Narrative:

Approximately 3.4 hours into our 5.0 hour flight; we were alerted via the EICAS system with a crew oxygen low message. We went to the checklist and followed up with the manual. The pressure at this point was about 650 psi on the status page. We asked for and received a clearance to FL250 and we immediately got maintenance control and dispatch involved. Maintenance control had us check the 4 02 masks in the cockpit which were all normal. During the 20 minutes of ACARS messages back and forth; our pressure went to 280 psi. Our checklist states that if the pressure gets to 250 psi or lower; descend. We asked for 10;000 ft. The pressure continued downward to 0 psi and I requested dispatch concurrence for a divert. Flight landed uneventful. Emergency was not declared. FBO mechanic came out and verified 02 bottle was 0 psi. Pilots stayed with aircraft for over 9 hours only to run out of duty time. A pressure regulator and an overpressure relief valve were both suspect in causing the rapid loss in pressure. The 02 bottle seemed in tact and no obvious leaks. Parts were ordered from the maintenance base and a new 02 tank was ordered and they were going to fix the aircraft at which point; we agreed to ferry it to the maintenance base in the morning. The following day; crew was told aircraft was fixed and signed off. I asked what work had been done. Maintenance control told me that they did not have an over pressure relief valve anywhere in the system however they did have a pressure regulator and when they installed the new part; it was defective. The mechanics then re-installed the old part; cleaned the connector and said the pressure was 1700 and they also did a pressure check. The system held pressure and they signed it off as repaired and airworthy. We were taken to the cargo pad where the aircraft sat and were going to taxi to the gate for fuel. Prior to engine start; the pressure was 1750 psi. Immediately after engine start; we got a crew oxygen low EICAS message and the pressure on the status page showed 0 psi. We taxied the plane to gate. We had operations call maintenance control who called an FBO mechanic to the plane. I called the acting chief pilot who said; 'we are going to shut this down and either send you to a hotel or deadhead you for the remainder of your assignment.' in the meantime; the mechanic and I checked the bottle pressure and it showed 1700 psi; however; the cockpit indication was still showing 0 psi and the secondary pressure indicator was showing 0 psi in the nose. Maintenance control told the mechanic to send in a deferral and that it was cleared to fly adding that 'the captain will turn down the aircraft and then we can fix it.' I was sitting with the FBO mechanic when he made this comment. I immediately got the acting chief pilot as well as maintenance control and flight operations management involved. Maintenance control told me he was going to defer the pressure regulator. I asked how would the crew know if they developed another leak and how would they be able to check this enroute? Maintenance control said 'if the captain wants to turn down the airplane; we can fix it.' I refused to turn down an airplane that I didn't sign for. I again called the acting chief pilot and relayed what was said by maintenance control. I told both that if the onus were put on me to turn down the aircraft; I would call the FAA and see what they would have to say with regards to the maintenance action performed and the fact that our maintenance department wanted to defer the 02 indicating and low pressure indicating system (both were inoperative in the cockpit at the present time). Captain questioned all parties involved how they would combat a smoke and fire problem or a depressurization problem if we had no way of knowing if we have 02 or that we are losing 02 via the EICAS system because both were now inoperative? For the next six hours; maintenance control tried to get the me to accept a plane with a deferred02 indicating system and with an EICAS system that was now unavailable in the event of a 02 loss of pressure. I asked if we are at FL380 and we started to lose our pressure again; how would we know? The first officer also brought up a valid point about smoke in the cockpit. How would we know that we have adequate 02 psi if the system is unavailable to the cockpit and we had to fight a fire or battle smoke? Maintenance control then told the flight operations manager that the 02 bottle was actually defective and that they had put a new bottle in place (the write up clearly showed that the pressure regulator was the faulty part with no mention of the 02 bottle being the culprit); which was another attempt to get me to accept a defective aircraft. I then came up with a plan to fly the aircraft to ZZZ at 10;000 MSL with two smoke goggles and two portable 02 bottles; which were brought to the cockpit. Everyone involved agreed with this compromise. Aircraft departed and flew at 10;000 MSL all the way to ZZZ. Landing was uneventful.

Related reports:

Google
 

Original NASA ASRS Text

Title: A B777-200 flight crew refused the aircraft due to an improperly resolved AML write up regarding the Crew Oxygen system.

