What happened
The aircraft was operating in the Gulf of Mexico when a critical mechanical failure occurred. The 90-degree gearbox, which included the tail rotor blades, separated from the main structure. This separation was attributed to an imbalance within the gearbox assembly.
Following the loss of the gearbox and associated components, the pilot initiated an autorotation to maintain control of the descending aircraft. Despite these efforts, the helicopter impacted the water with significant force, resulting in a hard landing in the Gulf of Mexico.
The investigation
Investigators examined the wreckage to determine the root cause of the mechanical failure. A primary challenge during the examination was the recovery of evidence from the crash site.
The 90-degree gearbox and the attached tail rotor blades were not recovered during the investigation. Consequently, physical inspection of the failed components was impossible. Without the ability to examine the gearbox directly, investigators could not determine the specific origin or mechanism of the imbalance that led to its separation.
Findings
The immediate cause of the accident was the in-flight separation of the 90-degree gearbox due to an imbalance. The inability to recover the gearbox prevented a definitive determination of why the imbalance existed. The aircraft sustained substantial damage from the hard landing in the water.