Posts about: "Engine Failure (All)" [Posts: 489 Pages: 25]

Originally Posted by Pilot DAR

The engine \x93run/cutoff\x94 switches have a well designed locking mechanism, visible in the photo in the report as being in place to \x93run\x94. Grip by a hand is required to lift them over a lock, before they can be repositioned.

Originally Posted by EXDAC

That account, which is posted as being authoritative, appears to disregard SAIB NM-18-33 which states, in part:

"In order to move the switch from one position to the other under the condition where the locking feature is engaged, it is necessary for the pilot to lift the switch up while transitioning the switch position. If the locking feature is disengaged, the switch can be moved between the two positions without lifting the switch during transition, and the switch would be exposed to the potential of inadvertent operation. Inadvertent operation of the switch could result in an unintended consequence, such as an in-flight engine shutdown.'

Since the preliminary report does not specify that this SAIB was actioned on this aircraft we do not know if it was fitted with defective switches.

In my personal opinion a defective locking feature does not explain the reported event sequence. That does not mean the switches were not defective.

Originally Posted by za9ra22

As a passenger, it may seem as simple as that, but in reality it isn't and this incident can't be derived down to a simple either/or like that.

It would have saved a thousand hours of internet posts if it could!

Originally Posted by island_airphoto

It pretty much can and the odds are vastly in favor of a human hand on the switches. I *hate* the idea someone is either that clueless turning off random things or that evil, but the odds of anything else being the cause are rapidly approaching being hit by lightning after winning the lottery.
I know.......it could turn out to be some way out cause no one has thought off.

A buddy went down with double engine failure in an Aztec, when he switched tanks water that had leaked into the airplane formed an ice ball that jammed the cables to the actual switches between tanks and cut off all fuel. If he hadn't landed in a field and gotten an A&P on it before the temps went above freezing maybe no one would have ever known why 2 engines with totally separate fuel systems died at the same time.

Originally Posted by tdracer

The left and right engine wiring is physically isolated from the other engine - nothing gets routed in common bundles between the engines. Hence there is simply no way a localized issue could affect both engine's wire bundles. So we're talking two independent events that cause the switch output to electrical change state between RUN and CUTOFF without associated switch movement. So now were out in a 10-16/hr. territory. Now, these independent events both occur a second apart - 3,600 seconds/hr., so we've just added ~8 orders of magnitude to the dual failure probability number (10-24/hr.). Now, they both somehow return to normal withing a few seconds of each other - another ~8 orders of magnitude so we're talking 10-32.

Originally Posted by Sailvi767

On the other hand pilots deciding to end their lives in a spectacular fashion is not inconceivable. In fact over the last 25 years it may be the single most numerous reason for a catastrophic loss of a transport category aircraft operated at a major airline.

Originally Posted by mh370rip

Tdracer has certainly explained that separation of cabling runs etc would have it very improbable that a single cable fault or short would impact both engines simultaneously in the same way. The CVR data is derived from local sensors with a dedicated battery backup, however all the FDR data and the fuel shut off commands are electrical signals which ultimately have a common source in the aircraft power buses. A water ingress into the EE bay at rotate which momentarily shorted all the low voltage buses to higher AC voltage is unlikely but is it unlikely to the same extent.

Originally Posted by Herc708

Does the EAFR record the electrical / physical contact of the RUN / CUTOFF switch or, does it record a software 'EVENT' which has the same 'signature' as the RUN / CUTOFF switch being toggled. My thoughts are that the RUN / CUTOFF switch never moved but, the underlying software / hardware system mal-functioned triggering a scenario similar to both RUN / CUTOFF switches being triggered

Some Boeing SB's describe circuit board failures triggering all sorts of unexpected / unpredictable failures

Originally Posted by CharlieMike

I\x92d counter that order of likelihood by suggesting

(1) It\x92s still a likely response to ask that question if your colleague had just switched them off by action-slip.
(2) See my post above. Routine use of these switches is in one \x93event\x94\x85below OAT 40C you start both simultaneously and at shutdown you operate one straight after another.
(3) The interim report seems to leave out all information on verbal exchanges not specifically involved with a response to the abnormal situation.

