Franklin, LA, USA
N991SP
Bell 407
When approaching a helipad for landing, the pilot realized that the anti-torque pedals were not effective. Due to obstacles, the pilot aborted his approach to the helipad and turned eastbound toward a sugar cane field. Subsequently, the helicopter started to rotate and the pilot realized he had no control of the tail rotor with the anti torque pedals. He then rolled the throttle to idle, and initiated an autorotation from approximately 75 feet AGL. The pilot reported that a high sink rate developed and the helicopter impacted the ground hard on the main landing skids. Inspection of the helicopter revealed that the pivot bolt (P/N: NAS6604D31), bushing (P/N: 206-011-726-005), nut (P/N: MS14144l4), and cotter pin (P/N: MS24665-155), that connects the rotor control idler assembly (P/N: 406-012-127-101) to the tail rotor control housing assembly was not found. Examination of the aircraft logbooks indicated that there was an annual maintenance inspection preformed on the helicopter 7 days hours prior to the accident. The helicopter accumulated 4.9 hours of flight time since time of inspection.
On May 19, 2003, at 0955 central daylight time, a Bell 407 helicopter, N991SP, registered to and operated by the Louisiana Department of Public Safety, was substantially damaged during a precautionary following a loss of tail rotor pitch control near Franklin, Louisiana. The commercial pilot and his passenger were not injured. Visual meteorological conditions prevailed and a Company VFR flight following plan was filed for the 14 Code of Federal Regulations Part 91 Public Use flight. The local flight originated from Baton Rouge Airport (BTR), Baton Rouge, Louisiana, at 0900, and was destined for Franklin, Louisiana. The pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that while he was approaching a helipad for landing, he realized that the anti-torque pedals were not effective. Due to obstacles he aborted his approach to the helipad and turned eastbound toward a sugar cane field. Subsequently, the helicopter started to rotate and he realized he had no control of the tail rotor with the anti torque pedals. He then rolled the throttle to idle, and initiated an autorotation from approximately 75 feet agl. The pilot further reported that a high sink rate developed and the helicopter impacted the ground hard on the main landing skids. An FAA inspector, who examined the helicopter at the accident site, reported that the main landing skids were compressed nearly flat. Further inspection revealed that the pivot bolt (P/N: NAS6604D31), bushing (P/N: 206-011-726-005), nut (P/N: MS14144l4), and cotter pin (P/N: MS24665-155), that connects the rotor control idler assembly (P/N: 406-012-127-101) to the tail rotor control housing assembly was not found. All part numbers were verified with the Bell Helicopter Textron 407 Illustrated Parts Bulletin (BHT-407-IPB). Examination of the aircraft logbooks indicated that there was an annual maintenance inspection preformed on the helicopter 7 days prior to the accident. The helicopter accumulated 4.9 hours of flight time since time of inspection. The company who preformed the maintenance inspection on the helicopter provided the NTSB investigator-in-charge with a written statement from the mechanic and supervisor who worked on the helicopter. The mechanic who was working on tail rotor gearbox area requested his supervisor inspect the area and double-check that the work was complete. It was discovered that the "pitch channel trunnion attach bolt was installed, but not tight or safety wired." The supervisor requested this be complied with. Later that day, the supervisor asked the mechanic if the work was complete, but did not verify it visually. The tail rotor gearbox cowling was then installed.
The loss of tail rotor effectiveness due to the inadequate maintenance performed by other company personnel.
Source: NTSB Aviation Accident Database
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