# NTSB WPR10LA003: Mateskon Fisher DAK, N359JM, Bozeman, MT, October 3, 2009 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: October 3, 2009, 09:48 local (15:48 UTC) - Place: Bozeman, MT - Coordinates: 45.714721, -111.188331 - Nearby events: https://openairdocs.org/map.md?lat=45.7147&lon=-111.1883&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report April 19, 2010 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 74843 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR10LA003 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/74843/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=74843 - Page: https://openairdocs.org/ntsb/WPR10LA003 ## Probable cause A loss of engine power due to shearing of the crankshaft gear cluster bolts. Contributing to the accident was the lack of regular overhaul periods as recommended by the engine manufacturer. ## 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 · Fatigue/wear/corrosion (probable cause); cases with it: [Mateskon John FISHER DAKOTA HAWK, 1 case](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=05619F9), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Not serviced/maintained (probable cause); cases with it: [Mateskon John FISHER DAKOTA HAWK, 1 case](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=05619F9), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Mateskon John FISHER DAKOTA HAWK, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=05619F9), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Mateskon John FISHER DAKOTA HAWK, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05619F9), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot was departing on a local flight when the engine lost power; the pilot force-landed the airplane in a field. Post accident examination of the engine showed that the bolts securing the crankshaft gear cluster to the crankshaft were sheared. The crankshaft gear cluster is geared to the camshaft gear and rotates as the engine operates. Examination of the bolts showed that all four bolts had sheared between the crankshaft gear cluster and the attach point to the crankshaft. Two bolt heads, including a portion of the bolts’ lengths, were missing. The other portions of these bolts remained threaded to the crankshaft attach points. The two remaining bolt heads were still safety-wired and in place; however, they had sheared from the crankshaft. The lower threaded portions of all four bolts remained threaded at the crankshaft attach points. No pieces of the missing bolt heads or bolt portions were identified in the accessory case or the oil sump. Examination of the fracture surfaces on the threaded bolt portions showed that the surfaces of the sheared bolts with the missing heads appeared battered. The portions of the bolts still threaded in the crankshaft that belonged to the remaining bolt heads were not battered. The engine had not undergone a complete overhaul of the type that would have exposed the accessory gear section to inspection for over 35 years. According to Teledyne Continental Motors Service Instruction Letter 98-9A, the C-85 engine should be overhauled every 12 years or 1,800 hours. ## Factual narrative HISTORY OF FLIGHT On October 3, 2009, at 0948 mountain daylight time, N359JM, a Mateskon Fisher Dakota Hawk, lost engine power during cruise and the pilot force-landed the airplane in a field approximately 5 miles southwest of Gallatin Field, Bozeman, Montana. During the landing, the right wing clipped a tree. The private pilot, who was also the registered owner of the airplane, operated it under the provisions of 14 Code of Federal Regulations Part 91. The pilot sustained minor injuries and the airplane was substantially damaged. Visual meteorological conditions prevailed and no flight plan was filed for the local area flight. The pilot reported that he had departed Gallatin Field about 10 minutes prior to the power loss. The power loss was sudden. He attempted to restart the engine but was unsuccessful. During his approach to a field, the right wing clipped a tree. AIRPLANE HISTORY The pilot had built the airplane over a period of three years. It had accrued approximately 141.4 hours. The pilot indicated that the engine, a Teledyne Continental Motors C-85-12, had been installed on another airplane in the 1980s. The previous engine owner was going to install it on another airplane but did not do so and the engine had been placed into storage. The pilot then purchased the engine for his airplane. The pilot did note that recently he had the piston rings changed due to a higher than normal oil burn. The pilot did not have any other problems with the engine. Review of the maintenance records for the engine showed that the last engine overhaul was a field overhaul that occurred on December 4, 1973. The engine was removed from another airplane in 1987, at 1085.8 hours since major overhaul, and 4,807.8 hours total time. It was in storage until the pilot/builder of the accident aircraft purchased it. The