EICAS: Flight controls on ENG page

[Hardy Heinlin]

In my screenshot, I forgot to disconnect AC bus 3 which powers all four oil pressure indication systems. On Delcom's photo AC bus 3 wasn't powered probably.

On Delcom's photo, I also wonder ...

... why the amber band is shown on the oil pressure tapes with the engine shut down.

... and why the magenta fuel-run lines are missing on the N2 bars with the fuel switch in cutoff.


Cheers,

|-|ardy

[John H Watson]

In my screenshot, I forgot to disconnect AC bus 3 which powers all four oil pressure indication systems. On Delcom's photo AC bus 3 wasn't powered probably.

It's unlikely a complete Bus was dead. Both Rudder Indicators require 28Vac from Bus 3.

... why the amber band is shown on the oil pressure tapes with the engine shut down.

... and why the magenta fuel-run lines are missing on the N2 bars with the fuel switch in cutoff.

Fuel Valve Control CBs pulled for 5 minutes? (L10~L13 on P6). The EECs remain unpowered, perhaps because the Ground Handling Bus is keeping relay R7307, etc, unpowered. Perhaps the magenta fuel run lines will disappear because of a lack of 28volts DC at EIU pin G7 (Ref Wiring Schematics 76-11-01 Sh1&2)?

Rgds
JHW

[John H Watson]

P.S.

Was the lower rudder removed from the aircraft without pulling the rudder indication CBs?  :twisted:

[Holger Wende]

Hi,

In Delcoms photo above #15 the right (outboard) elevator indicator is down.

What sort of indication would show up when inboard and outboard elevator positions (or related sensors) disagree?

And why is the elevator indication "limited" to outboard elevators only?
Just the larger surface is indicated?

Or is the chance of failing inboard elevators too remote because each of the inboard elevators are powered by 2 hyd. systems, whereas the outboard elevator seems to be powered by only one hyd. system?

Regards, Holger

[Jeroen Hoppenbrouwers]

From a previous message about this subject:

1. Inboard elevators are controlled by pilot/AP input.
2. Inboard elevators position is sensed by the outboard elevators actuators.
3. Outboard elevators therefore follow the inboard elevators.
4. Outboard elevators have the position feedback sensors for the flight deck.

Lots needs to go wrong before there is any disagreement between inboards and outboards plus a flight deck indication not suggesting this.

[John H Watson]

2. Inboard elevators position is sensed by the outboard elevators actuators.

i.e. there is a mechanical linkage between the inboard elevator surface and  the hydraulic actuator of the outboard elevator. The outboard elevator is essentially a "slave". If the linkage breaks, the outboard elevator returns to neutral. Unfortunately, this would leave you without any indication of what the inboard elevator was doing. You get the same lack of indication if you lose hydraulics to the outboard elevator.

After hydraulics are turned off, the outboard elevator is at the mercy of prevailing winds. However, there is hydraulic fluid retained in the mechanism to act as a damping force.

Rgds
JHW