History of the Flight
The pilot of Piper PA-28RT-201, N83196, returned to Shoreham Airport after a local flight. Upon selecting the landing gear down, the left main landing gear green 'down and locked' light failed to illuminate. The pilot followed the checklist procedures, including recycling the landing gear, but the indicator remained off. After a low fly-by of the tower, the pilot was informed that the landing gear appeared to be in the normal down position. The pilot elected to land on Runway 21 (1,036 x 18 m asphalt). As the aircraft touched down, the left main gear gently folded. The left wing tip contacted the runway, causing the aircraft to depart the left side and come to rest on soft grass. The airfield fire crew discharged foam over the left wing. The pilot completed a normal shutdown and vacated the aircraft without injury.
Landing Gear System
The aircraft is equipped with retractable tricycle landing gear, hydraulically operated by an electrically powered reversible pump. Landing gear position is indicated by three green lights for down and locked and a red light for unsafe. There is no light for fully retracted; all lights extinguish when retracted. Each downlock switch activates a green light when the gear is down and locked. Activation of all three switches shuts off the hydraulic pump.
Recovery and Repair
The aircraft wing was lifted using air bags, and the left main landing gear was manually pulled down and locked. After towing to a hangar, the aircraft was jacked up and the landing gear functioned. The airborne condition was replicated, and the left main gear would not lock down. The downlock and squat switches were checked; terminals were slightly corroded. New terminals were fitted, and all switch functions tested satisfactory. The landing control circuit wiring was then inspected, and the left landing gear downlock switch hydraulic pump wire was found broken in the fuselage. The broken wire would cause the hydraulic pump to shut off when the right main and nose landing gears activated their downlock switches, preventing the left main gear from locking. The wire was spliced and secured. The landing gear was cycled numerous times and functioned normally.