse at 10ft?