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System performance poor (aircraft

Travis on Tue July 29, 2008 8:48 PM User is offlineView users profile

Year: 2007
Make: Eclipse
Model: 500
Engine Size: Jet
Refrigerant Type: 134
Ambient Temp: 75
Pressure Low: 28
Pressure High: 220

Folks,

I'm currently working on an Eclipse 500 aircraft. The system performance is poor with front vent temps at 61F and rear temps at 55F with an outside temp of 75. Right before I took the vent temps I recovered, evacuated, leak checked and charged the system with the proper amount of 134. What could be causing the poor temps? First thing that I am thinking is the oil being grossly overcharged. Also, the low side steadily drops as the system is ran longer. It was at about 19psi when we shut it off after running it about 20 minutes. The high side stayed consistant.

Thanks
Travis

-------------------------
1993.5 Single Turbo Toyota Supra 714RWHP
1985 Suburban
1997 Pontiac Grand Prix GTP

NickD on Tue July 29, 2008 9:16 PM User is offline

My V5 works that way at low ambient temperatures, vent temperatures feel cool, but when getting in a hot car when the temperatures are in the 90's it blasts out ice cold air and cools the vehicle quickly. What kind of compressor does this aircraft have and what speed is the compressor running at?

Travis on Tue July 29, 2008 9:32 PM User is offlineView users profile

Compressors are 'Seamech' brand. No idea on operating speed. I'm going to up the charge a little bit and see what happens..

-------------------------
1993.5 Single Turbo Toyota Supra 714RWHP
1985 Suburban
1997 Pontiac Grand Prix GTP

TRB on Tue July 29, 2008 10:31 PM User is offlineView users profile

Travis I can't say many nice things about that companies a/c division. But knowing the fabricator it should be a pretty simple after market system. I have never worked on one of these systems! Pressures look to be fair to high at that ambient, if it's a TXV system. But with two evap cores it may not be out of spec. Compressor most likely is a Seltec. Lots of performance data was created by AMA employees back then! If I'm correct this system should have a couple electric fans cooling the condenser. Check that they are not wired back-wards. Also could be a cycling issue with the electronic control system. These types of control systems/thermostats are pretty reliable. But with any componet it could be the issue.



-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

NickD on Wed July 30, 2008 8:34 AM User is offline

We don't do jets here, but would love to see that installation, is that compressor driven somehow by the jet engine? Do you have a phototach? Do you even have a manual with performance specifications? Can either lack of or two much oil in that system affect of the performance of that aircraft in such a manner to cause a crash? Or is it an independent system that is electrically driven or whatever so the pilot can switch it off? Is it wise to play with the pressures? Just some questions I would have.

If 'Seamech' did make this system, would be on the horn with them.

HECAT on Wed July 30, 2008 9:03 AM User is offline

Surely with a jet, the compressor would be "bleed air" or APU driven. Are you doing warranty work on this new aircraft? What was the original complaint? Did your recharge procedure add more oil? Automated climate controls may be operating properly given 75 degree ambient. Put it in the sun and let it sit and get good and hot and see what the pressures and vent temps look like then.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

bohica2xo on Wed July 30, 2008 9:35 AM User is offline

Nick:

Much of the A/C stuff in the little birds like that is not as well designed as an aftermarket car A/C - some of it looks like it was designed by a drunk laid off when A-R-A closed up shop...

Hecat:

Bleed air on a P&W 610F ? LOL, that is quite a picture. Oh, sure there is some bleed available - but not much from a 14.5 inch turbofan. Those are tiny turbofan engines with a single stage turbofan running from a single stage low pressure turbine.

Guys, I would be surprised if there are even 100 of those little engines in service right now. I think the first Eclipse 500 with 610's was delivered in January 2007. Due to the very small volume of production, there is usually no time or budget to work out all of th kinks in the A/C system. Even Beechcraft has it's hands full with that job.


Travis:

As Tim already said check the condensor airflow & condition. Your high side looks like crap for a 75f ramp - did the painter hide your condensor fins behind a coat of EPP? With a nearly 3:1 p/t ratio, your little bird would have a high side close to 400 psi at PHX.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

HECAT on Wed July 30, 2008 10:08 AM User is offline

Quote
Originally posted by: bohica2xo



Bleed air on a P&W 610F ? LOL, that is quite a picture. Oh, sure there is some bleed available - but not much from a 14.5 inch turbofan. Those are tiny turbofan engines with a single stage turbofan running from a single stage low pressure turbine.

B.

Glad to give you a laugh this morning. Sorry, I am not as familiar with the actual jet engines as you are; thanks for the clarification.



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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mk378 on Wed July 30, 2008 10:17 AM User is offline

I seem to remember that one of the new big jets is going with purely electric drive for the A/C instead of bleed air from the engines. Though it would still be an air cycle machine.

bohica2xo on Wed July 30, 2008 10:29 AM User is offline

Hecat:

Your A/C know-how is fantastic and very broad - hell, you even knew about bleed air systems. I figured from your comment that you had never seen the engine in question - it is almost too small to be believed. The core looks like it came out of a model airplane.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

TRB on Wed July 30, 2008 10:30 AM User is offlineView users profile

I believe the compressor is driven by an electric motor. They used to have some limited data on this site. But it looks like they deleted all those links. The only one which works now is the contact data. I don't now much about these systems or this company. Just know a few ex-AMA employees went there for greener pastures among other things.

http://www.seamech.com/

Google search shows the Glendale listing and is where I believe these systems are produced.

http://www.manta.com/coms2/dnbcompany_hh0cwk

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

NickD on Wed July 30, 2008 12:21 PM User is offline

Brad did say they do not run off the bleed, but didn't say what drives the compressor. The only photo Seamech shows is a motor driven compressor, lots of motors, one for the compressor, one for the blower, and two for the condenser. If Travis has two evaporator units, must have one more motor.

That leads to another question, exactly what is powering all these motors and where did they find the space to mount all this extra stuff? Weight and balance is yet another concern, but just looking at Seamech's single specificationless photo, do not feel I would expect miracles from it.

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