# NTSB MIA99LA203: Air Tractor 301, N2368R, Drew, MS, July 23, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 23, 1999, 15:00 local (20:00 UTC) - Place: Drew, MS - Coordinates: 33.800975, -90.53096 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.8010&lon=-90.5310&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 2, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 46950 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA99LA203 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46950/pdf - Page: https://openairdocs.org/ntsb/MIA99LA203 ## Probable cause a loss of engine power due to the failure of cylinder No. 4 boss, which was caused by fatigue cracking, resulting in a forced landing in marshy terrain and subsequent nose over. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, takeoff - engine assembly,cylinder - fatigue (cause) - engine assembly,cylinder - failure - Forced landing, emergency landing after takeoff - In flight collision with terrain/water, emergency descent/landing ## Analysis The flight was departing from a 3,000 foot runway with a full load of fertilizer. The airplane became airborne, and according to the pilot, the engine lost power. The pilot was not able to maintain altitude, and the airplane impacted the ground about 2,500 feet from the departure end of the runway. The on scene investigation revealed that the No. 4 cylinder exhaust rocker box cover was fractured and missing, and appeared to not have been caused by impact with the ground. The No. 4 cylinder was removed from the engine and sent to the NTSB Materials Laboratory in Washington, D.C., for examination. The laboratory examination revealed that the No. 4 cylinder head had failed from fatigue cracking, probably the result of both mechanical and thermal stresses. It was likely that the fatigue originated first at the corners of the exhaust rocker shaft hole in boss '1', then initiated at localized casting defects in boss '2' as the fatigue in boss '1' grew and the local stresses increased in the remaining structure. ## Factual narrative On July 23, 1999, about 1500 central daylight time, an Air Tractor 301, N2368R, registered to Ward Air Service Inc., was substantially damaged during takeoff at Ruleville-Drew Airport, Drew, Mississippi. The commercial-rated pilot reported no injuries. Visual meteorological conditions (VMC) prevailed in the vicinity, and no flight plan had been filed. The local aerial application flight was being conducted in accordance with Title 14 CFR Part 137. The flight was originating at the time. The flight was departing from a 3,000-foot runway with a full load of fertilizer. The airplane became airborne, and according to the pilot, the engine lost power. The pilot was not able to maintain altitude, and the airplane impacted the ground about 2,500 feet from the departure end of the runway. According to the FAA, the on-scene investigation revealed that the No. 4 cylinder exhaust rocker box cover was "...fractured and missing. This appeared to be not caused by the post accident phase or impact with the ground." The No. 4 cylinder was removed from the engine and sent to the NTSB Materials Laboratory in Washington, D.C., for examination. The NTSB Materials Laboratory factual report revealed that the No. 4 cylinder head had failed from fatigue cracking. It was found that the cylinder head was separated through the rocker arm bosses on the exhaust side. The fracture intersected the rocker shaft hole on the boss that had been labeled "1" for identification purposes, and the push rod tube attachment on both bosses "1" and "2". The rocker arm and the mating half of the fracture were not recovered. The fracture through boss "1" was flat, with evidence of casting porosity on the fracture surface. Cracking arrest positions were faintly recognizable on the surface of the fracture in boss "1". According to the NTSB Materials Laboratory factual report, "...the curvature of these arrest markings and the flow patterns on the surface were consistent with fatigue cracking that originated in the corners between the rocker shaft hole and the surface of the casting." The origin areas revealed "heavy oxidation" which prevented identification of the exact origin locations. The fracture surface of boss "2" was stepped, containing several plateaus in the surface. Large ratchet marks (Steps in the surface formed when two fatigue cracks, growing independently on two different planes, join together and proceed as one crack front) joined these plateaus, and many smaller ratchet marks were noted within several of the levels. Multiple crack arrest locations were noted on the surface. Scanning electron microscopy of the surface revealed striations throughout the region. The ratchet marks and striation geometry were "consistent with fatigue from multiple origins...." Many of the origins seemed to originate from two casting discontinuities. These discontinuities did not contain the smooth, nodular surface of the many shrinkage voids that were noted in the material, but appeared relatively flat with a large amount of oxide on the surface. (See the NTSB Materials Laboratory factual report, an attachment to this report.) The reported temperature in the vicinity about the time of the accident was 96 degrees F, and the winds were from 330 degrees, at 3 knots. The calculated density altitude was 2,559 feet. The field elevation was 137 feet. ## Aircraft - Registration: [N2368R](https://openairdocs.org/deregistered/N2368R-2001-11-02), registration cancelled 2001-11-02, S/N 301-0418, built 1981 (OpenAirDocs) - Reported make and model: Air Tractor 301 - Registry model: [Air Tractor AT-301](https://openairdocs.org/model/air-tractor-at-301) (registry code 0390103) (OpenAirDocs) - Registry engine: [Pratt & Whitney R1340 series](https://openairdocs.org/engine/pratt-whitney-r1340-series) (registry code 52016, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 301-0418 - Airframe hours: 6500 - Engines: P&W R-1340 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Ward Air Service Inc. - Last inspection: Annual, March 8, 1999, 300 hours before - Departed: M37 - Airport: M37, Ruleville, runway 18, 3,000 × 80 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 31; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 4,200 total, 1,000 in this make and model, 4,100 as pilot in command, 300 in the last 90 days, 150 in the last 30 days, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 330° at 3 knots - Visibility: 7 statute miles - Lowest ceiling: 5,000 ft broken - Temperature: 97 °F, dew point 73 °F - Altimeter: 30.00 inHg - Observed at: GLH ## 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 19990723009519A](https://openairdocs.org/incident/19990723009519A), Jul 23, 1999: Airtrc AT301, Drew, MS, Substantial damage. Crashed on takeoff. (.19) on July 23, 1999, about 1500 central daylight time, an air tractor 301, N2368R, registered to ward air service inc., was… 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.