# NTSB CEN17LA372: Piper PA 25-235, N7336Z, Westphalia, KS, September 28, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 28, 2017, 17:16 local (22:16 UTC) - Place: Westphalia, KS - Coordinates: 38.185001, -95.483612 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.1850&lon=-95.4836&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report May 29, 2019 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 96129 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN17LA372 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/96129/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=96129 - Page: https://openairdocs.org/ntsb/CEN17LA372 ## Probable cause A total loss of engine power due to a fatigue failure of the crankshaft that resulted from main bearing shift and lack of lubrication. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip engine power section](https://openairdocs.org/ntsb-findings/01058520): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Piper PA-25-235, 1 case](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=7102504), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [Engine (reciprocating): recip engine power section](https://openairdocs.org/ntsb-findings/01058520): Aircraft › Aircraft power plant · Fatigue/wear/corrosion (probable cause); cases with it: [Piper PA-25-235, 1 case](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=7102504), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/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 (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Piper PA-25-235, 10 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=7102504), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Piper PA-25-235, 28 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7102504), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The commercial pilot reported that he departed in the airplane with full fuel and chemical for the aerial application flight. After spraying a field for about 20 minutes, the engine experienced a total loss of power. The pilot jettisoned the chemical load and initiated a forced landing to a field. About 5 ft above the field, as the pilot tried to bleed off airspeed, the airplane stalled and impacted terrain. Disassembly and examination of the engine revealed that the crankshaft was fractured, and the main bearings displayed thermal damage and smearing. Material examination of the crankshaft showed features consistent with a subsurface crack initiation and fatigue crack propagation. The fatigue striations, particularly near the initiation site, were consistent with high-cycle fatigue. The forward main bearings exhibited spalling, displacement, and cracking consistent with bearing wear fatigue. All the bearing damage was typical of similar bearings that had been operated at elevated temperatures using inadequate lubrication. The main bearing damage was likely the result of main bearing shift and a blockage of the lubrication paths. The blockage resulted in a lack of lubrication, main bearing failure, and a fatigue failure of the crankshaft. The reason for the main bearing shift could not be determined based on the available information. ## Factual narrative On September 28, 2017, at 1716 central daylight time, a Piper PA-25-235 airplane, N7336Z, impacted terrain following a loss of engine power while maneuvering at low altitude near Westphalia, Kansas. The commercial pilot, who was the sole occupant, was not injured, and the airplane sustained substantial damage. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed, and no flight plan had been filed for the flight. The local flight departed the Garnett Municipal Airport (K68), Garnett, Kansas, about 1630. According to the pilot, the airplane departed K68 with full fuel and chemical for the aerial application flight. After spraying a field for about 20 minutes, the engine lost power. The pilot jettisoned his chemical load and initiated a forced landing to a field. About 5 feet above the field as the pilot tried to bleed off airspeed, the airplane stalled and impacted terrain. The airplane sustained substantial damage to the left wing. The Lycoming O-540-B2B5 engine was removed from the airframe for further examination. A review of the maintenance records showed the engine underwent a field major overhaul on January 28, 2016, about 218 hours prior to the accident. On October 25, 2017, the engine was disassembled under the supervision of the Federal Aviation Administration inspectors. Disassembly of the engine revealed the crankshaft was fractured, and the main bearings displayed thermal damage and smearing. The crankshaft and main bearings were retained for further examination. The fractured crankshaft and forward main journal bearings were examined by the National Transportation Safety Board Materials Laboratory. Examination of the crankshaft showed a fracture across a web located between the second cylinder (C2) journal and the second main (M2) journal. Approximately 60% of the fracture surface exhibited a general flat portion with crack arrest marks. The crack arrest marks appeared to emanate out from near the corner of the web near the M2 journal. The crack arrest features were not consistent with having progressed from a surface or from an internal feature, but were consistent with a subsurface crack initiation, and fatigue crack propagation. The fatigue striations, particularly near the initiation site, were consistent with high-cycle fatigue. The forward main bearing (M1) journal displayed discoloration and dark circumferential wear marks on the aft most two inches. One aft bearing surface revealed spalling, displacement, and cracking consistent with bearing wear fatigue. The other aft bearing surface exhibited spalling, material displacement, and smearing. Much of the spalled and smeared material was found accumulated in the lubrication groove. All the bearing damage was typical of similar bearings that operated at elevated temperatures with inadequate lubrication. ## Aircraft - Registration: [N7336Z](https://openairdocs.org/aircraft/N7336Z), registered now, S/N 25-3285, built 1965 (OpenAirDocs) - Reported make and model: PIPER PA 25-235 (UNDESIGNAT) - Registry model: [Piper PA-25-235](https://openairdocs.org/model/piper-pa-25-235) (registry code 7102504) (OpenAirDocs) - Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 25-3285 - Year built: 1965 - Engines: LYCOMING O-540-B2B5 260 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, January 1, 2017, 110 hours before - Departed: K68, Garnett, KS - Destination: K68, Garnett, KS - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 43; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review January 5, 2017; seat: center; restraint: 4-point; flight hours: 463 total, 233 in this make and model, 408 as pilot in command, 96 in the last 90 days, 32 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 54 °F - Altimeter: 30.20 inHg - Observed at: KIXD, 36 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 20170928014209A](https://openairdocs.org/incident/20170928014209A), Sep 28, 2017: Piper PA-25-235, Westphalia, KS, Substantial damage. On 09/28/2017 Piper PA-25-235, N7336Z while conducting agricultural 14 CFR part 137 operations (certificate no. 9VSG528O) experienced a loss of power and… ## Other investigations on N7336Z (2) 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. - [NTSB DEN85LA159](https://openairdocs.org/ntsb/DEN85LA159), Jun 8, 1985: Piper PA-25-235-B (N7336Z), Lovington, NM, substantial damage - [NTSB DEN71DQA02](https://openairdocs.org/ntsb/DEN71DQA02), Jul 23, 1970: Piper PA-25 (N7336Z), Raton, NM, substantial damage ## Docket (4 files) The files NTSB released with the investigation on June 19, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=96129. 7.0 MB in all. - Materials Laboratory Factual Report (item 1, .PDF, 6.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464229&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 635 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464230&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - FAA Inspector Statement (item 3, .PDF, 87 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464231&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement-Master.PDF - Excerpts of Maintenance Records (item 4, .PDF, 142 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464232&FileExtension=.PDF&FileName=Excerpts%20of%20Maintenance%20Records-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.