Narrative:
A DHC-8-315 aircraft, operated by Surveillance Australia, was about to start the take-off roll from Darwin Airport, Australia, on a surveillance flight. There were four crew on board.
The aircraft was on the departure runway with the brakes on. Power was applied to both engines, but when take-off power was reached, and prior to the release of the brakes, the crew heard a loud bang. In response, the captain aborted the take-off, reduced both power levers to flight idle, and instructed the FO to contact air traffic control (ATC) to advise they were aborting the take-off and had an engine issue. Air traffic control acknowledged the advice and reported sighting smoke from the right engine before informing emergency services. The captain checked the right engine instrumentation and advised the crew that the torque gauge had failed, and the propeller RPM gauge indicated zero. Other indications for the gas core of the engine, such as fuel flow, appeared normal. The captain instructed the FO to shut down the engine.
After confirming the aircraft brake, hydraulic and electrical systems were functioning, the crew returned the aircraft to the maintenance hangar. A subsequent inspection of the runway by a safety car identified metal fragments behind the take-off position.
The right engine was subsequently removed from the aircraft with an external inspection revealing that all of the second-stage power turbine (PT2) blades had separated from the disk. The PT assembly could not be rotated but the propeller shaft turned freely.
Contributing factors
- The power turbine shaft of the aircrafts right engine fractured due to fatigue cracking, resulting in secondary damage and engine failure.
- The fatigue cracking in the engines power turbine shaft initiated at corrosion pitting, which probably resulted from prolonged low-altitude operation in a marine environment.
- The power turbine shaft in Pratt & Whitney Canada PW100 series engines operating in certain marine environments is susceptible to corrosion pitting, which can grow undetected between scheduled inspections. This increases the risk of shaft fracture resulting in engine failure. [Safety issue]
Runway mishap
| Status: | Accident investigation report completed and information captured |
| Date: | Monday 11 November 2019 |
| Time: | 15:10 |
| Type: |  de Havilland Canada DHC-8-315Q MPA |
| Operator: | Surveillance Australia |
| On behalf of: | Australian Border Force |
| Registration: | VH-ZZE |
| MSN: | 640 |
| First flight: | 2006-12-11 (12 years 11 months) |
| Engines: | 2 Pratt & Whitney Canada PW123E |
| Crew: | Fatalities: 0 / Occupants: 4 |
| Passengers: | Fatalities: 0 / Occupants: 0 |
| Total: | Fatalities: 0 / Occupants: 4 |
| Aircraft damage: | None |
| Location: | Darwin Airport, NT (DRW) ( Australia)
|
| Phase: | Takeoff (TOF) |
| Nature: | Survey/research |
| Departure airport: | Darwin Airport, NT (DRW/YPDN), Australia |
| Darwin Airport, NT (DRW/YPDN), Australia |
A DHC-8-315 aircraft, operated by Surveillance Australia, was about to start the take-off roll from Darwin Airport, Australia, on a surveillance flight. There were four crew on board.
The aircraft was on the departure runway with the brakes on. Power was applied to both engines, but when take-off power was reached, and prior to the release of the brakes, the crew heard a loud bang. In response, the captain aborted the take-off, reduced both power levers to flight idle, and instructed the FO to contact air traffic control (ATC) to advise they were aborting the take-off and had an engine issue. Air traffic control acknowledged the advice and reported sighting smoke from the right engine before informing emergency services. The captain checked the right engine instrumentation and advised the crew that the torque gauge had failed, and the propeller RPM gauge indicated zero. Other indications for the gas core of the engine, such as fuel flow, appeared normal. The captain instructed the FO to shut down the engine.
After confirming the aircraft brake, hydraulic and electrical systems were functioning, the crew returned the aircraft to the maintenance hangar. A subsequent inspection of the runway by a safety car identified metal fragments behind the take-off position.
The right engine was subsequently removed from the aircraft with an external inspection revealing that all of the second-stage power turbine (PT2) blades had separated from the disk. The PT assembly could not be rotated but the propeller shaft turned freely.
Probable Cause:
Contributing factors
- The power turbine shaft of the aircrafts right engine fractured due to fatigue cracking, resulting in secondary damage and engine failure.
- The fatigue cracking in the engines power turbine shaft initiated at corrosion pitting, which probably resulted from prolonged low-altitude operation in a marine environment.
- The power turbine shaft in Pratt & Whitney Canada PW100 series engines operating in certain marine environments is susceptible to corrosion pitting, which can grow undetected between scheduled inspections. This increases the risk of shaft fracture resulting in engine failure. [Safety issue]
Accident investigation:
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Classification:
Runway mishap
Sources:
» ATSBPhotos
Map
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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