What happened
On November 24, 2016, a Cessna A188B agricultural aircraft, registration PR-UAM, was performing crop dusting operations near Tapera, Rio Grande do Sul. The aircraft departed from Espumoso to spray a rice field in the Barra do Colorado area. During its third pass of the third application cycle, the pilot attempted a reversal turn while overflying a eucalyptus grove. During this maneuver, the lower fuselage of the aircraft struck the treetops.
In an attempt to recover the flight, the pilot activated the electric fuel pump and increased power. However, the engine failed immediately following this action. The aircraft continued to descend for approximately 350 meters, struck bushes, and eventually came to rest in a wooded valley. The aircraft sustained substantial damage, including a damaged left wing and a broken right wingtip, but the pilot escaped uninjured.
The investigation
The investigation conducted by SERIPA V revealed several critical irregularities. While the aircraft's airworthiness certificate and annual maintenance inspections were up to date, and the pilot held valid agricultural and single-engine ratings, the pilot's medical certificate had expired prior to the accident. Furthermore, the operator failed to provide maintenance logs, aircraft logbooks, or technical records during the investigation process. The accident was not reported to the aeronautical authority by the operator; CENIPA only became aware of the event through a notification from the local Civil Police.
A critical finding during the investigation was the discovery of mismatched fuels within the aircraft. The left wing tank contained ethanol, while the right wing tank contained Avgas. The aircraft's Continental IO-520-D engine is designed to operate exclusively on Avgas.
Findings
- The presence of incompatible fuel types (ethanol and Avgas) in the wing tanks likely caused the engine failure when increased power was demanded.
- Flight indiscipline and errors in the decision-making process.
- The pilot was operating with an expired medical certificate.
- The operator failed to report the occurrence to the aeronautical authority.