A/c train
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Posts: 674
Joined: Sun Jun 10, 2001 7:57 am

Bleed Valve Faults

Sat Sep 29, 2001 8:31 am

When we were on holiday in Corfu this year, my brother who is a member of Cabin crew' lol ', only joking, phoned and said he had gone out of hours because the a/c had gone Tech due to a bleed valve fault, so my Dad said he didn't want anything to do with it as he was on holiday, as we were on the phone to my brother he said it had been Tech for 18hours and he said all he could see was some Tech with his head under the cowling and a load of line engineers standing round troubleshooting, now when my brother informed my father of this fault he said straight away, they need to change the PRSOV, now I knew what this stood for but my dad has been a licenced a/f engine guy for 28yrs, and would you believe it, my Dad got a phone call on holiday informing him of the situation from maintrol, and the action taken was a PRSOV change, I really did find this amasing and extremely impressive, but what does a PRSOV do? I couldn't believe all he was told was minimum info and he knew what to do straight away!!! does anyone know what a PRSOV does? and how do you become that good at troubleshooting??
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RE: Bleed Valve Faults

Sat Sep 29, 2001 12:49 pm

With all due respects...it sounds to me like an educated "shotgun" guess that just worked out- but in fairness it's impossible to gauge without first hand knowledge of the exact symptoms and findings during troubleshooting. -- Bleed systems, with their myriad of valves, sense and "muscle" air lines, thermostats, regulators and other items can be challenging to troubleshoot. -- You did not mention the A/C type, but PRSOVs are ( on the A/C that do use them ) generally do the same thing- even if they may go by different terminology. It is an electro/pneumatically controlled, pneumatically operated valve that: 1) turns the bleeds off or on. 2) Regulates the pressure of the bleed air from the engine to the user systems via pneaumatic sensing. I have yet to see an A/C where removing and replacing a PRSOV is not an absolute S.O.B.
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RE: Bleed Valve Faults

Sat Sep 29, 2001 7:27 pm

I guess your Dad spoke from Experience.Its quite common to have what one calls a repeatative snag [A snag that occurs again on a same Aircraft or another aircraft of the same type].
Your dad has rectified the similiar snag before & every troubleshooting chart has a pattern of troubleshooting to follow.
I would be surprised if your dad after 28yrs experience could not guess the problem.
The PRSOV is a Pressure regulating shut off valve. As the name says so its Electrically controlled & pneumatically operated to operate Surge bleed valves on the Engine depending on the Type,controlling the Airflow to eliminate a surge.
I may not win often, but I damn well never lose!!! ;)
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Joined: Wed Jul 05, 2000 11:37 am

RE: Bleed Valve Faults

Sat Sep 29, 2001 10:26 pm

I agree with NKP. The gunshots were pretty loud on that one. Bleeds systems are one of the more complicated systems as he said because of all teh sense lines, and the inability to physically look at the system while it is actually working (The components are located in the aircraft hot section, which is concealed by the Thrust reverser during engine runs).
I've heard of bleed problems going on for the longest and finding that sense lines (which are a common culprit) were the problem.....and you'd never know it until the hoses actaully got to a certain temp.

U never know...that's why you take every problem individually...at least I try to.
Now if you see a landing light out with a darkened bulb, then......................

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