Casualties unknown

1983-12-18: Bell 47-G3B1 (N48316) — Dummerston, VT

Dummerston, VT, US

On December 18, 1983, a Bell 47-G3B1 (registration N48316) was involved in an aviation accident near Dummerston, VT. 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 APIEditorial standards

During a practice autorotation from 600 ft AGL at 55 kts with low rotor rpm, a flare reduced airspeed to 40 kts, but collective application failed to arrest descent. The tail rotor struck the ground, causing a tip breakage and vibrations, leading to loss of tail rotor drive, right yaw, left skid collapse, and mast projection through the canopy.

Incident Overview

The pilot initiated a practice autorotation from approximately 600 ft above ground level. The airspeed was about 55 knots during the maneuver, with low main rotor rpm attributed to a low gross weight. In an effort to increase rotor rpm, a moderate flare was executed, which reduced the airspeed to 40 knots. However, the subsequent application of collective pitch did not arrest the descent rate.

Sequence of Events

As the helicopter continued its descent, the tail rotor struck the ground. Upon impact, approximately 6 inches of one tail rotor tip broke off, resulting in increased vibration. The pilot attempted to land the helicopter, but the drive to the tail rotor ceased to respond. Consequently, the helicopter yawed to the right. The left skid then struck the ground and collapsed. During the event, the mast assembly was projected through the canopy bubble.

Damage

The helicopter sustained damage including a broken tail rotor tip, a collapsed left skid, and the mast assembly penetrating the canopy.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001214X45405. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.