What happened
On July 21, 2015, a Bell 206B helicopter, registration PP-EJH, was conducting a flight crew check-out maneuver at Aeródromo 14 Bis in Londrina, Brazil. The flight involved a 180-degree autorotation followed by a running landing on a grassy area adjacent to runway 10.
During the landing, the aircraft's skids began to sink progressively into the soft ground. This caused the helicopter to pitch forward at a steep angle until it struck a low-level wire guard. In an attempt to prevent the main rotor from striking the ground, the examiner moved the cyclic control fully aft. This maneuver resulted in mast bumping and caused the main rotor to strike the terrain, which subsequently severed the tail boom. The impact also caused the disintegration of both main rotor blades.
The investigation
CENIPA investigators examined the wreckage and reviewed security camera footage from the airfield. The footage confirmed the aircraft was in a controlled approach at approximately 10 to 15 knots before the forward pitch occurred. Physical evidence, including soil residue on the upper and lower wire guards and the pitot tube, confirmed the significant forward tilt of the aircraft.
Investigators also noted that while previous training sessions had been conducted in the same area, the specific patch of ground used during this maneuver was less stable due to recent efforts to patch exposed earth with grass sods, which had not yet fully adhered to the terrain. The investigation also noted that the pilot being checked out had an expired type rating for the B-206, though the flight was being conducted by a certified examiner.
Findings
- The primary cause of the accident was the main rotor striking the ground following a forward pitch caused by the skids sinking into the soft terrain.
- The crew failed to perform a ground reconnaissance of the intended landing area to identify surface hazards or obstacles.
- The attempt to avoid the rotor strike via aft cyclic input contributed to mast bumping and the subsequent failure of the tail boom.
- The two crew members were uninjured during the occurrence.