Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 100; Flight Crew Total 13900; Flight Crew Type 175
Situational Awareness
Deviation / Discrepancy - Procedural Other / Unknown; Ground Event / Encounter Ground Strike - Aircraft; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Ramp
Aircraft Aircraft Damaged
Human Factors
Aircraft is non-electrical with no starter; and based at a private airpark home.  Aircraft was tied down at tail and triple chocked. Preflighted and prepared for a normal start and flight. Normal start; but as I was walking around wing to the cockpit engine power increased more quickly than expected after start. I was unable to reach the cockpit to shut the engine down before the chocks gave way followed by the tiedown stake pulling out of the ground. Aircraft traveled unoccupied down sloping yard and hit a ditch coming to rest on the taxiway; resulting in landing gear damage and propeller striking ground and pavement and engine shutdown. No injuries or property damage occurred. In retrospect I have always been careful to secure the aircraft for start correctly with triple chocks and tie down. It's possible; on this start; I may not have tightened the throttle friction lock fully which may have allowed the throttle position to travel partially forward after start. The chocks in front of all three tires started to strain; then failed and the aircraft rolled forward as I was moving around the wing. The last available restraint was a tiedown at the tailwheel position. Momentum and some slack in the tie down rope caused the tiedown stake to pull loose from the ground as the slack was taken up. The downhill slope of the yard added to the acceleration before impact with the ditch. I should have double checked the throttle setting and friction lock to make sure that throttle position would not change. The increase in power would not have happened.
Pilot reported that after a prop start the aircraft jumped the chocks and separated from the single tiedown.