Posts about: "EICAS" [Posts: 79 Pages: 4]

During a post-flight inspection, engineering discovered that all four engine fan cowl static ports on the 787-9 aircraft were covered with tape. This oversight, which occurred despite the aircraft's flight being uneventful, reduced redundancy in the engine electronic control system. Assuming here that only one engine was affected by taping.
https://www.atsb.gov.au/media/news-i...d-static-ports
"While the flight was uneventful, the covered ports meant that redundancy for the engine electronic control system was reduced;"

Not sure whether this aspect has been covered in respect of the Air India accident? Obviously did not adversely affect or alarm this QANTAS 787 freighter flight to the USA. If it had been a passenger-carrier, would the pax have noticed?
However the pitot obstruction/covers and static port taped/NZ A320 not taped (for a high-pressure hose wash) did kill many in past crashes.
A Lufthansa 777 Freighter's Static port left disconnected from its ADM nearly did. AoA damage by ramp vehicles have also killed many (Abidjan A310-300): Kenya Airways Flight 431 stick-shaker on rotate.
Any port in icing, a dust- or a rain-storm can become a portal to Paradise. Water ingested/sucked into a static system once gave me a very interesting ride/recovery challenge once above FZLvl in total IMC.
For maintainers, it's the ImPORTance of being earnest. Per the photo at the link above, what is a "barricade tape?"

Was there a follow-up "probe"? This raises a few flags. Blanks are everywhere on an aircraft parked for a few days or weeks. You need to develop a "blank stare". We'd have to assume that the ATSB pulled and reviewed the QF 787 recorders to ascertain the effect upon critical engine data. Yet maybe not? Doing so would have grounded the next freighter flight ex the US. But were they (later in OZ) able to post-flight compare the two engines comparative take-off and enroute/approach data? If not/why not? - and if so, what may they have found? Did the engines report anything of consequence via ACARS enroute? Are those engine cowl ports critical in any operational respects? IS/Was the tape used intentionally porous? Two totally different types of tape were used on the QF787.
Perhaps of greater significance: Are the various I/O plugs and ports (that festoon the EEC) prone to a mis-connect/disconnect?. I would imagine that an ECAM/EICAS would raise a red flag on some/most? Would a poorly-made connection or a duff-plug on an EEC severely affect its arcane functionalities and outputs?
Could the Air India event indicate yet another format outcome of pitot/static input error blight with the EEC. I'm sure that it must have those inputs. Like any port or orifice on an airplane, I'm sure that the EEC's sensors could well be partially or wholly internally obstructed. I've not heard of any such incident on another type being sheeted home to such an intrusion.

Covered at:
Dreamliner preflight error, ground and tech crew?

"The engine electronic control (EEC) uses the ambient air pressure data from the ADRS for engine control algorithms, engine thrust calculations and to optimize engine performance. The fan cowl static port air pressure data is only used when an EEC determines that the ADRS data is unreliable. Where no ambient pressure data is available, the EEC assigns a failsafe mode for continued engine operation."

"It would have set numerous FADEC maintenance faults and the "L/R ENG CONTROL" EICAS messages. However the ENG CONTROL messages are inhibited above 80 knots, so the crew would not have seen them until they landed, and we don't expect the flight crew to check CMC faults (I don't think there is anything that would prevent it, but unlikely there would be any reason for them to look).
Engine operation may have been a bit 'abnormal' - not up-to -speed on the Trent 1000 Air Data Logic, but the general rule is if both engine sensors agree but disagree with aircraft, the system defaults to the engine sensors to protect engine-to-engine isolation. Of course when engine sensed Pamb became greater than the P total, it likely would have faulted everything and gone to some default failsafe value."

The equipment on RAT/battery is limited:


(from the online 2010 FCOM)


(from the maintenance training )

The 787 battery fire report says the two recorders are on the left and right 28VDC buses. I don't think those get powered on RAT by the looks of it. I would wager you get whatever is on the 235VAC 'backup bus', plus the captain's and F/O's instrument buses via C1/C2 TRUs. You won't get all of that (like the F/O's screens) because the 787 energises/de-energises specific bits of equipment, not just whole buses.

Losing recorder power looks entirely expected.


400VAC/540VDC (+-270V) is not really known for blowing past input protection in the same way as actual HV or lightning. I would expect some optocouplers and/or transformers to be both present and adequate. There's definitely some big MOVs scattered around the main 235VAC buses.

Weight on wheels appears to go into data concentrators that go into the common core system (i.e. data network).

