What happened
On December 12, 1993, a Piper PA-28R, registration PT-CDK, was conducting a private passenger transport flight from Fazenda Maricultura, in Valença, Bahia, toward Feira de Santana. During the flight, the pilot noticed smoke inside the cabin. Shortly thereafter, as the aircraft began its descent toward the destination, a significant oil leak occurred, causing a layer of oil to coat the windshield and obscuring visibility. With the engine oil pressure dropping to zero, the pilot was forced to perform an emergency landing in an unprepared field near Feered de Santana.
All three occupants—the pilot and two passengers—escaped the aircraft without injuries. However, the aircraft sustained substantial damage due to the impact.
The investigation
CENIPA's investigation focused on the engine's failure and the maintenance history of the aircraft. Investigators found that the engine had operated without lubrication for approximately 30 minutes, leading to extreme temperatures, metal shavings, and a total engine seizure. While the exact source of the oil leak could not be identified because all examined components, including the engine drain and crankshaft, appeared airworthy, evidence suggested the leak may have been present since the aircraft's last inspection.
Maintenance records revealed several discrepancies. Although the aircraft had undergone a 500-hour inspection and an annual maintenance inspection within the previous year, investigators found that several internal and external engine bolts had been torqued below the required specifications, despite maintenance logs indicating the work had been properly inspected. Additionally, the propeller's overhaul records were signed by a company that was not authorized to perform such services, and the propeller's maintenance was being tracked by flight hours rather than calendar time, which caused certain service bulletins to be missed.
Findings
- Pilot judgment: The pilot continued the flight for an extended period after the initial symptoms of the oil leak appeared. The investigation noted that an alternative landing site was available in Itaparica, only 10 minutes from the departure point, but the pilot proceeded toward the destination, allowing the engine to run without oil for a prolonged duration.
- Maintenance: Improper torque application on engine bolts and the use of unauthorized service providers for propeller maintenance contributed to the aircraft's condition.
- Management supervision: Failures in oversight regarding maintenance intervals and the validation of service records were identified as contributing factors.