Posts about: "FAA" [Posts: 62 Pages: 4]

Look at FAA SAIB AIR 22-09.

Likely what happened here. ALT wiNdow set to 300.

Altitude hold and throttles rolled back, plane stopped climbing and descended into the ground.

Would explain the lack of thrust, but not the RAT deployment.

Survivor and eye witness recollections can be very unreliable and need to be treated with caution. There is easy access to the flight data recorders so hopefully it won't be too long before a preliminary report is out. Boeing must be praying for the cause to be pilot error, after the way in which the company handled the crashes of the B737 MAX, the FAA won't be impressed with a video of the CEO flying onboard and telling everyone how safe the aircraft is. Anything aircraft related and you can guarantee a worldwide grounding of the type, they won't be flying while Boeing works on a software fix.

Another hour spent sifting through the stuff since last night (my sympathies to the mods ). A few more comments:

"Real time engine monitoring" is typically not 'real time' - it's recorded and sent in periodic bursts. Very unlikely anything was sent from the event aircraft on this flight.

Commanded engine cutoff - the aisle stand fuel switch sends electrical signals to the spar valve and the "High Pressure Shutoff Valve" (HPSOV) in the Fuel Metering Unit, commanding them to open/close using aircraft power. The HPSOV is solenoid controlled, and near instantaneous. The solenoid is of a 'locking' type that needs to be powered both ways (for obvious reasons, you wouldn't want a loss of electrical power to shut down the engine). The fire handle does the same thing, via different electrical paths (i.e. separate wiring).

As I've noted previously, a complete loss of aircraft electrical power would not cause the engines to flameout (or even lose meaningful thrust) during takeoff. In the takeoff altitude envelope, 'suction feed' (I think Airbus calls it 'gravity feed') is more than sufficient to supply the engine driven fuel pumps. It's only when you get up to ~20k ft. that suction feed can become an issue - and this event happened near sea level.

Not matter what's happening on the aircraft side - pushing the thrust levers to the forward stop will give you (at least) rated takeoff power since the only thing required from the aircraft is fuel and thrust lever position (and the thrust lever position resolver is powered by the FADEC).

The TCMA logic is designed and scrubbed so as to be quite robust - flight test data of the engine response to throttle slams is reviewed to insure there is adequate margin between the TCMA limits and the actual engine responses to prevent improper TCMA activation. Again, never say never, but a whole lot would have had to go wrong in the TCMA logic for it to have activated on this flight.

Now, if I assume the speculation that the RAT deployed is correct, I keep coming up with two potential scenarios that could explain what's known regarding this accident:
1) TCMA activation shutdown the engines
or
2) The fuel cutoff switches were activated.
I literally can come up with no other plausible scenarios.

In all due respect to all the pilots on this forum, I really hope it wasn't TCMA. It wouldn't be the first time a mandated 'safety system' has caused an accident (it wouldn't just be Boeing and GE - TCMA was forced by the FAA and EASA to prevent a scenario that had never caused a fatal accident) - and there would be a lot embarrassing questions for all involved. But I personally know many of the people who created, validated, and certified the GEnx-1B TCMA logic - and can't imagine what they would be going through if they missed something (coincidentally, one of them was at my birthday party last weekend and inevitably we ended up talking about what we used to do at Boeing (he's also retired)). Worse, similar TCMA logic is on the GEnx-2B (747-8) - which I was personally responsible for certifying - as well as the GE90-115B and the 737 MAX Leap engine - the consequences of that logic causing this accident would be massive.

A TCMA bug just doesn't bear thinking about, I really hope that doesn't turn out to be the case.

TD, in this case, the RT call suggests we are a grand total of 1 choice, and that goes to a fair likelihood that a fleet wide grounding is in the offing. Adding system complexity dependent on sensor reliability has bitten us all in the past and will do again, and I have a bad feeling that is where we are at with this. The SSA guys will be working overtime, but this has had the hall marks of being a bad sensor/system event from the outset. Am laying bets that there will be a fleet wide grounding in the next 3-4 days, if not sooner. Inadvertent GA thrust after landing has occurred before, (had it on a B744 myself), and it is curious but straightforward to handle.

Possibly, but if it\x92s a problem that is due to negligence from say, the engineering department at Air India, then silence will likely continue while they go back in time trying to piece it together.

