DC-9 30
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Human Factors
The original discovery of the left-hand Aft [Center Tank] Circuit Breakers being popped was out of a 10;000 FT climb departing OKC. The Captain was the pilot not flying and First Officer was the pilot flying. After the discovery of the circuit breakers being out we referenced to the Flight Operations Manual [FOM] and there is no reference to determining actions to take; other than it is a limitation NOT to reset [fuel system] circuit breakers. The crew continued to watch the fuel scheduling and noticed no abnormal burns nor were there any problems with engine acceleration etc. Once within range of air to ground contact with Operations the company was notified that upon arrival we would have a discrepancy. Company was informed that it was left-hand aft circuit breakers and no other defects were noted. Fuel out of OKC was less than 18;000. Therefore the center tank pumps were never 'ON' for this leg when the defect was noted. The Captain wrote the discrepancy in the logbook. 'Left Fuel Tank Pump Circuit Breakers 0B [phase B] and 0C popped; AFT Breakers Row H.' This was done with the specific intent to help define exactly what pump was in question. After the write up was complete the Captain entered the New TAT on the log page and faxed the page to Maintenance Control. Maintenance Control confirmed with the Captain as to the description of the discrepancy and over the phone we confirmed which circuit breakers and pump it was to be deferred.Maintenance Control then sent then log page back to the Captain with the reference to the deferral 28-1-1; the paper work to enter the aircraft 'can' 'Special Procedures' and then the Captain was to pull the third circuit breaker for that specific pump; 0A. After the third circuit breaker was pulled and all three breakers collared and the orange sticker placards C/W; the deferral was written: Deferred left-hand Fuel Tank Aft Boost Pump in accordance with MEL 28-1-1 CAT-C. Special Procedures C/W Placards Installed Per Maintenance Control. The log page was sent back to Maintenance Control and a new page was started to return to base. At this point the aircraft was released by Maintenance Control to return home. Fuel required to return was approximately 8;200; the aircraft was fueled to 9;000 LBS. Fuel quantity and fuel balance (scheduling) was never inadequate; imbalanced or was never outside of what was normal burn.A week later communication began between the Captain and the Chief Pilot. At that time the Chief Pilot was trying to gather information concerning the possibility of the wrong circuit breakers being collared or the possibility of the incorrect discrepancy being logged. It was understood that the deferral was for the left-hand aft boost pump and during earlier inspection and testing maintenance personnel found the center forward boost pump collared. At this time it is unclear to me; the Captain; when the deference occurred. But it is clear to me that the original pumps collared were the left-hand aft boost pump (they popped and were never reset). In the write up; it is written that the popped breakers were in Row H and that would include both sets of breakers in question. But each area where the breakers are labeled in their own outlined box; forward for the center fuel tank boost pump in Row H and aft for the left fuel tank boost pump in Row H. With knowledge of the left AC and right AC (Lazy - L it is some times called; electrical) power distribution to the pumps I understand why the aft and forward are different in Row H. During our conversation it was mentioned that this should be listed in a report. This report reflects what I as the Captain noticed during my operating of the aircraft and during conversations with the Chief Pilot. It should be noted that I believe that the center forward boost pump were accidentally collared at a later date than from the time that I operated the aircraft. It is my understanding per the Chief Pilot; that other crews have operated the aircraft with center fuel required since I brought the plane back to base. If the center forward boost pump was inoperative or the circuit breakers pulled on it; those crews should not have been able to get fuel out of the center tank due to the one pump only providing 15 PSI reduced to approximately 13.5 PSI from the spring loaded ball valve. The 13.5 PSI would have not over come the 15 PSI the wings would have provided unless those crews referred to the FOM and followed the procedure guiding you to shut off the wing pumps to get the fuel out of the center. Therefore I believe both center pumps most have been functioning properly and that the left-hand aft pump was properly collared and identified.
It is my understanding that there may have been an unintentional non-compliance issue with a deferral concerning fuel boost pumps. As I was not directly involved with the deferral process; I only recall a few items that may be pertinent. First I remember the Captain making a couple trips inside the FBO to use their fax machine. Second I remember asking the Captain if there were any special procedures that needed to be complied with. He stated nothing for each leg; but we needed to add a small amount of fuel to the 'required' section of the flight plan (I believe it was 330 LBS). Third I remember the phone call with Operations where the Captain wrote down the Flight Followers initials and received clearance to return.
DC9 flight crew is informed after the fact that incorrect circuit breakers may have been pulled and collared to comply with a center tank pump failure. The Captain believes the error occurred days later.