B747 Undifferentiated or Other Model
Training / Qualification
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Human Factors
This [report] is to highlight an aircraft maintenance issue. Upon arriving to the cockpit we noticed that the cockpit was much hotter than the rest of the aircraft. The cockpit temp was over 90 degrees and airflow was marginal. Just outside the cockpit it was noticeably cooler. There was a write up the previous day for cockpit temperature being hot and unable to cool. The maintenance corrective action was filters cleaned; all packs checked; and airflow was normal. There were no related EICAS or Status messages. During the walk around the relief pilot noticed there wasn't any flow out the electronics equipment bay exhaust port even though the door was open. We wrote up the electronics equipment bay exhaust fan. That would explain the much hotter than normal cockpit temperatures. Mechanic came to the cockpit and checked the maintenance messages and stated there were no problems everything was alright as if we were making up the issue. Surprised at this I proceeded to explain the issue and how the system worked. He left the cockpit and apparently went to the EE compartment. During this time; the relief pilot recalled flying an airplane with the hot cockpit and her PFD (primary flight display) subsequently failed in an over temp mode. Looking through her logbook she was able to identify this airplane as the culprit. At this point; we became very concerned as this airplane probably had been flying for over three months with an inoperative EE cooling fan during the summer months.The mechanic returned with a deferral sticker. The Captain refused to fly given the history of the aircraft and the need to replace the exhaust fan. During this time the PFDs reverted from a color background to a black (over temp) degraded mode. Apparently maintenance found an exhaust fan circuit breaker popped. Reset it and it popped again. Maintenance initiated the process to replace the fan. A follow up conversation with the Captain revealed checked with maintenance and found out they replaced the wrong fan. The input fan was replaced not the exhaust.Flight Ops needs to ensure that pilots doing the walk arounds are checking the exhaust fan and that it is blowing strongly.Maintenance needs to listen more closely to the problem presented especially if it's a reoccurring issue. It might not be the easy fix.
B747 First Officer reported; during preflight; discovering the electronic equipment bay exhaust fan was not working. Maintenance initially wanted to defer; Captain refused the aircraft; and then Maintenance replaced the wrong fan.