Accident
On 16 November 2005 at 13:25 local time, a Piper PA-28R-201T, registration EC-GDF, operated by Panamedia, S.L., was on a local training flight from Son Bonet Aerodrome (Palma de Mallorca) with an instructor and two students. After completing maneuvers, the aircraft returned for touch-and-goes. Cleared to land on runway 24, the crew flew a left base and conducted checklists. The aircraft touched down and rolled to the last runway exit. As the crew initiated a right turn onto the taxiway, the right main landing gear gradually retracted. The instructor immediately took control and steered the aircraft off the paved area to avoid remaining on the taxiway. The occupants shut down the fuel and master switch and evacuated without difficulty. During recovery, the wing tips repeatedly struck the ground, and the left main gear folded twice.
Damage
The aircraft sustained minor damage to the wing tips, pitot tube, and both sides of the horizontal stabilizer.
Aircraft Information
The aircraft and engine were maintained per schedule. The last 100-hour inspection was performed on 11 October 2005, with 45 hours flown since.
Ground Functional Tests
After moving the aircraft to a hangar, a thorough inspection of the landing gear and related systems found no hydraulic failure; extension and retraction pressures were correct. However, examination of the left main landing gear revealed that a bracket (part of the squat switch assembly, which prevents gear retraction when the aircraft is on the ground) was incorrectly installed. The bracket was shortened and secured only by the bolt head, allowing it to rotate around the bolt. This installation did not follow the service manual. The manual allows inverting the upper link for alignment, but then the bracket must be shortened to fit the smaller recess and the bolt reversed. In this case, the link was in its normal position, but the bracket was shortened and held only by the bolt head.
Crew Statement
The crew reported that during the turn they applied brakes, the landing was not hard, and the three green landing gear indicator lights were illuminated.
Analysis
During the turn, the right gear retracted progressively. The landing loads were within normal parameters as no abrupt maneuvers were performed. The incorrect mounting of the squat switch bracket could render the squat switch inoperative, as the bracket could rotate and lose its proper adjustment. With the squat switch disabled, the gear retraction prevention function was lost. Consequently, any movement of the gear lever would cause retraction.