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| BugBear
June 13, 2025, 17:11:00 GMT permalink Post: 11900702 |
Early number a/c
An early number 787 (in the first twenty four), had to make an emergency landing at New Orleans on a Houston to Newark flight. At this point, re Air India, with the RAT screaming in the original video, an electrical issue of some magnitude is at the fore. Each engine has two generated power unit (GPU). Total of four (NOT ground power unit). If one of these goes offline, the system adjusts. If an engine quits, two are gone, and the remaining two supply e power.
Powering up all four at once can cause a shutdown of all generated power. The question becomes which failed first, the engines or the electrics. The RAT deployment signals either both engines shutting down, or four GPUs. I think negative on Pilot Error. Whatever the direct cause, this amount of grief is impossible to imagine. God have mercy Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Electrical Failure RAT (All) RAT (Deployment) |
| BugBear
June 13, 2025, 17:59:00 GMT permalink Post: 11900750 |
Gear interrupted...
""I have now watched a number of "normal" 787 takeoffs online and in none of them does the gear go up super early, certainly not before the 10 seconds or so where this one seems to loose power. I think the flap/gear raising is wrong personally..."". Wazzajnr (below). #781
If trying to launch Flaps 0, and noticed by crew at liftoff then trying to extend flaps at 180 knots... While collecting gear? That must take gobs of power. Enough to cause overload and system trip? Perhaps a cascade of switching errors and system shutdown? Last edited by BugBear; 13th June 2025 at 18:15 . Subjects: None |
| BugBear
June 13, 2025, 18:24:00 GMT permalink Post: 11900781 |
Can I just clarify: the 787 has FBW and certain flight envelope protections. If the pilots suffered a dual engine failure after takeoff, they would pull back to stretch the glide as the computers will not allow the aircraft to stall. This is effectively what Sully did when he kissed it into the Hudson like a pro.
In any other aircraft, if you lose thrust in all your engines, you would be pushing the nose down immediately! Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Dual Engine Failure Engine Failure (All) FBW |
| BugBear
June 14, 2025, 00:19:00 GMT permalink Post: 11901019 |
Do you recall a 787 made an emergency landing in Louisiana on a revenue flight Houston/Newark in 2012? Your Post referenced an abnormal that may lend credence to a major power loss in this wreck. Never expected to see any surviving tail cone or Empennage structure. Quite a find Forgive the intrusion sir Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Generators/Alternators |
| BugBear
June 14, 2025, 02:34:00 GMT permalink Post: 11901089 |
Subjects: None |
| BugBear
June 14, 2025, 04:30:00 GMT permalink Post: 11901129 |
CompressorStall
""The chances of this are non zero, but remote. I say that as there appears to be no yaw, or other controlling of the aircraft - either by pilot or automation - that would suggest an asymmetric thrust scenario, even for a few seconds.""
Look again at the initial video. The heading of the a/c is definitely right of centerline. Look at the background as the fuselage points right, and the aircraft "drifts" left. Something's up, either an input yaw to counter a cross, or asymmetric thrust. Not a lot, but noticeable. It diminished as the a/c disappears.....So, not an exact simultaneous loss of thrust, but almost certainly a single cause. Can't see the Rudder, nor the orientation of the gear, either or both could cause the slight yaw I see. Last edited by BugBear; 14th June 2025 at 04:42 . Subjects: None |
| BugBear
June 14, 2025, 19:19:00 GMT permalink Post: 11901747 |
Unless ailerons float, she's rolling. Left
The left aileron needs to be viewed on another image. This comports with the aircraft pointing right, away from centerline. And would support pilots inputs if the starboard engine is the first to lose thrust. And an argument the controls were powered at this point
Subjects: None |
| BugBear
June 14, 2025, 19:36:00 GMT permalink Post: 11901759 |
Was....
