Cold in cocpit

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Cold in cocpit

Postby Stan » 13 Jun 2007, 10:12

Hi mates , we had this problem on our 738 thad pilots kept complaining about freezing in cocpit .
We did the FIM , changed some valves and sensors... and at the end we found that the trim air valve wasnt open
properly so there wasnt enough hot air for modulating valves even they were ful open... BUT... the temperature in cocpit
is fine now... but the problem is that even with new trim air valve , the valve doesnt open too much , not even halve during ground tests , maybe just 1cm from closed position , its better than the replaced one but for me it doesnt seem enough
I checked our other 800s and the valve opens more than halve

Have u ever have similar problem or do u have some suggests how to check trim air valve?? :?:

Thanks a lot
Stan
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Postby sjap » 13 Jun 2007, 15:39

-did you clean the air filter and sensor in the cockpit ceiling (common problem ) ?
-does the valve not open completely with temp sel in full hot (manual)?
Best regards
sjap
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Postby Stan » 13 Jun 2007, 16:04

Hi Jean

yes we did clean the filter and sensor in cocpit
yes the valve doesnt open completely with selector in full hot
on our other 800 is not open completely as well , but at least is more than half...

stan
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Postby sjap » 13 Jun 2007, 16:24

mmmmmmmm
strange,
Maybe the controller is not giving the correct input. Try to swap it with another one. Maybe it helps?
Sjap
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Postby xoz » 14 Jun 2007, 07:43

Precooler sensor or precooler wlv will cause this problem.
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Postby Stan » 14 Jun 2007, 11:08

During the FIM we changed the controlers as well , but there are 2 controlers and one trim air valve

Why would this problem cause the precooler or the sensor when there are 2 engines and one trim air valve

u mean both precooler sensors are bad??

We were solving this problem quite long becouse we are charter company and the arcrafts keep flying everywhere out
of homebase , we had this info from pilots that it was too cold and after switching the trim air off it was better , but sometimes it didnt help , strange , after the changing the trim air valve there are no more complains but still like I wrote , the Trim air valve doesnt open too much...
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Postby xmxmxmxm » 23 Jul 2007, 16:07

did you checked the temperature sensor fan.
or you can swap sensors such as anticipator sensor with other plane
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Postby mr fix it » 18 Oct 2007, 08:57

we had a similar problem with one of our 800 , the temp sensor fan in cockpit was touching a wire bundle on the back of the fan ,this friction used to stop fan rotation as fan torque is very less . check in the normal installed position wether fan is working.
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Re: Cold in cocpit

Postby saboor » 21 Apr 2015, 14:09

I would say that l/h bleed tripped off due to the high required airflow in the system after wing anti ice selection resulting in a high precooler outlet temperature (> 254°C is the trip point). Was the isolation valve open at that time???
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Re: Cold in cocpit

Postby avionic » 30 Apr 2015, 21:48

We had a same problem with our 800, but after TRIM AIR PRESSURE REGULATING and SHUTOFF VAlVE replacement pilots do not complain about the cold in the cockpit.
Before : Pack/zone temperature controller's, zone trim air modulating valve, cabin temp sensor were swapped but without result.
Don't drink and drive, let smoke and fly :-)
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