A B757-200 Captain reports that two company B757s he had just flown had the same pre-departure test failures of the Center Fuel Tank Right (R) Boost Pump and the associated EICAS messages not appearing as required.
Synopsis
A B757-200 Captain reports that two company B757s he had just flown had the same pre-departure test failures of the Center Fuel Tank Right (R) Boost Pump and the associated EICAS messages not appearing as required.
Narrative
B757-200 flight manual (Normal Procedures Pre-departure); specifies a test for (Center) C PUMP PRESS lights and EICAS messages if center tank fuel is planned and contains usable fuel. Both B757 aircraft that I just flew with planned and boarded center tank fueled partially; failed this required test. In both instances; the required EICAS message did NOT appear for the CTR R FUEL PUMP when the RIGHT C PUMP switch correctly displayed an illuminated amber low PRESS light. In both instances; the EICAS message correctly appeared for the CTR L FUEL PUMP. The first flight was company Aircraft X; a B757; in October 2011. The second flight was another B757; Aircraft Y; the next day. Company Maintenance addressed the first event in coordination with Maintenance Control. Company Maintenance at another base addressed the second event in coordination with Maintenance Control also. The second occurrence raised a warning flag that there might be more than an isolated problem. I advised Maintenance Control; Local Maintenance; Dispatch; and my First Officer that I intended to file a report. Maintenance Control replied that they had e-mailed Engineering. Local Maintenance replied that they planned to also report. A B757 flight planned without center tank fuel would not require this pre-departure test; so the existence of this malfunction would not be identified.
NASA callback
Reporter stated the pre-departure test for verifying that the center fuel tank 'left and right' electric boost pumps will shut off and also display EICAS messages indicating such was driven by an Airworthiness Directive (AD) that included any aircraft with fuel plumbing lines similar to the B747-400 aircraft; that included the B757.Reporter stated the center boost pumps shut-off requirement is overridden if the wing fueling panel door is open. If the wing fueling door is closed and the aircraft is on the ground and the two center pump switches are selected 'On' (pushed-in) prior to engine start; the switches will 'latch;' but will not electrically power the two center boost pumps until one engine is running.Reporter stated to get the correct EICAS messages that indicate the center 'L' and 'R' boost pumps show 'low' pressure; the wing fuel tank boost pumps must be operating during the pre-departure test. Company mechanics troubleshooting the 'R' center tank boost pump for not indicating properly during the test; believe the problem involves the micro switches in the wing fuel panel door. He was informed the wiring modifications to their B757s to satisfy the AD requirements were done by an outside Contract Maintenance Repair Station; not company mechanics. Reporter also stated all departments have serious concerns about the pre-departure test and the non-ETOPS domestic flights where the test is not required unless fuel is loaded in the center tank; but may still have a center boost pump that would not shut-off. One of the two B757's was removed from service; manually drained of fuel and the center right pump continued to operate without shutting off as required by the AD modifications. All their B757 aircraft have been modified per the AD.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.