What happened
On August 26, 2021, a Cessna T-210N Century, registration OB-1557, operated by Aero Palcazu S.A.C., was performing a non-scheduled flight from Yurimaguas to Contamana. During the approach to runway 27 at Contamana Airport, the pilot noticed that the green lights indicating the landing gear was extended and locked failed to illuminate after attempting the normal extension cycle.
Following the aircraft's Pilot Operating Handbook (POH) emergency procedures, the pilot attempted to cycle the gear by retracting it and extending it again, as well as using the manual emergency hydraulic pump. Although the cockpit indicators remained unlit, the pilot visually confirmed via a wing mirror and subsequently through ground personnel that the nose gear appeared to be extended.
Upon landing, the main gear made contact with the runway and the engine was shut down. However, as the nose gear made contact with the pavement, it unexpectedly retracted. This caused the aircraft to tilt forward, resulting in the propeller blades striking the runway surface. The aircraft continued to slide until it came to a halt. No injuries were reported for the pilot or the maintenance technician on board.
The investigation
An investigation by the CIAA established that the nose gear retraction was caused by a failure in the locking mechanism. Specifically, the nose gear actuator piston did not complete its full extension cycle due to a lack of hydraulic fluid pressure. This prevented the hooks from properly engaging and locking into the pins.
Investigators found that a recent 50-hour inspection had addressed a hydraulic leak at a nose gear actuator nipple, but the inspection process lacked specific tasks for verifying the hydraulic fluid level in the power pack reservoir. Additionally, the investigation noted that certain critical components of the locking mechanism were located in hard-to-access areas, making visual inspections during pre-flight difficult without specialized tools.