What happened
On the night of September 27, 1997, a Robinson R22 helicopter, registration PT-YFL, departed from Pampulha Airport in Belo Horizonte, Brazil, for a local night flight. The flight was intended to overfly a nearby church during a wedding ceremony. Approximately 15 minutes into the flight, the pilot experienced a loss of engine power, accompanied by a low rotor RPM warning alarm.
In an attempt to perform an emergency landing away from populated areas, the pilot initiated an autorotation procedure and maneuvered toward a railway zone. During this descent, the main rotor struck an unlit utility pole, causing a loss of control. The aircraft subsequently struck a canopy and impacted the ground violently. The crash resulted in severe injuries for the pilot and minor injuries for the passenger, while the aircraft was destroyed.
The investigation
CENIPA's investigation focused on the sequence of events leading to the loss of rotor RPM and the subsequent flight maneuvers. Investigators found that the pilot had experienced a similar drop in rotor RPM during a flight earlier that same day. Rather than seeking a professional mechanical inspection, the pilot performed a ground check and a flight test, erroneously concluding that the issue had been resolved.
The investigation also examined the operational environment, noting that the flight was being conducted at low altitudes, between 150 and 200 feet, over a populated area. This low altitude, combined with the nighttime conditions, significantly reduced the margin of safety and the pilot's ability to identify obstacles like the unlit pole.
Findings
- The pilot was qualified but lacked sufficient experience in this specific aircraft type and in night operations.
- The flight was conducted at a low altitude over a populated area, which provided insufficient height to execute a full, successful autorotation.
- The pilot's failure to seek professional mechanical assistance after a prior engine power anomaly led to the recurrence of the issue.
- The operator failed to provide adequate supervision or ensure the pilot's proficiency matched the complexity of the planned night operations.
- Nighttime visibility hindered the identification of the utility pole during the emergency maneuver.