Posts by user "NSEU" [Posts: 7 Total up-votes: 0 Pages: 1]

NSEU
June 13, 2025, 07:40:00 GMT
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Post: 11900117
Flight Radar 24 gives altitude with standard baro 1013mb. You'd have to know the QNH at the time to get the correct altitude.

Subjects: None

NSEU
June 30, 2025, 13:14:00 GMT
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Post: 11913615
A maintenance engineer looked into the gear tilt issue. The 787 has no hydraulic sequencing valves like traditional Boeings, and the bogie tilt command is simply generated by gear lever movement. So, I suppose the doors dropping before or after the gear tilting may simply be who gets there first.

That is not to say loss of hydraulics also causes "toes down" because of bogie imbalance or aerodynamics (as previously mentioned).

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Gear Lever

NSEU
June 30, 2025, 13:35:00 GMT
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Post: 11913630
Originally Posted by island_airphoto
If rigorously applied, an "engine thrust balancer" would cause the good engine to fail if something happened to the other one. Surely there is some logic in there somewhere to give up and disconnect past a certain amount of adjustment??
* as for why not before, probably because it didn't happen that way or in Boeing's worst nightmare some weird corner case in the software that does this if certain parameters are in rare combination.
The FCOM explains that the system only operates when there is a large thrust to weight ratio and will maintain the required climb performance. If applied during an engine out, it will provide directional control only when airspeed drops below normal operating speeds.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FCOM  Parameters

NSEU
June 30, 2025, 13:59:00 GMT
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Post: 11913644
Originally Posted by Phantom4
Have the spring loaded Fuel Shut Off Valves been examined by GE on both engines???
Why would spring loaded valves fail on both engines? The final valve in the GEnx Fuel Metering Unit (FMU) before the fuel flow meter and things like the fuel nozzles, is called the HPSOV and is spring loaded to closed, but fuel from the Fuel Metering Valve (FMV) can keep it open with minimal pressure (certainly enough presssure for engine start). Tank electric pumps and the engine-mounted, mechanically-driven two-stage pump supply fuel to the Fuel Metering Valve. During main tank pump failure, the engine mounted pump suction feeds the engine. There are altitude limitations during climb (according to the FCOM).

There are several ways that the HPSOV can close:
An EEC (engine ECU) can close the upstream Fuel Metering Valve (FMV) electronically, so the HPSOV will lose its opening pressure.
The HPSOV can be acted on by a Shutoff Solenoid Valve (which directs fuel pressure in an opposite manner to the pressure coming from the Fuel Metering Valve).

Unfortunately, the diagram I am using is truncated, and I can't see if the Shutoff Solenoid Valve is magnetically latched in its last commanded position like typical fuel shutoff valves. Nor can I see what controls it. I suspect things like the respective cockpit fire handle and fuel cutoff lever, but also EEC commands.

There is probably a copyright on the diagram, so I won't post it here. Perhaps someone can fill in the gaps for me?

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FCOM  Fuel (All)  Fuel Cutoff  Fuel Cutoff Switches  GEnx (ALL)  High Pressure Shutoff Valve

NSEU
June 30, 2025, 14:10:00 GMT
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Post: 11913661
Originally Posted by jdaley
ADS-B stops 330' from the end of the runway, well before top of climb. A previous poster stated that ADS-B granularity on the 787 was 25'. As the aircraft obviously climbed higher than 71', it's reasonable to assume that ADS-B was about to transmit 96' when the electrics failed. Looking at the CCTV, subjectively, the aircraft reaches the height of a wing about 7s after rotate and top of climb about 7s later.
By wingspan, I mean one tip to the other tip.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB  CCTV

NSEU
July 13, 2025, 06:47:00 GMT
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Post: 11921059
Originally Posted by Engineless
A douple-pole switch. One pole used for FDR signal for the physcial switch position. The other pole for the electrical switching circuit.
Only double? The 767, 737NG and 747-400 have 3 poles, the 777 has four. Have you looked at the wiring schematics for the 787? (ATA chapter 76)

The pin groupings are usually in 3's.

e.g.
1,2,3 is one pole
4,5,6 is another
7,8,9 etc.

I have one 787 fuel control diagram which suggests 3, but there may be more

Thanks in advance

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FDR

NSEU
July 13, 2025, 06:59:00 GMT
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Post: 11921065
Originally Posted by Alty7x7
Would not expect an FDR dedicated pole. They might pull the FCS position from the FADEC, since what really matters is what the FADEC receives as a command. I would expect two poles dedicated to the two circuits, one routed to each FADEC channel, and the others to the non-FADEC-reset-command functions.
I have a simplified 787 fuel control diagram showing 3 outputs from the fuel control levers. I suspect it represents poles. One signal goes to the EEC for "reset". One signal goes the fuel valves. Another signal goes to a Remote Data Concentrator where the signal is digitised and sent to innumerable devices (including the EEC and the FDR). That is not to say there are more. I don't see a line to the wing spar valve.

The 747 has 3 poles per switch. To send signals to all the systems it needs to, splices and multi-output relays are involved. On some aircraft there are even separate power sources going to some of these poles.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FADEC  FDR  Spar Valves