# NTSB NYC00LA156: Stewart S-51, N51FY, Forty Fort, PA, June 9, 2000 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: June 9, 2000, 08:50 local (12:50 UTC) - Place: Forty Fort, PA - Coordinates: 41.296943, -75.851112 - Nearby events: https://openairdocs.org/map.md?lat=41.2969&lon=-75.8511&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report November 25, 2003 - Report: Approved by Office Director - Parties: ALLENTOWN - NTSB case key (mKey): 51277 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC00LA156 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/51277/pdf - Page: https://openairdocs.org/ntsb/NYC00LA156 ## Probable cause The owner/builder's inadequate design, resulting in total failure of the reduction gear assembly accessory drive shaft. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, takeoff - initial climb - aircraft/equipment inadequate, owner/builder (cause) - reduction gear assy,accessory drive shaft - failure,total (cause) - Forced landing, descent - emergency - In flight collision with object, emergency landing after takeoff - object - fence ## Analysis During takeoff, approximately 150 above the ground, the propeller reduction gearbox input shaft failed, and the airplane lost all power. The pilot performed a forced landing to a field where the airplane struck a fence. After reviewing the wreckage, the pilot stated that he machined his own shaft for the home built airplane. He stated that he machined the shaft too thin, and after about 150 hours of operation, it failed at its weakest point. The kit manufacturer stated that the production model shafts are larger, and used aviation splines, whereas the accident airplane had a smaller shaft that used automotive splines. ## Factual narrative On June 9, 2000, about 0850 Eastern Daylight Time, a homebuilt S-51, N51FY, was substantially damaged a force landing to a field at Forty Fort, Pennsylvania. The airplane departed from Wilkes-Barre Wyoming Valley Airport (WBW), Wilkes-Barre, Pennsylvania. The certificated commercial pilot sustained minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91. The pilot stated that during the initial climb, about 150 feet above the ground, the engine lost all power. The pilot performed a forced landing to a field. During the landing, the airplane struck a fence and sustained damage to the right wing. Examination of the wreckage by a Federal Aviation Administration inspector revealed that the propeller reduction gear box input shaft had sheared. When asked about the shaft, the pilot stated that it failed "at the weakest point." He added that the failed area was too thin, and needed to be re-machined. He believed that over an approximate 150 hours of operation, stress caused the component to fail. According to the kit manufacturers, the failure was limited to the pilot's airplane. A machine shop had provided the reduction gearbox input shaft for the production models. The pilot decided to machine his own parts for his particular airplane. The pilot obtained some rough castings from the machine shop, but that was the only similarity between the failed shaft and the production shafts. The manufacturer added that the shafts in the production models are larger, and use aviation splines, whereas the pilot used automotive splines. ## Aircraft - Registration: [N51FY](https://openairdocs.org/deregistered/N51FY-2018-01-17), registration cancelled 2018-01-17, S/N 001, built 1985 (OpenAirDocs) - Reported make and model: STEWART S-51 - Registry model: [Yamrick STEWART S-51](https://openairdocs.org/model/yamrick-stewart-s-51) (registry code 05613A8) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 001 - Airframe hours: 150 - Engines: General Motors GM 350 427 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Frank Yamrick - Registered owner: Frank Yamrick - Airworthiness certificate: Special, Experimental (Special) - Departed: WBW, FORTY FORT, PA - Airport: WBW, Wyoming Valley Airport, runway 25, 3,376 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; injuries: minor; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; last flight review March 20, 1999; seat: front; flight hours: 4,004 total, 200 in this make and model, 26 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 57 °F - Altimeter: 30.04 inHg - Observed at: AVP, 6 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 20000609012899A](https://openairdocs.org/incident/20000609012899A), Jun 9, 2000: Amtr STEWARTS51, Wilkes-Barre, PA, Substantial damage. (-23)No narrative (.4)on June 9, 2000, about 0850 eastern daylight time, a homebuilt S-51, N51FY, was substantially damaged a force landing to a field at forty… 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.