What happened
On January 21, 2008, a PA-18 aircraft, registration PT-CBO, departed from the Albatroz Glider Aeroclub in Osório, Rio Grande do Sul, to perform a glider tow operation along the coast. Shortly after takeoff, the pilot noticed the engine was not producing expected power, reporting only 2,200 RPM instead of the standard 2,350 RPM.
The pilot attempted to execute a left-hand turn to return to the runway. However, the power loss intensified, and the aircraft became uncontrollable, eventually striking the ground in the Medianeira neighborhood. The impact caused the death of the pilot and resulted in severe damage to the aircraft, including the fuselage, wings, engine, and propeller. The crash also caused damage to two nearby residences.
The investigation
CENIPA investigators examined the engine and the exhaust system to determine the cause of the power loss. While the Lycoming O-320-A2B engine showed no defects in the lubrication, fuel, or ignition systems, the investigation focused on the exhaust assembly.
Upon disassembly, the exhaust muffler was found to be in a state of advanced corrosion, with visible cracks and loose components. Analysis by the Institute of Aeronautics and Space (IAE) confirmed that the component had suffered generalized corrosion, likely due to being used beyond its recommended service life. Although maintenance logs indicated that the manufacturer's Airworthiness Directive (AD) regarding muffler inspections was being followed, investigators could not verify that the inspection had actually been performed effectively.
Findings
- The primary cause of the engine power loss was the obstruction of exhaust gases caused by the deterioration and fragmentation of the exhaust muffler.
- The maintenance of the aircraft was inadequate, as the required 50-hour inspection of the exhaust muffler was not being properly executed despite records suggesting otherwise.
- The pilot was properly licensed, qualified for the operation, and had sufficient rest prior to the flight.
- Meteorological conditions were suitable for visual flight operations and did not contribute to the accident.