Narrative:

Had an engine fire. Event took place at my regional airport on the ramp on startup. I did my preflight and was ready to get into the airplane. I had the line guys top off the fuel tanks and I got in and cranked the engine. The engine starter would turn over but no audible sound was heard of any cylinder combustion whatsoever. The airplane was just previously flown and was already warm; not to mention that it was near 85 degrees outside. It seemed weird that it had no combustion and just the starter was going; so I laid off on the ignition switch to keep from hurting the starter. I did this about twice or more; its hard to remember. I then thought to put some primer in because the engine was not previously primed. After priming the engine I tried another crank. This time it still had no noticeable indication of any fuel combustion in the cylinders either. After this ordeal; I assumed that I may have flooded it. (Which makes no sense because the engine shouldn't have needed primer in the first place; but putting primer in would not hurt anyway cause its part of the checklist). I then did my flooded engine procedures to compensate. Around this time between the primer injection and the flooded engine procedures I heard a backfire or a loud detonation. I knew something was wrong and smelled smoke. I then proceeded to run the emergency ground fire checklist and cranked the engine to put the fire out but the ignition then died and nothing moved. By this time the lines guy was there to put the fire out. As far as I could tell the aircraft damages were a burnt induction filter and a blown battery. I have my own suspicions that that the battery may have been faulty due to some previous times that it needed a jump or two to get it cranked.

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Original NASA ASRS Text

Title: A C152's engine did not start on previous attempts and after priming the already warm engine it backfired; lighting the excess fuel and causing an engine fire. A nearby ground crew extinguished the fire.

Narrative: Had an engine fire. Event took place at my regional airport on the ramp on startup. I did my preflight and was ready to get into the airplane. I had the line guys top off the fuel tanks and I got in and cranked the engine. The engine starter would turn over but no audible sound was heard of any cylinder combustion whatsoever. The airplane was just previously flown and was already warm; not to mention that it was near 85 degrees outside. It seemed weird that it had no combustion and just the starter was going; so I laid off on the ignition switch to keep from hurting the starter. I did this about twice or more; its hard to remember. I then thought to put some primer in because the engine was not previously primed. After priming the engine I tried another crank. This time it still had no noticeable indication of any fuel combustion in the cylinders either. After this ordeal; I assumed that I may have flooded it. (which makes no sense because the engine shouldn't have needed primer in the first place; but putting primer in would not hurt anyway cause its part of the checklist). I then did my flooded engine procedures to compensate. Around this time between the primer injection and the flooded engine procedures I heard a backfire or a loud detonation. I knew something was wrong and smelled smoke. I then proceeded to run the emergency ground fire checklist and cranked the engine to put the fire out but the ignition then died and nothing moved. By this time the lines guy was there to put the fire out. As far as I could tell the aircraft damages were a burnt induction filter and a blown battery. I have my own suspicions that that the battery may have been faulty due to some previous times that it needed a jump or two to get it cranked.

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.