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Author Topic: 680FP Pressurization System and Air  (Read 2945 times)

ghancock

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680FP Pressurization System and Air
« on: October 06, 2015, 07:22:21 am »
I've been having a conversation with my mechanic about the need for air conditioning in my 680FP.  Morris has told me that the air unit cools the air enough not to need the expense and added complexity of adding a true air conditioner to the plane.  I'm wondering if anyone here has any experience with the system in the 680FP and whether (if working properly) or not you think I will eventually end up installing air?

Currently my system comes on and blows cool air that would be just fine for about 3 or 4 minutes and then it starts getting warm.  I'm not sure why it ends up warming up but it most definitely would be awesome if it stayed the initial temp.

Anyone have any ideas of what might be wrong?

Thanks,

Glenn
--glenn
You can't win an argument with an ignorant person,  they'll just drag you down to their level and beat you with experience.

Adam Frisch

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Re: 680FP Pressurization System and Air
« Reply #1 on: October 06, 2015, 07:23:35 pm »
I suspect you have a similar system to the turbines. Basically, the hot bleed/supercharged air comes into the air cycle machine. On the ground there's a fan that supposed to blow air over the cooling fins to cool the incoming air. In the air the cooling is achieved by the airstream blowing past it (normally there's a scoop or similar at the top of the fuselage behind the main wing). What happens is that that fan and fan motor in the air cycle machine is notorious for breaking down. So if it's first cool when the bleed air is cool, then gets hot on the ground and then blows cool up in the air again, then that's most likely what's wrong.

But I could be wrong - maybe you don't even have an air cycle machine and it's something else.
Slumming it in the turboprop world - so you don't have to.

ghancock

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Re: 680FP Pressurization System and Air
« Reply #2 on: October 07, 2015, 10:43:26 am »
Yeah, I believe I have one, but it runs off hydraulic pressure, not bleed air.  Morris seemed to think the blower was the issue but we couldn't really tell if it was running or not during pre-buy.  I may end up taking it out to Morris to look at at some point but guess I'll wait until your plane is finished so I don't hold him up. :-)

--glenn
You can't win an argument with an ignorant person,  they'll just drag you down to their level and beat you with experience.