The ATSB has released a preliminary report into the in-flight propeller detachment involving a Regional Express SAAB 340 aircraft near Sydney Airport on 17 March 2017.
An inspection of the propeller revealed a fatigue fracture that began in the propeller mounting flange (the part that attaches the propeller to the gearbox) and continued into the propeller shaft. The inspection also found corrosion near the initiation of the fracture.
The ATSB stated that this was the first known critical failure of this type, initiating within the propeller hub flange of the GE Aviation CT7-9B engine.
The ATSB’s ongoing investigation will focus on maintenance procedures associated with the propeller gear box shaft and examine factors that may have contributed to the fatigue fracture at the propeller mounting flange.
Meanwhile the following Safety Recommendation was issued:
“The ATSB advises that those responsible for the operation and maintenance of SAAB 340 and EADS CASA CN-235 aircraft fitted with the GE Aviation CT7 engine type variants 5A2, 7A1, 9B, 9C, and 9C3 should note the facts presented in the preliminary report with a view to addressing any risks to their own operation.”