What happened
On May 12, 1994, at approximately 14:00Q, a Cessna 210L, registration PT-JMQ, departed from a FUNAI post en route to Alta Floresta, Mato Grosso. The aircraft was carrying one pilot and three passengers. Four minutes into the flight, while climbing through 2,000 feet, the first blade of the propeller assembly fractured. The failure triggered severe engine vibrations, forcing the pilot to shut down the engine.
Unable to return to the airfield, the pilot executed a controlled forced landing on the Teles Pires River. While the aircraft successfully completed the water landing with minimal fuselage damage, the impact and subsequent circumstances led to a tragedy. The pilot and one passenger managed to evacuate the aircraft, but two other passengers, unable to exit the cabin in time, died due to drowning.
The investigation
CENIPA investigators examined the wreckage and the propeller assembly, which had been acquired as "new" by the operator following a recent overhaul. Technical examinations conducted by the Instituto de Aeronáutica e Espaço (IAE) and PAMA-GL revealed significant irregularities in the propeller components.
On the fractured blade, investigators identified pitting and intergranular corrosion, along with fatigue marks (beach marks) on the fracture surface. Further non-destructive testing on the remaining blades revealed widespread corrosion across the entire set, a significant hole in the second blade, and suspected foreign material inclusions in the third blade. Additionally, the propeller hub showed signs of corrosion at the contact point with the blade roots. The investigation also noted that the maintenance records for the propeller assembly contained discrepancies regarding blade identification numbers.
Findings
- The primary cause of the accident was the failure of the first propeller blade due to fatigue propagation facilitated by pre-existing pitting and intergranular corrosion.
- The propeller assembly had been sold as "new" by a maintenance facility despite being in a corroded, used condition.
- Inadequate maintenance and a lack of flight safety awareness by the workshop responsible for the propeller's overhaul contributed to the material's degraded state.
- The lack of an emergency egress briefing for passengers contributed to the inability of two occupants to abandon the aircraft following the water landing.