B737-800 hyd. brake press

[Kuchan]

B737-800 could not maintain brake pressure of 3000 psi. It was around 1700 psi with B hyd. pump on and gradually down to 1000 psi after 6 hrs.

Found accumulator was leaking slowing that the pre-charge pressure was gradually down to 50psi after 15 hrs.

My questions:-

1) What is the brake pressure with hydraulic pump on (3000 psi) when accumulator has pre-charge of 800 psi, 500psi, 200psi, 50psi.


2) As the B system is maintaining 3000 psi although brake pressure on the gauge shows approx. 1000 psi. ( presumably only 500 pre-charged press ), will you sign off the aircraft.

3) What is the MEL or QRH on brake.

[Yeelep]

1) It will be 3000psi regardless of pre-charge pressure.
2) No, if the pre-charge pressure is below limits the aircraft cannot legally be dispatched. If the accumulator was within limits then the aircraft could be dispatched as long as the second pressure gauge (accumulator/flight deck) was reading approx. 3000psi with hydraulic pump on.
3) MEL 32-13D for flight deck brake gauge. MEL 32-13C for wheel well brake accumulator gauge.

[boeing_eng]

If you actually work on the aircraft type you mention you will have access to the FIM/AMM and MEL which is all you need. It never ceases to amaze me the number of questions relating to large passenger airliners like this cropping up .....truly concerning stuff!:ugh::ugh:

[Kuchan]

It never ceases to amaze me of a minority of intellectual instead of answering the question, but to throw in insults and comments.

I am off for days away from work without access to AMM and MEL. So I thought it would be easy to find answers here instead of searching in internet. How wrong I am again after vowing to retire from prune.

After spending times downloading MMEL and QRH to fill up my tablet, I have the answers here.

1) The hyd system pressure with B pump on remains 3000 psi. the acc. Gauge press varies with pre- charge press. A no go situation.

2) MMEL has no MEL regarding low acc press, at W/w gauge, so no go. even from the schematic, that the brakes appear to be fully functional with 3000 psi.

[TURIN]

Why would one need access to such info (AMM, MEL Etc.) if one is away from work?

Is this a hobby?



Posted from Pprune.org App for Android

[Kuchan]

Hobby???? No chance.

Don't bring work back to home. That is why I left my laptop with AMM etc at work. Same as mobile.

Unfortunately, some one manage to get hold of me much to my annoyance, on AOG.

Thought easy to get answer here, much disappointed.

Aircraft was grounded until ACC replaced.

[boeing_eng]

Hmmm.....There are plenty of options to source official maintenance publications (at work or not)

As an engineer, asking technical questions to diagnose a fault on a large transport aircraft currently in service on an open public forum, is extremely unprofessional in my opinion.

Obviously, it would be different if we were talking about an obscure GA type etc!

[Kuchan]

It never ceases to amaze me there is always someone who only throws in insult without showing any knowledge of aircraft.

The decision was made before me asking here, awaiting spare to arrive.

Just thought to refresh my memory as I was not on B737 in depth for over a year.

May be I would retire again from Pprune as there is always some cleaver one here jumping into conclusion.

The motto in CAA exam:-Always look at TFQ before answering. Answer what was being asked

Bye, retiring now, the very moment.

[boeing_eng]

Just thought to refresh my memory as I was not on B737 in depth for over a year.

Even more reason to use official publications! I'm sure your license issuer would be very interested if they discovered you were using this forum as a source for technical information!:ugh:

[TURIN]

I am off for days away from work without access to AMM and MEL. So I thought it would be easy to find answers here instead of searching in internet. How wrong I am again after vowing to retire from prune.

Yeelap made a good attempt at answering your questions I thought.

A thank you to him/her would have been nice. :hmm: