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weegsltl
3rd Nov 2003, 01:27
Hello,

I flew out of London City in July and was surprised to see a BA RJ100 parked up, however with its tail air brakes in the open position.

I have also recently flown out and back into Manchester and once again there were several BA RJ100's parked up with their tail air brakes open.

Can someone please explain as to why the tail brakes are left open when they are parked.

Thanks

fruitloop
3rd Nov 2003, 04:20
There are possibly a list of reasons but I will answer 2 that spring to mind
1. If the A/C was live to help cool the APU bay (high temps)Temp sensors above aircon bay and beside the packs have been known to cause pack trips.

2. As hydraulic pressure bleeds off the speed brake is at the wilms of the elements (no internal locking in actuator)so even a slight tail wind can open them.

weegsltl
3rd Nov 2003, 14:06
Thanks a lot fruitloop,

much appriciated

square leg
4th Nov 2003, 06:45
The above answers are absoloodle correct. Although I never heard or thought about the cooling effect when the A/B is open. But as far as I know, no pilot ever leaves the A/B open because he or she thinks of cooling the APU bay/packs etc. It's just the wind and the fact that the hydraulics are de-powered. The normal lever position of the A/B & Lift spoilers is left in the "IN" position (on ground). Otherwise you'd have the lift spoilers deployed too (provided the hydraulics are powered). So I don't think the cooling thing is really a reason. But hey, who knows? It could actually be a good idea. Are there any mechanics out there who'd recommend this?

fruitloop
4th Nov 2003, 15:17
square leg,
Yep I've done it myself trying to pre-cool an A/C on a
40+ degree C day with 80+ humidity.Moving the lever with spoiler's selected off work's for me !!

Jester146
4th Nov 2003, 16:35
Question ... opening the Airbrake on the ground is it to help cooling the APU/packs OR the Aircraft itself???

I never heard about this but our airline hardly operates in 40+ degree C with 80+ humidity conditions.

If you see an open Airbrake on a RJ in Europe (lets say EU-members and imm. surroundings) you can, according to me, be 100 percent sure it's open due to the lack op hydr. press.

I have been told that Lufthansa planes never have this because one of the bearings in the system has to be changed to solve this problem. But most companies will not spend money on this purely aesthetic issue!

Happy landings!

We climb because the earth is round but nobody performs a highspeed approach like a RJ-driver!!! :}

weegsltl
4th Nov 2003, 23:39
Thanks a lot guys (and maybe gals) for your replies - very useful.

weegsltl