Engine failure leads to heavy helicopter landing in Saskatchewan swamp

Casualties unknown • Porcupine Plain, Saskatchewan 19 nm S, CA

A Bell 206B JetRanger experienced a sudden loss of engine power during a wildlife survey flight, resulting in a hard landing in a swamp near Porcupine Plain.

What happened

While conducting charter flights for the Saskatchewan Environment and Resource Management Wildlife Branch, the pilot of a Bell 206B JetRanger was flying near Hudson Bay to locate and tag Trumpeter swans. At an altitude of approximately 3,000 feet, the crew heard a high-pitched buzzing sound coming from the engine compartment. The pilot noticed a decay in the power turbine RPM and immediately notified the three passengers to prepare for an emergency landing.

To avoid tall trees at the edge of a clearing, the pilot performed an autorotation into a swampy area. The helicopter struck the ground heavily, causing the skids to sink into the swamp. While the aircraft sustained substantial damage, including a bent landing gear and a damaged transmission, the pilot and all three passengers escaped without injury.

The investigation

Investigators examined the Allison 250-C20B engine to determine the cause of the power loss. A teardown of the engine revealed that a blade on the second stage gas producer turbine wheel had failed. This failure caused the blade to jam against the adjacent turbine blade and shear off a thermocouple probe. The debris traveled downstream, causing extensive foreign object damage to the nozzle guide vanes and subsequent turbine blades.

Technical analysis by the TSB Engineering Branch confirmed that the failure was a high-cycle fatigue fracture. Additionally, investigators looked into the aircraft's configuration and found that an 18-foot canoe mounted on an external cargo rack prevented the right-side doors from being opened, which was a violation of the approved flight manual supplement. Regarding the lack of cockpit warnings during the event, it was noted that the warning light circuit breaker was likely disengaged.

Findings

  • The engine lost power due to internal damage caused by a broken turbine blade.
  • The blade failure was the result of fatigue, likely driven by engine-induced stresses or vibrations, though the specific source of these stresses remains unknown.
  • The loading of the external cargo rack was inconsistent with approved procedures as it obstructed door egress.
  • The absence of warning lights and horns during the flight was likely due to the warning light circuit breaker being in the 'out' position.

Probable cause

The engine experienced a loss of power because a second-stage gas producer turbine blade failed due to fatigue, leading to internal component damage and subsequent power decay.

Related events

Same operator

Frequently asked questions

What happened in the 1994-07-26 Bell 206B III JetRanger C-GELT accident near Porcupine Plain, Saskatchewan 19 nm S, CA?

A Bell 206B JetRanger experienced a sudden loss of engine power during a wildlife survey flight, resulting in a hard landing in a swamp near Porcupine Plain.

What aircraft was involved and where did it happen?

The accident on 1994-07-26 involved a Bell 206B III JetRanger C-GELT, operated by Athabaska Airways Ltd., at Porcupine Plain, Saskatchewan 19 nm S, CA.

What was the probable cause of the accident?

The engine experienced a loss of power because a second-stage gas producer turbine blade failed due to fatigue, leading to internal component damage and subsequent power decay.

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