Posts about: "Engine Shutdown" [Posts: 105 Pages: 6]

787 gear and flaps/slats are both on the centre system, powered by 2x big electric pumps and no EDPs, so retraction should be minimally impacted by engine failure assuming electric power was still available and reconfiguration worked. Note the 787 has two generators per engine so generator failure is also unlikely to contribute, unless both engines failed taking out all four generators (and presumably no APU running).

From that thread, I believe it was discussed that on most/all other large transports, deploying the RAT re-powers the CVR/FDR. The 737 didn't have that happen because no RAT. You may still get a few second gap while the RAT deploys.

The 787 has 2x Enhanced Airborne Flight Recorders (EAFR), which each record both cockpit voice and flight data. I expect they are also fitted with the dedicated batteries that the Jeju was a year or two too early to require. Per the NTSB , the forward recorder has a 10-minute backup battery.

Hopefully flight data is not going to be an issue for this investigation.

The suggestion is that the buzzsaw/propeller sound is the RAT; it does sound a bit like an interference pattern, but you don't get the engine roar with it.

It's also maybe visible in a few stills (e.g. post 64).

Just to confirm.
The 787 is an aircraft which likes to, performance wise, use all of the available runway for takeoff. Sometimes you can be sat in the 787 and as you are rolling down the runway, you start wondering if Rotate has been called or not. It loves taking up all of the runway.

Nevertheless, there are some interesting speculations over on X. One guy even claimed the Captain was in the lavatory during the accident...

Many people have noted what appears to be the RAT deployed in the video footage suggesting dual engine failure. Possible wrong engine shutdown? But who diagnoses and actions an engine failure and shutdown below 400ft?

Considering the RAT is 100% out as evidenced from footage both visually and audibly; the initial conclusion can only be both engines have failed, or one failed, and the other unfortunately shut down.

I'm not convinced the RAT is out. I've looked several times and can't see it on any of the videos.
Happy to be corrected.

Nonsense. Please don\x92t post things as fact that are just speculation.

The entire flight from rotation to impact was 30 seconds. Is it even possible to complete an engine shutdown in that time?

You certainly should try that\x92s for sure. ANC and all that good stuff! In a panic it certainly is possible to just pull the wrong one. I\x92m not saying that\x92s what\x92s happened, to me it seems like dual engine failure, practically simultaneously.

In flight, the RAT deploys automatically if any of the following occur:
• both engines have failed
• all three hydraulic system pressures are low
• loss of all electrical power to captain’s and first officer’s flight
instruments
• loss of all four EMPs and faults in the flight control system occur on
approach
• loss of all four EMPs and an engine fails on takeoff or landing

(EMP = electric motor pump, hydraulic)
FYI the RAT is an emergency source for electrical and/or hydraulic power.

An aircraft using derated thrust will use most of the runway to reach V1. It's not far too late. The initial climb looks normal.

If the flaps weren't set then the aircraft would have accelerated on the runway faster, not slower. But I don't think the flaps were set wrong, or retracted early. The flaps appear extended in the video and the post crash photo. Why do you think a bird strike after V1 is unlikely? If you fly into a flock of birds a double engine failure is no less likely then a single failure. My initial thought watching the first video this lunchtime was power loss in both engines, probably bird strikes. I still think that.

If both engines failed then all four of those things would happen very soon afterwards.

Not 757 - it was a 767. Second time it happened in about 12 months.

Determined to be an ergonomics problem with the switch layout in the flightdeck.

Early 767s (JT9D and CF6-80A) had a supervisory "EEC" (Electronic Engine Control - Boeing still uses "EEC" to identify what most people call the FADEC on modern engines). The procedure if an EEC 'failed' was to switch both EECs off (to prevent excessive throttle stagger - unlike FADEC, the engine could operate just fine with a supervisory EEC failed).

Problem was that the EEC ON/OFF switch was located on the aisle stand - right above the fuel cutoff switches. Turned out 'muscle memory' was when the pilot reached down there, it was usually to turn the fuel ON or OFF - which is what they did. Fortunately realizing what he'd done wrong, the pilot quickly restored the switches to RUN and both engines recovered. And yes, they continued on to their destination (RAT was still deployed since there is no way to retract it in-flight).

Previous event was with JT9D engines (United IIRC). In that case, only one engine recovered (second engine went into an unrecoverable stall), they simply came back around and did a single engine landing.

Realizing the ergonomic issue, the EECs were relocated to the pilot's overhead (retrofit by AD).

To the best of my knowledge, there hasn't been a repeat of an inadvertent dual engine shutdown since the EEC switches were relocated. It's also very difficult to 'accidentally' move the switches as there is a locking detent - the switch must be pulled out slightly before it can be moved to CUTOFF.