There is at least one other. RTO? Who was flying. At V1 the tension can be too much for an inexperienced FO who is flying. The mayday may have been spoken by the FO, after Captain tried to snatch controls back. It would explain an inexperienced left hand on the levers, and a non concert close of the throttle(s)
Unless....Captain was guarding the throttles, Initiated abort, and rethinks. Engines run, and run, and run.... They die of thirst. Praying for an unbiased investigation and report ... Somebody needs to learn how to keep the lights on Last edited by BugBear; 14th June 2025 at 19:50 . Subjects (links are to this post in the relevant subject page so that this post can be seen in context): MAYDAY V1 |
| BugBear
June 14, 2025, 20:16:00 GMT permalink Post: 11901796 |
For me, I don't need to know. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR MAYDAY |
| BugBear
June 14, 2025, 21:19:00 GMT permalink Post: 11901847 |
Which side of V1
Also a newcomer here, but an experienced private pilot, Software Engineer with a degree in Aerospace Computer Science and former Head of Quality for Satellites and Interplanetary Missions. We have already seen bad software solutions and the results thereof in the 737 MAX accidents, which makes me wonder, if the TCMA can reach a state, where unintended engine shutdown is possible.
There is one system implemented in the 787, that has the authority to shut down the engines, based on software subsystem decision. Interestingly - according to the description in the patent below - the same TCMA software package determines the shutdown decision, in both redundant subsystems. Excerpt from the Patent: "Malfunctions in aircraft power plant thrust control systems can result in uncontrollable high engine power levels that are potentially hazardous or catastrophic for aircraft operation. A particularly hazardous situation is when a thrust control system failure results in one of the aircraft's engines continuing to operate at a high power condition and not responding to a throttle command to reduce power during takeoff, approach or landing. Typically, when this failure mode occurs, the actual thrust either increases to a significantly higher than commanded thrust and/or remains at a high level when the thrust levers are set for low thrust.... In one preferred embodiment the present invention is directed to a system and method for detecting and correcting a thrust control malfunction in an aircraft engine. The system includes an electronic engine control (EEC) unit that includes a first processing subsystem and a second processing subsystem, and a thrust control malfunction accommodation (TCMA) circuit included in the first processing subsystem and the second processing subsystem. Additionally, the system includes a TCMA software package executed by the first processing subsystem and the second processing subsystem, thereby providing redundant execution of the TCMA software package. The method of the present invention compares the engine's actual power level with a threshold contour defined by the TCMA software package. When the TCMA software package determines that a thrust control malfunction has occurred, based on the engine's power level exceeding the threshold contour, the engine is shut down by the TCMA circuit. The present invention is still further directed to an electronic engine control (EEC) unit configured to detect and correct an aircraft engine thrust control malfunction using an active-active functionality. The EEC includes a first processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs, and a second processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs." Just my 20 cents Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Engine Failure (All) Engine Shutdown V1 |
| BugBear
June 14, 2025, 21:31:00 GMT permalink Post: 11901857 |
TCMA
TCMA
Which side of V1 does TCMA lurk? If a pilot closes the throttles to abort, does the system allow it? After all, "too low thrust" is outside the contour.... Ya know, when every conceivable possibility (or close) has been de wormed, it"s usually something impossible, or too fearful...(Or dishonest, fraudulent, criminal ....etc ,? To include unnecessary, venal, and inappropriate) Sledgehammer, flyswatter.... MCAS Last edited by BugBear; 14th June 2025 at 21:41 . Subjects (links are to this post in the relevant subject page so that this post can be seen in context): V1 |
| BugBear
June 14, 2025, 21:50:00 GMT permalink Post: 11901869 |
Difficult!? Maybe not. If very late the flaps were tagged stowed, and there was a simultaneous gear up command, with FlapDown command, the overload could have failed a GCS. Then it becomes a switching exercise. (Automatics).
Alarms Warnings Impacted EICAS, ETC. it happened long ago, but we know what happens when an engine driven generator quits ..first it bangs for awhile, then it burns itself up, then ... Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EICAS Generators/Alternators |
| BugBear
June 14, 2025, 21:59:00 GMT permalink Post: 11901875 |
From tdracer
However, TCMA is only active on the ground (unfamiliar with the 787/GEnx TCMA air/ground logic - on the 747-8 we used 5 sources of air/ground - three Radio Altimeters and two Weight on Wheels - at least one of each had to indicate ground to enable TCMA). TCMA will shutdown the engine via the N2 overspeed protection - nearly instantaneous. For this to be TCMA, it would require at least two major failures - improper air ground indication or logic, and improper TCMA activation logic (completely separate software paths in the FADEC). Like I said, very, very unlikely. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FADEC Weight on Wheels |
| BugBear
June 14, 2025, 22:11:00 GMT permalink Post: 11901886 |
There was banging prior the failed generator in the 787 Emergency landing....plus loss of altitude, direction, and EE Does all elec load go to the opposite engine? Because if it does and that engine either fails or gets shut down mistakenly ....OOPS no Thrust, no Electrical power, only instruments from APU. If the APU started on climb, we know exactly what occurred....
