# NTSB FTW99LA107: Air Tractor AT-301, N8789S, Garwood, TX, March 31, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 31, 1999, 17:15 local (23:15 UTC) - Place: Garwood, TX - Coordinates: 29.44951, -96.510719 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=29.4495&lon=-96.5107&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 31, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46100 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW99LA107 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46100/pdf - Page: https://openairdocs.org/ntsb/FTW99LA107 ## Probable cause The pilot's inability to maintain directional control of the airplane as result of the failure of the right brake system due to the stripped threads on the eye bolt connecting the brake pedal to the brake master cylinder. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, landing - roll - landing gear,normal brake system - cross/stripped threaded (cause) - landing gear,normal brake system - disconnected (cause) - brakes(normal) - not possible, pilot in command (cause) - Loss of control - on ground/water, landing - roll - directional control - not possible, pilot in command (cause) - On ground/water collision with object, landing - roll - object - pole ## Analysis The commercial pilot lost control of the agricultural airplane during the landing roll following the failure of the right wheel brake system. The pilot initially applied brake pressure to slow down the airplane's landing roll. When the pilot attempted to re-apply brake pressure, the right brake pedal 'fell all the way to the floorboard.' The airplane made a gradual left turn, which the pilot could not compensate for with an inoperative right brake. The left wing impacted a concrete pole located on the west side of the airstrip. The FAA inspector stated that the failure of the right brake was due to the eye bolt, which connects the brake master cylinder to the top portion of the rudder pedal, pulling out to the master cylinder. The operator stated that the only possible way for the eye bolt to become separated from the master cylinder was for the eye bolt to 'pull out' of the threaded hole in the brake master cylinder. The operator reported that the time in service for the failed part was unknown. He added that the bottom 2 or 3 threads of the eye bolt appeared to be damaged or stripped, which 'could have resulted in the eye bolt pulling out' of the cylinder. ## Factual narrative On March 31, 1999, at 1715 central standard time, an Air Tractor AT-301 agricultural airplane, N8789S, was substantially damaged upon collision with a post following a loss of control while landing near Garwood, Texas. The instrument rated commercial pilot, sole occupant of the airplane, was not injured. The airplane was registered to and operated by A.N.F. Air Service Inc., of Garwood, Texas. Visual meteorological conditions prevailed for the Title 14 CFR Part 137 aerial application flight for which a flight plan was not filed. The local flight originated from the operator's private airstrip approximately 30 minutes prior to the accident. The pilot reported that he departed the 2,600 foot airstrip with a load of herbicide to be sprayed on a rice field approximately 2 miles southwest of the airstrip. After dispensing his load, the pilot returned to the airstrip for a landing on runway 35. The operator reported to the FAA inspector, who responded to the accident site, that after a normal landing and roll out, the pilot initially applied brake pressure to slow down the airplane's landing roll. The pilot reported that when he attempted to re-apply brake pressure, the right brake pedal "fell all the way to the floorboard." The pilot added that the airplane made a gradual left turn, which he could not compensate for with an inoperative right brake. The airplane came to a stop after the left wing impacted a concrete pole located on the west side of the airstrip. Examination of the airplane by the FAA inspector revealed structural damage to the left wing spar and the empennage. The inspector stated that the failure of the right brake was due to the eye bolt, which connects the brake master cylinder to the top portion of the rudder pedal, pulling out of the master cylinder. The inspector added that the eye bolt's jam nut was found still attached to the shaft of the rod end. The operator stated that the only possible way for the eye bolt to become separated from the master cylinder was for the eye bolt to pull out of the threaded hole in the brake master cylinder. The operator further stated that the time in service for the brake master cylinder was unknown. He added that the bottom 2 or 3 threads of the eye bolt appeared to be damaged or stripped, which "could have resulted in the eye bolt pulling out" of the master cylinder. The failed part (eye bolt, master cylinder attach) was manufactured by Parker Hannifin (formerly Cleveland) and assigned an Air Tractor part number 40002-1. The brake master cylinder was manufactured by Cleveland as part number 10-23A. The operator reported in the enclosed NTSB Form 6120.1/2 that the last annual inspection on the airplane was completed 23 hours prior to the accident. The failed components were not available for further metallurgical examination. ## Aircraft - Registration: [N8789S](https://openairdocs.org/deregistered/N8789S-2017-02-22), registration cancelled 2017-02-22, S/N 301-0193 (OpenAirDocs) - Reported make and model: Air Tractor AT-301 - Registry model: [Air Tractor AT-301](https://openairdocs.org/model/air-tractor-at-301) (registry code 0390103) (OpenAirDocs) - Category: Airplane - Serial number: 301-0193 - Airframe hours: 7400 - Engines: P&W R-1340-AN1 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Michael L. Thompson - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, March 9, 1999, 23 hours before - Airport: NONE, A.N.F Air Service, runway 35, 2,600 × 90 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 51; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 20,000 total, 4,500 in this make and model, 20,000 as pilot in command, 50 in the last 90 days, 30 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F ## 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 19990331003129A](https://openairdocs.org/incident/19990331003129A), Mar 31, 1999: Airtrc AT301, Garwood, TX, Substantial damage. Pilot lost control of the acft on landing, and the acft struck a concrete post with the left wing, a tree with the right wing, and a ditch with the tail wheel,… 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.