Posts about: "FCOM" [Posts: 38 Pages: 2]

I can only reiterate what I said, you can disagree if you like, I don\x92t have any current 767 documentation anymore (been off it for almost 10 years), I can 100% say that across all of the the 30+ airframes, 2 different models -200/300ER and 3 engine combinations (PW, GE, RR) that I flew... NONE OF THOSE 30+ airframes had a RAT. Maybe yours do? I don\x92t know. Feel free to post some 767-200/300 FCOM information if you have it.

What the 767s I flew did have, was a hydraulic generator (or 2 in some cases), but that sure ain\x92t a RAT.

LE devices extended on impact would correspond with the B787 auto-gap function that extends the slats in certain low-speed high AOA conditions for stall protection (aka "Autoslats"). Which this aircraft most certainly was in before impact.

Only to say, that LE devices seen extended on the crash a/c don't prove configuration on takeoff.

B777/787 rated/current/active pilot.

B787 FCOM:

I believe the loud bang that survivor heard was a (BTB) Bus Tie Breaker short.

Based on the comments made by the passenger who travelled on the aircrafts previous sector, speaking about air conditioning that was going on and off, I think a faulty (CAC) Cabin Air Compressors may have contributed.

The B787 FCOM has information about the about only two of four CAC’s being used for ground operation, maybe B787 crew can confirm.

I am curious if the increased electrical demand of the CAC’s shortly after take-off somehow contributed to this potential short.

If such a short did occur then the next question would be how this may influence the engine controls, but given the 248 day AD for electrical issues, it could potentially affect the engines.

I was also surprised to learn that the B787 EICAS actually has a ENG THRUST caution, so not a totally unexplored issue.

The aircraft register posted above does show an air compressor issue, albeit in 2015:

So one thing to keep in mind, the RAT can be deployed manually, but also comes automatically when certain conditions arise, everybody here is assuming it\x92s only on dual engine failure but there are 4 more conditions that trigger the RAT,

- all three hydraulic system pressures are low

- loss of all electrical power to the captain and first officers flight instruments

- loss of all four EMP\x92s (electro motor driven pump) and faults in the flight controls system occur during arrival

- loss of all four EMP\x92s and an engine fails during take off.

This all comes directly from B787 FCOM,



If we assume that what our survivor saw is correct, maybe it was an electrical failure, the aircraft had electrical issues in Delhi during departure and I checked the crash video again, I don\x92t see the strobe lights (neither wing or tail) and also no Anti collision light either. this might also explain the self starting APU on loss of the electrics (engine driven generators). That could also result in a loss of situational awareness with the speed, because of no indication, even the HUD would not work. The mayday call would still be doable because the radios work from the battery.

Yes.
1250m from the end of the runway, between high speed C and D, adjacent to the closed high speed.
There is nothing unusual with the rate of acceleration that is observable ninth video. You can work that out using google earth and the Indian AIP and/or state airport charts. The weight of the plane can be estimated by the flight time and pax load and an allowance for cargo. The simplified TO performance is in the inflight performance section of the FCOM, which you may find a copy on line.
The aircrafts rotation has no obvious issues, until a few seconds after achieving an attitude that is consistent with the V2+15-25 range, at which point the ROC visibly starts to decay.

Yes.
1250m from the end of the runway, between high speed C and D, adjacent to the closed high speed.
There is nothing unusual with the rate of acceleration that is observable ninth video. You can work that out using google earth and the Indian AIP and/or state airport charts. The weight of the plane can be estimated by the flight time and pax load and an allowance for cargo. The simplified TO performance is in the inflight performance section of the FCOM, which you may find a copy on line.
The aircrafts rotation has no obvious issues, until a few seconds after achieving an attitude that is consistent with the V2+15-25 range, at which point the ROC visibly starts to decay.

There’s been some debate over what electrical and hydraulic systems are powered. According to one unauthorized and Not For Flight -labeled FCOM copy that seems quite authentic:
The list of inoperative systems include most/all secondary fligh controls powered by the center hydraulic system. There we can conclude that centre hydraulic system electric pumps are not available when operating on APU RAT (or battery) only electrical mode.

Perhaps we could reincarnate Alex Trebek to moderate the forum--the first rule is that unless you have significant expertise or are providing uncontroversial factual information (posting and FCOM or MMEL for example), all posts should be in the form of a question.

I certainly am not advocating excluding crew actions from consideration but I am saying that uninformed rank speculation on that particular topic has much more potential to be harmful to actual people. PPRUNE is widely read by news outlets and Youtube pontificators. Give them a "credible" reason and they'll be digging into the personal lives of the crew in ways that none of us would like. If you want to ask "what would happen if the captain just switched off both engines at rotation?" then I suppose the answer might be that the result would be pretty much exactly what happened here. But I think it is a bad idea to go there so soon and without evidence, especially since we're likely to have more evidence soon.

