# NTSB FTW02LA161: Ayres S2R-T34, N4025Y, Aubrey, AR, May 24, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 24, 2002, 11:30 local (16:30 UTC) - Place: Aubrey, AR - Coordinates: 34.717224, -90.900001 - Nearby events: https://openairdocs.org/map.md?lat=34.7172&lon=-90.9000&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report May 13, 2003 - Report: Approved by Office Director - Parties: Federal Aviation Administartion (FSDO) - NTSB case key (mKey): 54778 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW02LA161 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/54778/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=54778 - Page: https://openairdocs.org/ntsb/FTW02LA161 ## Probable cause The failure of a compressor turbine blade(s) for an undetermined reason. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, takeoff - initial climb - reason for occurrence undetermined - compressor assembly,blade - separation (cause) - Forced landing, emergency landing after takeoff - On ground/water encounter with terrain/water, emergency landing - terrain condition - open field - Gear collapsed, emergency landing ## Analysis During the initial takeoff climb from a private airstrip, the pilot heard a "loud bang" and the engine lost total power. The pilot executed a forced landing, during which both main landing gear assemblies separated from the airplane and the right wing's spar was damaged. Examination of the engine revealed that the engine compressor turbine blades were fractured at varying heights. Material analysis determined that the blades fractured as a result of overload, and that the blades material conformity was in accordance with the manufacturer's specifications. The compressor's surrounding components, and all downstream components, exhibited damage from the separated compressor turbine blades. The engine had accumulated a total of 14,598 hours since new and had never received a complete overhaul. Pratt & Whitney recommended overhaul interval for this engine is 3,500 hours. The reason for the separation of compressor turbine blades was not determined. ## Factual narrative On May 24, 2002, at 1130 central daylight time, an Ayres S2R-T34 Thrush single-engine agricultural airplane, N4025Y, was substantially damaged during a forced landing following a loss of engine power during the initial takeoff climb from a private grass airstrip near Aubrey, Arkansas. The airplane was registered to and operated by Riddell Flying Service Inc., of West Helena, Arkansas. The commercial pilot, sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The local flight was originating from the Old Gibson Airstrip in Aubrey at the time of the accident. According to the pilot, he had flown approximately 16 spray runs prior to the accident and did not experience any anomalies with the airplane. The airplane departed for the 17th spray run with 200 gallons of fuel and 2,500 pounds of Urea, a fertilizer, on board. The airplane was climbing through 100 feet when he heard a "loud bang," and the engine lost total power. The loss of engine power was accompanied by smoke, which was emanating from the engine exhaust. The pilot noted that the oil pressure and fuel pressure gauge needles had dropped to zero. Subsequently, the pilot executed a forced landing to a field, during which both main landing gear assemblies separated from the airplane, and the right wing's spar was damaged. The airplane was powered by a Pratt & Whitney PT6A-34AG turboprop engine (serial number 56924) that had accumulated a total of 14,598 hours since new. On December 10, 1994, the compressor turbine blades were installed, at which time the engine had accumulated a total of 9,849 hours. On November 7, 2000, a hot section inspection was completed. On May 9, 2002, the engine's most recent inspection, a 100-hour inspection, was completed. A complete engine overhaul had never been performed. According to Pratt & Whitney Service Bulletin No. 1303, the recommended overhaul interval for the engine is 3,500 hours. The engine was examined at the Pratt & Whitney Facility in Montreal, Canada, under supervision of the Transportation Safety Board of Canada. The 1st stage compressor blades, shroud and stator displayed no indications of foreign object damage or other distress. The combustion chamber was intact and the flame pattern was consistent with normal operation. The compressor turbine guide vane ring's trailing edge and the compressor turbine shroud both displayed gouges and pockmarks consistent with contact from separated compressor turbine blade debris. The compressor turbine blades were all fractured at varying heights between 1/4 and 1/2 span. Macroscopic inspection of the blade fracture surfaces revealed signatures typical of overload, with collateral mechanical damage. Material analysis of the compressor blades, conducted by Pratt & Whitney, revealed no indications of fatigue or material creep. The blades material composition was in accordance with the manufacturer's specifications. The power turbine guide vane airfoil leading edges displayed nicks and gouge marks consistent with contact from separated compressor turbine blade debris. Approximately 3/4 of the power turbine blades were fractured at varying heights, and displayed characteristics of contact with separated compressor turbine blades debris and contact with the power turbine shroud. ## Aircraft - Registration: [N4025Y](https://openairdocs.org/aircraft/N4025Y), registered now, S/N T34-049DC, built 1981 (OpenAirDocs) - Reported make and model: Ayres S2R-T34 - Registry model: [Ayres S2R-T34](https://openairdocs.org/model/ayres-s2r-t34) (registry code 0970106) (OpenAirDocs) - Registry engine: [U/A Canada PT6A series](https://openairdocs.org/engine/u-a-canada-pt6a-series) (registry code 61508, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: T34-049DC - Airframe hours: 14779.6 - Engines: Pratt & Whitney Canada PT6A-34AG 750 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Riddell Flying Service Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, May 9, 2002, 52.8 hours before - Departed: NONE, Aubrey, AR - Airport: NONE, Old Gibson, runway 09, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; last flight review February 10, 2001; seat: center; flight hours: 9,745 total, 700 in this make and model, 200 in the last 90 days, 10 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 11,000 ft overcast - Temperature: 79 °F, dew point 63 °F - Altimeter: 30.11 inHg - Observed at: MEM, 47 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 20020524011149A](https://openairdocs.org/incident/20020524011149A), May 24, 2002: Ayres S2RT34RESTD, Aubrey, AR, No damage. (-23) On may 24, 2002, at 11:30 central daylight time, an Ayres S2R-T34 thrush agricultural airplane, N4025Y, was substantially damaged during a forced landing… ## Docket (6 files) The files NTSB released with the investigation on March 25, 2003, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=54778. 6.4 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 569 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40439195&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Report from Party to the Investigation (Pratt & Whitney Canada) (item 2, .PDF, 5.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40439196&FileExtension=.PDF&FileName=Report%20from%20Party%20to%20the%20Investigation%20(Pratt%20%26%20Whitney%20Canada)-Redacted.PDF - Engine Logbook (Excerpt) (item 3, .PDF, 230 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40439197&FileExtension=.PDF&FileName=Engine%20Logbook%20(Excerpt)-Redacted.PDF - Airframe Logbook (Excerpt) (item 4, .PDF, 102 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40439198&FileExtension=.PDF&FileName=Airframe%20Logbook%20(Excerpt)-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 5, .PDF, 77 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40439199&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 6, .PDF, 126 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40439200&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.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. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.