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

Flight Radar 24 gives altitude with standard baro 1013mb. You'd have to know the QNH at the time to get the correct altitude.

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).

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.

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?

By wingspan, I mean one tip to the other tip.

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

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.