Cessna 210N Landing Gear Collapse at Tzaneen Aerodrome (ZS-LTJ)

Accident Overview and Flight History On 18 May 2009, a privately operated Cessna 210N, registration ZS-LTJ, was involved in an accident at Tzaneen Aerodrome (FATZ) in Limpopo Province, South Africa. The aircraft was being ferried from a private aerodrome near Moketsi to Tzaneen Aerodrome. The pilot, a 39-year-old commercial pilot with 1,056 total flying hours, was the sole occupant. During the initial leg of the flight from Rand Aerodrome to Moketsi, the pilot experienced an electrical low-voltage warning and a negative ammeter reading. After landing at Moketsi, the pilot recommended ferrying the aircraft to a maintenance organization to investigate the electrical fault. The engine was started using an external battery pack due to low battery power. During the ferry flight to Tzaneen, the radio, GPS, and transponder experienced intermittent power supply. The pilot selected the landing gear down on downwind and observed a green down-and-locked indicator light, though it was less bright than normal. The pilot also confirmed the gear position using an underwing mirror. The aircraft touched down on runway 24 at approximately 90 knots. Approximately 800 meters after touchdown, both main landing gear struts collapsed, causing the aircraft to veer right off the runway. The aircraft came to rest on the grass clearway approximately 30 meters from the runway edge. The pilot was not injured, and minor damage was sustained to the lower fuselage and right-hand horizontal stabilizer. ## Investigation Findings and Probable Cause Following the accident, the aircraft was placed on jacks for landing gear testing. During retraction and extension tests, it was noted that the battery could not deliver enough power to the electrical hydraulic pump to provide adequate system pressure to lock the main landing gear in the down position. When tests were performed using the manual emergency hand-pump system, the landing gear operated normally, but the right-hand main landing gear locked just before the left-hand main landing gear. It was discovered that the left-hand landing gear was not locked, yet the green down-and-locked indicator light had already illuminated. The micro-switch on the left-hand main landing gear, responsible for the down-and-locked signal, was found to be misaligned. The probable cause of the accident was an incorrectly adjusted landing gear micro-switch, with low battery voltage identified as a contributory factor.