737NG ram air / deflector doors.

[Mr.Buzzy]

Hi all,
have recently heard of a couple of cases of pack / bleed trip events preceded by "RAM AIR DOOR FULL OPEN" caution lights.

Does the ground deflector door operate completely independently of the ram air door and what actions if any would you take if you saw a "RAM AIR DOOR FULL OPEN LIGHT" on at high altitude?

I understand that deflector door deployment at speed can restrict heat exchanger airflow with potential pack overtemp following. I also understand that the ram air doors can be locked full open by MEL but I'd like to know if there is any way of telling if the deflector doors are deployed in flight.

many thanks clever people.

[FCS Explorer]

the "RAM AIR DOOR FULL OPEN" light is blue. that means: it's not really a 'caution' light and there's no checklist since the ram air door being open is usually not a malfunction.
actually i don't know why that light is there at all.
and i doubt i would notice it in flight since it doesn't trigger a master caution and a blue light in a bright flight deck is hard to see.
if i operate the blue fuel X-feed valve i hold my hand over it to see if there's any change in indication...
and even if i would notice that light in flight i probably would just think "wtf... stoopid boeing engineering...another fault that can't be reproduced to show the mechs'... that coffee takes like crap.... "
we do have 2 cb's called RAM AIR CONT MOD / CONT (LEFT/RIGHT). but no doc saying what that means. ..

[Cough]

I forget about it in flight, but scribble a note in the tech log after landing back at base.

[BOAC]

'Ram Air door full open' CAN indicate a pack working harder than usual and requiring more air. A few years back I was F/O on a 400 on which both doors were 'full open' in the cruise, which we noted as 'unusual', and shortly thereafter a double pack trip focussed our attention. An immediate reset brought one pack back. It is certainly something to be aware of, and as 'Cough' says, write it up.

[Swedish Steve]

The Ram air doors should only be fully open on the ground. On lift off the doors should move towards fully closed, and then modulate between fully closed and flight open position depending on the airflow required over the heat exchangers. The ground deflectors are there to keep water and slush out of the packs on the ground. As soon as the doors move away from Fully open they pop out of the way to let the air in.
With the blue lights on in flight, the heat exchangers will not get enough cooling air and a pack trip for overtemp is very likely.
The doors can be locked out in the flight open position. Here the pack will work perfectly well, but there will be too much air going through the heat exchangers in the cruise, leading to a slight drag rise.

[IFixPlanes]

http://img90.imageshack.us/img90/4796/ramairmodulatingov8.th.jpg (http://img90.imageshack.us/my.php?image=ramairmodulatingov8.jpg)
You will notice that actuator position 3 is within the "RAM DOOR FULL OPEN" LT area.
So it is possible to get the LT without a mechanical or electrical defect.
Some years ago i find a baseball-cap in front of a heat exchanger. :}
If we found no mechanical or electrical defect during testing the complained system, a cleaning of the heat exchanger normally brings the actuator position out of the "RAM DOOR FULL OPEN" LT area.
http://tonga.subsites.gaming-inc.de/pics/smilies/bu.gif

[AALOOPY]

Hello to all First time posting here. I have worked Md80's for the past 10 years and just started working on the 737-800 a few months ago. Last night I had this exact problem and ended up changing the actuator after following the FIM. I found it strange that I had to put the A/c in air mode to trouble shoot the system. When biting the controller It faulted the actuator in ground mode. Of coarse the rig had to be in air mode so either way I guess it was getting off the ground.

[Tree]

Try this to extinguish the blue light in cruise with both packs on:

Isolation valve close
Bleed valve affected side off
Wait 5 sec. then bleed valve on
Isolation valve normal

[Pilot Pete]

Or better still, don't do anything in flight that is not a recognised procedure.:rolleyes:

[AEUENG]

Here Here Pete!

Wandering Fingers Can Cause More Harm Than Good! The Qrh And Checklists Are Produced By The Aircraft Manufacturers For A Reason, Use Them And Stick To Them Unless Yours And The Other Poor Folks Behind You Lives Depend On It! Then By All Means Improvise And Do What U Can.

Ram Air Door Faults On 737's Are Very Common, Seldom Causing Anything Traumatic And Are Normally Easily Rectified Once Parts Are Available By Mr.boeing!

Stay Safe All And A Happy New Year To One And All!:)