747-400 alternate gear extension
 

the uplocks that hold the gear up are released by...hydrolic or electric...when the alt gear extension switch is pushed ??
bear in mind that gear lever is in off position(in checklist)and hyd system loss may exist..

many thanks..

am I thick or is it that I just dont understand the question?

Electric....
One switch for the nose and body gear (failure of hyd. sys. 1).
One switch for the wing gear
(failure of hyd. sys. 4).

The Alternate gear actuation is by electric motors which drive the the uplock jaws through 180 degrees. The jaws are open ended - the uplock roller drops out and the gear drops under gravity and air loads. Same type of system for both Wing and Nose and Body.

Providing of course that the system first released the door actuator locks and the spring bungee is juuussssst strong enough to push the downlock linkage overcentre. :)

[This message has been edited by gas path (edited 23 May 2001).]
damned dys.. dysle.. dyslexia!

[This message has been edited by gas path (edited 23 May 2001).]