Propeller separation on Saab 340B during flight to Sydney

Casualties unknown • Serious incident with an aircraft of the type Saab 340B in Australia, SE

A propeller detached from a Regional Express Saab 340B mid-flight near Sydney after the crew attempted to manage engine fluctuations.

What happened

On 17 March 2017, a Saab 340B, registration VH-NRX, was performing a scheduled passenger flight from Albury to Sydney, carrying 16 passengers and three crew members. While flying approximately 55 nautical miles southwest of Sydney Airport, the flight crew observed fluctuations on the right engine torque gauge.

In an attempt to stabilize the engine, the crew adjusted the power and condition levers. However, as they began executing uncommanded engine operation checklists, vibrations from the right engine increased significantly. The crew initiated an engine shutdown procedure to manage the instability. During this process, the propeller separated from the aircraft. The crew declared a PAN PAN urgency call to air traffic control and successfully completed the shutdown. The aircraft subsequently landed at Sydney Airport without further incident. The detached propeller was later recovered by police in a forested area roughly 10 nautical miles southwest of the airport.

The investigation

The investigation focused on the mechanical failure of the propeller shaft. Physical examination of the aircraft at Sydney Airport revealed that the propeller gearbox shaft had fractured. Laboratory analysis of the recovered shaft identified a fatigue crack that had originated at the dowel pin hole of the propeller gearbox shaft flange. /nInvestigators also examined maintenance records and procedures. They found that the manufacturer's documentation lacked specific instructions for detecting fatigue cracks in the propeller shaft. Furthermore, the operator's maintenance worksheets did not require the recording of specific inspection findings, which limited the ability to monitor potential defects over time.

Findings

  • The propeller separation was caused by a fatigue crack in the propeller gearbox shaft flange.
  • The crack initiated at a dowel pin hole, driven by cyclic loading.
  • Localized corrosion and fretting damage were present near the fracture site.
  • Existing manufacturer maintenance documentation did not provide adequate procedures to detect such fatigue cracking.
  • The operator's inspection records lacked the detail necessary to effectively track and identify emerging defects.

Probable cause

The propeller separated due to a fatigue crack in the propeller gearbox shaft flange, a failure mode that was not detectable through the existing manufacturer inspection procedures or the operator's maintenance recording practices.

Frequently asked questions

What happened in the 2017-03-17 aircraft accident near Serious incident with an aircraft of the type Saab 340B in Australia, SE?

A propeller detached from a Regional Express Saab 340B mid-flight near Sydney after the crew attempted to manage engine fluctuations.

What aircraft was involved and where did it happen?

The accident on 2017-03-17 involved a aircraft, at Serious incident with an aircraft of the type Saab 340B in Australia, SE.

What was the probable cause of the accident?

The propeller separated due to a fatigue crack in the propeller gearbox shaft flange, a failure mode that was not detectable through the existing manufacturer inspection procedures or the operator's maintenance recording practices.

Loading the flight search…