Sorry but you are wrong. The RAT was basic on the 767 - every single 767 built has one. The Gimli glider deployed the RAT (1982), and the Delta dual engine shutdown out of LAX deployed the RAT.

As has already been pointed out, these deployments were deliberate for test purposes and the approaches were done into airfields used by manufacturers for trials. Unless the Air India crew thought it would be fun to see what happened if they deployed the RAT shortly after takeoff, we are looking at something triggered by one or more of:

System-wide electrical issues
Double engine failure
Selection of fuel switch and/or fire switch on both engines

Any speculation about gear, flap, runway, etc. is redundant if the RAT did auto-deploy as it points to a very serious technical issue with the airframe rather than what was done with thrust levers or what the pilots had for breakfast.

I haven\x92t seen what the 787 cockpit looks like on battery power only but on the 777 it gets pretty dark with only the essential P1 instruments and VHF1 available until the RAT comes online, which is a measurable amount of time after deployment is triggered.

Confirmed, as so we can all move on, reference attached. And for the guy that flew 767\x92s for 40 years and didn\x92t know anything about it 😂

This seems to be the best summary so far. Based on the detail of the mayday its probably time to rule out the flaps, load shift, and other suggestions. Latest news is a quote from the survivor: " Suddenly, the lights started flickering – green and white – then the plane rammed into some establishment that was there" .

I cant think of any reason for electrical failure and "no thrust" (as per statements) without any visual cues other than (a) suicide, or (b) starvation. Is there any electrical failure that can cause fuel valves to close? I dont fly Boeing, so can any Dreamliner driver explain what conditions could trigger an overspeed and auto engine shutdown (quote from Google below)? Would short runway, and hot/low QNH do it? Also, what happened to the order demanding a full power down/recycle every 51 days?

The EEC has build in protections to protect the engine. One of these protections is the Engine Overspeed Protection, when the core engine exceeds 120% the EEC shuts off the fuel to the applicable engine.

I didn\x92t think this could be a dual engine failure related accident until reports of RAT deployment started to gather steam.
A few years back a B787 previously had a dual engine shutdown after rollout when the TR was deployed too quickly and not allowing the air/GND logic time to transition to ground mode before the TR deployed. If the TCMA had inadvertently latched the TR deployment from the previous rollout then it theoretically could be possible to shutdown on transition back to air mode.
Anything is possible with these high tech machines.

SLF. I don\x92t know how B787 systems work but if that\x92s correct it must be a possibility. It seems as though engines are working fine until airborne. I\x92d just been asking elsewhere if it were possible that an electrical fault with the software could prevent both engines running? I know they don\x92t require outside power to continue to run, but if software was disrupted by a catastrophic electrical fault (issues reported on previous flight supposedly) would they shut down? But an error in the software could be more likely than the sort of failure requiring multiple backups to also fail I guess, and would also explain the timing of the engines shutting down/throttling back.

RIP to all the victims.

Many GE engines - including GEnx-1B/67s - require microprocessors to be routinely replaced due to soldered joints failing after multiple cycles. There is a 2021 AD that notes "This AD was prompted by an in-service occurrence of loss of engine thrust control resulting in uncommanded high thrust" (I cannot post a link but google: 2021-25491 (86 FR 66447))

I am NOT suggesting that this specific failure mode happened here - for one thing, this would happen to one engine, not both. But on any flight it is possible that a unique set of sensor inputs to occur that are the first time any system has encountered them (example: NATS incident in 2023), and then you need failover & redundancy to keep things working.

The GE Aviation CCS system, which includes thrust management, has up to now flown for 1m flight hours without incident. It would be interesting to hear the perspectives of any engineers familiar with the system.

I had wondered about TCMA being involved. Software is extremely complex and there have
been examples in the past where it does something it wasn't supposed to do, causing an incident.

Presumably a dual engine shutdown under TMCA (i.e. similar to the ANA incident) would cause the RAT to deploy.

Obviously difficult to envisage what could cause an TMCA activation on both engines simultaneously given the safeguards in place (weight on wheels etc). However maybe the time delay from an erroneous TMCA activation on the runway/at rotation would lead to a loss of power 10 seconds later.

This was handled in this PPrune thread:
ANA 787 Engines shutdown during landing
and in AvHerald:
https://avherald.com/h?article=4c2fe53a&opt=0

Just to clarify one point: the ANA B787 was powered with RR Trent 1000 engines while the Air India had GEnx-1B67 engines.
So, the Air India thrust failure may still have its source in the TCMA system, however, if it's the case, the logical path must be somewhat different than for the thrust reversers of the ANA airplane.