View Full Version : Source of Power NG

Capt Apache
10th Jul 2007, 08:52
What is the source of power for the Fcc A and Fcc B? Also can someone tell me the source for the EEC.Does the Fcc have back up battery power incase of loss of both IDG's?

10th Jul 2007, 17:58
I do not have specific knowledge of the NG however as a generalisation I would expect the FCCs to be powered from their respective AC Buses with no backup from the Stby system.

ALL EECs that I have come across are powered by a dedicated generator that is on side gearbox driven. Before engine start, until the DG is producing power, the EEC is powered by normal AC power. If the DG fails then normal AC power is again the power source.

10th Jul 2007, 19:14
Basically DC Bus 1, section 1 powers FCC A and DC Bus 2, section 1 powers FCC B (See full list of NG bus services here (http://www.b737.org.uk/ng_elec_busses.pdf)).
However, there are 6 other power inputs required for services to the FCC (MCP, Mach trim, stab trim, etc), the failure of any of these would give problems with the FCC or render it u/s.
Edit: link changed.

Capt Apache
10th Jul 2007, 22:10
So if there is a loss of both engine driven generators,there would be no Fcc's.Also no Flight Directors.But in such a case what works on the MCP?Also will the indication on the MASI still be the same.I mean the the flap maneuvering speed bugs and the arcs etc.

11th Jul 2007, 00:45
If both AC generators fail, you are stuck to standby power from the battery (batteries, depends if you have a single or dual battery installation), unless you can start the APU and get it on the busses.
Under Stby power you will have (for about 20-30 minutes):
1) Stby attitude indicator (also shows ILS information)
2) Stdy airspeed indicator / altimeter (illumination only, the standard instrument is mechanical)
3) ILS 1
4) VOR 1
5) Stby RMI
6) FMC 1
7) DEU 1 showing essential engine data on the upper center DU
8) Cpt outboard DU
9) Capt. EFIS panel
10) I haven't got the schematics here, but IIRC ADIRU 1 might also be powered by the Stdby system.

You will not have any autopilot components working.
The engine EECs will be running off the EEC alternators mounted on the respective gearboxes.



Capt Apache
12th Jul 2007, 11:25
Thanx for your inputs

12th Jul 2007, 16:03
http://img504.imageshack.us/img504/2687/fccpowersourcepk8.th.jpg (http://img504.imageshack.us/my.php?image=fccpowersourcepk8.jpg)

@ CaptainSandL
You write "(See full list of NG bus services here)." so i expect a full list of NG bus services and not commercial :yuk: