# NTSB ATL00LA046: Air Tractor AT-401-B, N6096P, Lawrenceburg, TN, April 22, 2000 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 22, 2000, 15:00 local (20:00 UTC) - Place: Lawrenceburg, TN - Coordinates: 35.23949, -87.330558 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.2395&lon=-87.3306&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 2, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 49030 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL00LA046 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/49030/pdf - Page: https://openairdocs.org/ntsb/ATL00LA046 ## Probable cause The loss of engine power due to a stuck exhaust valve that resulted in the collision with a tree while maneuvering 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(partial) - mech failure/malf, maneuvering - aerial application - engine assembly,rocker arm/tappet - jammed (cause) - Forced landing, descent - emergency - In flight collision with object, descent - emergency - object - tree(s) ## Analysis The pilot stated that, while on an aerial application run, he heard a loud pop and observed black smoke coming from the engine exhaust. The pilot selected an area for a forced landing. While maneuvering for the landing, the airplane collided with trees. Examination of the engine disclosed that, the number 3 cylinder's exhaust valve was stuck in the open position ## Factual narrative On April 22, 2000, at 1500 central daylight time, an Air Tractor AT-401-B, N6096P, collided with trees while maneuvering for a forced landing near Lawrenceburg, Tennessee. The aerial application flight was operated by Thornton Aerial Application under the provisions of 14 CFR Part 137, with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The airplane sustained substantial damage, and the commercial pilot was not injured. The flight departed Lawrenceburg, Tennessee, at 1450. The pilot stated that he had made an application run and was pulling up when he heard a loud pop and observed black smoke coming from the engine exhaust system. The pilot selected an area for a forced landing, and while maneuvering for the landing, the airplane collided with trees. According to the pilot, "due to the low altitude of this type of operation a suitable landing spot could not be chosen." During a subsequent examination of airframe systems, the carburetor model NAY91E1 S/N 5962942 was installed on another engine and tested for proper operation. The engine was operated at 700, 1200, 1400, 1600, and 2000 rpm for five minutes at each point. The engine was leaned with the mixture control and a normal magneto check was performed. The propeller lever was also cycled to various rpm. All operations of the carburetor were normal. Examination of the engine off of the airplane, S/N ZP10053, revealed that the number 3 cylinder's exhaust valve was stuck in the open position. Weather conditions reported in the area at the time of the accident were favorable for the formation of carburetor ice as indicated by the icing probability curves chart. ## Aircraft - Registration: [N6096P](https://openairdocs.org/deregistered/N6096P-2018-01-25), registration cancelled 2018-01-25, S/N 401B-0999 (OpenAirDocs) - Reported make and model: Air Tractor AT-401-B - Registry model: [Air Tractor AT-401B](https://openairdocs.org/model/air-tractor-at-401b) (registry code 0390207) (OpenAirDocs) - Category: Airplane - Serial number: 0999 - Engines: P&W R-1340 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Thornton Aerial Application - Airworthiness certificate: Special, Restricted (Special) - Flight plan: Unknown - Airport: 2M2, Lawrence County Airport, runway 35, 4,800 × 100 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 30; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 4,120 total, 1,315 in this make and model, 3,984 as pilot in command, 38 in the last 90 days, 21 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 310° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: 25,000 ft broken - Temperature: 66 °F, dew point 39 °F - Altimeter: 29.00 inHg - Observed at: BNA, 75 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 20000422012689A](https://openairdocs.org/incident/20000422012689A), Apr 22, 2000: Airtrc AT401B, Lawrenceburg, TN, Substantial damage. (-23) Aircraft lost power during aerial application near lewisburg, TN airport. Pilot stated that he had just made an application run and was pulling up when… 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.