Narrative:

I flew the same airplane on a previous date. The airplane had the same item deferred in the same way. The same deferral language; which I believe is wrong and dangerous. The deferral requires the pilots to place the remaining adp pump selector to 'on.' maintenance action requires the adp with the automatic function failure to have its pump selector switch in the 'on' position; ie; both C1 and C2 demand pump selector switches will be on. Therefore; only C1 demand pump will work and C2 will never function. During the preflight; I reviewed the release and tried to make sense of the deferred item; demand C1 hydraulic pump. The defect was C1 demand air driven pump automatic function inoperative. The flight crew action was written as follows: flight crew: a) the following must operate normally: 1) remaining adp (including automatic function). 2) associated adp on and off selector position. B) after engine start: 1) position remaining air demand pump selector to 'on' for all phases of flight. My question for maintenance control was: what is the position of the off/automatic/on selector for the associated adp after engine start? After reading the maintenance actions; maintenance control said that the associated pump should be on for all phases of flight. If C1 demand pump should fail; then C2 would take over. I pointed out that with both C1 and C2 demand pump switches on; that C2 would be deactivated and never come on. This action also causes the irregular procedure EICAS caution message 'hydraulic pressure dem C2' to be displayed with an icon. The flight crew procedures do not tell us to ignore the caution; override the checklist or complete the checklist; which tells you turn off C2 if the message remains displayed. From my conversation with maintenance control prior to the flight; it was clear that both C1 and C2 demand pumps would be on for the entire flight. On sep/xa/06 prior to the flight back to nagoya; I called dispatch from my hotel room and arranged for a conference call with maintenance control. I still was not satisfied with the procedure as written in the aircraft maintenance log. Going back over all the ground that had been covered the previous day; maintenance control said that the associated demand pump C1 should be on for the entire flight; but then in additional review of the maintenance procedures stated that there are 3 variations: 1) both automatic functions inoperative (deferrable) -- 1 pump on the entire flight. 2) 1 automatic function inoperative (deferrable) -- associated pump on entire flight. 3) 1 adp inoperative (deferrable) -- remaining adp selector on the entire flight. Maintenance control's interpretation of situation #2 is with 1 adp automatic function inoperative that pump switch will be turned on after engine start and stay on for all phases of flight and the remaining pump is operated normally in the automatic position. Which eliminates the caution message problem; but will C2 actually work in automatic with C1 positioned to 'on.' if the automatic function doesn't work; let's say so. The pilot actions for this deferral; need to be written more clearly. My thought is that it is an incorrect procedure the way it is written now. I agreed to take the aircraft if the pump was considered failed. Which required maintenance to disconnect the pump and various other action listed in MEL. Among the pilot required items the APU is used for air source for takeoff; runway limited is reduced by 9600 pounds and performance limit is reduced by 1400 pounds. I am not sure why; the APU is running the adp so bleed air is not coming off the engine. Maybe the gear and flap retraction will be slower with only 1 demand pump operating. Deferring the automatic function using MEL; the way it is written; only C1 demand pump will operate using the engine as the bleed source. Should there not; also; be a runway and performance reduction. What if the left engine fails at V1; now; no demand pump is operating and gear retraction and flap retraction will be extremely slow under the worse possible conditions engine failed and the gear down. If adp C1 is selected on and adp C2 is selected to automatic; then maybe the C2 demand pump will work. The flight manual says with both C1 and C2 selected to automatic; both pumps will operate if needed. The manual does not address one in automatic and one selectedto on.

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Original NASA ASRS Text

Title: CAPT OF B777-200 IS CONFUSED BY DEFERRAL OF AUTO FUNCTION OF THE HYD AIR DEMAND PUMP.

