B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 219; Flight Crew Type 8000
Confusion; Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Aircraft; Incorrect / Not Installed / Unavailable Part
In-flight; the Master Caution annunciation along with the 'ELEC' light on the system annunciator panel flickered. Upon further investigation; we discovered the number two Gen Drive oil temp was elevated. The 'High Oil Temp' light was not illuminated; even in the test mode. We checked all the circuit breakers and none were popped. We monitored the Constant Speed Drive temperature for the remainder of the flight and started the APU as a precaution. We landed at our destination uneventfully. Contract Maintenance met the aircraft and noted that the light bulbs were missing from the annunciator. The light bulbs were then replaced. We accomplished an 'engine run-up' to check the Generator Drive oil temp. As the temperature was still elevated; we accomplished the Generator Drive High Oil Temperature Checklist in the QRH. Maintenance deferred the item and we continued on our trip with the MEL restrictions.
Upon climb out; we received an intermittent Master Caution light with associated ELEC. No other lights were illuminated. On investigation we observed the number two Constant Speed Drive (CSD) oil temp noticeably higher than the number one. The 'High Oil Temp' light was not illuminated even in the test mode. Circuit breakers were all in. We continued to monitor and landed without any other issues. Contract Maintenance was notified and discovered that four light bulbs were missing from the number two 'High Oil Temp and Low Oil Pressure' annunciators associated with the CSD. We performed an engine run on the number two engine and observed the number two CSD oil temperature increasing at idle and disconnected the CSD drive per Contract Maintenance instructions and the QRH.
B737 flight crew reported observing a Master Caution 'ELEC' warning light. They noted that one of the generator drive units indicated an elevated temperature; but without the associated warning light. They landed uneventfully and discovered during post flight troubleshooting that several bulbs were missing from the annunciator panel.