last top overhaul occurred on June 1, 2006. A typical top overhaul does not involve inspection of the accessory gear section. TESTS AND RESEARCH The engine was examined following the accident. The valve covers were removed and the propeller was rotated. No valve movement was evident. Investigators then removed the magnetos and starter from the accessory case and noted that none of the accessory gears turned when the propeller was rotated. Further examination revealed that the crankshaft gear cluster had separated from the crankshaft. The crankshaft gear cluster is geared to the camshaft gear and rotates as the engine operates. The crankshaft gear cluster is attached to the aft section of the crankshaft by four bolts. Examination of the bolts showed that all four bolts had sheared between the crankshaft gear cluster and the attach point to the crankshaft. Two bolt heads, including a portion of the bolts’ lengths, were missing. The other portions of these bolts remained threaded in the crankshaft attach points. The two remaining bolt heads were still safety wired and in place; however, they had sheared from the crankshaft. The lower threaded portions ofall four bolts remained threaded at the crankshaft attach points. No pieces of the missing bolt heads or bolt portions were identified in the accessory case or the oil sump. Examination of the fracture surfaces on the threaded bolt portions showed that the surfaces of the sheared bolts with the missing heads appeared battered. The portions of the bolts still threaded in the crankshaft that belonged to the remaining bolt heads were not battered. ADDITIONAL INFORMATION According to TCM Service Instruction Letter 98-9A, the C-85 engine should be overhauled every 12 years or 1,800 hours. ## Aircraft - Registration: [N359JM](https://openairdocs.org/deregistered/N359JM-2017-05-31), registration cancelled 2017-05-31, S/N DH38, built 2005 (OpenAirDocs) - Reported make and model: MATESKON FISHER DAK - Registry model: [Mateskon John FISHER DAKOTA HAWK](https://openairdocs.org/model/mateskon-john-fisher-dakota-hawk) (registry code 05619F9) (OpenAirDocs) - Registry engine: [Continental C85 series](https://openairdocs.org/engine/continental-c85-series) (registry code 17008, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: DH38 - Airframe hours: 141 - Engines: CONT MOTOR C85 SERIES 85 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, October 23, 2008, 25 hours before - Departed: BZN, Bozeman, MT - Destination: BZN, Bozeman, MT - Airport: BZN, Gallatin Field ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: minor; private; airplane ratings: single-engine land; medical: sport pilot; last flight review July 15, 2008; seat: left; flight hours: 193 total, 141 in this make and model, 10 in the last 90 days, 3 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 43 °F, dew point 30 °F - Altimeter: 29.90 inHg - Observed at: BZN, 4 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 20091003019989A](https://openairdocs.org/incident/20091003019989A), Oct 3, 2009: Amtr FISHERDAKOTA, Belgrade, MT, Substantial damage. On October 3, 2009, at 0940 MDT, the right-hand wing of an amateur-built fisher dakota hawk, registered as N359JM to [privacy data omitted] of bozeman,… ## Docket (8 files) The files NTSB released with the investigation on February 9, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=74843. 3.4 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 334 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40320799&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Conversation Pilot (item 2, .PDF, 13 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40325145&FileExtension=.PDF&FileName=Record%20of%20Conversation%20Pilot-Master.PDF - Engine Maintenance Records Excerpts (item 3, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40325143&FileExtension=.PDF&FileName=Engine%20Maintenance%20Records%20Excerpts-Redacted.PDF - Tcm sil 98-9A (item 4, .PDF, 132 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40324497&FileExtension=.PDF&FileName=TCM%20SIL%2098-9A-Master.PDF - Photo 1. Accident Site (Provided by FAA) (item 5, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40320817&FileExtension=.PDF&FileName=Photo%201.%20Accident%20Site%20(Provided%20by%20FAA)-Master.PDF - Photo 2. Engine (Provided by TCM) (item 6, .PDF, 102 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40324090&FileExtension=.PDF&FileName=Photo%202.%20Engine%20(Provided%20by%20TCM)-Master.PDF - Photo 3. Gear Cluster with Bolt Heads (Provided by TCM) (item 7, .PDF, 150 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40324092&FileExtension=.PDF&FileName=Photo%203.%20Gear%20Cluster%20with%20Bolt%20Heads%20(Provided%20by%20TCM)-Master.PDF - Photo 4. Bolts at Crankshaft (Provided by TCM) (item 8, .PDF, 150 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40324093&FileExtension=.PDF&FileName=Photo%204.%20Bolts%20at%20Crankshaft%20(Provided%20by%20TCM)-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.