# NTSB WPR16LA159: Air Tractor AT 301, N23923, Weiser, ID, August 2, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 2, 2016, 09:35 local (15:35 UTC) - Place: Weiser, ID - Coordinates: 44.220275, -116.907501 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=44.2203&lon=-116.9075&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report September 11, 2018 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 93759 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR16LA159 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93759/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93759 - Page: https://openairdocs.org/ntsb/WPR16LA159 ## Probable cause A partial loss of engine power due to an internal catastrophic failure of the master rod crankpin bearing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Air Tractor AT-301, 6 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=0390103), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Damaged/degraded (probable cause); cases with it: [Air Tractor AT-301, 2 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=0390103), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Object/animal/substance: ground equipment](https://openairdocs.org/ntsb-findings/03022050): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Air Tractor AT-301, 1 case](https://openairdocs.org/ntsb-findings/03022050/cases.md?model=0390103), [All aircraft, 52 cases](https://openairdocs.org/ntsb-findings/03022050/cases.md) - [Object/animal/substance: tree(s)](https://openairdocs.org/ntsb-findings/03022020): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Air Tractor AT-301, 6 cases](https://openairdocs.org/ntsb-findings/03022020/cases.md?model=0390103), [All aircraft, 933 cases](https://openairdocs.org/ntsb-findings/03022020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Air Tractor AT-301, 9 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=0390103), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Landing-landing roll: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Air Tractor AT-301, 19 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=0390103), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Air Tractor AT-301, 25 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0390103), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The airline transport pilot reported that, during an aerial application flight, he observed rising engine cylinder head temperatures and a partial loss of engine power. Unable to maintain altitude, he jettisoned the load of liquid fertilizer and made a forced landing to an alfalfa field. During the landing, the airplane collided with a wheel line sprinkler system. A postaccident examination of the radial engine revealed damage to the No. 1 cylinder lower piston skirt and the oil scraper ring. The inside of the piston exhibited multiple indentations consistent with continued battering. The remaining eight cylinders and pistons were removed and exhibited similar signatures. Multiple metallic fragments that resembled bearing material were found in the crankcase, and the magnetic chip detector displayed metallic debris. The master rod and link rod assembly were 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, consistent with its failure initiating the engine failure. The master rod crankpin bearing was thinned, or gouged out, consistent with the metallic shavings found in the crankcase and oil galley. No maintenance records were provided, and the engine's service and maintenance history could not be determined. ## Factual narrative 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 wereremoved, 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. ## Aircraft - Registration: [N23923](https://openairdocs.org/deregistered/N23923-2018-07-17), registration cancelled 2018-07-17, S/N 301-0466, built 1982 (OpenAirDocs) - Reported make and model: AIR TRACTOR INC AT 301 (NO SERIES) - 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: 301-0466 - Year built: 1982 - Engines: P&W R1340 SERIES 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Airworthiness certificate: Special, Restricted (Special) - Departed: S87, WEISER, ID - Destination: S87, WEISER, ID - Equipment: Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review March 21, 2016; seat: single; restraint: 4-point; flight hours: 9,205 total, 110 in this make and model, 6,420 as pilot in command, 220 in the last 90 days, 95 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 48 °F - Altimeter: 30.00 inHg - Observed at: KONO, 13 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 20160802016729A](https://openairdocs.org/incident/20160802016729A), Aug 2, 2016: Air Tractor Inc AT-301, Weiser, ID, Substantial damage. Pilot reported that after departing Weiser airport (S87) with a load of liquid sulfur, he noted the cylinder head temperature (CHT) was increasing. He… ## Docket (3 files) The files NTSB released with the investigation on April 25, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93759. 4.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 741 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40462512&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 2, .PDF, 71 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40462513&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Master.PDF - Engine Examination Report (item 3, .PDF, 16 photos, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40462514&FileExtension=.PDF&FileName=Engine%20Examination%20Report-Master.PDF 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.