Individually Owned: 150,657
Corporate Owned: 137,281
Gallatin Field Airport
Aircraft Accident/Incident Report
Bozeman, Montana 59718
Saturday, October 3, 2009 9:48 MDT
NTSB Narrative Summary Released at Completion of Accident
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.
NTSB Probable Cause Narrative
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.
Event Information
| Type of Event | Accident |
| Event Date | 10/3/2009 |
| Event Day of the Week | Saturday |
| Time of Event | 948 |
| Event Time Zone | Mountain Daylight Time |
| Event City | Bozeman |
| Event State | MONTANA |
| Event Country | -- |
| Zipcode of the event site | 59718 |
| Event Date Year | 2009 |
| Event Date Month | 10 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 454253N |
| Event Location Longitude | 1111118W |
| Event Location Airport | Gallatin Field |
| Event Location Nearest Airport ID | BZN |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 5 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 4473 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 956 Mountain Daylight Time |
| Direction of event from weather observation facility (degrees) | 200 |
| Weather Observation Facility ID | BZN |
| Elevation of weather observation facility | 4473 |
| Distance of event from weather observation facility (units?) | 4 |
| Time Zone of the weather observation | MDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 6 |
| Dew Point at event time (in degress fahrenheit) | -1 |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | -- |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | Calm |
| Wind Gust Indicator | -- |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 29.91 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Minor |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | 1 |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 1 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 26612 |
| NTSB Notification Source | FAA |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Apr 6 2010 11:13AM |
| User who most recently changed record | johb |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N359JM |
| NTSB Number | WPR10LA003 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | MATESKON |
| Aircraft Model | FISHER DAK |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | DH38 |
| Certified Max Gross Weight | 1150 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | Yes |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Conditional |
| Date of Last Inspection | Oct 23 2008 12:00AM |
| Airframe hours since last inspection | 25 |
| Airframe Hours | 141 |
| ELT Installed | Yes |
| ELT Activated | Yes |
| ELT Aided Location of Event Site | No |
| ELT Type | C91 |
| Aircraft Owner Name | John V Mateskon |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Bozeman |
| Aircraft Owner State | MT |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 59718-3691 |
| Operator is an individual? | Yes |
| Operator Name | John V Mateskon |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | Bozeman |
| Operator State | MT |
| Operator Country | USA |
| Operator Zip code | 59718-3691 |
| Operator Code | -- |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Personal |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | BZN |
| Departure City | Bozeman |
| Departure State | MT |
| Departure Country | USA |
| Departure Time | 945 |
| Departure Time Zone | MDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | BZN |
| Destination City | Bozeman |
| Destination State | MT |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Feb 9 2010 6:40PM |
| User who most recently changed record | stam |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |