Incident Overview
A pilot reported that shortly after landing, a passenger retracted the landing gear of a retractable landing gear-equipped airplane without the pilot's permission or guidance. The landing gear retracted, causing the airplane to impact the runway and slide approximately 600 feet before coming to rest.
Passenger Account
The pilot-rated passenger stated that, without the pilot's guidance, he mistakenly raised the gear handle and then quickly lowered it again, believing it was the flap handle. He reported that he was attempting to assist the pilot.
Aircraft Damage
The airplane sustained substantial damage to the center wing spar.
Mechanical Condition
The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.