ERA17LA042 · North American NAVION UNDESIGNAT

**This report was modified on April 10, 2025. Please see the docket for the original report.** The private pilot had not flown the accident airplane for almost 1 year while it underwent repairs following a gear-up landing. The purpose of the accident flight was to ferry the airplane to a nearby airport to receive an annual inspection after completion of the repairs. On the morning of the accident, a mechanic taxied the airplane and performed an engine run-up; he did not note any anomalies. The pilot fueled the airplane and started the engine for the flight. Upon starting, the engine went immediately to full power, where it remained as the airplane taxied at high speed about 1,000 ft into a tree. Witnesses reported that the pilot was awake and alert after the accident; thus, there was no evidence of pilot incapacitation. Examination of the wreckage did not reveal any preimpact mechanical malfunctions or anomalies. The preaccident position and functionality of the throttle and mixture controls could not be determined due to damage sustained during the event; however, it is likely that the throttle control was pulled forward during the accident sequence. Further, the mechanic conducted an unremarkable taxi and run-up before the accident, and the engine immediately climbed to full power after the pilot started it. Considering the pilot’s subsequent failure to avail himself of multiple other avenues to halt or slow the airplane, including applying the brakes, cutting the engine mixture, or turning off the magnetos, the pilot likely performed a hot start procedure to purge the lines of the hot fuel and vapor from the run-up and taxi, failed to reduce the throttle afterward and, possibly startled by the sudden onset of engine power, was unable to regain control of the airplane.

Verbatim NTSB analysis and probable cause from the NTSB dataset