Narrative: Approximately 3.4 hours into our 5.0 hour flight; we were alerted via the EICAS system with a CREW OXYGEN LOW message. We went to the checklist and followed up with the manual. The pressure at this point was about 650 PSI on the Status Page. We asked for and received a clearance to FL250 and we immediately got Maintenance Control and Dispatch involved. Maintenance Control had us check the 4 02 masks in the cockpit which were all normal. During the 20 minutes of ACARS messages back and forth; our pressure went to 280 PSI. Our checklist states that if the pressure gets to 250 PSI or lower; descend. We asked for 10;000 FT. The pressure continued downward to 0 PSI and I requested Dispatch concurrence for a divert. Flight landed uneventful. Emergency was not declared. FBO Mechanic came out and verified 02 bottle was 0 PSI. Pilots stayed with aircraft for over 9 hours only to run out of duty time. A pressure regulator and an overpressure relief valve were both suspect in causing the rapid loss in pressure. The 02 bottle seemed in tact and no obvious leaks. Parts were ordered from the maintenance base and a new 02 tank was ordered and they were going to fix the aircraft at which point; we agreed to ferry it to the maintenance base in the morning. The following day; crew was told aircraft was fixed and signed off. I asked what work had been done. Maintenance Control told me that they did not have an over pressure relief valve anywhere in the system however they did have a pressure regulator and when they installed the new part; it was defective. The mechanics then re-installed the old part; cleaned the connector and said the pressure was 1700 and they also did a pressure check. The system held pressure and they signed it off as repaired and airworthy. We were taken to the cargo pad where the aircraft sat and were going to taxi to the gate for fuel. Prior to engine start; the pressure was 1750 PSI. Immediately after engine start; we got a CREW OXYGEN LOW EICAS message and the pressure on the status page showed 0 PSI. We taxied the plane to gate. We had Operations call Maintenance Control who called an FBO Mechanic to the plane. I called the Acting Chief Pilot who said; 'we are going to shut this down and either send you to a hotel or deadhead you for the remainder of your assignment.' In the meantime; the Mechanic and I checked the bottle pressure and it showed 1700 PSI; however; the cockpit indication was still showing 0 PSI and the secondary pressure indicator was showing 0 PSI in the nose. Maintenance Control told the Mechanic to send in a deferral and that it was cleared to fly adding that 'the Captain will turn down the aircraft and then we can fix it.' I was sitting with the FBO Mechanic when he made this comment. I immediately got the Acting Chief Pilot as well as maintenance control and flight operations management involved. Maintenance control told me he was going to defer the pressure regulator. I asked how would the crew know if they developed another leak and how would they be able to check this enroute? Maintenance Control said 'If the Captain wants to turn down the airplane; we can fix it.' I refused to turn down an airplane that I didn't sign for. I again called the Acting Chief Pilot and relayed what was said by Maintenance Control. I told both that if the onus were put on me to turn down the aircraft; I would call the FAA and see what they would have to say with regards to the maintenance action performed and the fact that our maintenance department wanted to defer the 02 indicating and low pressure indicating system (both were inoperative in the cockpit at the present time). Captain questioned all parties involved how they would combat a smoke and fire problem or a depressurization problem if we had no way of knowing if we have 02 or that we are losing 02 via the EICAS system because both were now inoperative? For the next six hours; Maintenance Control tried to get the me to accept a plane with a deferred02 indicating system and with an EICAS system that was now unavailable in the event of a 02 loss of pressure. I asked if we are at FL380 and we started to lose our pressure again; how would we know? The First Officer also brought up a valid point about smoke in the cockpit. How would we know that we have adequate 02 PSI if the system is unavailable to the cockpit and we had to fight a fire or battle smoke? Maintenance Control then told the Flight Operations Manager that the 02 bottle was actually defective and that they had put a new bottle in place (the write up clearly showed that the pressure regulator was the faulty part with no mention of the 02 bottle being the culprit); which was another attempt to get me to accept a defective aircraft. I then came up with a plan to fly the aircraft to ZZZ at 10;000 MSL with two smoke goggles and two portable 02 bottles; which were brought to the cockpit. Everyone involved agreed with this compromise. Aircraft departed and flew at 10;000 MSL all the way to ZZZ. Landing was uneventful.

Data retrieved from NASA's ASRS site as of April 2012 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.