What happened
On the evening of April 15, 1997, an Eurocopter AS350 B helicopter, registration F-GOCH, was performing an aerial work mission over Bougy-Lez-Neuville. The flight was executing a U-shaped takeoff maneuver from a shoreline over a pond. During this translation, a flock of birds flew directly into the aircraft's path.
In an attempt to avoid the birds, the pilot applied full cyclic input. However, the aircraft reached its power limits and failed to climb. Instead, the helicopter pitched up, causing the tail rotor to strike the surface of the water. This impact resulted in a loss of directional control (yaw). To manage the situation, the pilot intentionally brought the aircraft down onto the pond. The helicopter settled on its right side in approximately one meter of water.
There were two persons on board. The passenger, a photographer, was not restrained by a seatbelt and was ejected from the aircraft before it came to rest on the water. The passenger was subsequently able to assist the pilot in exiting the wreckage.
The investigation
The investigation focused on the mechanical failures and the sequence of the impact. Investigators examined the rear transmission components, which had suffered structural failures. The analysis determined that these breaks were caused by static stresses. These stresses were likely the result of two distinct events: the initial contact of the tail rotor with the water and the subsequent impact when the pilot placed the aircraft onto the pond surface.