What happened
On May 1, 2024, at approximately 16:10 EDT, an Airbus Helicopters AS350, registration N413JM, was involved in an accident near Plant City, Florida. The aircraft, operated by the Hillsborough County Sheriff’s Office, was performing a Part 91 positioning flight from Lakeland Linder International Airport (LAL) to Tampa Executive Airport (VDF).
While en route, the pilot elected to perform practice maneuvers, including confined area approaches and slope landings, in a nearby field. After completing an initial approach to a 15-foot hover, the pilot maneuvered the helicopter at approximately 20 knots and 50 feet above the ground. During this maneuver, the aircraft entered an uncommanded left turn that the pilot was unable to correct. The aircraft entered a left spin, rotating two to three times before impacting the ground. The helicopter came to rest upright with the engine running and no fire. The crew, consisting of a commercial pilot and a private pilot-rated copilot, were not injured.
The investigation
Post-accident examination of the aircraft revealed several structural issues. The tailboom exhibited multiple bends and wrinkles, and there was damage to the tail rotor guard and the tail "stinger." While the tail rotor driveshaft, hub, and blade assembly remained attached, the tail rotor gearbox had separated. One of the two tail rotor blades was found separated, which was consistent with the impact.
Upon inspection of the tail rotor driveshaft cover, investigators found that the most aft-mounted hanger bearing (No. 1 of 5) was severely damaged and had become free of its bearing race and mount. The investigation of the bearing mount revealed that the left-side attach bolt had not been installed and was found resting on the tailboom near the mount. The right-side bolt was installed, but the attachment nut was not fully seated.