Accident Overview
On April 29, 2017, at approximately 1600 Alaska daylight time, a Piper PA-18 airplane, registration N82563, sustained substantial damage during a landing on a gravel runway in Chugiak, Alaska. The aircraft was operated as a personal flight under Title 14 Code of Federal Regulations Part 91. The pilot and one passenger were not injured.
According to the pilot's report, upon touchdown, the right main landing gear collapsed. Subsequently, both wings contacted the ground, resulting in substantial damage.
Landing Gear Examination
The main landing gear were equipped with hydrasorb shock units. These units consisted of automotive-type oleo struts combined with light shock cords. The hydrasorb's outboard end was connected to the wheel axle via an extension tube, which was attached to the shock unit by a lug fitting and a through bolt.
A postaccident examination of the right main landing gear system found that the hydrasorb shock unit's extension tube lug fitting was fractured through the radius where it would typically be bolted to the hydrasorb's outboard end. Examination of the broken lug fitting revealed a flat fracture perpendicular to the long axis of the fitting. The fracture surface had evidence of extensive rust and pitting throughout the circumference of the fitting.