What happened
On July 1, 2011, at approximately 13:17 local time, a Cessna 337H, registration OB-1968, operated by Aeronegocios J.L.E., departed from the David Abensur Rengifo Airport in Pucallpa, Peru. The flight was destined for Contamana with one pilot and six passengers on board.
During the initial climb, at an altitude of approximately 450 feet, the pilot heard a loud impact from the rear engine compartment. The rear engine subsequently lost power. Despite applying maximum power to the front engine, the aircraft was unable to maintain altitude and began to descend. To avoid a more dangerous impact, the pilot directed the aircraft toward a shallow area of the Yarin_acocha Lagoon.
The aircraft struck the water, resulting in the loss of the right landing gear and structural damage to the lower fuselage. All occupants, including the pilot and six passengers, evacuated the aircraft and sustained minor injuries. Local police and navy vessels assisted in the rescue operation.
The investigation
The CIAA investigation examined the mechanical failure, the pilot's emergency response, and the aircraft's weight and configuration. The investigation established that the aircraft was heavier than the declared takeoff weight because the weight of the pilot and cargo had been omitted from the calculations.
Furthermore, the investigation found that the pilot did not fully execute the required emergency procedures for an engine failure during takeoff. Specifically, the pilot failed to properly feather the propeller, retract the landing gear, or adjust the flaps and cowl flaps to reduce drag. These omissions, combined with the high weight, prevented the aircraft from maintaining level flight. The investigation also noted that the aircraft's checklist was not properly structured according to Peruvian regulations and that the pilot's English proficiency limited his ability to fully utilize the English-language flight manual.
Findings
- The primary cause of the accident was the failure of the rear engine due to a broken crankshaft.
- The pilot's failure to implement specific emergency procedures for engine failure during takeoff increased aerodynamic drag, preventing the aircraft from maintaining altitude.
- There was a failure to detect potential cracks or hidden damage in the crankshaft during previous maintenance, as the specialized ultrasonic inspection could not be verified against required inspector qualifications.
- The aircraft's actual takeoff weight exceeded the declared weight due to the omission of the pilot and cargo weights.