Dehumidifying to improve Avionic Reliability
Joined: May 2004
Posts: 110
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From: Britain
Like insty said, DH is pretty much the done thing on Tornados now. Bear in mind that the avionics bays will have conditioned air bled from the engines throughout flight, so fitting a DH as soon as possible replicates the longhaul jet characteristics you mention. Also, the German airforce study that was mentioned went as far as dehumidifying the engines whilst on the ground by using specially adapted intake blanks. The photos comparing a stripped down DH engine to a 'normal' one of the same use showed a marked difference in wear and corrosion. The corrosion avoidance benefits would also apply to the rest of the airframe surrounding the avionics kit that is susceptible to creating condensation.
Hope this helps, and have you tried contacting the GAF about their study? You know how ruthlessly efficient those Germans are...!
Hope this helps, and have you tried contacting the GAF about their study? You know how ruthlessly efficient those Germans are...!
Thread Starter
Joined: Feb 2004
Posts: 372
Likes: 0
From: Angel N1
It works!
Well, thanks for the leads. In case anyone is interested, I am well into the project now and it seems that for aircraft that remain on the ground a fair deal, dehumidifying has a massive positive effect on the life of your avionics. We are talking almost doubling their life in many cases.
I got hold of reports from the German Air Force, Swedish Air Force , US Marine Corps trials of dehumidification the results are quite impressive.
In most cases the investment paid off in under a year. The only downside I can see is the effort to appply the dehumidifier and convince those whose responsibility it is that it is so worthwhile.
I would love to highlight fleets other than air forces that might respond to dehumidification. Anyone know any routes that see an aircraft locked up and left for a while at the end of a flight. Most airlines turn around so fast that dehumidifiying is pointless but I would like to highlight an airline that, because of wind conditions say, delays its return trip leaving it on the ground for more than 12 hours and doesn't air condition throughout. Maybe a long haul route. Anyone know of any such operation?
This would give my project an airline angle, which I am supposed to be focusing on.
I got hold of reports from the German Air Force, Swedish Air Force , US Marine Corps trials of dehumidification the results are quite impressive.
In most cases the investment paid off in under a year. The only downside I can see is the effort to appply the dehumidifier and convince those whose responsibility it is that it is so worthwhile.
I would love to highlight fleets other than air forces that might respond to dehumidification. Anyone know any routes that see an aircraft locked up and left for a while at the end of a flight. Most airlines turn around so fast that dehumidifiying is pointless but I would like to highlight an airline that, because of wind conditions say, delays its return trip leaving it on the ground for more than 12 hours and doesn't air condition throughout. Maybe a long haul route. Anyone know of any such operation?
This would give my project an airline angle, which I am supposed to be focusing on.
Joined: Apr 2002
Posts: 103
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From: Carry be Anne
Blacksheep, I too used to work on VC 10s at Brize, but unlike you have had an experience where condesation cause repeated failures in the autopilot system, mainly lat and long amps. We were playing around in Malaysia with the tankers doing 4 or 5 hour sectors. Then on the ground overnight. Come the following morning during crew-in, AP would fail to engage. Replacement on long or lat amps would fix it, but when taking those bloody heavy boxes out from the radio racks, there was water coming out them! Relative humidity was 100% and it was monsoon season and very wet and hot. We later found that the main cause of this problem was the use of airconditioning carts plugged into the AC system. This must have cause the radio rack cooling to get too cold and consequently condensation when the cart was removed and the aircraft downpowered for the night.
On the subject of dehumidifying aircraft, my airline is to trail a system on our B757s and A320s. 757s are notorious for "plane rain" and the usual cause for TCAS and enhanced GPWS failures due to moisture ingress in the antenna connectors. However this is not the motivating factor to trail this mod. The expected result is weight saving of over 500kgs of water saturated in the insulation.
On the subject of dehumidifying aircraft, my airline is to trail a system on our B757s and A320s. 757s are notorious for "plane rain" and the usual cause for TCAS and enhanced GPWS failures due to moisture ingress in the antenna connectors. However this is not the motivating factor to trail this mod. The expected result is weight saving of over 500kgs of water saturated in the insulation.
