Incident Overview
Description
A de Havilland Canada DHC-3 Otter, registered C-GGON, sustained substantial damage in an accident 4 km east of Lac du Bonnet, MB, Canada. All three passengers and the pilot survived. The airplane operated on a flight from Lac du Bonnet, MB to George Lake, MB. The pilot completed a normal takeoff from the Winnipeg River in an easterly direction and began a shallow climb over the shoreline. As the aircraft levelled at approximately 400 feet agl, there was a loud backfire followed by a complete loss of engine power. The pilot force landed straight ahead; the aircraft struck several large trees and came to rest in a swampy area. The aircraft struck the ground on its left side, both wings broke off, and the engine was buried in the swampy ground. FINDINGS AS TO CAUSES AND CONTRIBUTING FACTORS: 1. A spacer in the No. 3 cylinder push rod tube was installed incorrectly. This initiated the increased wear that eventually prevented the No. 3 exhaust valve from opening, resulting in hot exhaust gases migrating into the induction system and causing the engine failure. 2. Following replacement of the No. 1 cylinder, the operator did not complete a field barometric power reference check, which is used in early identification of an engine problem. 3. The valve adjustment screw protrusion was set beyond specified limits. Had the out-of-limits screw protrusion been noted during adjustment or during a scheduled inspection, an examination might have revealed the excessive wear in the valve train and prevented the engine failure.
Primary Cause
Incorrectly installed spacer in the No. 3 cylinder push rod tube.Incorrectly installed spacer in the No. 3 cylinder push rod tube.Share on:
