What happened
On January 21, 2015, a Raytheon 58, registration PP-OLE, departed from Salgado Filho Airport (SBPA) in Porto Alegre, RS, bound for Lauro Kurt and Kurtz Airport (SBPF) in Passo Fundo, RS. The aircraft was operating a private flight with a pilot and two passengers on board.
Following the landing at SBPF, the aircraft began taxiing toward the parking apron. During a right-hand turn while entering the apron, the left landing gear retracted. The aircraft subsequently performed a 270-degree left turn before coming to a complete stop. The incident resulted in substantial damage to the engine, propeller, left wing, and left elevator. All three occupants were uninjured.
The investigation
CENIPA investigators examined the mechanical condition of the landing gear and the aircraft's weight parameters. Initial inspections revealed that the landing gear lock bearings were blocked and lacked the required clearance (specified in the maintenance manual as 0.01 to 0.02 inches), likely due to dirt accumulation from operations on unpaved runways. This condition could cause jolts during gear cycles, potentially weakening components.
Technical analysis of the left landing gear strut (Braze Assy-LH) by the Department of Aerospace Science and Technology (DCTA) determined that the fracture and plastic deformation occurred simultaneously due to an overload in non-axial compression. The analysis ruled out fatigue or corrosion as causes, concluding that the damage occurred during the gear retraction on the ground rather than contributing to the initial failure.
Discrepancies were noted in the statements provided by the pilot and passengers regarding the landing runway and taxi maneuvers. While the pilot reported a backtrack on runway 08, passengers indicated the landing occurred on runway 26 without a backtrack. The investigation also found that the aircraft was operating with an excess weight of 54kg at departure and 34kg at the time of the incident.
Findings
- The aircraft was operating above the maximum weight limit.
- The landing gear lock bearings were blocked by dirt, preventing proper clearance and potentially causing mechanical jolts.
- It is hypothesized that the combination of excess weight and potentially excessive taxi speed generated enough force to trigger the retraction of the left landing gear during the turn.