Gear and flaps are both hydraulic, and the hydraulic pumps typically act as effective fault-containment - a hydraulic failure or excess load doesn't result in excess demand on the electric side; the pump just starts to run out of output flow/pressure.

In addition, the 787 has four main generators and I believe the switching is segregated into at least two controllers, on top of the four separate generator control units.

And again, electrical failure should not cause engine failure - consider QF32 where the wiring to the engine was mostly severed and they had to drown it with a fire truck.

It's not. Boost pumps should be more-or-less unnecessary at sea level.

I believe the valves are almost all bi-stable power-open power-close. When not powered, they remain in the last commanded position.

The valves are located in the spar (hence being called 'spar valves'. The fuel tank is immediately above the engine so it is a very short pipe for suction feeding. Tail mount engines are potentially a different story...

A Prelimnary Report must be prepared within 30 days, but does not need to be public. May or may not have CVR/FDR data.

I agree. The subject aircraft was fitted with two Enhanced Airborne Flight Recorders (EAFRs), one of which is located forward and one in the rear. These recorders capture both voice (traditional CVR) and data (traditional FDR), and provide redundancy. One - presumably the one in the rear - has already been recovered.

Two weeks is likely long enough for the investigators to determine if a systems failure might, in any way, have been a possible cause. I am sure that if there is any reason to suspect that a systems failure may have been a probable cause, or even contributed in any way to the accident, Boeing, GE, the FAA, or the Indian DGAC will promptly advise 787 operators.

No evidence of engine failure

No evidence of RAT deployment from a poor image.

No evidence of electrical failure.

The teams of lawyers in the UK representing 53 grieving families will be working over the weekend to sign up said families to a class action.

​​​​​​​This is going to get messy.
​​​​​​​

The problem with the way the probability of events is calculated, is that that can only be done with the available events/data that is known or can be foreseen or at least theorized. Throw in an event that wasn't foreseen and the whole 1 in a billion suddenly drops to something a lot more likely. The one that springs to mind is AA191. MD convinced the FAA that the LE Slats did not need a physical interlock to prevent inadvertent retraction in the event of hydraulic failure as the probability of multiple systems failing at the same time was 1 in 1 billion or whatever it was. But no one foresaw the airlines using forklift trucks to remove the engine and pylon assembly to save 100's of hours labour. When you add this into the calculations, the odds must drop dramatically. And on that day, the event happened. No 1 engine departed the aircraft over the port wing, the slats retracted, slat disagree warning system was disabled, the stick shaker and stick pusher failed on the Captains side (PF) and as he allowed the speed to decay to get to the SE climb out speed, it dropped below 162kts and the port wing stalled as the slats were retracted. If MD had fitted a physical lock on the slats, AA 191 on that day would have been an emergency but very likely have returned for a safe SE landing.

In summary, these billion to one events are only billion to one taking into account what we knew and predicted at the time. Throw in a wild or unpredicted event and all bets are off.

Also, a Billion to 1 event only happens 1 in a billion times. So if you run the sequence 10 billion times, then in theory, it will happen 10 times but it may happen 20 in the 1st 10 billion or 5 and as skwdenyer stated, it can happen at event 1! Toss a coin 20 times and probability says you will get 10 heads and 10 tails but all the tosses are independent, so you could get 20 heads or 20 tails or any other combination. The same applies to billion to 1 events.

At this time I think whether or not the 787 fleet will be subjected to a grounding order is indeterminate. The recorder units have been available for enough time so that it is reasonable to believe the fundamental "what" of the accident has been identified, even though the "how" and "why" will require more information than will be found in the recorders. I don't think the status of this component of the investigation points one way or the other to a grounding order.

However, the fact that the very highly authoritative poster fdr has anticipated a grounding order, and if I understood the very succinct (adjacent) post by another such authoritative person, PJ2 also anticipates it .... while I do not claim to understand their reasoning or the aeronautical or systems information on which it is based, but despite anything else I'm not going to disagree.

Several prior instances have been referenced. The deferral of a grounding order following Lion Air 610 strikes me as part of the overall MCAS debacle; regulatory capture, "narrative management" by the OEM. This accident has happened in a considerably different context. The previous grounding order that gives some concern is the one issued after American 191.