Not saying you aren\x92t correct, but it doesn\x92t change the order of likelihood in my mind.

Originally Posted by RexBanner

It actually doesn\x92t matter who said it for the purposes of diagnosing deliberate action, if it\x92s someone trying to cover their tracks and deflect blame onto the other person it still represents cognition that the movement of the switches was a deliberate act and will have been recorded as such.

Originally Posted by adfad

(1) is true I give you that, but there is no followup "I didn't.. oh crap", denial is a reasonable response if you truly haven't registered doing something, but it is also a reasonable response if you want to confuse to delay

By precedent in routine operations I mean: is there a single example of these switches being cut off at takeoff like this? There is precedent for the wrong engine being shut down in a fire sure, and there is perhaps precedent for mishaps with the fuel switches in other cockpit layouts - but in the case of this layout, with this model of switch or even this 'style' of switch and placement, I cannot find a single example that would come close to the level of catastrophic action slip of pulling out and setting to cutoff both switches one by one.

I think the preliminary report is supposed to present all factual information - they could have left out "why did you cutoff / I did not" - I could understand if they left out sounds that could be ambiguous, perhaps indicating a struggle but not clear enough to present as fact. However, "positive rate / gear up" followed by 2 switches instead of gear handle is completely factual and relevant information, to exclude it makes no sense.

Originally Posted by Hawkeye777

THE LANDING GEAR

There are many missing jigsaw pieces here that are highly relevant to building an understanding of what these guys were going through.
One being that the gear was not raised. The report ( very oddly in my opinion ) is NOT declaring any voice data on the prompts/commands to raise it once they achieved a positive ROC after lift-off.
At lift off, it's pretty safe to assume ( yes, I know ) that everything was going according to plan....so why, oh why wasn't the gear raised.....?

This is quite extraordinary because:-

1. This sequence is muscle memory for every commercial pilot. It\x92s drilled into simulator sessions, route checks, and emergency training. Even during non-normal scenarios like an engine failure, the gear is typically raised before handling other procedures.
   
2. The delay is not explained in the preliminary report. The gear lever was found in the DOWN position in the wreckage. No mention is made of any mechanical failure or crew discussion about the gear. That silence is notable.
   
3. There was no declared emergency prior to 180 kt. No CVR audio so far suggests anything unusual before the sudden power loss\x97so there was no obvious reason to skip this SOP.
   
   
   

Originally Posted by Captain Biggles 101

With the greatest respect, I don't think any deliberate act has been proven. Allocating blame on assumptions should be avoided. People should work on facts, and then unconfirmed assumptions.

The only known fact is that engines for some reason were shut down. The other known fact is that there is a recorded indication that the start lever command was recorded as both cutoff in short succession then followed by idle detent causing a restart attempt.

I think the key unknowns here are important.
1. Was the start lever position recorded, or only the electrical signal? My money is on an electrical signal not position, therefore the manual positioning of the start levers is not conclusively proven.

2. The bulletin for locking mechanism for the start levers has been mentioned in the preliminary report. This is a huge unknown. Did that mean that in a failure that the levers could both move into cutoff at the same time? This occurred exactly as the aircraft was rotating and increasing pitch.

3. The information from the CVR if taken at face value must not be discounted. No pilot actually confirmed conclusively seeing the other move the switch. This could have been an assumption noticing an engine failure, seeing the start levers positions in cutoff or indeed seeing the start levers moved deliberately. This is a huge critical unknown.

4. One pilot asked 'why did you cutoff' and the other responded 'I didn't'. This is not a confirmation of anything for sure. In fact it is equally a suggestion nobody pilot moved the switches as it is saying they did. This is not conclusive. This raises an important question, was this genuine, did either pilot have any reason in their life to attempt to do this and then cover their actions? There is zero suggestion here either way, but hopefully investigators will already be looking at their backgrounds and state of affairs.

