Posts about: "Engine Failure (All)" [Posts: 410 Pages: 21]

Of course the RAT will deploy if all three hydraulic systems have low pressure even with both engines running. This is the case on the 77/78.

Well, the certainly sound like they are working; failed engines sound different. No sign of smoke or damage either.

Conceivably, it could be a double engine failure but that's very unlikely.

The chances of a double engine failure on take off are like a billion to one, and I think are certified to a million to one occurrence.

As you say they still provide power and pressure even if not running

Ok, so...

Some have said the RAT appears to have been deployed. This would suggest a hydraulic/electrical failure on the plane.

A hydraulic/electrical failure could well make it impossible to retract the gear immediately.

But, what do flaps do in the event of a major hydraulic/electrical failure? Is there a default that they revert back to? I was under the impression the RAT can't power the flaps?

We can, I think, rule out engine failure, at least single engine failure because the rudder is still straight on in the
Video. You can also hear the engines..

Doesn't work like that, and significant logical errors have been made on that basis in the past. The chances of simultaneous independent engine failure might be a trillion to one, being a million million.
​​​​​
But failure is often not independent. Hit a flock of birds with both engines, run out of good fuel, etc etc - then the probability is primarily that of the root event.
​​​​
Edit: I make no comment on whether they were running or not in this case, only the statistics

Primary trigger: Loss of all four AC power sources.

• These include:
  • Left Integrated Drive Generator (IDG)
    
  • Right IDG
    
  • Left Backup Generator
    
  • Right Backup Generator
    Engine failure alone does not trigger the RAT, must be all of above

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.

Regarding that possibility some members here are posting a scenario where RAT are deployed, could this be possible (im no 787 driver at all)?

1) Near the moment of Rotation or a few seconds after it, an Engine failure occurred. (Bird, Fod, Mx, Tech, etc)
2) By destiny irony as in Kegworth or Taipei aviators cut the good one by mistake.
3) No running engines, RAT comes alive...

May all RIP, such a sad day for us all...

I think it may be a simple case of inaccurate takeoff performance data, or inadvertent retraction of flaps instead of gear (this can happen and does happen).

I'm no expert and open to discussion, but it looks to me like the slats are somewhat extended but the flaps weren't, or at least not from the angles we have seen so far. The autogap system on the B787 will automatically extend the slats if they are already in the middle position (i.e Flaps 1) with KIAS <225. Perhaps, either the inaccurate input for takeoff performance produced figures that allowed a Flaps 1 departure, leading to a longer takeoff roll and then once out of ground effect, insufficient climb gradient and a pilot induced stall. Alternatively, at the point where you would likely ask for gear up, the PM has inadvertently selected Flaps 1 from Flaps 5 leading to the same effect. Pilots experienced startle and shock, declared a Mayday as they knew they were descending when they shouldn't be and didn't have time to appropriately react.

Dual engine failure is obviously a possibilty however rare it might be. but it doesn't look like any catastrophic failure from the video. Clearly a sad day for all in aviation and looking forward to the official investigation and results, hopefully something we can all learn from.

and people are saying this happened all at the same time within 30-45 seconds ?

Forgive me if appear to be being a bit pedantic but the 787 does not have IDGs and BUGs.
Each engine has two identical Variable Frequency Starter Motor Generators.
They are a combined starter motor and generator.

More in this ancient thread here-
787 electrical system - variable frequency generators?

the plane took off too slowly the issue was from before the plane left the air

The screen height requirement relates to an engine failure at V1 with a continued take off. Without an engine failure, ( I.e. on the vast majority of take offs) the height at the end of TODA should be much higher, regardless of the use of reduced thrust.

The chances of hitting a flock of migratory birds on take off near a tidal estuary are considerably less than a billion to one.

That looks like wing tip vortices, spreading out after rotation/liftoff, picking up some dust from beside the runway well behind and below the aircraft.

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.

Both videos evidence a normal rotation and climb followed swiftly by an abrupt cessation of the climb. No sign of yaw. But an apparent catastrophic loss of thrust. To me this points to dual engine failure. Statistically the most likely cause would be bird strike. The flap/gear configurations are probably not causative.

The theories concerning inadvertent flap retraction are not consistent with the apparent transcript from the mayday call made or rat deployment. In the first video that circulated, the engines can\x92t really be heard (certainly not producing any significant amount of thrust). If the aircraft was climbing out misconfigured, those engines would be screaming. Instead, all you can hear is the rat.

Similarly - a bird strike, knocking out two engines simultaneously is a noisy/messy event and I would expect to see evidence of this occurring in both videos, and in the area at the point of ingestion. The engines don\x92t just roll back with a bird strike - they surge, smoke, bang and splutter. It would be very apparent.

At this time, I think everything is pointing towards both engines simultaneously having their fuel feeds interrupted between V1 and Vr. CVR/FDR will be interesting.

I hate to say it but it looks to me like a dual engine failure or both engine master switches set to off after take-off.

Both situations are harrowing 😣

RIP and thoughts to all the families

The issue I have with the \x91mis-selected flaps up\x92 theory is that if PM had accidentally retracted flaps, I\x92d expect the PF to lower the nose, apply max thrust to try and accelerate by flying level or in a minimal descent. In this accident, the nose never seems to get lowered to decrease the AoA, in fact pitch increases just before it seems to stall. I\x92d also expect similar for an overweight takeoff, thrust or loadsheet error.

The fact none of the above happened, coupled with the lack of landing gear coming up, makes me think they didn\x92t have thrust to play with.