What aircraft was involved and where did it happen?

The accident on 1987-03-30 involved an Agusta A109, registration N4GH, at Lincoln, NE.

Helicopter Tail Rotor Driveshaft Failure During Ground Taxi (N4GH)

On March 30, 1987, an Agusta A109 (registration N4GH) was involved in an aviation accident near Lincoln, NE. Investigators recorded the probable cause as: The tail rotor driveshaft failed in a manner characteristic of torsional overload. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

A helicopter experienced a tail rotor driveshaft failure during ground taxi at Duncan Aviation, prompting an emergency shutdown. Metallurgical examination revealed the shaft failed due to torsional overload.

Incident Overview

A helicopter was being taxied on the ground to the ramp area at Duncan Aviation for refueling when the pilot in command (PIC) heard a loud bang emanating from the rear of the aircraft. The PIC lowered the collective pitch, after which no further noise was heard and no vibration was felt.

Pilot Actions

Upon reapplying collective pitch to continue moving forward, the helicopter began to yaw and vibrate. The PIC then lowered the collective to flat pitch and shut down the engine. The helicopter did not contact the ground or any stationary object during the event, according to the PIC.

Examination Findings

After the incident, maintenance personnel removed components and found a broken portion of the tail rotor (T/R) driveshaft approximately 1 foot forward of the gearbox. The National Transportation Safety Board (NTSB) laboratory and an independent metallurgist conducted a metallurgical examination of the failed driveshaft.

Conclusion

The examination concluded that the driveshaft failed in a manner characteristic of torsional overload. No other contributing factors were identified in the report.

Probable cause

The tail rotor driveshaft failed in a manner characteristic of torsional overload.

1987-03-30: Agusta A109 (N4GH) — Lincoln, NE