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Author Topic: lack of cabin heat - Sundstrand  (Read 1109 times)

Mike Lever

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lack of cabin heat - Sundstrand
« on: December 15, 2018, 07:21:05 pm »
Wondering if anybody else has experienced problems with lack of cabin heat in a jet prop or turbo commander ??   

 In our new-to-us 1000 with an overhauled sundstrand and tight cabin, it gets really chilly in the flight levels when the OAT < minus 20.   I wore thermal underwear and socks and multiple layers on the trip that I just came back from and it was still chilly.

I've tried running in both auto mode and manual overide and that doesn't make any difference.   

We confirmed that the bleed air valve at the mixing plenum is fully open.   We measured the output blended air at 38C with an IR gun.   So hot air is going into the cabin ducts but not warming up the cabin.   The output on the sidewall at my feet could best be described as luke warm

The Sundstrand definitely runs cold!

We did discover that the airplane has "late model recirculating fans" although the POH states that this serial number 0054 was not fitted that way at the factory. The cabin is noticeably warmer with the recirc fans on but definitely not warm enough to carry passengers.   Interesting this airframe has some other late model features not applicable to this serial number  ie.  emergency pressurization.

I'm making full diff at 6.7 psi.   So that's not the problem.

The logical explanation would be problem with blockage or disconnected cabin duct?     Has anyone experienced something like this?    I think we should boroscope the ducts before we start ripping the interior apart...

Help!!

SKYFLYER

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Re: lack of cabin heat - Sundstrand
« Reply #1 on: December 15, 2018, 07:52:10 pm »
Seems I recall Bruce saying a duct (heat?) was dislocated (not connected) and not making good pressure or heat.


Thanks guys.  It?s a good plane.  It?s priced to sell and not sit. It does need some TLC to bring it to my standards which I plan to incorporate into a deal with the next owner. Example: it just came out of major maintenance and wouldn?t pressurize.  I flew it 7 hours the long way home with a showing along the way.  Within 15 minutes, the guys found a duct missing in the tail.


Maybe Bruce or one of his crew can help direct you to a good starting point.

Adam Frisch

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Re: lack of cabin heat - Sundstrand
« Reply #2 on: December 15, 2018, 11:48:20 pm »
Sounds like a duct problem.
Slumming it in the turboprop world - so you don't have to.

donv

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Re: lack of cabin heat - Sundstrand
« Reply #3 on: December 16, 2018, 12:55:42 pm »
Was your airplane converted to 695B specs? Walmart converted a bunch of them (I used to fly one), at very great expense.

As for the temperature, I agree that a duct is probably not connected. My airplane struggles a bit with heat too, but generally only when it's -40 or below at night. I get hot air out the duct by the pilot seats, so I know that is working.

JMA

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Re: lack of cabin heat - Sundstrand
« Reply #4 on: December 17, 2018, 10:46:23 am »
Walmart had twin commanders?!?!

donv

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Re: lack of cabin heat - Sundstrand
« Reply #5 on: December 17, 2018, 11:39:26 am »
They had a bunch of them. Apparently Sam Walton enjoyed flying them. I think at one point they might have been the largest Twin Commander fleet operator in the world.

On the heat question, I assume you are using OVRD and pressing the manual heat switch? Sometimes the auto system can be a bit flaky, or so I've heard.

JMA

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Re: lack of cabin heat - Sundstrand
« Reply #6 on: December 17, 2018, 03:40:33 pm »
Thats amazing Don-
quick search once again proves you correct.

http://jetav.com/memories-of-the-turbo-commander-900-by-paul-pitts-the-jetav-blog/


N81674   Wal-Mart Stores Inc   00.00.77   Left Fleet

JMA

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Re: lack of cabin heat - Sundstrand
« Reply #7 on: December 17, 2018, 05:09:02 pm »
Sorry didn't mean to hijack the thread- Don peaked my interest:
https://abpic.co.uk/pictures/view/1280428

Mike Lever

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Re: lack of cabin heat - Sundstrand
« Reply #8 on: December 17, 2018, 05:56:49 pm »
That's super interesting on the DEA fleet.   Bruce tells me that our 1000 was part of that fleet for a while.   Interestingly the cockpit in the pic in the link is strikingly similar to ours from the funny colour of the rudder pedals to the massive flight director and HSI on the copilot's side  (still can't figure why that would be installed on the copilot side)..   Maybe that was the standard when DEA upgraded airplanes they seized..

Mike Lever

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Re: lack of cabin heat - Sundstrand
« Reply #9 on: December 17, 2018, 06:06:17 pm »
Appreciate the suggestions re lack of heat.  Please keep them coming....   Bruce and his guys are being very supportive in the trouble shooting but we have not yet figured out what the problem is.

We've ruled out any problems with the auto temp control and overide by visually checking the position of the valve that controls the mixing of hot bleed air.  it's fully open and we are getting 38C air delivered to the pressure bulkhead

We tested the cabin ducts with a shop vac last night and it seems that the input of air into the ducts (from the shop vac) is the same as the output at the pilots feet.   It was somewhat subjective but there was a good flow of air whistling out at the pilots feet.

It's a puzzle.  I can't believe that Gulfstream (and Commander) expected pilots to be layered up with thermal underwear etc at ISA temps at altitude!   If it's this cold at FL 280, there is no reason to consider putting RVSM on the airplane and risk frostbite at 350!

I'm wondering about baseline on any other commanders??   has anybody else had a similar problem?   is the air coming out of the vents at the pilots feet quite warm or "hot" on other airframes??



Mike Lever

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Re: lack of cabin heat - Sundstrand
« Reply #10 on: December 17, 2018, 06:11:42 pm »
Was your airplane converted to 695B specs? Walmart converted a bunch of them (I used to fly one), at very great expense.

As for the temperature, I agree that a duct is probably not connected. My airplane struggles a bit with heat too, but generally only when it's -40 or below at night. I get hot air out the duct by the pilot seats, so I know that is working.


Appreciate the info.  Cheers!    I've definitely noticed the difference in interior temps when it's at night.    So if I understand correctly, the air that is coming out the duct by your pilot's seat feels "hot".   That's super valuable info for us.   I would describe our output air from the vent as very mildly warm.   definitely not "warm" or "hot".  This could be a big clue.

It's a 695A without the mod's.    Scott kindly offered to look into the cost of upgrading to a "B" model.  it would be sweet to get the extra useful load.   My understanding right now is that the landing gear has to be modded but no airframe mod's needed.    We'll see I guess

donv

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Re: lack of cabin heat - Sundstrand
« Reply #11 on: December 17, 2018, 06:29:04 pm »
Thats amazing Don-
quick search once again proves you correct.

http://jetav.com/memories-of-the-turbo-commander-900-by-paul-pitts-the-jetav-blog/


N81674   Wal-Mart Stores Inc   00.00.77   Left Fleet

I used to fly N83WA, which was a WalMart 1000 for a long time... very high time airplane, too. Worked great, though. Converted to a 695B at great expense...