Ayres Corporation S2R-T34 N4004D accident near Donalsonville, Georgia

Probable cause

A total loss of engine power due to a failure of the compressor turbine blades for undetermined reasons.

NTSB analysis

According to the pilot, he was applying chemicals to a field at 200 feet above ground level when the engine lost power. He said that he heard a "pop" sound, heard the engine "spool down," and observed blue smoke trailing from the top of the engine cowling. He selected a nearby field and performed a forced landing. The airplane was substantially damaged when it impacted trees and terrain during the landing. The pilot said that he heard the sound of "something spinning" coming from the engine cowling before he subsequently shut down the engine, after which the sound ceased. Upon exiting the airplane, he saw oil draining from the lower aft portion of the engine cowling.

Postaccident examination revealed internal engine damage along the gas-path downstream of the compressor turbine. The compressor turbine blades were fractured about 1/3 to 1/2 of their respective spans and displayed burning erosion and coating loss. Visual and macroscopic inspection of the blade fracture surfaces displayed no indications of fatigue or other progressive fracture mechanism. The definitive failure mechanism of the blades was not determined. The compressor turbine blades were manufactured by a third-party vendor under a Federal Aviation Administration Parts Manufacturer Approval. The blade manufacturer required that the blades be submitted for overhaul inspection after the first 5,000, and each subsequent 3,000 hours of operation thereafter. The installation and overhaul history of the blades could not be determined from maintenance records provided.

Text from the NTSB. Open the NTSB docket for ERA10LA401 for the full record.