What happened
On August 10, 2021, at approximately 21:00 UTC, an Aero Boero AB-115, registration PP-GAS, was performing a ferry flight from Aeródromo APLIC Aviação Agrícola II in Itaporã, Mato Grosso do Sul, to Dourados. The flight was being operated by the Aeroclube de Dourados.
Shortly after takeoff, the aircraft experienced a sudden loss of engine power. The pilot attempted to manage the situation by rapidly manipulating the throttle, a procedure not prescribed in the aircraft's flight manual. Unable to maintain flight, the pilot performed an emergency landing in an area ahead of the runway. Upon contacting the irregular terrain, the aircraft overturned, resulting in substantial damage to the airframe. The pilot escaped the wreckage without injury.
The investigation
CENIPA investigators examined the engine, the fuel, and the maintenance records of the aircraft. Laboratory analysis of the fuel and oil samples confirmed they met established quality standards. The engine, a Lycoming O-235-C2A, was inspected by a certified maintenance organization. While the ignition system and magneto synchronization were found to be correct, investigators discovered that the lower spark plugs for cylinders 2 and 4 were contaminated.
Further investigation into the pilot's actions revealed that the pre-flight sequence, including taxiing and the checklist execution, had been performed in an accelerated manner. The pilot failed to perform the full "Before Takeoff" checklist, which might have identified the engine anomaly while the aircraft was still on the ground. Additionally, the investigation reviewed the Safety Management System (SMS) of the flight school, noting a lack of documented risk mitigation records related to this operation.
Findings
- Inadequate maintenance execution: The condition of the spark plugs indicated that recent 50-hour and 100-hour inspections had not effectively ensured the proper cleaning and servicing of the ignition components.
- Inadequate management supervision: A lack of oversight regarding maintenance activities allowed the aircraft to be released for flight with components that compromised engine performance.
- Improper emergency procedures: The pilot's attempt to rectify the power loss by rapidly cycling the throttle was not a recognized procedure in the Aero Boero 115 emergency manual.
- Checklist non-compliance: The accelerated execution of taxi and takeoff procedures led to the omission of critical pre-takeoff checks.