Air Tractor AT 502 N4531K

Summary

On 15 September 2017 at about 14:15 local time, a Air Tractor AT 502 registered N4531K, operated by Londe Air LLC, was involved in an accident near Union City, Tennessee, 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

15 September 2017 at 14:15

Classification

Accident

Location

Union City, Tennessee, United States

Coordinates

36.3928, -89.1167

Aircraft

Air Tractor AT 502

Registration

N4531K

Category

Airplane

Year built

1990

Engines

1

Operator

Londe Air LLC

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Hickman → Hickman

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA17LA326

Nobody was injured.

The catastrophic failure of the compressor turbine blades, which resulted in a total loss of engine power. Contributing to the accident was the installation of undocumented, time-limited engine components of indeterminate age.

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

Read the full NTSB narrative

The pilot of the aerial application flight indicated that the airplane was in cruise flight on its way to an application site when he heard a "pop," and the engine lost total power. The pilot maneuvered the airplane for a forced landing on a roadway but changed his forced landing site to a corn field due to vehicle traffic. After touchdown, the main landing gear separated, which resulted in substantial damage to the fuselage. Examination of the engine revealed catastrophic internal damage; all compressor turbine blades were fractured. Metallurgical examination revealed fracture features consistent with high-velocity impact and high-temperature deformation such as "creep." The primary fracture could not be identified; therefore, the sequence in which the fractures occurred could not be determined. The engine was an assembled compilation of manufacturer and aftermarket parts manufacturer approval (PMA) parts. Some PMA parts installed were not authorized for the application, and the serial numbers reflected in the maintenance records did not match the components installed. For example, the factory original compressor turbine disk was installed, but the logbook indicated another disk was installed. The compressor turbine disk was a time-limited item, and the total hours on the installed disk could not be verified.

Quoted verbatim from the NTSB record.