# NTSB CEN11LA404: Ayres S2R-T34, N30902, Athleimer, AR, June 16, 2011

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: June 16, 2011, 13:30 local (18:30 UTC)
- Place: Athleimer, AR
- Coordinates: 34.319721, -91.84111 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=34.3197&lon=-91.8411&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Defining event: [Maneuvering: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report September 5, 2013
- Report: Approved by Office Director
- NTSB office: Central Region
- Parties: FAA/FSDO, Pratt&Whitney Canada, NTSB
- NTSB case key (mKey): 80825
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11LA404
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/80825/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=80825
- Page: https://openairdocs.org/ntsb/CEN11LA404

## Probable cause

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.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Engine (turbine/turboprop): turbine section](https://openairdocs.org/ntsb-findings/01057250): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Ayres S2R-T34, 1 case](https://openairdocs.org/ntsb-findings/01057250/cases.md?model=0970106), [All aircraft, 74 cases](https://openairdocs.org/ntsb-findings/01057250/cases.md)
- [Intentional act](https://openairdocs.org/ntsb-findings/02051000): Personnel issues › Miscellaneous · Not specified (probable cause); cases with it: [Ayres S2R-T34, 1 case](https://openairdocs.org/ntsb-findings/02051000/cases.md?model=0970106), [All aircraft, 9 cases](https://openairdocs.org/ntsb-findings/02051000/cases.md)
- [Engine (turbine/turboprop): reduction gear and shaft](https://openairdocs.org/ntsb-findings/01057210): Aircraft › Aircraft power plant · Related maintenance info (probable cause); cases with it: [Ayres S2R-T34, 1 case](https://openairdocs.org/ntsb-findings/01057210/cases.md?model=0970106), [All aircraft, 8 cases](https://openairdocs.org/ntsb-findings/01057210/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Maneuvering: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Ayres S2R-T34, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=0970106), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md)

## Analysis

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.

## Factual narrative

On June 16, 2011, at 1330 central daylight time, N30902, an Ayres Corporation S2R-T34, sustained substantial damage when it made a forced landing to a soybean field after an uncontained engine failure and in-flight fire. The commercial pilot sustained minor injuries. The airplane was registered to and operated by Swan Lake Flying Service, Altheimer, Arkansas. No flight plan was filed for the local flight that departed a private airstrip near Altheimer, about 1320. Visual meteorological conditions prevailed for the agricultural spraying flight conducted under 14 CFR Part 137. According to the pilot, he departed with 2,400 pounds of fertilizer and flew to a 23-acre field approximately one-mile from where he departed. Just as he started his first pass, and without any warning, the engine "exploded" and the propeller "slammed" to a stop. He also saw flames around the cowling and exiting the exhaust stack. The pilot immediately established best glide speed and headed toward a soybean field while dumping the fertilizer. He said that as he was approaching the field, there was a lot of black soot coming from the engine and he could still see flames and pieces of metal exiting the exhaust stack. As he touched down in the field, he wanted to avoid hitting a canal, but the smoke was too thick for him to see. The landing gear struck the canal and was torn off the airplane. It then skidded for approximately 75 feet before coming to a stop, and the pilot was able to exit the airplane before it was consumed by fire. The engine was examined at Pratt & Whitney Canada, St, Hubert, Quebec, Canada on October 31, 2011, under the supervision of a NTSB powerplant engineer. The teardown revealed a failure in the first stage planetary gear-set of the propeller reduction gearbox (RGB). 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 2/3 of the gear teeth height remaining. The review of the documentation of the last repair revealed that, contrary to guidance in Pratt & Whitney Canada overhaul and service bulletin instructions, which state that the 1st stage planetary gears should be replaced with a new set, the gearset was actually replaced with a used set from another engine. The shop which sold the used gearset had misrepresented the gearset as being zero-timed. The hours accumulated on the used gearset were beyond the allowed time between overhaul (TBO) time of the engine in which it was installed.

## Aircraft

- Registration: [N30902](https://openairdocs.org/deregistered/N30902-2017-05-23), registration cancelled 2017-05-23, S/N T41-179, built 1992 (OpenAirDocs)
- Reported make and model: AYRES CORPORATION S2R-T34
- Registry model: [Ayres S2R-T34](https://openairdocs.org/model/ayres-s2r-t34) (registry code 0970106) (OpenAirDocs)
- Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52032, turbo-prop) (OpenAirDocs)
- Category: Airplane
- Serial number: T41-179
- Airframe hours: 5328
- Engines: P&W PT6A SER 750 horsepower turbo prop
- Damage: Substantial damage
- Fire: Both
- Flight: Aerial application, Part 137
- Operator: Swan Lake Flying Services Inc
- Registered owner: Swan Lake Flying Services Inc
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: 100 hour, June 13, 2011
- Departed: None, Athleimer, AR
- Destination: Athleimer, AR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 56; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; last flight review March 15, 2011; seat: single; flight hours: 9,392 total, 5,100 in this make and model, 9,392 as pilot in command, 250 in the last 90 days, 150 in the last 30 days, 8 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 6 knots
- Visibility: 10 statute miles
- Temperature: 90 °F, dew point 72 °F
- Altimeter: 30.00 inHg
- Observed at: PBF, 12 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20110616025109A](https://openairdocs.org/incident/20110616025109A), Jun 16, 2011: Ayres Corporation S2R-T34, Altheimer, AR, Destroyed. On June 16, 2011, at 1330 CST, an Ayres thrush, model S2R-T34, N30902, registered to swan lake flying services inc., suffered an engine stoppage, followed by…

## Docket (3 files)

The files NTSB released with the investigation on July 19, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=80825. 4.4 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 472 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40394172&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF
- Record of Conversation-Pilot (item 2, .PDF, 70 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40394173&FileExtension=.PDF&FileName=Record%20of%20Conversation-Pilot-Master.PDF
- Powerplants 8 - Factual Report of Group Chairman (item 3, .PDF, 3.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40394834&FileExtension=.PDF&FileName=Powerplants%208%20-%20Factual%20Report%20of%20Group%20Chairman-Master.PDF

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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