Ayres S2R G6 N3300U

Summary

On 20 May 2015 at about 19:40 local time, a Ayres S2R G6 registered N3300U, operated by A T Ag Services, LLC, was involved in an accident near Tivoli, Texas, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

20 May 2015 at 19:40

Classification

Accident

Location

Tivoli, Texas, United States

Coordinates

28.3922, -96.8933

Aircraft

Ayres S2R G6

Registration

N3300U

Category

Airplane

Year built

1996

Engines

1

Operator

A T Ag Services, LLC

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Tivoli → Tivoli

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN15LA239

1 person had minor injuries.

The failure of the fuel control unit due to the worn stub shaft spline, which resulted in an engine overspeed. Contributing to the accident was maintenance personnel's inadequate inspection of the fuel control unit.

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

Read the full NTSB narrative

The pilot reported that, during the accident flight, which was the twelfth aerial application flight of the day, the engine made an uncommanded power acceleration. The pilot retarded the throttle lever, but the engine did not respond. The pilot subsequently made a forced landing into a field, and the airplane nosed over and then came to rest inverted. A postaccident examination of the airplane revealed no anomalies with the engine rigging. Examination of the fuel control unit revealed that the stub shaft spline was worn beyond the allowable limits. Such wear can allow the fuel control underspeed governor to be driven at a lower speed than the engine speed, which can increase fuel flow and engine speed and is consistent with the uncommanded power acceleration that occurred during the accident flight. A review of the airplane's maintenance records revealed that, 2 months before the accident flight, the fuel control unit was inspected for wear and damage in accordance with an airworthiness directive (AD). It is unlikely that the wear observed during the postaccident examination could have occurred between the time of the AD inspection and the accident. It is likely that the AD was either not accomplished as noted in the maintenance records or that maintenance personnel inadequately conducted the inspection.  

Quoted verbatim from the NTSB record.