On June 15, 2001, a Cosmic Air Dornier 228-101 experienced a failure of the right engine, a Honeywell TPE331-5B-252D turbo propeller, during a training flight for stall and recovery at Pokhara Airport, Nepal. After inducing the stall, power was applied to both engine for airplane recovery and a loud bang was heard coming from the right engine. A corresponding low oil pressure warning light and a right engine fire light illuminated. The engine was shutdown and an uneventful landing was made. Examination of the right engine revealed that the turbine rotating section had exited the engine. The 1st- and 2nd-stage turbine wheels were recovered separate from the rest of the engine, along with pieces of the tie-shaft and torsion shaft. The 3rd-stage wheel was not recovered. Metallurgical examination of the 1st- and 2nd-stage turbine wheels revealed that the disk rim had separated in overload while the 2nd-stage turbine wheel rim had separated from a low cycle fatigue crack that originated from multiple origins within a rivet hole. Evidence found on the aft side of the 1st- stage wheel and 2nd-stage stators suggest that these parts experienced higher than normal temperatures. Temperatures estimated on the 1st-stage wheel were 1700F and on the 2nd-stage stator in excess of 2000F.

The investigation is under the jurisdiction of the government of Nepal. Further information pertaining to this incident may be obtained from:

Director General of Civil Aviation
Civil Aviation Authority
Babar Mahal

Tel.: (977) 1-262387 / 262518
E-mail: cnsatm@mos.com.np
Fax: (977) 1-262516
Telex: 2553 DCA NP

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

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