Presumably there is a set of comms buses between the FADECs and the CCS to allow all the pretty indicators and EICAS alerts in the cockpit to work. The WoW sensors might flow back via that, or via dedicated digital inputs from whatever the reverse of a data concentrator is called (surely they have need for field actuators other than big motors?). Either way, left and right engine data should come from completely different computers, that are in the fwd e/e bay (or concentrators/repeaters in the wings, maybe) rather than in with the big power stuff in the aft e/e bay.

It's exactly the same on the B777 - the centre fuel pump switches go on before start if the FUEL IN CENTER EICAS message is displayed. The switches go off again when the FUEL LOW CENTER message is displayed. On the ground, the B777 needs two power sources for both centre tank pumps to operate, so one pump is normally shed until after engine start. The centre tank pumps output about three times the pressure of the main tank pumps. Fuel is fed from the centre tank until the centre tank pumps are selected off.

Surely when the switches turn off there would be an EICAS warning (I didn't see any mention in the report of what messages were being displayed) to the effect that switches were in CUTOFF which might have prompted the query.

The phrasing “Why did you cut off?” doesn’t suggest surprise at an EICAS message, it implies direct observation or perception of manual action. This quote from the preliminary report reads exactly like what it appears to be; one pilot reacting to a control input he didn’t expect for which there was no plausible explanation .

Read the report. There is no evidence to support your contention that the question was asked as you have quoted.
The report simply says:

All the supposed quote does, is tell you that the person asking the question didn't perform the action, thus presumed the other had.

There are many plausible explanations, not just the one or two you might choose to see in this scenario.

There is an EICAS message that comes up when an engine is shutdown (there is a small delay), which might prompt them to look at the switch - or just the sound the switch makes could prompt a quick glance down at the switch.

I don’t know if the FDR measures the switch position or the electrical signal. The latter is probably more likely, although there has been much discussion around potential scenarios involving accidental switch movement as well as possible causes of electrical glitches. Let’s assume that the switches were actually moved, and ignoring the “bad faith” scenario, we need a situation that encompasses the switches being moved to Cutoff by one pilot, this action being queried by the other pilot and denied by the pilot who moved the switches.

For consideration, here is a possible scenario that hasn’t been mentioned yet and encompasses the frailty of human performance. The report mentions that the flight crew on the immediately prior flight had written up a "STAB POS XDCR" status message, and that troubleshooting was carried out. I wonder if the scenario could be that the accident crew received a Stabiliser EICAS message on or around take-off and the Capt (who was PM) decided to action the first checklist item immediately from memory, by intending to move the Stab switches to Cutoff but moving the fuel switches instead. As in all modern Boeings, the Stabiliser Cutoff switches are immediately next to the Fuel Cutoff switches and operate in the same sense (i.e. down for Cutoff). They are guarded and never normally moved but, with an intent to move the stab switches, “muscle memory” (cerebellum activation if you prefer) may have taken the Captain’s hand to the Fuel switches, which are operated on every flight. The FO (who is PF) is manually flying at this stage sees and queries it. The Capt denies it, as he doesn’t realise what he has done (confirmation bias perhaps). After a few seconds, the terrible mistake is realised, and the fuel switches are moved back to run, but sadly too late and the Capt makes a Mayday call.

Perhaps a bit of a stretch but not as much of a stretch as many of the other scenarios in this thread. I think it is a real possibility. Sadly, the only other explanation that I can see is the deliberate “bad faith” scenario, which we would all hope is incorrect.

Fly Safe
PJ88

This is pure speculation but I can envision the following sequence of events that would match the timeline and the little we know from the CVR and sequence of events.
- While PF is concentrated on flying the airplane, PNF moves the switches from RUN to CUTOFF in quick succession (for whatever reason).
- PF doesn't notice that the switches have been moved (again, he is concentrated on flying) but soon perceives the loss of thrust and sees a message on EICAS.
- PF looks down to check throttle position. It takes him a couple seconds to realize that the switches are in CUTOFF position.
- PF asks PNF (and his superior) "Why did you cut off the engines?" (or something similar). PNF anwers that he didn't (a lie, but we don't know if deliberate or just confusion / mental breakdown)
- PF realizes that PNF is in a wrong mental state, and attempts to restart the engines. It takes him a couple of seconds to move both switches because his other hand is on the yoke trying to stabilize the airplane.
- By then the airplane has lost too much energy for a successful recovery. One of the pilots calls MAYDAY because he knows that they are about to crash.
This sequence would match the timeline between the initial fuel cutoff, and when the switches were moved back to run position, and would actually indicate great presence of mind and quick decision from the PF.
Again, this is pure speculation but it would match well with the little information we have.

