Accident Overview
On October 28, 2017, at about 1250 Pacific daylight time, a Cessna P210N airplane, registration N6582P, experienced a collapse of its right main landing gear during the landing roll at Skagit Regional Airport (BVS) in Burlington, Washington. The commercial pilot and two passengers were not injured. The airplane was substantially damaged, specifically to the right aileron and right elevator.
Flight Details
The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The airplane departed Snohomish County Airport (PAE), Everett, Washington, at 1150.
Pilot Account
According to the pilot, after an uneventful flight, he began a descent for a straight-in approach to land on runway 29. He deployed the landing gear about 8 nautical miles from the airport and verified the gear down indicator light illuminated, also observing the gear through a mirror mounted to the right wing radar. He checked the gear again at about 4 nautical miles and configured for a normal landing with 10° of flaps. Moments before touchdown, he extended flaps to 30°. The airplane touched down normally and transitioned into a landing roll, but the right main landing gear collapsed. The pilot perceived this as a loss of tire pressure and immediately retarded the mixture to full lean, shut off the engine, and steered the airplane to a stop on a grass area to the right of the runway.
Aircraft Information
The high-wing, retractable gear airplane was manufactured in 1978 and held 6 seats. It was registered to Insurance Solutions, Inc. and operated by the pilot, who had owned it since August 8, 2016. At the time of the accident, the airplane had accumulated 3 flight hours since its most recent annual inspection, completed on October 9, 2017, at a recorded airframe total time of 4,342 hours. The logbook entry noted that the right main landing gear saddle screws were tightened but did not indicate that a landing gear swing was performed. The pilot reported no prior landing gear problems, and the previous owner (from 1999 to 2016) had not disclosed any landing gear anomalies.
Landing Gear System
The main landing gear system was hydraulically powered with electrical circuits for control and indication. Normal operation involved moving a gear selector handle in the switch panel, which powered an electrically-driven power pack to supply hydraulic fluid to actuators, driving the gear into position. According to the airframe manufacturer's representative, the deployment system uses a down lock hook that must be over center to remain locked. Proper rigging, including verification of the over center condition, should be performed periodically, as the hook can wear over cycles or if not rigged correctly. The service manual recommended verifying proper downlock rigging every 200 flight hours.
Post-Accident Examination
An airframe and powerplant mechanic who recovered the airplane attempted to force the right main landing gear to free fall from its retracted position after the accident but was unable to do so. Subsequently, with oversight from a Federal Aviation Administration representative, the mechanic removed fuselage floor panels and performed two full landing gear retractions and extensions. The failure could not be replicated; during both extensions, the downlock tube seated within the saddle as designed, and the instrument panel indicator showed the gear down and locked. However, the right main landing gear down lock hook appeared worn when compared to the left hook. A later test of the right gear up lock rigging revealed that the down lock hook over center exceeded the prescribed maximum tolerance when compared to the left main landing gear, using a tool designed to verify the over center position.