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU Generators/Alternators |
| BugBear
June 14, 2025, 22:15:00 GMT permalink Post: 11901891 |
Philosophically, it is primarily pre-V1. It prevents uncommanded high thrust when you are trying to chop the thrust on a RTO. Overthrust can generally get you off the ground post V1, as can (stating the obvious on a pilot forum) a single-engine loss post V1. So OK to shut down post V1 if still on ground.
Last edited by T28B; 14th June 2025 at 22:20 . Reason: brackets completed Subjects (links are to this post in the relevant subject page so that this post can be seen in context): V1 |
| BugBear
June 14, 2025, 22:19:00 GMT permalink Post: 11901897 |
Could this potentially be tied to the 51 day reboot bug that was previously addressed? Specifically the part about \x93engine operating indications\x94
According to the directive itself, if the aircraft is powered on for more than 51 days this can lead to "display of misleading data" to the pilots, with that data including airspeed, attitude, altitude and engine operating indications. Subjects: None |
| BugBear
June 14, 2025, 22:24:00 GMT permalink Post: 11901903 |
OK, but even if we do assume that there was a major electrical fault which brought down the main supplies: multiple posts in this thread have already asserted that this would not cause the shutdown of the engines, and that even if the fuel pumps failed, suction would keep the engines running.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Electrical Failure Fuel (All) |
| BugBear
June 14, 2025, 23:40:00 GMT permalink Post: 11901962 |
Howdy
I am curious to learn what power source drives the high-pressure fuel pumps in the engine. If there is such a thing, I suppose there would.
Gearbox? This is at odds with a possible cascading electric failure that (might have) caused a loss of engine fuel feed. To my understanding on my ancient plane and engine design, the HP pumps that feed the nozzles are driven mechanically, which enables gravity feeding among other scenarios, but also assures the fuel supply is independent of whatever happens upstream of the nacelle. Except for LP/fire shut-off cocks.
There have been conflicting reports about the call to ATC. Original reports quoted the Captain saying "Mayday...no thrust, losing power, cannot lift". But I've seen reports today stating the call was simply "Mayday, Mayday" and then no further response.
Difficult to confirm so I wouldn't put too much weight behind it until something more official is released. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) MAYDAY |
| BugBear
June 14, 2025, 23:51:00 GMT permalink Post: 11901969 |
Not sure I would rely on the Times of India as a reliable source, but this is what they have reported...
Ahmedabad police confirmed the pilot's chilling distress call. It reached air traffic control (ATC) seconds before all communication ceased. Top officials said the jet had nearly exhausted the 3.5km runway at Sardar Vallabhbhai Patel International Airport - usually, 2.5 to 3km is needed for a wide-bodied jet. "The longer runway roll hints at a possibility of the aircraft not having adequate thrust for take-off," said a source close to the investigation. "The facts can be ascertained only after the black box is decoded." Subjects (links are to this post in the relevant subject page so that this post can be seen in context): MAYDAY |
| BugBear
June 15, 2025, 00:08:00 GMT permalink Post: 11901978 |
Lull
Consider losing one engine on the Dream. If it is a generator that's failed let's say #2 . Do the electric fuel pumps lose power? Only in #2? Does the mechanical pump start feeding right away? If so, is there a lull? Are both engines fuel pumps supplied off one Gen?
See I think there was no simultaneous loss of both 1, 2. The odds give me a migraine. I still wonder if TCMA knows the difference between parked, rolling, rotated brakes and stowed. Only parenthetically, it didn't do this Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Generators/Alternators |