What happened
On March 27, 2022, at approximately 13:00 UTC, an EMB-202A aircraft, registration PT-VXY, was performing a local agricultural spraying flight from a landing strip at Fazenda Boa Sorte in Guarani D'Oeste, SP. The pilot was conducting a routine operation when, shortly after liftoff, the engine suffered a sudden loss of power.
Unable to maintain flight, the pilot performed an emergency landing further ahead on the runway. During the deceleration process on the runway extension, the aircraft experienced a series of intermittent impacts with the uneven dirt surface, eventually exiting the paved/prepared area. The aircraft sustained substantial damage, though the pilot emerged uninjured.
The investigation
CENIPA investigators examined the engine, specifically the Lycoming IO-540-K1J5, and the ignition system. The investigation focused on the timing of the magnetos and the condition of the spark plugs. While the pilot had performed post-start procedures and magneto checks, investigators found discrepancies in the engine's ignition timing.
Technical analysis of the magnetos revealed that the timing was not set according to the manufacturer's specifications. Additionally, a bench test of the twelve spark plugs showed significant degradation; only four plugs functioned normally, while the remaining eight exhibited intermittent, weak, or irregular performance. The investigation also noted that the aircraft had undergone a 100-hour inspection approximately 82 flight hours prior to the accident, yet the components showed signs of failure shortly after this service.
Findings
- The primary contributing factor was improper aircraft maintenance regarding the ignition system.
- The left magneto timing was advanced by 2° beyond the manufacturer's specification, and the right magneto was advanced by 5°.
- Eight of the twelve spark plugs were found to be malfunctioning, with several showing physical degradation and irregular spark patterns.
- The uneven and sloping nature of the dirt runway contributed to the aircraft's unstable deceleration and eventual excursion.
- The pilot was fully qualified, and the aircraft was within weight and balance limits with valid airworthiness certification.