Not the order itself. Rather, after the non-U.S. operators had inspected their fleets and were able to report whether or not any engine-attachment structures (I don't want to get it wrong so I'm not specifically referring to "pylon" or "bolt" etc.) were damaged, they sought lifting of the order. The FAA Administrator kept it in place. The non-U.S. operators sued in federal court, arguing (at hopefully only slight over-simplification) that the U.S. was obligated by international convention to accept the airworthiness certificates of the other States in which those operators were legally organized. They won their case, too. . . . .

But at the time British Caledonian among other non-U.S. operators challenged the FAA Admin. to lift the grounding order, were any of those non-U.S. operators aware only of the proper maintenance condition of their engines' attachments, or were they also aware of the change in the aerodynamic qualities of the aircraft resulting from the asymmetric slats caused, in turn, by the severance of the hydraulics? If they did not yet know about the fact that the asymmetric slats caused the stall speed to increase, then their airworthiness certificates should not have been given legal deference. (If anyone knows the state of knowledge of the non-U.S. operators when they first challenged the FAA's grounding order, any information (or reprimand either for my lack of knowledge or thread drift) via PM will be greatly appreciated.)

So if the 787 fleet is in fact subjected to a grounding order, one hopes that the conditions for lifting it will be determined with great clarity. Not to drift over the edge, but the MAX order and its lifting might not give great confidence on this point.

Related to all this is the suggestion, way upthread, that Annex 13 is no longer fit for purpose. Respectfully stated, but I disagree. What would be proposed to update it? Until this tragic accident is resolved, what prospect is there to engage Member States (of ICAO) plus all the credentialed observer organizations in the process to rewrite it? Also, since Sully changed retirement careers the U.S. has not had a Permanent Rep to ICAO (let alone one confirmed by the Senate for Ambassador rank).

What about keeping the investigation process and results insulated from the pressures for drawing into the litigation process? Early disclosures of partial information would tend to erode that insulation - and for what gain?

The phrase by Icarus (post at 09:25) is one I would like to borrow - though giving attribution to an anonymous callsign could get tricky . . . . "narrative management, damage control, and pass the liability parcel."

I recall an extremely pissed-off Freddie Laker expressing his view that it was a maintenance error and that "the last thing you should do is graunch the engine up there with a forklift."

Would anyone know whether this AD is relevant?

FAA Orders Boeing 787 Inspections to Fix Water Leak Issues

​​​​​​​
I add this note: the background on this AD is here:
https://www.federalregister.gov/docu...pany-airplanes
T28B

Water ingress into the E/E bay is a serious issue. The B744 had this issue in the past causing serious problems, one of which was fortunate to not lead to a loss of the aircraft, on a B744F. The B744 pax aircraft had a number of water problems related to the toilets and the galley. The forward galley on the B742/3s had many issues.

Any large aircraft going through maintenance is interesting to observe the extent of corrosion that occurs near toilets and galleys, and from water lines.

The B777 was not immune to this either. The potable water tank failing caused one of our aircraft to have 6.5 tons of ice accumulating in the underfloor area of the aft cargo hold, which we detected on a preflight walk around as a series of water streams from the drain holes in one area of the aircraft. This was an interesting item for CG, a note on weight, but only affected the electrical services related to the aft cargo systems.

Water accumulations on the B744 came to light at rotate, and took out a lot of electrical services.

My suspicion is some cause such as this will come to light shortly.

The water leak issues with the B787 go back to in service reports in 2014 and before, considered an unsafe condition in 2016, and were covered by AD 2016-14-04. This latest AD is curious as it stems from an administrative oversight in the drawings of the aircraft, that arose on aircraft manufactured from 2018 onwards. 2025-09-12 stands alone related to missing sealant, following the drawing oversight in production. It did not affect all aircraft. The earlier AD, 2016-14-04 was related to water line coupling issues, and is in Service Bulletin B787-81205-SB380009-00 WATER/WASTE - Water System- Potable Water System - Couplings Replacement. It notes on page 21 of 229 the reason for the work

The latest AD and the earlier AD highlight that problems can occur, and have done so in the past. Both of the E/E bays contain stuff that is nice to keep dry and operating, and prior events have shown that multiple system failures can and have occurred when a flood is added to all the black boxes sitting innocently on their racks.

The ADs are not necessarily directly related to the specific cause, they highlight the potential for water damage and that bad stuff happens. In two cases I investigated, the event occurred at rotate. Both were B744's one pax, one F.

Compound, unrelated system failures at rotate? Single cause? Water in the E/E bay.

