Air Tractor AT-802A N528MB

Summary

On 9 August 2017 at about 12:30 local time, a Air Tractor AT-802A registered N528MB, operated by Lesco Aviation Inc., was involved in an accident near Galesburg, Illinois, 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

9 August 2017 at 12:30

Classification

Accident

Location

Galesburg, Illinois, United States

Coordinates

40.9731, -90.3036

Aircraft

Air Tractor AT-802A

Registration

N528MB

Category

Airplane

Year built

2010

Engines

1

Operator

Lesco Aviation Inc.

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Monmouth → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN17LA309

Nobody was injured.

A total loss of engine power due to the fracture of a single 1st stage compressor rotor airfoil in high-cycle fatigue as a result of the erosion and thinning of the airfoil's leading edge. Contributing to the fractured airfoil and loss of engine power was the operator’s decision to operate the engine past the manufacturer’s recommended time between overhaul.

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

Read the full NTSB narrative

The pilot was on an agricultural flight when the engine lost total power. The pilot completed a forced landing in a nearby field, but he was unable to maintain directional control of the airplane after it landed in the dense soybean crop. The outboard portion of the right wing and aileron were substantially damaged during the forced landing. A postaccident engine examination revealed that a single 1st stage compressor rotor airfoil had fractured near its root. The fatigue crack originated from a thinned leading edge due to significant erosion at the bottom of the airfoil pressure side; however, the exact location of the fatigue origin could not be determined because it had been obliterated by the erosion. The observed fracture features were consistent with a crack that had progressed in highcycle fatigue. Dimensional measurements of the fractured airfoil and the two adjacent airfoils revealed that they were under the minimum requirement for an airfoil. The airfoils also exhibited evidence of fine wear scratches, characteristic of fine abrasive particles impacting the airfoil, and thinning of their leading edges. The underlying cause of the airfoil erosion could not be determined with certainty; however, based on the observed damage, it was possibly the result of environmental conditions. The engine had accumulated 4,349.3 hours since new and had never been overhauled. The engine manufacturer’s recommended time between overhaul (TBO) was 3,000 hours; however, the operator was not required to comply with the recommended TBO interval under current regulations due to the type of operation.

Quoted verbatim from the NTSB record.