# NTSB SEA02LA121: Grumman-Schweizer G-164B, N297AL, Shelley, ID, July 4, 2002 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 3, 2002, 20:30 local (Jul 4, 2002, 02:30 UTC) - Place: Shelley, ID - Coordinates: 43.45, -112.166664 - Nearby events: https://openairdocs.org/map.md?lat=43.4500&lon=-112.1667&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report March 30, 2004 - Report: Approved by Office Director - Parties: FAA FSDO - NTSB case key (mKey): 55157 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA02LA121 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/55157/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=55157 - Page: https://openairdocs.org/ntsb/SEA02LA121 ## Probable cause A loss of engine power due to the manufacturer's improperly machined threads, which prevented the cylinder base/head halves from being properly assembled, leading to fatigue propagation and the ultimate separation of the cylinder. A contributing factor was the rough terrain. ## 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, maneuvering - aerial application - engine assembly,cylinder - fatigue (cause) - maintenance,installation - improper, manufacturer (cause) - engine assembly,cylinder - cracked - engine assembly,cylinder - separation - Forced landing, emergency landing - On ground/water encounter with terrain/water, landing - roll - terrain condition - rough/uneven (contributing factor) ## Analysis The pilot had just commenced a spray run when there was an abrupt loss of power accompanied by engine roughness and vibration. Unable to maintain flight, the pilot executed a forced landing into the field being sprayed, landing across the rough, furrowed terrain. Post crash examination revealed that the top of the number five cylinder had separated from the lower half of the cylinder. Further metallurgical examination revealed that the cylinder split circumferentially due to fatigue which originated at the first and second thread roots of the cylinder threads on the inside of the cylinder head. Dimensional examination revealed that the threads between the cylinder base and head had been improperly machined resulting in the cylinder's abutting surfaces not coming into complete contact during assembly of the two components. ## Factual narrative On July 3, 2002, approximately 2030 mountain daylight time, a Grumman G-164B "Agcat," N297AL, registered to and operated by Nef Flying Service, Inc., and being flown by a commercial pilot, was destroyed during a forced landing following a loss of power during a spray run approximately six nautical miles northwest of Shelley, Idaho. The pilot sustained minor injuries. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was a crop dusting flight, was operated under 14 CFR 137, and originated from a private landing site just west of Shelley, approximately 2000 on the evening of the accident. The pilot reported that he had just rolled out of a turn to begin a spray run when there was an abrupt loss of power accompanied by engine roughness and vibration. The pilot, unable to maintain altitude, executed a forced landing into the field he was spraying. The aircraft touched down roughly perpendicular to the furrows and the aircraft tumbled end over end several times shedding both the engine and the empennage before coming to rest inverted (refer to photographs 1 and 2). Post-crash examination revealed the top of the number five cylinder had separated from the lower half of the cylinder and departed the engine (refer to photographs 3 and 4). The cylinder had separated circumferentially about an inch inside the barrel. The pilot reported that the engine had undergone a zero-time overhaul within the previous 120 hours. The number five cylinder and associated piston was sent to the Safety Board's metallurgical laboratory for subsequent examination and testing. The examination revealed that the cylinder had split circumferentially between the fifth and sixth inboard cooling fins and that the fracture surfaces displayed characteristic crack arrest lines (fatigue). Multiple fatigue crack points of origin were noted within the first and second thread roots of the cylinder threads on the inside of the cylinder head, and no mechanical damage was observed within the threads. Dimensional examination revealed that the threads between the cylinder base and head had been improperly machined resulting in the cylinder's abutting surfaces not coming into complete contact during assembly of the two components (refer to attached metallurgical report). ## Aircraft - Registration: [N297AL](https://openairdocs.org/deregistered/N297AL-2003-04-16), registration cancelled 2003-04-16, S/N 188B, built 1977 (OpenAirDocs) - Reported make and model: Grumman-Schweizer G-164B - Registry model: [Grumman Acft ENG Cor-Schweizer G-164B](https://openairdocs.org/model/grumman-acft-eng-cor-schweizer-g-164b) (registry code 3952802) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985 series](https://openairdocs.org/engine/pratt-whitney-r-985-series) (registry code 52008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 188B - Airframe hours: 6500 - Engines: Pratt & Whitney R-1340 600 horsepower reciprocating - Damage: Destroyed - Flight: Aerial application, Part 137 - Registered owner: Nef Flying Service, Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, May 1, 2002, 120 hours before - Departed: Shelley, ID ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: minor; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; last flight review January 20, 2002; seat: front; flight hours: 6,000 total, 2,800 in this make and model, 5,800 as pilot in command, 120 in the last 90 days, 60 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 39 °F - Altimeter: 30.03 inHg - Observed at: IDA, 5 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 20020703015199A](https://openairdocs.org/incident/20020703015199A), Jul 3, 2002: Scwzer G164B, Shelley, ID, Substantial damage. (.19) On July 3, 2002, approximately 2030 mountain daylight time, a Grumman G-164B "agcat," N297AL, registered to nef flying service, inc., and being flown by… ## Docket (6 files) The files NTSB released with the investigation on February 10, 2004, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=55157. 1.5 MB in all. - Materials Laboratory 15 - Factual Report 03-113 (item 1, .PDF, 4 photos, 343 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40202898&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2003-113-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 295 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40460450&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Photo 1. A left side view of N297AL at the accident showing the fuselage and wings absent the engine and empennage. No Negative. (item 3, .PDF, 213 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40205398&FileExtension=.PDF&FileName=Photo%201.%20%20A%20left%20side%20view%20of%20N297AL%20at%20the%20accident%20showing%20the%20fuselage%20and%20wings%20absent%20the%20engine%20and%20empennage.%20%20No%20Negative.-Master.PDF - Photo 2. A right side view of N297AL at the accident showing the fuselage and wings absent the engine. Note the empennage and aft control surfaces (far right). No Negative. (item 4, .PDF, 168 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40205399&FileExtension=.PDF&FileName=Photo%202.%20%20A%20right%20side%20view%20of%20N297AL%20at%20the%20accident%20showing%20the%20fuselage%20and%20wings%20absent%20the%20engine.%20%20Note%20the%20empennage%20and%20aft%20control%20surfaces%20(far%20right).%20%20No%20Negative.-Master.PDF - Photo 3. A close up of the Pratt & Whitney R-1340 engine separated from the airframe. No Negative. (item 5, .PDF, 265 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40205400&FileExtension=.PDF&FileName=Photo%203.%20%20A%20close%20up%20of%20the%20Pratt%20%26%20Whitney%20R-1340%20engine%20separated%20from%20the%20airframe.%20%20No%20Negative.-Master.PDF - Photo 4. A close up view of the separated number five cylinder on the Pratt & Whitney R-1340 engine. No Negative. (item 6, .PDF, 168 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40205401&FileExtension=.PDF&FileName=Photo%204.%20%20A%20close%20up%20view%20of%20the%20separated%20number%20five%20cylinder%20on%20the%20Pratt%20%26%20Whitney%20R-1340%20engine.%20%20No%20Negative.-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.