# NTSB FTW99LA226: Air Tractor AT-402, N4523L, Snyder, TX, August 17, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 17, 1999, 08:45 local (13:45 UTC) - Place: Snyder, TX - Coordinates: 32.709636, -100.910614 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=32.7096&lon=-100.9106&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 4, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 47082 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW99LA226 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/47082/pdf - Page: https://openairdocs.org/ntsb/FTW99LA226 ## Probable cause The loss of engine power due to fuel starvation as result of a leak in the engine fuel control. A factor was the lack of suitable terrain for the forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, maneuvering - aerial application - fuel system,fuel control - leak (cause) - fluid,fuel - starvation (cause) - Forced landing, descent - emergency - On ground/water encounter with terrain/water, emergency landing - terrain condition - high vegetation - terrain condition - none suitable (contributing factor) ## Analysis The turbine powered agricultural airplane experienced a loss of engine power during an aerial application flight. The commercial pilot turned the airplane into the wind and lowered the flaps for a forced landing in a hay field. During the landing roll, the airplane collided with a terrace. A detailed examination of the aircraft fuel system revealed that fuel was present in both tanks and in the fuel lines. The FAA inspector stated that the top right bolt securing the fuel control assembly to the engine case was missing, and the remaining three bolts securing the fuel control were found loose. The missing bolt, with a piece of safety wire still attached to it, was found laying at the bottom of the engine cowling. Evidence of a 'severe fuel leak' was found at the base of the fuel control assembly. ## Factual narrative On August 17, 1999, at 0845 central daylight time, an Air Tractor AT-402 agricultural airplane, N4523L, was substantially damaged during a forced landing following a loss of engine power while maneuvering near Snyder, Texas. The non-instrument rated commercial pilot, sole occupant of the airplane, was not injured. The airplane was owned and operated by J.R. Davis Flying Service, of Seminole, 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 departed from the Winston Field Airport, near Snyder, Texas, approximately 2 hours prior to the accident. According to the operator, the aerial application flight was scheduled to spray cotton fields to the east and southeast of Snyder, as part of the federally sponsored boll weevil eradication program. In the narrative portion of the enclosed NTSB Form 6120.1/2, the pilot reported that the airplane was in a turn at approximately 500 feet agl when the engine lost power. The pilot added that he turned the airplane into the wind and lowered the flaps for a forced landing on a hay field. During the landing roll, the airplane impacted the top of a terrace on a heading of 241 degrees and then slid to a stop within 70 feet. Examination of the turbine powered airplane by the FAA inspector, who traveled to the accident site, revealed that the lower forward portion of the airframe, forward of the engine firewall, sustained structural damage. Both main landing gear assemblies "were knocked out." Approximately 25 gallons of Malathion pesticide remained in the hopper. A detailed examination of the aircraft fuel system revealed that fuel was present in both tanks, as well as in the fuel lines. The FAA inspector stated that the top right bolt securing the fuel control housing/assembly to the engine case was missing, and the remaining three bolts securing the fuel control were found loose. The missing bolt, with a piece of safety wire still attached to it, was found laying at the bottom of the engine cowling. The fuel control assembly was not mated to the gasket and evidence of a "severe fuel leak" was found at the base of the fuel control. According to the maintenance records, the Bendix fuel control, part number 2524439-4, serial number 194160, was last overhauled/installed on June 16, 1995. The last annual inspection was performed on April 1, 1999, at 12,493.9 hours, approximately 200 flight hours prior to the accident. No recent engine maintenance was reported by the operator. ## Aircraft - Registration: [N4523L](https://openairdocs.org/aircraft/N4523L), registered now, S/N 402-0757 (OpenAirDocs) - Reported make and model: Air Tractor AT-402 - Registry model: [Air Tractor AT-402](https://openairdocs.org/model/air-tractor-at-402) (registry code 0390205) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52034, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 402-0757 - Airframe hours: 12700 - Engines: P&W PT6A-20 550 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: James R. Davis - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, April 15, 1999, 200 hours before - Departed: SNK, SNYDER, TX ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 2,000 total, 400 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 180° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °F, dew point 57 °F - Altimeter: 30.00 inHg - Observed at: SNK, 8 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 19990817012409A](https://openairdocs.org/incident/19990817012409A), Aug 17, 1999: Airtrc AT402, Snyder, TX, Substantial damage. Acft engine failed during aerial application, the pilot made an emergency landing in a corn field, and the acft sustained substantial damage on landing. (-23)… ## Other investigations on N4523L (1) 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. - [NTSB FTW91DRG04](https://openairdocs.org/ntsb/FTW91DRG04), Jul 21, 1991: Air Tractor AT-402 (N4523L), Taft, TX, minor damage. Probable cause: THE PILOT'S FAILURE TO MAINTAIN PROPER TERRAIN CLEARANCE. 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.