B737-700
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 111
Aircraft Equipment Problem Critical
Flight Crew Diverted
Aircraft; Company Policy; Human Factors
We swapped into this aircraft. It had had two previous write-ups for the illumination of the engine driven LOW PRESSURE light on the B-system. The aircraft was originating in the evening due to the replacement of the engine driven hydraulic pump earlier that day. On initial climb (a little before FL 180); we also received the same LOW PRESSURE light. Our B-system quantity was at 96 at that time. We ran the QRH; which required us to turn off that pump. We continued; and elected to cruise at FL280; due to the QRH suggestion to remain in warmer temperature; in case of cavitation. Later; at cruise; our electric driven B-pump failed; and we noted that the quantity had gone to zero. We also received the FLT CONTL light; due to the yaw damper failure. The Captain was PF; so the autopilot remained engaged. We ran the QRH procedures for Hydraulic System-B Failure; and elected to divert since we were near [a suitable airport] and we were not sure that we weren't going to lose the A-system as well. ATC vectored us for a landing. We followed the QRH procedure to lower the flaps and landed uneventfully. After landing; we elected to leave the flaps in the 15 degree position; instead of electrically retracting them.Since the engine driven B-system pump had failed twice before and it failed a third time; the problem clearly had not been diagnosed or repaired properly. I hate to blame Maintenance; but after our engine driven pump failed on departure; we felt like we were 'test flying' the aircraft with passengers on board. The subsequent complete system loss after extensive hydraulic Maintenance seems suspect.
Dispatched in an aircraft that had just had the right engine driven pump replaced due to two previous system failures; the flight crew of a B737-700 nonetheless suffered yet another failure followed closely by a failure of the right electric pump. They diverted to the nearest suitable airport. The reporter expressed concern that; even after three write-ups and a replaced engine driven pump; Maintenance had apparently failed to properly diagnose and repair the system.