Narrative: I FLEW THE SAME AIRPLANE ON A PREVIOUS DATE. THE AIRPLANE HAD THE SAME ITEM DEFERRED IN THE SAME WAY. THE SAME DEFERRAL LANGUAGE; WHICH I BELIEVE IS WRONG AND DANGEROUS. THE DEFERRAL REQUIRES THE PLTS TO PLACE THE REMAINING ADP PUMP SELECTOR TO 'ON.' MAINT ACTION REQUIRES THE ADP WITH THE AUTO FUNCTION FAILURE TO HAVE ITS PUMP SELECTOR SWITCH IN THE 'ON' POS; IE; BOTH C1 AND C2 DEMAND PUMP SELECTOR SWITCHES WILL BE ON. THEREFORE; ONLY C1 DEMAND PUMP WILL WORK AND C2 WILL NEVER FUNCTION. DURING THE PREFLT; I REVIEWED THE RELEASE AND TRIED TO MAKE SENSE OF THE DEFERRED ITEM; DEMAND C1 HYD PUMP. THE DEFECT WAS C1 DEMAND AIR DRIVEN PUMP AUTO FUNCTION INOP. THE FLT CREW ACTION WAS WRITTEN AS FOLLOWS: FLT CREW: A) THE FOLLOWING MUST OPERATE NORMALLY: 1) REMAINING ADP (INCLUDING AUTO FUNCTION). 2) ASSOCIATED ADP ON AND OFF SELECTOR POS. B) AFTER ENG START: 1) POS REMAINING AIR DEMAND PUMP SELECTOR TO 'ON' FOR ALL PHASES OF FLT. MY QUESTION FOR MAINT CTL WAS: WHAT IS THE POS OF THE OFF/AUTO/ON SELECTOR FOR THE ASSOCIATED ADP AFTER ENG START? AFTER READING THE MAINT ACTIONS; MAINT CTL SAID THAT THE ASSOCIATED PUMP SHOULD BE ON FOR ALL PHASES OF FLT. IF C1 DEMAND PUMP SHOULD FAIL; THEN C2 WOULD TAKE OVER. I POINTED OUT THAT WITH BOTH C1 AND C2 DEMAND PUMP SWITCHES ON; THAT C2 WOULD BE DEACTIVATED AND NEVER COME ON. THIS ACTION ALSO CAUSES THE IRREGULAR PROC EICAS CAUTION MESSAGE 'HYD PRESSURE DEM C2' TO BE DISPLAYED WITH AN ICON. THE FLT CREW PROCS DO NOT TELL US TO IGNORE THE CAUTION; OVERRIDE THE CHKLIST OR COMPLETE THE CHKLIST; WHICH TELLS YOU TURN OFF C2 IF THE MESSAGE REMAINS DISPLAYED. FROM MY CONVERSATION WITH MAINT CTL PRIOR TO THE FLT; IT WAS CLR THAT BOTH C1 AND C2 DEMAND PUMPS WOULD BE ON FOR THE ENTIRE FLT. ON SEP/XA/06 PRIOR TO THE FLT BACK TO NAGOYA; I CALLED DISPATCH FROM MY HOTEL ROOM AND ARRANGED FOR A CONFERENCE CALL WITH MAINT CTL. I STILL WAS NOT SATISFIED WITH THE PROC AS WRITTEN IN THE ACFT MAINT LOG. GOING BACK OVER ALL THE GROUND THAT HAD BEEN COVERED THE PREVIOUS DAY; MAINT CTL SAID THAT THE ASSOCIATED DEMAND PUMP C1 SHOULD BE ON FOR THE ENTIRE FLT; BUT THEN IN ADDITIONAL REVIEW OF THE MAINT PROCS STATED THAT THERE ARE 3 VARIATIONS: 1) BOTH AUTO FUNCTIONS INOP (DEFERRABLE) -- 1 PUMP ON THE ENTIRE FLT. 2) 1 AUTO FUNCTION INOP (DEFERRABLE) -- ASSOCIATED PUMP ON ENTIRE FLT. 3) 1 ADP INOP (DEFERRABLE) -- REMAINING ADP SELECTOR ON THE ENTIRE FLT. MAINT CTL'S INTERP OF SITUATION #2 IS WITH 1 ADP AUTO FUNCTION INOP THAT PUMP SWITCH WILL BE TURNED ON AFTER ENG START AND STAY ON FOR ALL PHASES OF FLT AND THE REMAINING PUMP IS OPERATED NORMALLY IN THE AUTO POS. WHICH ELIMINATES THE CAUTION MESSAGE PROB; BUT WILL C2 ACTUALLY WORK IN AUTO WITH C1 POSITIONED TO 'ON.' IF THE AUTO FUNCTION DOESN'T WORK; LET'S SAY SO. THE PLT ACTIONS FOR THIS DEFERRAL; NEED TO BE WRITTEN MORE CLRLY. MY THOUGHT IS THAT IT IS AN INCORRECT PROC THE WAY IT IS WRITTEN NOW. I AGREED TO TAKE THE ACFT IF THE PUMP WAS CONSIDERED FAILED. WHICH REQUIRED MAINT TO DISCONNECT THE PUMP AND VARIOUS OTHER ACTION LISTED IN MEL. AMONG THE PLT REQUIRED ITEMS THE APU IS USED FOR AIR SOURCE FOR TKOF; RWY LIMITED IS REDUCED BY 9600 LBS AND PERFORMANCE LIMIT IS REDUCED BY 1400 LBS. I AM NOT SURE WHY; THE APU IS RUNNING THE ADP SO BLEED AIR IS NOT COMING OFF THE ENG. MAYBE THE GEAR AND FLAP RETRACTION WILL BE SLOWER WITH ONLY 1 DEMAND PUMP OPERATING. DEFERRING THE AUTO FUNCTION USING MEL; THE WAY IT IS WRITTEN; ONLY C1 DEMAND PUMP WILL OPERATE USING THE ENG AS THE BLEED SOURCE. SHOULD THERE NOT; ALSO; BE A RWY AND PERFORMANCE REDUCTION. WHAT IF THE L ENG FAILS AT V1; NOW; NO DEMAND PUMP IS OPERATING AND GEAR RETRACTION AND FLAP RETRACTION WILL BE EXTREMELY SLOW UNDER THE WORSE POSSIBLE CONDITIONS ENG FAILED AND THE GEAR DOWN. IF ADP C1 IS SELECTED ON AND ADP C2 IS SELECTED TO AUTO; THEN MAYBE THE C2 DEMAND PUMP WILL WORK. THE FLT MANUAL SAYS WITH BOTH C1 AND C2 SELECTED TO AUTO; BOTH PUMPS WILL OPERATE IF NEEDED. THE MANUAL DOES NOT ADDRESS ONE IN AUTO AND ONE SELECTEDTO ON.

Data retrieved from NASA's ASRS site as of January 2009 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.