popee
Posts: 151
Joined: Fri Feb 23, 2001 10:26 pm

Speed Brake Lever ---- A310

Tue Jan 24, 2006 1:44 am

Hi.

Can some one pl tell y the speed brake lever has detents ( eleven in number ) and not smooth like on Boeings ?

Does eleven detents also means that the spoilers hv same 11 discrete positions ??

Thanks.

Popee
 
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Jetlagged
Posts: 2562
Joined: Sun Jan 23, 2005 3:00 pm

RE: Speed Brake Lever ---- A310

Tue Jan 24, 2006 8:03 am

The Airbus A300/A310 speedbrake lever will return to the retracted position unless held in one of the detents. The number of detents allows the pilot to select and hold varying degrees of flight spoiler. On a Boeing the lever will stay where it is put, unless the speedbrake actuator is in operation. However the Boeing speedbrake does have detents: a flight detent and an armed detent.

Flight spoiler position is infinitely variable but since the flight spoilers follow the speedbrake lever position, there are in effect discrete positions. However, as airspeed increases the spoiler panels blow down with increasing dynamic pressure.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
popee
Posts: 151
Joined: Fri Feb 23, 2001 10:26 pm

RE: Speed Brake Lever ---- A310

Tue Jan 24, 2006 11:45 pm

Hi Jetlagged.

Do u mean to say that notches r there to keep the lever in its place otherwise the lever is going to change its place ??

I think there r some other reasons than this, because there is no mechanical/aerodynamic load on lever as it gives an electrical signal only, to EFCU.

Popee.
 
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Jetlagged
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RE: Speed Brake Lever ---- A310

Wed Jan 25, 2006 2:09 am

Quoting Popee (Reply 2):
there is no mechanical/aerodynamic load on lever as it gives an electrical signal only, to EFCU.

That doesn't mean to say there is no mechanical load on the lever. For example, the throttles on an A320 only provide electrical signals, but still have a mechanical loading system (friction, detents, etc). The speedbrake detents are there simply to give a positive positioning of the lever, allowing the pilot to release the handle, knowing it will stay in place.

The Boeing design uses friction to keep the speedbrake lever in place, connected via a lost motion device to the automatic actuator. Airbus uses mechanical detents to keep the speedbrake in place (just like Douglas on the DC-9/MD80). For ground spoiler deployment the whole speedbrake assembly moves, detents and all (from memory, it's a while since I was in an A310 cockpit).
The glass isn't half empty, or half full, it's twice as big as it needs to be.

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