Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 240; Flight Crew Total 20000; Flight Crew Type 2500
Time Pressure; Workload; Communication Breakdown; Confusion; Distraction; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL
Flight Crew Rejected Takeoff; Flight Crew Returned To Gate; Flight Crew Took Evasive Action; General Maintenance Action
Aircraft; Procedure
[We] dispatched with inoperative auto speedbrakes due to continually displayed 'SPEEDBRAKE ARMED' status message. Delay in receiving final maintenance release due to late discovery of possible hydraulic leak. Maintenance did not inform me of the airplane's status until well into the problem. The hydraulic pumps were turned on per pre-start SOP because I was left out of the loop. Someone could have been injured. Fortunately; it was just a distraction as the problem was fixed. We pushed and received a final MRD. I checked it and the EICAS annunciations were as described in the maintenance release. We taxied to the assigned runway and were cleared for take off while lining up. I mentioned to the flying First Officer that we might not have the gear completely straightened out. The First Officer advanced power and we got a Takeoff Warning. I thought it was a gear steering issue caused by me so I delayed a second or two to see if it would resolve itself as the airplane moved forward a bit. It didn't so the takeoff was abandoned. Airspeed was not yet indicated so we were at least below 30 KTS IAS. Tower was notified and we turned right onto the parallel C. We called Dispatch and linked Maintenance Control in. They were asking about Circuit Breaker positions and such and I got the idea that they thought that we were going to attempt another take off. I had no intention of doing so. All flight controls and flaps were positioned correctly. Spoilers were all showing down. I couldn't see what caused the warning so I elected to return to the gate. Upon arrival to the gate the mechanics came aboard and quickly trouble shot the system. They determined that the aircraft had probably been deferred in error as the speedbrake actuator was mis-rigged. You could hear it activate whenever the throttles moved forward or back; a sound that one would normally only hear if the speedbrakes were actually armed or deployed. The distractions pre-push are typical. The RTO was at such a low speed that there was no threat and the brake temps did not indicate above 0 the entire time that we were in the airplane. The problem that I see with the situation is that for one; we are willing to Dispatch a B747 with that problem. Secondly; the required maintenance actions either were not correctly performed; the true problem was misidentified; or the MEL procedure was incorrect. In any case; the speedbrake actuator was actuating. This is not meant to cast maintenance in an unfavorable light. The Mechanics that met the airplane diagnosed the issue within a couple of minutes and said that the aircraft should not have been signed off in that condition. That was obvious in the outcome of the takeoff attempt. Imagine the confusion that we felt when presented with two EICAS messages relating to ground spoilers presented as normal and safe per MEL; being distracted by the body gear possibly being a little out of line and seeing a Takeoff Warning with the expected BIAS that we might momentarily get it and that it would quickly disappear. Reality is always stranger than the simulator. Fortunately; everything happened slowly; at low speed and was easily handled. Do we; as a company that prides itself on safety; really find value in dispatching our largest aircraft with these kinds of systems inoperative? It is unlikely that I will accept another B747 with this malfunction; all politics aside; it just seems unreasonable. The B747 isn't like the B727. Two many systems are interrelated in ways that are unknown to the pilots.
A B747 status display constantly indicated SPEEDBRAKE ARMED so maintenance MELed the system prior to flight but because the Takeoff Warning sounded; a slow speed reject was completed. The flight returned to the gate where Maintenance determined the speedbrake system should not have been MELed.