Garlick UH-1H N869W

Summary

On 18 June 1998 at about 15:20 local time, a Garlick UH-1H registered N869W was involved in an accident near Couer D'alene, Idaho, 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

18 June 1998 at 15:20

Classification

Accident

Location

Couer D'alene, Idaho, United States

Coordinates

47.5908, -116.9105

Aircraft

Garlick UH-1H

Registration

N869W

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Route

Coeur D'alene → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA98FA104

Nobody was injured.

Fatigue failure of a reduction drive planetary gear. Factors include an unapproved part and plating process, and uneven terrain at the emergency landing site.

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

Read the full NTSB narrative

The pilot stated that he heard a loud metallic bang coming from the rear of the aircraft, followed immediately by a loss of power. He elected not to auto-rotate to a landing at the log-landing because of personnel in the vicinity, so he initiated an approach to a logging road adjacent to the log-landing. He landed with skids level, no power, and very low rotor rpm, but felt that he had the road made. After touching down, the helicopter rocked backward and rolled over on its left side. The engine was still running, and the pilot shut it down with the fuel valve. During the course of engine disassembly and inspection, output reduction gearbox damage was found to be consistent with a number one planet gearshaft separation caused by fatigue initiating at the outside diameter of the gear shaft within the shaft/gear web shoulder fillet radius. Laboratory analysis of the remnants of the number one planet gear noted that a cross section through the apparent fatigue origin did not exhibit evidence of material defects; however the fatigue initiation area was obscured as a result of secondary damage. The outer diameter of the planet gear shaft was found to have been plated with chromium or nickel and the case hardness of the carburized case on the planet gear was below that specified by the manufacturer. Investigation determined that none of the three planet gears in this engine were of OEM manufacture. Plating of the planet gear is not an authorized repair procedure, and no military repair procedure was identified authorizing this type of repair.

Quoted verbatim from the NTSB record.