What happened
On May 27, 2005, a Cessna 140A, registration PT-AHZ, departed from the Areia Branca aerodrome in Mato Grosso for a local flight. Approximately ten minutes into the flight, the engine failed. The pilot attempted an emergency landing in a field adjacent to the BR-364 highway. During the approach, the aircraft lost altitude, the propeller struck the ground, and the aircraft subsequently collided with trees located beside the roadway. The accident resulted in the death of the pilot and serious injuries to the passenger. The aircraft sustained severe damage.
The investigation
CENIPA investigators determined that the engine failure was caused by a failure in the lubrication system. The investigation revealed that the engine's front lubrication paths had been blocked with plugs to divert oil to an unapproved radiator. This modification caused insufficient lubrication to the front of the crankshaft, leading to excessive friction and the melting of the bearing. This resulted in a loss of power.
Furthermore, the investigation found that the aircraft was operating with a suspended Certificate of Airworthiness. Maintenance records for the airframe, engine, and propeller had not been updated since 1998. Additionally, the aircraft was operating above its maximum takeoff weight, which was specified at 681 kg, while the actual weight at takeoff was approximately 735 kg. The investigation also noted that the carburetor's acceleration valve was improperly adjusted, causing an excessively rich fuel mixture.
Findings
- Improper maintenance and unapproved modifications: The use of unapproved parts and the blocking of essential lubrication paths led to the engine seizure.
- Flight indiscipline: The pilot operated the aircraft despite significant regulatory irregularities.
- Inadequate flight planning: The pilot failed to verify the airworthiness of the aircraft, which had expired documentation and no recent maintenance records.
- Management oversight: The operator failed to ensure the aircraft was in a legal and airworthy condition prior to flight.