Narrative:

I reported to ZZZ in order to reposition a lear 35. I had flown this aircraft exactly one month earlier to ZZZ. Our company manager briefed me he had run the aircraft up that morning and all systems checked ok. I specifically inquired as to all recent maintenance performed on the aircraft and was advised the only significant maintenance performed was to the thrust reversers. I was then instructed to exercise the reversers thoroughly upon arrival.after a thorough preflight my first officer and I systematically ran all checklists; obtained our clearance and taxied out to runway 25R for departure as instructed by ATC. After approximately a 15 minute delay at the hold line for departing airline traffic we were cleared for takeoff runway 25R intersection juliet. Line up items were completed and takeoff power set by myself as pilot flying. Accelerating down the runway just prior to airspeeds called alive I observed a flashing red fire warning light on the #1 engine t-handle annunciator. This was at first difficult to discern because of direct sunlight on the handle and lack of a warning horn on the aircraft. I immediately reduced power and applied brakes and the first officer instructed to advise ATC we were rejecting the takeoff. No other indications of fire or any other malfunctions observed. As I taxied clear of the runway I moved the #1 thrust lever to idle cutoff and the associated fire extinguished. We advised ATC no assistance was required and proceeded to taxi the short distance to the FBO using our #2 engine. Upon exiting the aircraft we noticed a small amount of smoke coming from the #1 engine cowling and line service approaching with fire extinguishers. I loosened the lower cowling latches to allow better access for the extinguishers if needed. Closer inspection revealed small pieces of the hard insulation and bits of wire winding loose in the lower cowling as the generator itself had partially disintegrated. Apparently it had become hot enough during this event to bubble the paint off cowling adjacent to its location. Later I debriefed with our manager and the mechanics at which time it was explained to me those mechanics had noticed a problem with the affected generator to the extent they expected it would self-destruct if left in service. They told me they had warned our manager to replace this generator. He responded that hours prior to our departure he ran the engine with the lower cowling removed in case the gen did in fact 'grenade' (in those words). It was also explained to me that run up was performed at only idle power because the manager believed the generator ran at a fixed speed not tied to N2. The aircraft was subsequently signed off and released to me for flight. In any case I had no prior knowledge of any warning signs from anyone including those inside and outside of our maintenance department. In my opinion this aircraft should not have been released into service unless all parties who had knowledge of a suspect generator had agreed it was safe for flight which apparently it wasn't.

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Original NASA ASRS Text

Title: Learjet 35 Captain reported a fire warning on the left engine at low speed during takeoff and rejected. When the cowl was opened the generator was found to have disintegrated.

Narrative: I reported to ZZZ in order to reposition a Lear 35. I had flown this aircraft exactly one month earlier to ZZZ. Our company Manager briefed me he had run the aircraft up that morning and all systems checked ok. I specifically inquired as to all recent maintenance performed on the aircraft and was advised the only significant maintenance performed was to the thrust reversers. I was then instructed to exercise the reversers thoroughly upon arrival.After a thorough preflight my FO and I systematically ran all checklists; obtained our clearance and taxied out to Runway 25R for departure as instructed by ATC. After approximately a 15 minute delay at the hold line for departing airline traffic we were cleared for takeoff Runway 25R intersection Juliet. Line up items were completed and takeoff power set by myself as pilot flying. Accelerating down the runway just prior to airspeeds called alive I observed a flashing red fire warning light on the #1 engine T-handle annunciator. This was at first difficult to discern because of direct sunlight on the handle and lack of a warning horn on the aircraft. I immediately reduced power and applied brakes and the FO instructed to advise ATC we were rejecting the takeoff. No other indications of fire or any other malfunctions observed. As I taxied clear of the runway I moved the #1 thrust lever to idle cutoff and the associated fire extinguished. We advised ATC no assistance was required and proceeded to taxi the short distance to the FBO using our #2 engine. Upon exiting the aircraft we noticed a small amount of smoke coming from the #1 engine cowling and line service approaching with fire extinguishers. I loosened the lower cowling latches to allow better access for the extinguishers if needed. Closer inspection revealed small pieces of the hard insulation and bits of wire winding loose in the lower cowling as the generator itself had partially disintegrated. Apparently it had become hot enough during this event to bubble the paint off cowling adjacent to its location. Later I debriefed with our Manager and the mechanics at which time it was explained to me those mechanics had noticed a problem with the affected generator to the extent they expected it would self-destruct if left in service. They told me they had warned our Manager to replace this generator. He responded that hours prior to our departure he ran the engine with the lower cowling removed in case the gen did in fact 'grenade' (in those words). It was also explained to me that run up was performed at only idle power because the Manager believed the generator ran at a fixed speed not tied to N2. The aircraft was subsequently signed off and released to me for flight. In any case I had no prior knowledge of any warning signs from anyone including those inside and outside of our maintenance department. In my opinion this aircraft should not have been released into service unless all parties who had knowledge of a suspect generator had agreed it was safe for flight which apparently it wasn't.

Data retrieved from NASA's ASRS site 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.