The amount of flooding that occurs in the toilet cubicles is unfortunate, apparently towels still fit well into toilet bowls, signs are disregarded etc. Coffee grounds block galley drains with monotonous regularity, the planes are only as good as we care for them, and passengers seem to have odd ways of treating the conveniences.

This page https://i1.prth.gr/images/w880/jpg/f...air-india.webp (update: also https://www.protothema.gr/images/w13.../air-india.jpg ) is an alleged summary of the preliminary report, posted by the Greek journal. One suspicious thing is it lists the URL of the report, but that's 404.

I'm posting this so that others can scrutinize the thing.

[update] The more I look at it, the less I believe it. The "Immediate ActionsTaken" and "Next Step" sections could not be in a preliminary report at this stage. Some details are wrong (like the state of the surviving passenger) or made up (the FAA emergency AD 2025-16-51 listed as source is not there: https://drs.faa.gov/browse/ADFREAD/doctypeDetails ).

The Ipeco seats fitted on the 787 (and other airframes) have had numerous problems and numerous Airworthiness Directives to correct issues of uncommanded movement. They are not exclusively electric (i.e. can also be manually adjusted), and presumably there is some sort of pin or locking mechanism to hold them in place and this mechanism (at least in original form or if not corrected) has been known to fail.

The most famous incidents involving the 787 resulted in uncommanded forward movement of the seat, resulting in inadvertent depressing of the yoke and an unexpected pitch down. Other Ipeco seats have been implicated in unexpected forward AND rearward movements. The FAA published an AD just a couple of days ago related to an Ipeco seat doing just that (different model seat not on Boeing planes, FWIW).


You're probably right. Until we start getting reliable information from official sources it's wise to take the theories of a single news outlet with a huge chunk of salt.

It was assumed for decades that in the event of uncontrollable high thrust (UHT) that the pilot would cut the fuel. Until there was a UHT event (1999?) on the takeoff roll and the crew - in an RTO - rode it all the way down and off the runway without cutting fuel. TCMA is primarily about the RTO scenario (throttle back to idle), and after that fleet event it became a requirement for FAA Part 25 certification.

What Alty posted is correct. There have always been single faults in the engine control systems that could cause uncommanded high thrust (UHT) - and such failures were considered in the safety analysis (e.g. FMEA) with the note that it wasn't unsafe as the pilot would shutdown the affected engine. Then there was a 737-200 event (JT8D engines) (1999 sounds about right - I'm thinking it was either an Egyptian operator or it happened in Egypt, but don't hold me to that) - the JT8D had an issue with excessive wear of the splined shaft that provided the N2 input into the hydromechanical fuel control. In this event, that splined shaft started slipping - causing the fuel control to think the N2 was below idle, and it keep adding fuel to try to get the N2 back above idle. This caused the engine to accelerate uncontrollably - the pilots pulled back the throttle and performed an RTO, but the engine didn't respond, and they went off the runway at low speed. Everyone evacuated safely, but the aircraft was destroyed by fire.

The FAA pointed to this accident and said we couldn't depend on crew action to shutdown a runway engine, and therefore any single failure that could result in uncontrollable high thrust was not compliant with 25.901(c) (basically says no single fault can result in an unsafe condition). This basically made every commercial airliner flying non-compliant as every turbine engine control system at that time had single faults that could cause UHT . A consequence of this was everyone was effectively prevented from certifying any further engine control changes since we couldn't show compliance with 25.901(c) (even if the change actually improved safety). The FAA and EASA were forced to issue partial exemptions for all existing aircraft/engine combinations, with the stipulation that they wouldn't certify any new engines that didn't address UHT. A working group was put together at Boeing to come up with some way to comply - and they eventually came up with TCMA , only active on the ground since UHT was only considered unsafe when on the ground - first incorporated on the GE90-115B/777-300ER/200LR.

I've never been 100% comfortable with TCMA (for reasons that should be all to obvious right now), but the regulators gave us few options.
BTW, during the early development of the 747-8, we didn't have a robust way of providing air/ground to the FADECs - which the FAA immediately found objectionable since they never wanted the risk of TCMA being active in-flight. I eventually came up with a design change that would provide a robust air/ground indication (it solved several issues we were confronting at the time), so that concern went away - which made the FAA very happy.

FLS here with engineering background, a simple question, how the TCMA software is coded, multiple designers, on different hardware and redundant? Can be a bug on that system definetevely impossible?