Ayres S2R-T34 N30902

Summary

On 16 June 2011 at about 18:30 local time, a Ayres S2R-T34 registered N30902, operated by Swan Lake Flying Services Inc, was involved in an accident near Athleimer, Arkansas, 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

16 June 2011 at 18:30

Classification

Accident

Location

Athleimer, Arkansas, United States

Coordinates

34.3197, -91.8411

Aircraft

Ayres S2R-T34

Registration

N30902

Category

Airplane

Engines

1

Operator

Swan Lake Flying Services Inc

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Athleimer → Athleimer

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN11LA404

1 person had minor injuries.

Failure of the first stage planetary gearset in the propeller reduction gearbox, which resulted in catastrophic engine failure. Contributing to the failure was the misrepresentation of the gearset being zero-timed by the company that sold the gearset to the operator. Also contributing was the total accumulated hours on the used gearset, which were beyond 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 had just started his first pass spraying fertilizer when the turboprop engine “exploded” and the propeller suddenly stopped. He saw flames around the cowling and soot and pieces of metal were exiting the exhaust stack. The pilot made a forced landing to a field, which resulted in the landing gear being torn from the airplane. The pilot was able to exit before the airplane was completely consumed by fire. A teardown examination of the engine revealed a failure in the first stage planetary gearset of the propeller reduction gearbox. All the gear teeth of the sun gear were ground down as far as the gear tooth roots, and the three meshing planetary gear teeth were battered and mutilated with only about 2/3 of the gear teeth height remaining. Review of the documentation of the last repair revealed that the gearset was a used replacement from another engine, contrary to manufacturer guidance, which states that first stage planetary gears should be replaced with a new gearset. The shop that sold the used gearset had misrepresented it as being zero-timed. The hours accumulated on the used gearset were beyond the manufacturer’s recommended time between overhaul.

Quoted verbatim from the NTSB record.