Helicopter Crash Caused By Manufacturing Defect

(Image courtesy of the Transportation Safety Board of Canada.)

It's every pilot's nightmare: engine failure while taking off heavily loaded.

For a two-man crew fighting a fire in British Columbia in last year, however, it was a lucky escape. On 4 August 2013, a Kamov Ka-32 helicopter was carrying out forest fire suppression operations near Bella Coola, British Columbia using a water bucket on a long line. Just as the helicopter lifted a load of water out of a lake, there was a series of unusual sounds and the aircraft began to shake severely. The pilot not flying released the water bucket, and the pilot flying flew towards land for an emergency landing. The crew experienced difficulties controlling the aircraft on the way to the intended landing area. The helicopter touched down while drifting sideways to the right, and subsequently bounced and rolled onto its right side. The crew, who suffered minor injuries, shut down the engines and exited the helicopter without difficulties. There was no fire.

Transportation Safety Board of Canada Issues Accident Report

(Image courtesy of the Transportation Safety Board of Canada.)

In its investigation report (A13P0163) released yesterday, the Transportation Safety Board of Canada (TSB) has found that the Ka-32 helicopter, operated by VIH Helicopters Ltd. suffered an engine power loss due to anomalies in one of the helicopter's Klimov turboshaft engines. VIH is an experienced user of Ka-32 helicopters since 1997, with some airframes logging over 250 flight hours per month. VIH has worked with Kamov to extend the powerplant's useful life in VIH's typically heavy bush operations. By 2006, Kamov had extended the engine's useful life from 1500 to 6000 flight hours hours, reflecting eight years of logging and construction operations.

The investigation found that compressor turbine components failed, causing the engine to lose power. Quality control during the manufacture and assembly of the engine's compressor turbine section did not identify the anomalies in the components, which were visible to the naked eye. FOD (foreign object ingestion) damage is not uncommon in gas turbine internal components, but manufacturing quality issues visible to the naked eye are very unusual in turbine engine rotating assemblies. The report did not state whether the quality control failure was systemic or a one-off occurrence, but did note that the the compressor turbine is a safety critical component and that failure can have serious consequences for aircraft, crew, and passengers.

(Image courtesy of the Transportation Safety Board of Canada.)

The TV3-117VMA series 02 turboshaft engine is a version of the TV3-117 series for Ka-32 civil helicopters. Type certificates for this engine were awarded by the IAC Aviation Register, Transport Canada and Switzerland. Mass production started in 1993. Over 25,000 of the 2000 horsepower-class TV3-117 series power units have been produced since 1974.

Following the occurrence, the Russian aviation regulator issued a revised airworthiness directive that increased maintenance requirements for engines installed in Kamov Ka-32 helicopters used for external load operations.

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