Helicopter Sustains Tailboom Severance During Autorotation on Wet Grass (N312SH)

Q: What aircraft was involved and where did it happen?

The accident on 1991-07-22 involved a Bell 47G-2, registration N312SH, operated by Sunrise Helicopters, Inc., at Slidell, LA.

On July 22, 1991, a Bell 47G-2 (registration N312SH) operated by Sunrise Helicopters, Inc. was involved in an aviation accident near Slidell, LA. Investigators recorded the probable cause as: THE PILOT PERFORMING A TOUCHDOWN AUTOROTATION TO UNSUITABLE TERRAIN. FACTORS WERE THE SOFT TERRAIN AND THE INADEQUATE SUPERVISION BY THE FAA INSPECTOR. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data API Editorial standards

During an autorotation, a helicopter experienced partial loss of control in the flare, sank into wet grass, skidded, and the main rotors severed the tailboom. The pilot had noted wet conditions; the check airman did not intervene.

Incident Overview

During a training flight, the pilot initiated an autorotation at approximately 500 feet and 60 knots. Both the pilot and the FAA check airman reported that the main rotor RPM was in the 'low green' range during the maneuver.

Loss of Control and Landing

As the helicopter flared, a partial loss of control occurred. The right skid sank several inches into the wet, grassy terrain. The helicopter then skidded approximately 15 feet before coming to rest in a nose-low, left bank attitude.

Rotor Strike and Damage

The main rotors struck the tailboom, severing it. The pilot stated that he had informed the check airman that the grass was wet prior to the maneuver.

Maneuver Status

According to the report, the autorotation to touchdown was not a required maneuver, nor was it prohibited. The check airman did not intervene during the conduct of the autorotation.

Key Facts

Autorotation initiated at 500 feet and 60 knots
Main rotor RPM in low green range
Partial loss of control during flare
Right skid sank into wet grass
Helicopter skidded 15 feet
Main rotors severed tailboom
Pilot informed check airman of wet grass
Maneuver was not required, but not prohibited
Check airman did not intervene

1991-07-22: Bell 47G-2 (N312SH) — Sunrise Helicopters, Inc. — Slidell, LA