Garlick UH 1H N462CC

Summary

On 31 May 2015 at about 18:26 local time, a Garlick UH 1H registered N462CC was involved in an accident near Cove, Oregon, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

31 May 2015 at 18:26

Classification

Accident

Location

Cove, Oregon, United States

Coordinates

45.3531, -117.6339

Aircraft

Garlick UH 1H

Registration

N462CC

Category

Helicopter

Year built

1965

Engines

1

Operator

Not recorded

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

External Load

Phase of flight

Not recorded

Route

Cove → Cove

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR15LA178

Nobody was injured.

The failure of the engine-to-transmission drive shaft coupling assembly due to a fatigue fracture of one of its attachment bolts, which resulted in a loss of power to the main rotor.

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

Read the full NTSB narrative

The commercial pilot reported that, while maneuvering the helicopter at low altitude during logging operations, he felt a vibration and heard a howling sound coming from the transmission area. He immediately initiated a precautionary landing; however, as the helicopter settled to the ground, the main rotor rpm dropped, and the pilot attempted to cushion the landing with aggressive collective input. The helicopter subsequently landed hard. Postaccident examination revealed multiple fractures of the Kaflex engine-to-transmission drive shaft coupling assembly. According to the flight manual, a failure of the engine-to-transmission drive shaft would lead to a complete loss of power to the main rotor. The coupling assembly failure was initiated by the failure of an attachment bolt due to a fatigue crack on the flange section that attached the coupling assembly to the transmission shaft flange. No evidence of any material anomalies were found in the fractured bolt, and the fatigue crack was likely caused by the severe stress imposed by logging operations. The manufacturer did not specify a replacement interval for the bolt. The investigation could not determine when the fatigue crack developed and propagated; therefore, it could not be determined whether the crack would have been identified during an annual inspection.

Quoted verbatim from the NTSB record.