747-400 EICAS maintenance page - Aircon system
Thread Starter
Joined: Dec 2002
Posts: 194
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From: UK
747-400 EICAS maintenance page - Aircon system
Anybody more technically minded than myself able to answer this question?!
On the EICAS maintenance page for the Air Con system, individual valve positions for the trim air valves are displayed. If a valve was locked mechanically into eg. 25% open position (as per certain MEL requirements) would this show up on the EICAS?
In other words, where does the EICAS valve position take its input from, electronic signal or physical (mechanical) position?
rgds
JD
On the EICAS maintenance page for the Air Con system, individual valve positions for the trim air valves are displayed. If a valve was locked mechanically into eg. 25% open position (as per certain MEL requirements) would this show up on the EICAS?
In other words, where does the EICAS valve position take its input from, electronic signal or physical (mechanical) position?
rgds
JD
Joined: Jul 2005
Posts: 580
Likes: 0
From: OZ
Thank you SMOC... I am specifically interested in what should be displayed on EICAS in the event of a mechanically locked out valve. Rgds
Joined: Apr 2005
Posts: 41
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From: Aust
We manually wind the valves for a certain chk we do and as soon as you disconnect the canon plug for these valves you loose your indication and it goes blank. If you lock a valve in a certain position for an MEL you have to disconnect the plug because you can not wind it with the plug on. With the plug on it will always run to the position that the pax temp master selector knob is set to in the cockpit, through the zone temp controller. The valves are under control of the zone temp controller it feeds the position signal from the valve back to the ztc then to eicas. Its not a rvdt it is a potentiometer. The MEL will tell you to wind the manual drive with an allen key so many turns. 30% open is 3/4 of a turn from the closed position. Hope this helps.
