A bit more engineering input...
Probe heat (static, pitot) are powered by:
28V DC Bus 1 & 2
Essential AC bus (1)
Main AC bus 2
Emerg AC bus (via inverter)
Therefore one or more heaters are always powered even in emerg elec config.
ADIRU's
#1 & 2 are located together in rear AV bay
#3 is off to the side but in the
same AV bay below the cockpit floor.
The Air Data Modules are located
more forward of the ADIRU's in the
AV bay. #1 & 3 are on the left
side while #2 is on the FO's side.
Cabin Press controllers:
Report ADIRU data failure
ADIRU Data to the press controllers:
TAT, Mach and Static pressure
The descent rate warning as mentioned previously is for rapid aircraft descent where the cabin altitude will catch the aircraft altitude.
I was also given a run down on the mechanics of the standby
flight instruments, altimeter, airspeed and artificial horizon.
It seems that the airspeed and altimeter are piped to the air sources: no ADIRU needed and the standby artificial horizon is a gyro. This does not jive with some of the comments regarding loss of all three ADIRU's and the crew being 'in the dark' unless all of the ports were iced over and only attitude was available via the gyro.
Can someone shed some light on the above observation? Could it be that newer build aircraft have placed these old-timer gauges on the same train that the dodo bird rode out on?
Last edited by vapilot2004; 6th Jun 2009 at 08:22.
Reason: Italics indicate a running production change - backup no longer simple and straightforward