Best theory I've seen so far.


I assume the unusual alarm cacophony that erupted after cutting the engines would have been overwhelming. Agree an error in good faith. If bad faith were involved, the switches wouldn't have returned to the run position, or at least they wouldn't have been allowed to remain there.

A plausible theory, however, if that were indeed the case wouldn't supporting FDR data be available/have been included in the initial report?

If there was some kind of Stabiliser error message during the timeline of this accident it would certainly be mentioned in the preliminary report. I am sure that the investigators would have noted it and arrived to similar conclusion you did. A Stabiliser error message would be too relevant piece of information to ignore it in the preliminary report.

No he\x92s not.
Any EICAS message would have been recorded.
Straight from the report:

NOW READ IT AGAIN - SLOWLY

Excellent point!

Question: I imagine the accident crew /Captain at least would have been aware of this status message, or at least that it had been looked into. Is that fair comment, or known anywhere? Or maybe he even knew what they did, which may well have been FNF.*

I mean, possibly the Captain decided, since he had a young pilot flying, that he would try to avoid any potential Stabiliser problems from startling his junior pilot by pre-emptively cutting off the Stab control while they were still good. And didn't announce the intention because he didn't want to distract the PF, or make him even more nervous. Stuff like this does happen.

If he happened, as you say, to flip the Fuel Cutoffs instead, that's all that would show on the FDR.

Knowing who said what would be a big help.

*Fault Not Found, in case that's not an Aviation acronym.

You shouldn't be doing anything but flying the airplane soon after rotation, regardless of any EICAS messages appearing. Most airlines would have a 'no action until 400 feet' requirement.

Um, the flap and gear levers are a totally different design and they look, feel, operate differently. They are not even co-located, and occasionally people confuse them, withstanding decades of design efforts.
The fact that EICAS messages were recorded does not mean that they were provided in the preliminary report.

The notion is that around liftoff EICAS reported an error related to an error logged on the previous flight, that the PM felt it prudent to remedy the problem by cutting the stab cutoff switches, inadvertently cutting fuel. Action-slip, as mentioned countless times in these threads.

Totally agree. But look at the Luxair article linked earlier. ALL the PF did to apparently throw the PNF off and cause the crash was say "Looks like spring".

When I read that transcript, even I, a non-pilot, thought WTF!? (In that case, maybe the PNF thought "(He)'s trying to chat me up, and at the worst possible time," which could really have unsettled her, caused her to be reactive and 'snappy'.)

Funny how, when you think someone's doing something wrong, you're more likely to stuff up as well. The Staines crash had a big element of that. It seems to be contagious. We are suggestible creatures, or something.

P.S.
That's a funny rule. When one pilot breaks the rule and does something wrong, is the other pilot is not bound to follow?

no experience of Boeing at all here but would a stab trim issue have been highlighted by EICAS that early? I assume Boeings have take off inhibit logic to hide certain less than emergency conditions until above ~1500AGL? Would a Stab issue have been serious enough to immediately pop up?

Language:

Having lived in the Middle East for over 20 years, I am somewhat used to the Indian use of the English language. Therefore, I wouldn't look too closely at the usage of "transitioned"; it simply means moving from one condition to another.

The conversation of the pilots, on the other hand, will be very interesting. It should be analysed in the language they were speaking, considering whether this was their native language to start with. I assume that the conversation was in Hindi, translated to English for the report. In that case alone, a lot of nuance might have been lost in translation. That's without even considering the tone, volume etc. of the conversation.


Procedure:

I am an Airbus driver, so I am not familiar with the B787 EICAS. On the Bus, the ECAM would generate an ENG FAIL, followed shortly thereafter by an ENG ALL ENGINE FAILURE. I assume the B787 would have a similar event on the EICAS. Now, considering the time frame of how quickly things happened, there is absolutely no reason for the pilots to assume something was wrong with both engine cutoffs, unless they were physically switched off by someone. We are not trained to consider a fuel cutoff switch as the main reason for an engine failure, especially on the takeoff roll.


Question?

When I was a young F/O, some of the captains I flew with had the (annoying) habit of resting their hands just behind the thrust levers on their PM (PNF) sectors to 'be ready' to reject the takeoff. This would put the hands in the vicinity of the Fuel Cutoffs, which would, in turn, increase the chances of an unintended action on these switches. Is this a possibility, or am I way off?