5. There is no indication who or what commanded the engines back to idle detent again. There is proof of both engines attempting to restart. I would take this as confirmation of teamwork existing on the flight deck, and this would suggest a lack of deliberate interference by either pilot. Should that have been deliberately done, so much more could have happened. It just hasn't been alluded to in the preliminary report.

My own impression is that it did not appear to be a situation of a deliberate act to crash. I say this as they appear to have both tried to save the aircraft and immediately restart the engines and recover taking some critical timely actions demonstrating competent reaction.

The timing of the commanding fuel to cutoff os critical imo. The aircraft was pitching. If an accidental command to cutoff occurred then I feel this however unlikely would have been made instead of another action. The only likely thing happening at that exact time or due 2-3 seconds after lift off was gear up. The CVR and recorded timing of engine failure in relation to that challenge and response in SOP will be key imo. Did the challenge for gear up occur before the idle detent electrical signals? Also, the focus should be on that bulletin for the locking mechanism for the start levers.

I just cannot imagine an experienced crew doing this by accident and the information just doesn't suggest a deliberate act.

My post is just to highlight huge lists of unknowns. The media appears to have made their mind up that the flight crew did this. I just highlight that is definitely not confirmed yet. We have a whole list of unknowns and conflicting communication that raises more questions than they solve.

I would urge zero conclusions be made, and RIP the crew and passengers. There are zero conclusions to what happened yet in my opinion, and I think the suggestion to relatives of the flight crew and families tragically killed that this is a known pilot deliberate action simply cannot be made at this point. We must not blame the flight crew prematurely or pretend we know what happened. I think the media should take note and back off from all the assumptions.

Originally Posted by andihce

I would like to raise a subject that I don't believe has been discussed here since the Preliminary Report was published, namely what happened to the aircraft's electrical systems as a consequence of the dual engine rollback and thereafter (RAT deployment, partial engine recovery, etc.). Apologies if I've missed posts on this topic here, but I have tried to review all of this thread quickly after previously reading most of it in detail.

As I understand it from previous discussions, without the APU, all electrical power except for that DC power provided by battery to essential systems would have been lost.

With the copilot as PF, would he have lost his instrument displays? If so, possibly additional startle effect and workload for him.

Why did the ADS-B information keep going on for so long? My understanding from previous threads was that loss of ADS-B was considered an indication of loss of electrical power.

What else would be expected with loss of power?

Some general speculation: I find it hard to understand the long delay from what must have been the onset of obvious issues to the time the first engine is set to "RUN". I wonder if much more cockpit dialog intervened, e.g. PF requesting PM to turn the fuel switches back on (since he had his hands full), and eventually operating the switches himself, with the delay and time gap between the two switches being turned to "RUN" being attributable to being preoccupied with flying the aircraft under trying conditions.

Originally Posted by Mrshed

These for me are very interesting questions.

There seems to be a period around second 12/13 post V1 where engines are (or should) be likely below idle, but prior to RAT power generation.

Note that the report explicitly states the RAT started providing hydraulic power 5 seconds after engine shutdown commenced. It doesn't reference electrical power. So we don't know whether this was at the same time - others may clarify re: RAT operation.

Originally Posted by Contact Approach

I\x92m at a loss as to why the discussion of an apu inlet door is relevant as it\x92s been clearly stated in the report to be working as per the conditions that were met.

Originally Posted by Semreh

Non-pilot here.

For those interested in reading more about 'action slips', including performing one routine function in place of another, the following free-access article goes into more detail:

Wiley Online Library: Oops! I Did it Again: The Psychology of Everyday Action Slips



As other people have perspicaciously pointed out, assuming that it was the Pilot Monitoring that transitioned the Fuel Cut-Off Switches from RUN to CUTOFF, what action would they likely have been attempting to perform at that stage of the flight for an action slip to be a likely possibility?

Alternatively, given that the PM was used to operating simulators, what conditions could have prompted him to do a sequence that was familiar to him of resetting the simulator (including operating the FCS switches), doing things that are inadvisable in a real aircraft?

If these are stupid questions, I apologise for taking up a mod's time processing the comment deletion.