Three Line Mechanics and two Line Maintenance supervisors report about the troubleshooting; locking-out; and deferral of the High Pressure Valve (HPV) on #2 engine of an A330 aircraft. Downline Maintenance Station had reported the wrong valve was locked-out. Questions were raised whether Downline Maintenance had used a Pratt & Whitney manual instead of Rolls Royce Trent 770 engine manual.
Synopsis
Three Line Mechanics and two Line Maintenance supervisors report about the troubleshooting; locking-out; and deferral of the High Pressure Valve (HPV) on #2 engine of an A330 aircraft. Downline Maintenance Station had reported the wrong valve was locked-out. Questions were raised whether Downline Maintenance had used a Pratt & Whitney manual instead of Rolls Royce Trent 770 engine manual.
Narrative
While troubleshooting inbound write-up; we were advised to defer item by Maintenance Control per MEL/AMM (Aircraft Maintenance Manual) and proceeded to 'lock-out' the high pressure (HP) valve. After opening the left inboard cowl; we then locked-out the HP valve per the maintenance manual and MEL procedures. There were two supervisors and two mechanics; as well as myself; observing the operation. My position while observing the procedure was from behind Mechanic Y; who was doing the valve lock-out. The position of the valve was the most aft of the engine. I could not see the pressure regulating valve (PRV) from my vantage point. All of us agreed and confirmed the lockout procedure and visually checked the valve to make sure of the proper valve position via the position indicator as well as the correct valve was locked-out; verified by maintenance manual task 36-11-00-040.If the incorrect valve had been locked-out; there would have been no air from the #2 engine and no bleed air indication on the ECAM air page. The aircraft would have [had] to taxi back to the gate; as well as [had] an ECAM warning message.A hard copy was printed of the Aircraft Condition Monitoring System (ACMS) real time cruise performance report from the date; time; and flight after valve lockout. The correct valve position; status; and operation was confirmed in the Description of Parameter page in the AMM.Maintenance Control notified that the incorrect valve had been locked-out. There is no possible way the incorrect valve had been locked-out by ZZZ Maintenance. There was no maintenance performed on the PRV by ZZZ station that night; only the HP valve. [This was the] other station's troubleshooting problem.
Second reporter narrative
Maintenance was deferred on #2 engine high pressure valve (HPV) due to inbound write-up that mentioned; at engine start (idle power) and after landing (idle); the HPV didn't open with ECAM message. I was onboard to verify the message; which didn't show on engine warning display (EWD). Performed bleed air monitoring computer (BMC) bite test [and] found a class-3 message. Performed #2 engine run by flight crew and confirmed the HPV stayed closed and bleed air was supplied by 8th stage with 36 PSI [pneumatic pressure] downstream of pressure regulating valve (PRV). Maintenance decided to defer #2 HPV after resetting FADEC and BMC without success. Per MEL 36-11-7b maintenance procedure; needed to lock-out the HPV per aircraft maintenance manual (AMM) 36-11-00. [The] jobs were performed by Mechanics X; Y; and Z.Maintenance Control informed; and computer 'discrepancy histories' indicates; that ZZZ1 Maintenance team found HPV wasn't locked-out. Instead; they found PRV was locked-out in 'closed' position with lock pin sheared. If it was true (by locking out PRV); the bleed page in system display (S/D) shouldn't have had any pressure downstream of the PRV indicator (neither 8th nor 14th stage). I believe the flight crew would not accept an engine with no bleed air.Also; there were many [flight] legs flown after the valve was locked-out. Why [would] no one complain about not [having] air from the #2 engine? Besides; 2nd Shift Lead Mechanic recalled Aircraft Condition Monitoring System (ACMS) #2 engine report (cruise performance report) on this flight leg and found that PRV being indicated 1 (one) (open) with HPV being indicated 0 (zero) (close). I am unable to explain why ZZZ1 team had found this discrepancy; but there is a possibility that they probably used the wrong AMM that is effective on Pratt-Whitney PW-4160 engines; in which the PRV is at the 9 [o'clock] position; same position that the HPV on Rolls Royce Trent 772 engines.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.