Narrative:

I work for an air carrier based at ZZZ international airport, ZZZ, us I am trained to perform transit and ETOPS-pre departure clearance maintenance on boeing 777 aircraft for abc on fri, april 2001. I was assigned to perform transit and ETOPS-pre departure clearance maintenance on aircraft xyz of air carrier abc at gate. The aircraft arrived at XA48 local XB48 GMT. The flight deck crew wrote-up in the tech log, that on taxi-out from XXX they noted status message 'trim air prsov left' and EICAS message 'trim air left'- left trim air switched off in accordance with checklist! Cabin temperature very difficult to control, especially zone F. After service of both engine oil systems, amt bx and myself used the aircraft. Mat computer to retrieve all present leg faults. At this time, it was noted that both messages (status message 'trim air prsov' and EICAS message 'trim air left') occurred on taxi-out from XXX. We performed a grd test of the left/H trim air system. The messages extinguished, but a few mins later re-appeared on the FMC status page. We decided to defer inoperative the left/H trim air prsov valve, per the boeing 777 MEL. The aircraft left ZZZ as flight rok at XC25 local. XC25 GMT. Approximately 30 mins later, while flying over obx, the flight crew communicated via VHF, that they had indication the left/H trim air prsov was in the open position! Therefore they had uncontrolled high temperatures on the flight deck and fwd cabin areas. We contacted abc maintrol-they stated that there was no way you could lock-open this valve! After some research of the MEL, to lock close the valve. Item notes to turn the manual wrench until the manual lock indicator shows the valve is in the closed (cl) position. Item states to install the locking plug in the hole and tighten. Accomplishing this procedure actually locks the valve open! Because of the vague position markings on the valve and with the circuit breaker's pulled, the valve is mechanically driven to the closed position, before one even starts the procedure per MEL, to lock-close the valve. Later, after conferring with supervisor Z, we ordered a trim air prsov from air carrier stores (this valve is the same one installed on abc, xyz aircraft) to verify the valve position configuration we performed on the abc aircraft. We noted the valve, with the procedure we followed was partially open! We contacted flight control of the condition, and they told us that the aircraft was diverting to DDD the maintenance controller patched us through to abc engineering, to notify them of our findings! So, they could correct the valve position! The aircraft dumped 4,000 kgs of fuel before landing at DDD. The ground time at DDD was 50 mins and arrived at XXX 3 hours late! Human performance considerations--the aircraft arrived extremely late, due to bad winds north of the arctic circle. Local and regional abc management puts undue pressure and stress on the aircraft maintenance staff, to get their aircraft out on its original departure time. It is extremely hard to address these types of maintenance issues in 1 1/2 hours from arrival to departure! Callback conversation with reporter revealed the following information: the reporter stated after reviewing the log report, the maintenance access terminal was checked and indicated the left trim air pressure regulator valve was failed in the open position. The reporter said the min equipment list allowed deferral of the valve in the closed and locked condition. The reporter said neither the min equipment list nor the maintenance manual indicates that after preliminary procedures of pulling circuit breakers and removing pneumatic pressure the valve is spring loaded closed. The reporter stated the valve location against the compartment ceiling makes the position of the valve almost impossible to determine even with inspection mirrors and the markings on the valve are vague. The reporter said the locking plug will fit in any valve position and is a departure from any kind of reasoning that a lock plug must only fit in the lock position. The reporter stated the valve wrenching fixture has no valve position indication or directional arrow to prevent valve damage. The reporter stated the valve configuration is poorly designed for maintenance.

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Original NASA ASRS Text

Title: A B777-200 WAS DISPATCHED IN NONCOMPLIANCE WITH THE LEFT TRIM AIR VALVE DEFERRED INOPERATIVE CLOSED PER THE MIN EQUIP LIST, BUT THE VALVE WAS ACTUALLY LOCKED OPEN DUE TO PUBLICATION DEFICIENCY.

