What happened
On July 30, 2019, a Cessna 177RG (registration OB-1332) operated by Red Wing Aviation S.R.L. departed Contamana for Pucallpa. During the cruise phase, approximately 42 nautical miles from Pucallpa, the engine began losing power, accompanied by heavy vibrations and a drop in oil pressure. The pilot declared an emergency with Pucall and attempted an in-flight restart, which was unsuccessful.
Seeking a landing site, the pilot identified a beach along the Ucayali River. Due to the irregular terrain, the pilot elected to perform a gear-up landing to prevent the aircraft from flipping. During the emergency touchdown, the aircraft made several light impacts with the sand before coming to a stop. The pilot and three passengers evacuated the aircraft immediately; no injuries were reported.
The investigation
The CIAA investigation focused on the mechanical failure of the engine. Laboratory analysis of the crankshaft revealed that the failure originated from material defects, including non-metallic inclusions and voids, located on the external surface and within the microstructure of the No. 3 connecting rod journal. The investigation also identified surface corrosion and loss of coating on the crankshaft.
Findings
- The primary cause of the accident was an uncommanded engine shutdown and power loss resulting from a crankshaft fracture.
- Contributing factors included prolonged engine inactivity without documented preservation or storage procedures.
- Deficiencies in the engine overhaul process failed to detect pre-existing material defects and surface corrosion on the crankshaft.
- The engine was found to be seized (locked) following the impact.