Cessna T206H N164CS accident near Piggott, Arkansas

Probable cause

The loss of engine power due to a malfunctioning magneto. Contributing to the accident was maintenance personnel's improper use of a drill bit instead of a timing pin during magneto installation, which resulted in a section of the drill bit breaking off and ultimately to the magneto failure.

NTSB analysis

**This report was modified on August 28, 2016. Please see the docket for this accident to view the original report.**

The airline transport rated pilot reported that, after an en route stop, he planned to continue his cross-country personal flight. The pilot reported that, during takeoff and as the airplane was between about 20 and 30 ft above the ground, he felt the engine surge, and it then lost power. The airplane was traveling too fast to stop on the remaining runway, and it impacted a ditch at the end of the runway.

Examinations of the airframe and engine revealed that the left magneto was malfunctioning. During subsequent examination of the magneto, a section of a drill bit, which approximated the diameter of a timing pin, was found inside of it. A review of maintenance records revealed that the left magneto had been replaced 15.6 hours before the accident.

A review of engine monitor data revealed that the exhaust gas temperature spiked three times; two of the spikes were attributed to the "before takeoff" magneto checks. The third spike occurred during the takeoff and just before a power reduction. The data are consistent with the left magneto failing during the takeoff. The accident is consistent with maintenance personnel improperly using a drill bit as a timing pin to time the magneto before installing it on the engine. Maintenance personnel likely rotated the engine while the drill bit was still in the magneto, which resulted in a section of the drill bit then breaking off and eventually causing the magneto to fail.

Text from the NTSB. Open the NTSB docket for CEN15LA233 for the full record.