# NTSB ATL93LA157: Air Tractor AT301, N36613, Deatsville, AL, September 11, 1993

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: September 11, 1993, 09:15 local (14:15 UTC)
- Place: Deatsville, AL
- Coordinates: 32.61993, -86.399482 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=32.6199&lon=-86.3995&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report August 17, 1994
- Report: Approved by Office Director
- NTSB case key (mKey): 3262
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL93LA157
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3262/pdf
- Page: https://openairdocs.org/ntsb/ATL93LA157

## Probable cause

WAS A CRACK IN NO.3 CYLINDER HEAD WHICH RESULTED IN THE LOSS OF ENGINE POWER.

## 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, cruise
  - engine assembly,cylinder - cracked (cause)
- Forced landing, descent - emergency
- On ground/water collision with object, descent - emergency
  - object - tree(s)

## Analysis

WHILE IN CRUISE FLIGHT BETWEEN AERIAL APPLICATION SITES, THE PILOT REPORTED THAT THE ENGINE BACKFIRED THREE TIMES AND THEN LOST POWER. THE PILOT'S ATTEMPTS TO RESTORE FULL POWER WERE UNSUCCESSFUL AND THE PILOT SELECTED AN OPEN FIELD FOR AN EMERGENCY LANDING; DURING LANDING ROLL, THE AIRPLANE STRUCK A TREE. DURING THE AIRCRAFT EXAMINATION, AN ENGINE RUN WAS ACCOMPLISHED USING INSTALLED AIRFRAME COMPONENTS AND SYSTEMS, BUT FULL POWER WAS NOT DEVELOPED. THE SUBSEQUENT EXAMINATION OF THE ENGINE ASSEMBLY REVEALED A CRACK IN THE NUMBER THREE CYLINDER HEAD BETWEEN THE SPARK PLUGS. ACCORDING TO AN ENGINE OVERHAUL FACILITY, THESE TYPE CRACKS ARE COMMON IN THE OLD RADIAL TYPE ENGINES.

## Factual narrative

On September 11, 1993, at 0915 central daylight time, an Airtractor AT301, N36613, collided with a tree while attempting an emergency landing near Deatsville, Alabama. The aerial application flight operated under 14 CFR Part 137 with no flight plan filed. Visual weather conditions prevailed at the time of the collision. The airplane sustained substantial damage and the pilot was not injured. The flight departed Deatsville at 0900 hours.

The pilot dispensed the first load of chemicals and was enroute to the staging area for another load. While at cruise flight, the pilot reported that the engine backfired three times, followed by a loss in engine power. He immediately increased the ower lever, but the engine did not respond. The pilot selected an open field and attempted an emergency landing. During the landing roll the airplane struck a tree.

During the wreckage examination at the accident site, the engine was started on the airplane with all existing systems; however, the engine would not develop full power. A subsequent examination of the engine at an overhaul facility, disclosed a crack in the  number three cylinder head. The crack extended the distance  between the two spark plugs, and according to the overhaul facility, cylinder head cracking is common on the old radial type engines.

## Aircraft

- Registration: [N36613](https://openairdocs.org/deregistered/N36613-2011-09-28), registration cancelled 2011-09-28, S/N 301-0344, built 1981 (OpenAirDocs)
- Reported make and model: Air Tractor AT301
- 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: 301-0344
- Airframe hours: 5100
- Engines: P&W R-1340 600 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: Roberts, Charles
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, April 20, 1993, 410 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 54; commercial; airplane ratings: multi-engine land, single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 12,000 total, 5,500 in this make and model, 300 in the last 90 days, 60 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 80° at 5 knots
- Visibility: 7 statute miles
- Lowest ceiling: none
- Temperature: 75 °F, dew point 52 °F
- Altimeter: 30.00 inHg
- Observed at: MGM, 330 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 19930911037609A](https://openairdocs.org/incident/19930911037609A), Sep 11, 1993: Airtrc AT301, Deatsville, AL, Substantial damage. En route to base ops engine backfired and quit. Struck tree landing. NR3 cylinder cracked. Common in type engine.

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.