Rockwell International S-2R N8472V accident near Uvalde, Texas

Probable cause

A total loss of engine power due to the improper use of unauthorized replacement parts in the engine and repeated operation of the engine in an over-temperature condition.

NTSB analysis

The engine of the agricultural airplane lost power while it was maneuvering at low altitude. The airplane impacted thick vegetation and terrain, causing substantial damage to the right wing, nose and tail. A subsequent teardown examination of the engine showed little evidence that the engine was operating at the time of impact, but the ingestion of vegetation into the combustor and the torsional failure of the torsion shaft suggests that there was some rotation of the engine at the time of impact. The engine examination also revealed that several turbine rotors had damage and missing blade material due to short term operation of the engine at an over temperature condition. There was evidence that the rotors had been operating for several hours after the over temperature event that caused the stress rupture of the blades. Further, the examination showed that the first stage turbine rotor and the prop pitch control cam did not conform to Honeywell specifications and were not authorized replacement parts, and a previous weld repair on the engine combustor plenum did not conform to standard practices for weld repairs on aerospace parts.

Text from the NTSB. Open the NTSB docket for DFW08LA223 for the full record.