Narrative:

At runup, engine performed well. Shortly after liftoff right magneto distributor gear teeth failed catastrophically. Engine lost power sufficiently so that level flight could not be maintained. After examination a mechanic indicated that his examination showed that failure of the gear teeth affected the timing for both magnetos because of random pulses from the right magnetic. I would suggest development of a solid state sensor which could detect asynchronous timing between the magnetos and which would then shut down the failed magnetic (i.e., the one which provided worse performance). The mechanic suggested that I could have switched to the left magnetic to maintain power, but I did not have sufficient altitude at the time of occurrence to experiment. A solid state device could have achieved the proper result almost instantaneously. A report of this incident has been made to the FAA. The engine was about 3 hours after its most recent 100 hour inspection at the time of the part failure.

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Original NASA ASRS Text

Title: MAGNETO FAILURE SHORTLY AFTER TKOF FORCED PLT OF SMA TO RETURN LAND.

Narrative: AT RUNUP, ENGINE PERFORMED WELL. SHORTLY AFTER LIFTOFF RIGHT MAGNETO DISTRIBUTOR GEAR TEETH FAILED CATASTROPHICALLY. ENGINE LOST POWER SUFFICIENTLY SO THAT LEVEL FLT COULD NOT BE MAINTAINED. AFTER EXAMINATION A MECHANIC INDICATED THAT HIS EXAMINATION SHOWED THAT FAILURE OF THE GEAR TEETH AFFECTED THE TIMING FOR BOTH MAGNETOS BECAUSE OF RANDOM PULSES FROM THE RIGHT MAG. I WOULD SUGGEST DEVELOPMENT OF A SOLID STATE SENSOR WHICH COULD DETECT ASYNCHRONOUS TIMING BETWEEN THE MAGNETOS AND WHICH WOULD THEN SHUT DOWN THE FAILED MAG (I.E., THE ONE WHICH PROVIDED WORSE PERFORMANCE). THE MECHANIC SUGGESTED THAT I COULD HAVE SWITCHED TO THE LEFT MAG TO MAINTAIN POWER, BUT I DID NOT HAVE SUFFICIENT ALT AT THE TIME OF OCCURRENCE TO EXPERIMENT. A SOLID STATE DEVICE COULD HAVE ACHIEVED THE PROPER RESULT ALMOST INSTANTANEOUSLY. A REPORT OF THIS INCIDENT HAS BEEN MADE TO THE FAA. THE ENGINE WAS ABOUT 3 HRS AFTER ITS MOST RECENT 100 HR INSPECTION AT THE TIME OF THE PART FAILURE.

Data retrieved from NASA's ASRS site as of July 2007 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.