What happened
On October 18, 2011, a Bell 212 helicopter, registration CS-HFJ, operated by Helisul lda., was conducting aerial firefighting operations near Vila Boa do Mondego. After completing approximately 29 water dropping circuits, the crew began the return flight to the Mêda Air Means Center (CMA).
During the return flight near the Trancoso area, the pilot observed "FUEL LOW" indications in both fuel systems. Shortly thereafter, engine #2 failed. While attempting an emergency landing in a clear area, the pilot reported that engine #1 also failed. During the subsequent autorotative emergency landing, the helicopter drifted to the left and struck the ground on its right skid, causing the aircraft to roll over into a nearly inverted position. All 9 occupants (one pilot and eight passengers) escaped the wreckage without injury.
The investigation
The investigation examined the aircraft's fuel system, the pilot's qualifications, and the operational context of the firefighting mission. The investigation team noted that the pilot held a valid Airline Pilot's License for the Bell 212/412 type and a Class 1 medical certificate. The aircraft was equipped with Pratt & Whitney PT6T Twin Pack engines. The investigation also considered the psychological and operational pressures inherent in aerial firefighting, such as high mental workload and peer pressure, which can influence risk assessment.
Findings
- The primary cause of the engine failures was fuel exhaustion.
- The fuel quantity indicator was found to be inaccurate, indicating approximately 100lb of fuel remained when the tanks were actually empty.
- The pilot was managing a high mental workload, including terrain avoidance, radio communications, and coordinating water drops, which may have diverted attention from monitoring fuel levels.
- The mission environment involved "peer pressure," where the drive to complete tasks can lead to the normalization of reduced safety margins.
- The aircraft sustained substantial damage, including the destruction of the main rotor, the transmission gearbox, and significant damage to the tail and skids.
Safety action
While the investigation authority determined that formal safety recommendations were not necessary for this specific event, the report highlights the need for operators to combat the normalization of deviance. It is recommended that aerial firefighting operators implement fuel policies in their Operations Manuals, as specified in ICAO Annex 6, to ensure mandatory minimum fuel reserves are maintained to complete missions without triggering low fuel warnings.