Question regarding which is used first, ptu or stby hydraulics when hydraulic B has failed on b737ng?
Posted by Mrcigs@reddit | flying | View on Reddit | 5 comments
Basically the question is up there already I'm about 2 weeks into a type and it's something that's stumping me and can't find an clear answer on the fcom or from mates on the line.
No-Version-1924@reddit
If you read the FCOM carefully, it will tell you that PTU only operates with a loss of EDP 2, and it's not designed to work with a full loss of system B - can't provide pressure to system B, if there's no fluid in the system. Its main aim is to drive the LE flaps/slats (and autoslats, if you're really having a bad day) at a normal speed with eng no. 2 or EDP 2 failed.
The standby system is a backup for system A and/or B to provider pressure for operation of reversers, rudder, LE slats/flaps and standby yaw damper. It does so with a separate fluid reservoir and pump, which are independent of the main system.
If you have a full loss of system B (i.e. a leak), you'll be using the standby system, not the PTU.
hotelcc@reddit
I’m starting to think you’re Chris Brady
Mrcigs@reddit (OP)
Thank you much appreciated. That makes total sense. I'll have to look back over the fcom and also see if I need glasses, thanks again
mbgalpmd@reddit
The answer is obvious if you read your Tech Manual: 13 - Hydraulics > 13-20 System Description > A and B Hydraulic Systems> Power Transfer Unit
rFlyingTower@reddit
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Basically the question is up there already I'm about 2 weeks into a type and it's something that's stumping me and can't find an clear answer on the fcom or from mates on the line.
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