Narrative: I WORK FOR AN ACR BASED AT ZZZ INTERNATIONAL ARPT, ZZZ, U.S. I AM TRAINED TO PERFORM TRANSIT AND ETOPS-PDC MAINT ON BOEING 777 ACFT FOR ABC ON FRI, APRIL 2001. I WAS ASSIGNED TO PERFORM TRANSIT AND ETOPS-PDC MAINT ON ACFT XYZ OF ACR ABC AT GATE. THE ACFT ARRIVED AT XA48 LOCAL XB48 GMT. THE FLT DECK CREW WROTE-UP IN THE TECH LOG, THAT ON TAXI-OUT FROM XXX THEY NOTED STATUS MSG 'TRIM AIR PRSOV L' AND EICAS MSG 'TRIM AIR L'- L TRIM AIR SWITCHED OFF IAW CHKLIST! CABIN TEMP VERY DIFFICULT TO CTL, ESPECIALLY ZONE F. AFTER SVC OF BOTH ENG OIL SYSTEMS, AMT BX AND MYSELF USED THE ACFT. MAT COMPUTER TO RETRIEVE ALL PRESENT LEG FAULTS. AT THIS TIME, IT WAS NOTED THAT BOTH MESSAGES (STATUS MSG 'TRIM AIR PRSOV' AND EICAS MSG 'TRIM AIR L') OCCURRED ON TAXI-OUT FROM XXX. WE PERFORMED A GRD TEST OF THE L/H TRIM AIR SYS. THE MESSAGES EXTINGUISHED, BUT A FEW MINS LATER RE-APPEARED ON THE FMC STATUS PAGE. WE DECIDED TO DEFER INOP THE L/H TRIM AIR PRSOV VALVE, PER THE BOEING 777 MEL. THE ACFT LEFT ZZZ AS FLT ROK AT XC25 LCL. XC25 GMT. APPROX 30 MINS LATER, WHILE FLYING OVER OBX, THE FLC COMMUNICATED VIA VHF, THAT THEY HAD INDICATION THE L/H TRIM AIR PRSOV WAS IN THE OPEN POS! THEREFORE THEY HAD UNCTLED HIGH TEMPS ON THE FLT DECK AND FWD CABIN AREAS. WE CONTACTED ABC MAINTROL-THEY STATED THAT THERE WAS NO WAY YOU COULD LOCK-OPEN THIS VALVE! AFTER SOME RESEARCH OF THE MEL, TO LOCK CLOSE THE VALVE. ITEM NOTES TO TURN THE MANUAL WRENCH UNTIL THE MANUAL LOCK INDICATOR SHOWS THE VALVE IS IN THE CLOSED (CL) POS. ITEM STATES TO INSTALL THE LOCKING PLUG IN THE HOLE AND TIGHTEN. ACCOMPLISHING THIS PROC ACTUALLY LOCKS THE VALVE OPEN! BECAUSE OF THE VAGUE POS MARKINGS ON THE VALVE AND WITH THE CB'S PULLED, THE VALVE IS MECHANICALLY DRIVEN TO THE CLOSED POS, BEFORE ONE EVEN STARTS THE PROC PER MEL, TO LOCK-CLOSE THE VALVE. LATER, AFTER CONFERRING WITH SUPVR Z, WE ORDERED A TRIM AIR PRSOV FROM ACR STORES (THIS VALVE IS THE SAME ONE INSTALLED ON ABC, XYZ ACFT) TO VERIFY THE VALVE POS CONFIGURATION WE PERFORMED ON THE ABC ACFT. WE NOTED THE VALVE, WITH THE PROC WE FOLLOWED WAS PARTIALLY OPEN! WE CONTACTED FLT CTL OF THE CONDITION, AND THEY TOLD US THAT THE ACFT WAS DIVERTING TO DDD THE MAINT CTLR PATCHED US THROUGH TO ABC ENGINEERING, TO NOTIFY THEM OF OUR FINDINGS! SO, THEY COULD CORRECT THE VALVE POS! THE ACFT DUMPED 4,000 KGS OF FUEL BEFORE LNDG AT DDD. THE GND TIME AT DDD WAS 50 MINS AND ARRIVED AT XXX 3 HRS LATE! HUMAN PERFORMANCE CONSIDERATIONS--THE ACFT ARRIVED EXTREMELY LATE, DUE TO BAD WINDS N OF THE ARCTIC CIRCLE. LOCAL AND REGIONAL ABC MGMNT PUTS UNDUE PRESSURE AND STRESS ON THE ACFT MAINT STAFF, TO GET THEIR ACFT OUT ON ITS ORIGINAL DEP TIME. IT IS EXTREMELY HARD TO ADDRESS THESE TYPES OF MAINT ISSUES IN 1 1/2 HRS FROM ARR TO DEP! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED AFTER REVIEWING THE LOG RPT, THE MAINT ACCESS TERMINAL WAS CHKED AND INDICATED THE L TRIM AIR PRESSURE REGULATOR VALVE WAS FAILED IN THE OPEN POS. THE RPTR SAID THE MIN EQUIP LIST ALLOWED DEFERRAL OF THE VALVE IN THE CLOSED AND LOCKED CONDITION. THE RPTR SAID NEITHER THE MIN EQUIP LIST NOR THE MAINT MANUAL INDICATES THAT AFTER PRELIMINARY PROCS OF PULLING CIRCUIT BREAKERS AND REMOVING PNEUMATIC PRESSURE THE VALVE IS SPRING LOADED CLOSED. THE RPTR STATED THE VALVE LOCATION AGAINST THE COMPARTMENT CEILING MAKES THE POSITION OF THE VALVE ALMOST IMPOSSIBLE TO DETERMINE EVEN WITH INSPECTION MIRRORS AND THE MARKINGS ON THE VALVE ARE VAGUE. THE RPTR SAID THE LOCKING PLUG WILL FIT IN ANY VALVE POS AND IS A DEP FROM ANY KIND OF REASONING THAT A LOCK PLUG MUST ONLY FIT IN THE LOCK POS. THE RPTR STATED THE VALVE WRENCHING FIXTURE HAS NO VALVE POS INDICATION OR DIRECTIONAL ARROW TO PREVENT VALVE DAMAGE. THE RPTR STATED THE VALVE CONFIGURATION IS POORLY DESIGNED FOR MAINT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.