Incident Overview

Date: Monday 24 March 1986
Aircraft Type: de Havilland Canada DHC-3 Otter
Owner/operator: Goose Bay Air Services
Registration Number: C-FAGM
Location: 76 km N of Goose Bay, NL – ÿ Canada
Phase of Flight: En route
Status: Destroyed, written off
Casualties: Fatalities: 4 / Occupants: 5
Component Affected: Number nine cylinder headNumber nine cylinder head
Investigating Agency: CASBCASB
Category: Accident
A DHC-3 Otter aircraft on a return charter flight to Snegamook Lake crashed after encountering engine issues during a landing near Nipishish Lake. The pilot initiated a precautionary landing on the Crooked River, reporting a rough engine and an odor of smoke. The aircraft struck the river, bouncing clear and landing upright. A fatigue-initiated crack in the number nine cylinder head was identified as the probable cause of the engine failure and subsequent crash.A DHC-3 Otter aircraft on a return charter flight to Snegamook Lake crashed after encountering engine issues during a landing near Nipishish Lake. The pilot initiated a precautionary landing on the Crooked River, reporting a rough engine and an odor of smoke. The aircraft struck the river, bouncing clear and landing upright. A fatigue-initiated crack in the number nine cylinder head was identified as the probable cause of the engine failure and subsequent crash.

Description

A wheel/ski-equipped DHC-3 Otter aircraft was on the return leg of a charter flight to Snegamook Lake to retrieve a hunting party of four, along with their hunting gear and bounty of several hundred ptarmigan. It departed Snegamook Lake at 09:15. After takeoff, the engine began to run rough but improved somewhat when the power was reduced for cruising. As the aircraft was approaching Nipishish Lake, the pilot reported to company dispatch that the engine was again running rough, but he was able to maintain altitude, and he would follow the Crooked River toward Goose Bay in case a precautionary landing became necessary. Three minutes later, C-FAGM called dispatch again, advising them that he was intending to land on a large area on the Crooked River. He also indicated that there was an odour of smoke in the aircraft. The aircraft was in a nose-down, left- bank attitude, with the flaps fully extended and the skis retracted when it struck the frozen surface of the river. The Otter bounced clear of the surface, turned left came to rest in an upright position. PROBABLE CAUSE: “The Canadian Aviation Safety Board determined that a fatigue-initiated crack in the number nine cylinder head caused the engine to run rough and lose power. While the pilot was manoeuvring for the precautionary landing in whiteout conditions, the aircraft crashed. At impact, the fuel cells ruptured, and a fire erupted which destroyed the aircraft.”

Primary Cause

Fatigue-initiated crack in the number nine cylinder headFatigue-initiated crack in the number nine cylinder head

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