What happened
On June 1, 2020, a Piper PA-24-250, registration LV-HFZ, was conducting a training flight at the Marcos Juárez Aerodrome in the Córdoba province of Argentina. Following the third execution of a touch-and-go maneuver, the pilot attempted to retract the landing gear. However, the cockpit indicator light failed to signal that the gear was up and locked. Despite subsequent attempts to cycle the gear using the landing gear lever, the system failed to respond. The pilot followed the emergency procedures outlined in the flight manual and notified the aerodrome authorities of the emergency. The aircraft subsequently performed a gear-up landing on the runway safety strip. There were no injuries to the pilot or the passenger, and the aircraft sustained light damage.
The investigation
The investigation examined the mechanical condition of the retractable landing gear system and the maintenance history of the aircraft. Investigators found that the landing gear's electrical system had a blown thermal fuse, which had been removed, indicating a previous condition of excessive power consumption by the electric motor.
Upon physical inspection of the landing gear components, investigators identified that the push-pull cable for the right main gear had detached at one end. Additionally, the investigation noted corrosion and paint residue on the push-pull cable, as well as a lack of safety wire (locking wire) on the component. While these findings indicated maintenance deficiencies, they were not determined to be the direct cause of the immediate failure. The aircraft had undergone an annual inspection and a 100-hour inspection approximately five months prior to the incident.
Findings
- The primary cause of the incident was a mechanical failure in the retractable landing gear system, specifically a defect in the right main gear's push-pull cable.
- The failure of the push-pull cable prevented the transmission of force required to retract the gear.
- The landing gear system had previously experienced a failure involving the activation of the thermal fuse prior to the most recent annual maintenance.
- The preventive maintenance performed five months prior to the event failed to detect or correct the deteriorating condition of the push-pull cable.
- The landing was performed on the runway safety strip because the primary asphalt runway, taxiway, and apron were in poor condition, covered with loose stones, prompting local pilots to use the grass strip as a standard operating procedure.
Safety action
- The investigation emphasizes the necessity for aircraft owners and maintenance facilities to strictly adhere to manufacturer-provided maintenance recommendations, procedures, and inspection intervals to ensure the continued airworthiness of critical components.