History
On June 23, 2009, at approximately 0830 mountain standard time, an experimental Mayo RV-6A, registration N413RV, impacted the ground after takeoff about half a mile north of Cottonwood Airport (P52) in Cottonwood, Arizona. The pilot/owner operated the airplane under 14 Code of Federal Regulations Part 91 as a local instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed. Witnesses at the airport reported that the takeoff appeared normal. During climb out, the engine began to sputter. The airplane momentarily dipped and then recovered, followed by a high-pitch revving sound from the engine. The airplane then rocked back and forth, the left wing dropped, and it appeared to stall before entering a nose dive and impacting the ground.
Personnel Information
The 64-year-old pilot/owner held a private pilot certificate with a single-engine land rating and a third-class medical certificate issued July 16, 2007, with a requirement for corrective lenses. His logbook indicated an estimated total flight time of 284 hours, with the last recorded flight on June 20, 2009, in the accident airplane. He completed a flight review on August 2, 2008. The 73-year-old certified flight instructor (CFI) held an airline transport pilot certificate, a commercial pilot certificate with single-engine land and glider ratings, and a flight instructor certificate. He held a second-class medical certificate dated March 17, 2008, with a limitation for near vision glasses. According to his last medical application, he reported an estimated total flight time of 31,300 hours with 30 hours in the previous six months.
Aircraft Information
The accident airplane was a 2000 experimental amateur-built Mayo RV-6A, serial number 60117, equipped with an Aero-Sport O-360-A2A engine. It was sold to the pilot on May 8, 2009. The last condition inspection was performed on March 11, 2009, at which time the airframe and engine had 471.9 total hours.
Wreckage and Impact Information
At the accident site, the airplane was found in an upright position. The propeller assembly had separated from the crankshaft and was partially embedded in hard desert dirt about 10 feet from the main wreckage. Both wings remained attached but sustained extensive impact damage. The empennage and tail section were still attached to the fuselage.
Tests and Research
Post-accident engine inspection revealed that the top spark plugs exhibited worn operating signatures. The propeller assembly showed angular and granular separation at the crankshaft; one blade had S-bending with chord-wise scratching, and the other was bent aft with tip scratching. The FAA inspector reported that the airplane had been flown two days prior without refueling, but fuel was smelled at the scene and a fuel stain was visible. Local RV-6 builders who assisted with a pre-buy inspection reported no issues. The inspection concluded with no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation.