What happened
On 5 May 2024, a Cessna T210L, registration ZS-NVM, departed from Landfontein private airstrip for a flight to Welkom Aerodrome. During the flight, the pilot noticed an anomaly when the landing gear indicator light failed to illuminate after selecting the gear to the 'down' position. Despite attempts to use the emergency manual handpump, the landing gear failed to extend.
The pilot diverted to New Tempe Aerodrometo consult with an aircraft maintenance engineer. In an attempt to restore hydraulic pressure, the crew added one litre of engine oil to the system. While this action successfully extended the nose landing gear, the main landing gears remained retracted. Consequently, the pilot performed a planned wheels-up landing with emergency services on standby. The aircraft touched down on Runway 01 with the nose gear extended and the underbelly contacting the runway. The aircraft skidded 400 metres before veering onto the grass, resulting in substantial damage to the aircraft, including the fuselage, stabilizers, and elevator. There were no injuries to the pilot or the three passengers.
The investigation
SACAA AIID examined the hydraulic system and discovered that the reservoir was nearly empty. Post-accident inspections of the aircraft revealed that a retaining ring on the left main landing gear door actuator had broken free, allowing hydraulic fluid to escape the system. While the investigation could not definitively determine if the ring failed during flight or during the impact of the landing, the loss of fluid was the primary driver of the malfunction.
Findings
- The primary cause of the landing gear failure was a lack of hydraulic fluid in the system.
- The loss of fluid was caused by the separation of a gland retaining ring from the left main landing gear door actuator.
- A contributing factor was the poor fitment of the locking or retaining pin, which led to the component's failure approximately 24.5 hours after the last periodic maintenance inspection.
- The use of engine oil as a temporary measure in the hydraulic system required a full system flush during subsequent repairs.