VH-SBA

On 4 October 2009, at 1257 EST, a SAAB 340B aircraft, registered VH-SBA, experienced a failure of the left engine during initial climb out from Wagga Wagga Aerodrome, NSW, Australia on a regular scheduled flight to Melbourne, Victoria, Australia. The flight crew reported that they noticed abnormally high indications of the left engine inter-turbine temperature and they then conducted the non-normal checklist items, shut down the left engine, and returned to the aerodrome without further incident. Subsequent inspection of the left engine indicated internal damage, specifically to the 1st stage compressor blisk airfoil section (blade). Of the 34 passengers, and 3 crewmembers on board, there were no reported injuries.

The aircraft, serial number 340B-311, was built in Sweden in 1992 and was a twin-engine turboprop fixed wing regional airliner with a tricycle-type landing gear. The engine was a General Electric Company, model CT7-9B, serial number 785210.

The subsequent engine disassembly, examination and inspection was completed on behalf of the ATSB under the supervision of a representative of the UK Air Accidents Investigation Branch (AAIB).

The observations included:

-all compressor blades were mechanically damaged

-the 1st stage compressor blisk had 4 blades broken off at approximately mid span, while the others had tip damage and diameter reduction apparently from impact and trapping of debris, much like those further downstream

-the four failed 1st stage blades had fracture faces which look similar to each other

Further metallurgy examination of the failed blades from the 1st stage blisk was performed in the UK. That examination confirmed that the four failed blades on the 1st stage blisk of the compressor showed a fatigue mechanism related to the failure.

The investigation is being conducted by the Australian Transportation Safety Board. Further information pertaining to this accident may be obtained from:

Australian Transport Safety Bureau (ATSB)

P.O. Box 967, Civic Square

Canberra A.C.T. 2608

Australia

Tel.:

(61) 2 6257-4150 (24/7 Notifications)

(61) 2 6274-6464 (International liaison)

E-mail:

atsbasir@atsb.gov.au (Notifications)

atsbinfo@atsb.gov.au (International liaison)

Fax:

(61) 2 6274-6434 (Notifications)

(61) 2 6274-6474 (International liaison)

Website: http://www.atsb.gov.au

This report is for informational purposes only and contains only information obtained for, or released by, the Government of Australia.