Most? The Airbus I'm familiar with is 100' AGL or 5s after liftoff and I think this is common to all Airbus FBW. The B787 & B777 appear to be 200' AGL but I'm taking this from online FCOM extracts. The B737 does appear to be 400'. Company limitations may be higher.

As mentioned elsewhere both EK and Air NZ have had messy low level mis-set altitude capture incidents with the B777, but in isolation, obviously, this wouldn't cause RAT extension.

About airport cameras. Someone pointed out on the other thread that airports have more coverage than they would necessarily advertise. Presumably available to investigators but not to the public or press.

Even lower for the Tristar!

Yes yes back into my box.

yeah the low MCP alt setting/alt capture doesn\x92t make a whole lot of sense- the plane didn\x92t pitch forward it just failed to climb/lost lift

that\x92s not conducive with what happened nor does it explain why the gear is still down (although seemingly selected up given the boogie tilt) or the RAT deployed (if it really was)

I think the minimum autopilot engagement height is a FCOM limitation but not necessarily a limitation of the system, i.e. you can engage the AP lower than that but it hasn\x92t been technically qualified to work in all circumstances, although it might actually do that. Much like autolands on the B777 which specify F20 or F30 - it works fine with F25 in the field but it\x92s not certified. I know from personal experience that the AP on the 777 will engage below 200\x92 as I did it myself when the cockpit started filling with acrid smoke during rotation and needed to get the mask on ASAP. You used to be able to engage it on the ground (there was an RTO some while back due to \x93stuck controls\x94) but that might be inhibited now.

The ideas of mis-set MCP, AT modes, etc. were worth exploring but by this point, like the gear/flap/performance ones, there is enough convincing evidence now that a) the takeoff was normal until it suddenly wasn\x92t and b) none of the above would cause RAT deployment and a glide into the ground.

No it is actually a system limitation on the 787. A/P won't engage after TO below 200' rad alt. There is some form of interconnect/lockout in place. If you try engage at 195' you just get the AP disconnect tone.

An FCOM available in the net says that the FMC doesn\x92t accept Vr entry lower than Vr min or V1 min.

amazing thanks for the help !

I think this has been answered for 76 and 77 on the first thread but I can\x92t recall an answer for 78.
Can anyone confirm if you have inputed F15 in the FMC but selected F5 you would have some sort of FMC message displayed ?

I (and I think everyone else here) have been assuming that the FADEC does in fact have a dedicated permanent-magnet alternator, as is the case on the Airbuses (confirmed by FCOM) and surely the 737.

I have been told elsewhere that this is not the case. A read of the draft FCOM available online for the 777 & 787 makes no mention of a FADEC generator, but then neither does the 737 manuals. Is this simply a case of "Boeing thinks you don't need to know"?

It has been proposed that the primary source of power for the FADECs is actually the flight control PMGs, mounted on the engine gearbox, but that this power goes to the avionics bay, has failover switching gear, and comes back to the EEC.

Can anyone shed concrete light on this (e.g. a source that clearly states there is both an EEC alternator and a flight control PMG on the accessory gearbox)?

Alternator and generator seem to be used interchangeably in this context.

It's not quite that, but there is a list of received channels for a GEnx 787 in the FDR report into one of the original battery fires . Unfortunately, it is only a list of parameters that they used and verified in the investigation - the only ones listed for the engines are N1 and cutoff switch. Other accident/incident FDR reports might be more focused on engines and include a similar table.

I don't think you'll find an actual wire list for it (or it won't be useful) as apparently most/all of the data is via an ARINC bus.

I attempted to PM this but your inbox is full.

[SLF with an electrical background and some exposure to ground-side critical facilities power]

The details don't really matter, but this is the certification requirement:

​​​​​​​ https://www.easa.europa.eu/en/docume...s-engines-cs-e

Once again tdracer confirmed the PMGs for the FADECs in the first AI171 thread. He even explained the logic behind it and the connections with the onboard electronics:
- Each engine has a PMG for the FADECs
- Only for engine start the FADECs are powered by the aircraft
- Once the engines are running, this connection is opened
- It is verified, that the FADECs are then no longer connected to the aircraft electrical system. A failure to open the connection triggers a "No dispatch" message
- In case the PMG fails, the FADECs are once again powered by the aircraft electrical system

Yes, and probably much to @Roo's disgust, we had an instance where an engine shut down all by itself in the cruise; it was concluded that the fuel switch hadn't been "locked" in the ON position and was just sitting on the edge. It was then highlighted to all of us that the FCOM stated "give it a good jiggle" to make doubly sure it was locked in ON.