Thursday, August 04, 2016

Air Tractor AT-301, N23923: Accident occurred August 02, 2016 in Weiser, Washington County, Idaho

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Boise, Idaho

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Aviation Accident Factual Report - National Transportation Safety Board

Location: Weiser, ID
Accident Number: WPR16LA159
Date & Time: 08/02/2016, 0935 MDT
Registration: N23923
Aircraft: AIR TRACTOR INC AT 301
Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial)
Injuries: 1 None
Flight Conducted Under: Part 137: Agricultural 

On August 2, 2016, about 0935 mountain daylight time, an Air Tractor, AT 301 airplane, N23923, experienced a partial loss of engine power. The pilot subsequently initiated an off airport landing to a field near Weiser, Idaho. The airline transport pilot was not injured. The airplane was substantially damaged during the landing roll when it collided with a sprinkler system. The airplane was operated by Beck's Flying Service under the provisions of Title 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed, and no flight plan had been filed. The local agricultural application flight departed Weiser, Idaho, about 0920.

In a report submitted to the National Transportation Safety Board investigator-in-charge, the pilot reported that after departing on the fifth aerial application load of the morning, and while approaching the target field, the cylinder head temperatures (CHTs) rose to over 400o; the airplane had just enough power at 30 inches of manifold pressure (MP) to maintain altitude and airspeed above stall speed. The pilot stated that after making one pass on the field, he observed that the cylinder head temperatures had risen to 414o. The pilot further stated that to stay above gradually rising terrain, he increased engine power to 32 inches MP and half flaps, at which time he noticed that the CHTs had risen to 454o with a full rich mixture. With wings level and about 40 ft above the ground and descending, the pilot dumped part of the load and set his power to 30 inches MP; CHTs remained around 440o. The pilot opined that the airplane would only continue to fly in a slight descent, which prompted him to dump the remainder of the load. With no improved performance, the pilot abandoned the idea of being able to return to the departure airport. However, he was able to maneuver slightly in order to reach an alfalfa field, [avoiding] pear trees before touching ground with the wings in buffet. During the landing [roll], the airplane collided with a wheel line sprinkler system and a tree bordering the field, which resulted in substantial damage to the airplane.

A postaccident examination of the engine was performed at the facilities of Anderson Aeromotive, Inc., Grangeville, Idaho.

All nine cylinders remained attached to the engine crankcase. A visual examination of the engine revealed that the cylinder head temperature (CHT) and exhaust gas temperature (EGT) probes were connected to the No. 1 cylinder.

The front spark plugs were removed from all cylinders with no anomalies noted. The crankshaft was manually rotated, and internal mechanical continuity was established throughout. The cylinders developed compression when the crankshaft was manually rotated.

The No. 1 cylinder was removed. When the piston was removed, the lower piston skirt and the oil scraper ring were observed damaged. The inside of the piston had multiple indentations consistent with continued battering. The remaining eight cylinders and pistons were removed, with the similar results noted. Multiple metallic fragments that resembled bearing material were found in the crankcase throughout this process.

The chip detector was covered with metallic debris consistent with debris found throughout the internal portion of the engine.

The front case, cam ring assembly, and front crankcase assembly were removed with no anomalies noted. The master rod counterweight revealed multiple battering like indentations consistent with the damage observed to the inside of the pistons. Multiple metallic fragments were found in the oil galley.

The master rod and link rod assembly was removed from the crankshaft, and the front side of the master rod exhibited two perpendicular dents. The master rod crankpin bearing revealed substantial wear and gouging type damage. The master rod crankpin bearing was thinned or gouged out consistent with the metallic shavings found in the crankcase and oil galley. (Refer to the engine examination report, which is appended to the docket for this accident.)

Historical records for the engine were not made available during the investigation.

Pilot Information

Certificate: Airline Transport
Age: 49, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Single
Other Aircraft Rating(s): None
Restraint Used: 4-point
Instrument Rating(s): Airplane
Second Pilot Present: No
Instructor Rating(s): Airplane Multi-engine; Airplane Single-engine
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 07/01/2016
Occupational Pilot: Yes
Last Flight Review or Equivalent: 03/21/2016
Flight Time:  9205 hours (Total, all aircraft), 110 hours (Total, this make and model), 6420 hours (Pilot In Command, all aircraft), 220 hours (Last 90 days, all aircraft), 95 hours (Last 30 days, all aircraft), 3 hours (Last 24 hours, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Manufacturer: AIR TRACTOR INC
Registration: N23923
Model/Series: AT 301 NO SERIES
Aircraft Category: Airplane
Year of Manufacture: 1982
Amateur Built: No
Airworthiness Certificate: Restricted
Serial Number: 301-0466
Landing Gear Type: Tailwheel
Seats: 1
Date/Type of Last Inspection:
Certified Max Gross Wt.: 7400 lbs
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time:
Engine Manufacturer: P&W
ELT: Not installed
Engine Model/Series: R1340 SERIES
Registered Owner: On file
Rated Power: 600 hp
Operator: On file
Operating Certificate(s) Held: Agricultural Aircraft (137) 

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KONO, 2193 ft msl
Observation Time: 1553 UTC
Distance from Accident Site: 13 Nautical Miles
Direction from Accident Site: 201°
Lowest Cloud Condition: Clear
Temperature/Dew Point: 21°C / 9°C
Lowest Ceiling: None
Visibility: 10 Miles
Wind Speed/Gusts, Direction: Calm
Visibility (RVR):
Altimeter Setting: 30 inches Hg
Visibility (RVV):
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: WEISER, ID (S87)
Type of Flight Plan Filed: None
Destination: WEISER, ID (S87)
Type of Clearance: None
Departure Time: 0920 MDT
Type of Airspace: Class G

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude: 44.220278, -116.907500 (est)

NTSB Identification: WPR16LA159
14 CFR Part 137: Agricultural
Accident occurred Tuesday, August 02, 2016 in Weiser, ID
Aircraft: AIR TRACTOR INC AT 301, registration: N23923
Injuries: 1 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On August 2, 2016, about 0930 mountain daylight time (MDT), an Air Tractor, AT 301, N23923, lost partial engine power near Weiser, Idaho. The airplane was operated by Beck's Flying Service under the provisions of 14 Code of Federal Regulations (CFR) Part 137. The airline transport pilot was not injured. The airplane sustained substantial damage during the accident sequence. The local agricultural application flight departed Weiser, Idaho, about 0920. Visual meteorological conditions prevailed and no flight plan had been filed.

The pilot reported that after departing with a load of liquid sulfur he noted the cylinder head temperature was increasing but he attributed it to having a heavy load. He attempted to lighten the load by applying the sulfur to the field but noted that the cylinder temperature was continuing to increase, and engine power was decreasing. The pilot was able to jettison the remaining sulfur load and make a forced landing in to a field. During the landing the left wing impacted vegetation which caused the airplane to rotate, followed by the left main landing gear separating from the fuselage.

Post-accident examination revealed damage to the engine mounts and to the attach point for the left main landing gear.

The airplane was recovered for further examination.

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