Hiller UH-12E N4029S

Summary

On 29 May 1997 at about 13:20 local time, a Hiller UH-12E registered N4029S was involved in an accident near Granby, New York, United States. One person was on board and one was seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

29 May 1997 at 13:20

Classification

Accident

Location

Granby, New York, United States

Coordinates

43.3106, -76.4107

Aircraft

Hiller UH-12E

Registration

N4029S

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 137: Agricultural

Purpose of flight

Positioning

Phase of flight

Not recorded

Route

Fulton → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

NYC97LA101

1 person was seriously injured.

failure of the pilot/owner to replace the torsional clutch as specified by the manufacturer, and subsequent failure of the helicopter's clutch, which resulted in a forced landing (autorotation). A related factor was: the encounter with trees in the emergency landing area.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The pilot/owner had completed an uneventful aerial application flight, and he began to reposition the helicopter to another site. En route, at 500 feet AGL, the helicopter's engine began to overspeed. The pilot entered autorotation, and the helicopter struck trees and landed hard. Examination revealed the elastomeric torsional coupling inside the transmission, and the secondary steel drive flanges were sheared. The manufacturer's service data for the coupling stated that mandatory replacement of the coupling should occur at 5,000 hours or 5 years from the date embossed on the rubber, or in accordance with maintenance requirements for the coupling, which ever occurred first. The raised numbers on the coupling indicated a date of May 1988, 9 years before the accident.

Quoted verbatim from the NTSB record.