Ayres S2RT-34RE N4010X

Summary

On 25 March 1998 at about 01:45 local time, a Ayres S2RT-34RE registered N4010X was involved in an accident near Buckeye, Arizona, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 March 1998 at 01:45

Classification

Accident

Location

Buckeye, Arizona, United States

Coordinates

33.3805, -112.5493

Aircraft

Ayres S2RT-34RE

Registration

N4010X

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Positioning

Phase of flight

Not recorded

Route

Buckeye → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX98LA129

Nobody was injured.

The incorrect turbine blades installed on the engine, the fractured compressor turbine blades and separation of the blade, and the improper maintenance installation of the incorrect CT blades by the repair station. A factor in the accident was the inadequate quality control procedures by both the shipper of the CT blades and the maintenance facility which installed the blades.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

An Ayres S2R airplane lost power and crashed following a landing attempt to a field. The subsequent disassembly of the engine revealed that the compressor turbine disk was intact, but that all of the CT blades were fractured across the airfoils adjacent to the blade root platform. The Canadian Transportation Safety Board's engineering branch found that there were 55 blades of one part number and 3 blades of another part number which were not authorized for use in a PT6A-34AG engine. The three unapproved blades had a different heat code than was approved for this engine. One of the unapproved blades revealed a fatigue fracture on the surface as seen by the scanning electron microscope. The blades were manufactured by Doncaster, under a FAA Parts Manufacturing Approval as an alternate part for PWC CT blades. They were then packaged and shipped to Superior Air Parts. Superior Air parts would repackage the blades in Superior Air parts packaging prior to reshipping the blades. Doncaster's stated that Superior was the sole distributor of the Doncaster blades. Both the quality control standards at Superior Air Parts and Air Force Turbine Services did not notice the three incorrect CT blades, which were shipped from Superior Air Parts and subsequently, installed on the engine. Additionally, when the engine underwent repair work and these blades were installed, the new CT blades were installed and the radial tip clearance between the blades and segments was 0.0025 inches less than the minimum required by the PT6 engine manual.

Quoted verbatim from the NTSB record.