capt_smith
Posts: 65
Joined: Sun May 14, 2000 3:57 am

A-320 Flight Management Computers

Mon May 15, 2000 11:54 pm

I understand that the A-320 flight management computers are redundant. I know it's near impossible, but what if something caused a complete failure? Is there some kind of hydraulic back up? How would the pilot fly the plane or control the flight surfaces without the computer?
 
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GreenArc
Posts: 83
Joined: Thu May 11, 2000 10:59 am

RE: A-320 Flight Management Computers

Tue May 16, 2000 12:42 am

Capt. Smith,

I believe you are confusing the flight management computers with the flight control computers (FCC's).

IIRC, there are five FCC's. If all five were to fail or lose power, the plane can be controlled using rudder and trimmable horizontal stabilizer, both of which are independant of the FBW chain.

The A3XX will do away with this redundancy as it has proved unnecessary.

GreenArc
 
NKP S2
Posts: 1665
Joined: Mon Dec 20, 1999 3:16 am

RE: A-320 Flight Management Computers

Tue May 16, 2000 1:15 am

RE: "Hydraulic backup" I want to clear something up here. It should be noted that on FBW aircraft,only the control,or shall I say command of flight control surfaces are electronic. The surfaces themselves are still physically actuated hydraulically. Instead of a cable or rod commanding a hydraulic power control unit metering valve as on a 'traditional' a/c,the said metering valve is moved by an electrical servo. So you see,it's not a matter of "cables vs. wires" actually moving flight controls as some think it may be. Yeah,the 319-321 horizontal stab and rudder have cable control for redundancy. (the brake metering valves are also cable operated BTW) When we first got the A319's,I made it a point to crawl up in the E&E bay to verify for my own curiosity that yes,there are cables on a 320 family a/c!  
 
VC-10
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RE: A-320 Flight Management Computers - NKP S2

Tue May 16, 2000 8:24 am

I have to disagree with you regarding the A320 Brake System. There are no mechanical cables in this system, braking is normally acheived (excepting auto-brake) by electrical transducers on the brake pedals transmitting the pedal postion to the Brake & Steering Control Unit and the brake pressure and anti-skid function being controlled by this unit. Should this system fail there is alternate brakes. In this case a low pressure hydraulic circuit from the master cylinders on the pedals control a Dual Brake Metering Valve in the u/c bay that ports the main system hydraulics to the brake units.


 
airbuspilot
Posts: 382
Joined: Sat Apr 22, 2000 8:47 pm

RE: A-320 Flight Management Computers - NKP S2

Sat May 27, 2000 1:11 am

Only rudder and stabilisers have a mechanical backup with cables. But this was done only because it was needed for US approaval. I can assure you that the aircraft becomes almost impossible to fly when you loose all hydraulics. When i am flying ,the mechanical backup is NO option!!!
 
VC-10
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RE: A-320 Flight Management Computers

Sat May 27, 2000 1:57 am

The cables operate the servo's for the stab & rudder, so hyds are still rqd. So no hyds no control.
 
A330
Posts: 688
Joined: Wed May 19, 1999 12:31 am

RE: A-320 Flight Management Computers

Sat May 27, 2000 7:40 am

Airbuspilot, Capt. L. Bondroit (I think you know him...) says "it works". Off course, THE pilot of Sabena has some experience...! (great man, btw.)
Using rudder for heading, trim for pitch!! How long does it take to get it right in the sim??
Shiek!
 
airbuspilot
Posts: 382
Joined: Sat Apr 22, 2000 8:47 pm

RE: A-320 Flight Management Computers

Mon May 29, 2000 11:01 pm

Off course I know Luc Bondroit. I know him rather well and I have a huge respect for the man. If you know him you should know that he is an airbus addict! I love airbus but I am not an addict. We exercised the mechanical backup in the sim several times and I must say, I managed ONCE to set it on the ground but it was nearly a crash-landing. So as I said before , for me this is no option anymore.
A330, are you studying at SFA? My guess is you do.Good luck anyway with the atpl!!! Been there, done that. Prom7 day.
 
FlyBoeing
Posts: 835
Joined: Fri May 05, 2000 2:08 am

RE: A-320 Flight Management Computers

Tue May 30, 2000 10:57 am

Oh, my God. Remind me to NOT fly on any Airbus planes. Admittedly, fly-by-wire reduces weight and makes the aircraft more efficient, but not having a backup that works is kind of scary. Is this situation different in Boeing aircraft?
 
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DL_Mech
Posts: 2074
Joined: Fri Feb 18, 2000 7:48 am

RE: A-320 Flight Management Computers

Tue May 30, 2000 1:04 pm

The only cable operated systems on the 777 are for spoilers four and eleven (one on each wing) and alternate stabilizer pitch trim control. This Direct mode can be selected by the pilot or is automatic in case of total FBW failure (this can't happen right?). The 757/767 have FBW spoiler systems.
This plane is built to withstand anything... except a bad pilot.
 
VC-10
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RE: A-320 Flight Management Computers

Wed May 31, 2000 10:40 am

Airbus or Boeing, you still require hydraulics to actually move the control surface

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