Narrative:

My first officer and I were taking over an aircraft at ZZZ that was inbound to ZZZ. We were on the last day of a 3 day trip with remaining legs to ZZZ1; ZZZ2 and finally ZZZ3. Maintenance was waiting as the plane arrived. The pilots explained to me that they had had multiple failures of both the normal and alternate equipment cooling fans on both the ground and while enroute to ZZZ. This had occurred in spite of the fact that the plane had been in maintenance the night before and that there had been a history of this problem in the logbook from at least 3 previous write-ups. Our mechanic cleaned some sensors and determined that the normal fan was working properly; however; he needed to MEL the alternate because it was shorting somewhere causing it to trip a circuit breaker. After reviewing the logbook and listening to the pilots who brought the plane in and the mechanic working on it; I decided to call my chief pilot. The plane obviously had a recurring problem and the fact that it had been in a heavy check the night before made me somewhat suspect. I relayed these concerns to my chief but his response was that the applied MEL was legal and I really had no choice. We took off for ZZZ1 and out of 10;000 ft the normal cooling fan off light illuminated. It remained on until descending through approximately FL200 when it extinguished. The off light then illuminated several times after we had arrived at the gate. I notified dispatch and maintenance who then had a contract mechanic work on the plane. The contract mechanic cleaned sensors again and after a lot of phone conversations with our maintenance; he made some logbook entries. He explained to me that the normal cooling fan was in fact the culprit and the alternate was working fine. An MEL was; therefore; applied to reflect this change. I was incredulous and spoke to my dispatcher; maintenance; and the chief pilot again. The plane was at that time operating on the alternate cooling fan while at the gate for quite a lengthy period. It had not tripped any cbs and appeared to be working normally. I mulled all of this information over again and ended up flying the plane to ZZZ2; which is a maintenance base for our airline. The flight was uneventful and the alternate fan worked fine until we landed and parked at the gate. Immediately after shutting down the #1 engine; the off light illuminated on the alternate cooling fan and the circuit breaker tripped. Maintenance took the plane out of service to be repaired. I regret flying the plane after ZZZ1. Documented multiple failures of both the normal and alternate cooling fans; heavy maintenance on the plane the night before with no resolution of the problem; and MEL swapping by mechanics were all indications that this plane should have been grounded and repaired.

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Original NASA ASRS Text

Title: Captain reports he regrets flying a B737-300 that had documented; multiple failures of the normal and alternate cooling fans; heavy maintenance on the plane the night before with no resolution of the problem and MEL swapping by mechanics.

Narrative: My First Officer and I were taking over an aircraft at ZZZ that was inbound to ZZZ. We were on the last day of a 3 day trip with remaining legs to ZZZ1; ZZZ2 and finally ZZZ3. Maintenance was waiting as the plane arrived. The pilots explained to me that they had had multiple failures of both the normal and alternate equipment cooling fans on both the ground and while enroute to ZZZ. This had occurred in spite of the fact that the plane had been in maintenance the night before and that there had been a history of this problem in the logbook from at least 3 previous write-ups. Our Mechanic cleaned some sensors and determined that the normal fan was working properly; however; he needed to MEL the alternate because it was shorting somewhere causing it to trip a CB. After reviewing the logbook and listening to the pilots who brought the plane in and the Mechanic working on it; I decided to call my Chief Pilot. The plane obviously had a recurring problem and the fact that it had been in a heavy check the night before made me somewhat suspect. I relayed these concerns to my Chief but his response was that the applied MEL was legal and I really had no choice. We took off for ZZZ1 and out of 10;000 FT the normal cooling fan off light illuminated. It remained on until descending through approximately FL200 when it extinguished. The off light then illuminated several times after we had arrived at the gate. I notified dispatch and maintenance who then had a contract mechanic work on the plane. The Contract Mechanic cleaned sensors again and after a lot of phone conversations with our maintenance; he made some logbook entries. He explained to me that the normal cooling fan was in fact the culprit and the alternate was working fine. An MEL was; therefore; applied to reflect this change. I was incredulous and spoke to my Dispatcher; maintenance; and the Chief Pilot again. The plane was at that time operating on the alternate cooling fan while at the gate for quite a lengthy period. It had not tripped any CBs and appeared to be working normally. I mulled all of this information over again and ended up flying the plane to ZZZ2; which is a maintenance base for our airline. The flight was uneventful and the alternate fan worked fine until we landed and parked at the gate. Immediately after shutting down the #1 engine; the off light illuminated on the alternate cooling fan and the CB tripped. Maintenance took the plane out of service to be repaired. I regret flying the plane after ZZZ1. Documented multiple failures of both the normal and alternate cooling fans; heavy maintenance on the plane the night before with no resolution of the problem; and MEL swapping by mechanics were all indications that this plane should have been grounded and repaired.

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.