What happened
On 12 March 2002, a private Cessna 210N, registration EI-CGH, departed from a private airfield in Tullamore for a short flight to Abbeyshrule. The flight, intended for equipment reinstallation, began with significant difficulties. After struggling to start the engine using the aircraft's onboard battery, the pilot utilized a 12-volt car battery to jump-start the engine.
During the pre-takeoff phase, the pilot observed that the flaps were slow to operate and remained at a 10-degree setting. Following takeoff, an attempt to retract the landing gear resulted in the main undercarriage remaining extended. The pilot subsequently moved the gear lever back to the down position and continued the flight, noting a low voltage warning light was active.
Upon arrival at Abbeyshrule, the pilot attempted to adjust the flap angle, but the system failed to extend beyond the initial 10 degrees. During the landing roll, the aircraft pitched forward, causing the nose undercarriage to collapse. The three-bladed propeller struck the runway surface, followed by the nose gear strut and forward doors scraping along the tarmac for approximately 200 metres. The pilot exited the aircraft without injury.
The investigation
The AAIU examined the electrical and mechanical state of the aircraft and the procedures used prior to departure. Investigators found that the aircraft's battery was in an unserviceable state, with a capacity of only 3.8% of its nominal rating and critically low electrolyte levels. This lack of power prevented the alternator from maintaining the necessary voltage to charge the battery or power the hydraulic components.
Testing confirmed that the aircraft's charging system was capable of producing correct voltage, but the depleted battery could not support the electrical load required for the gear and flap actuators. Furthermore, the investigation highlighted that the use of a 12-volt car battery to start a 24-volt system was an unapproved and unsafe procedure.
Findings
- The primary cause of the accident was the failure of the nose undercarriage to lock in the down position, which led to the collapse upon landing.
- The pilot elected to proceed with the flight despite knowing the aircraft was in an unserviceable condition.
- The aircraft had not been maintained according to the required schedule, specifically regarding battery electrolyte checks.
- The engine was started using an unapproved method involving a 12-volt car battery, which was contrary to safe practice.
- Insufficient battery voltage prevented the proper operation of the flap and undercarriage systems.