Amateur/Home Built/Experimental
Flight Crew Sea; Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 8; Flight Crew Total 2500; Flight Crew Type 35
Aircraft Equipment Problem Less Severe; Ground Event / Encounter Loss Of Aircraft Control; Ground Event / Encounter Ground Strike - Aircraft; Ground Excursion Runway
Flight Crew Regained Aircraft Control; General Maintenance Action
Procedure; Aircraft; Human Factors
After landing the left gear mechanism broke causing the left gear to raise; the hull skidded on the runway; and the aircraft made a left 90 uncontrolled turn exiting the runway to the adjacent grass. Aircraft came to rest upright.There were no injuries; no fire; no fuel leakage and no structural damage done to the aircraft; no airport facilities (lights; markers) were struck nor damaged.First responders contacted maintenance personnel; and thru manual lifting; we lifted the aircraft; supported with wooden blocks; lowered the left gear; and secured in place with wooden blocks. This rendered the aircraft towable. (In fact; the aircraft could have been safely flown under this condition except for activating the electric gear reposition mechanism.)I speculate that the collapse of the gear mechanism was caused by normal 'wear and tear' from typical runway landing loads over the past two years; which lead to an undiscovered bowing of the actuator clevis (U Channel Part) and it's mounting bar which in turn lead to a deformity which prevented the gear; when lowered for runway landing; to be secured in the designed over-center and locked position. I would recommend this mechanism (behind both seats) to be visually inspected at least after every 20 runway (land) landings.
The pilot of an experimental amphibian aircraft described the failure of a landing gear mechanism that resulted in a left main landing gear collapse and subsequent runway excursion. He speculated the cause and suggested repetitive inspections of the mechanism.