Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Laurel, Montana 59044
Friday, July 12, 2002 10:20 MDT
NTSB Narrative Summary Released at Completion of Accident
The pilot of the homebuilt aircraft and installer of the wooden propeller assembly reported that during a performance test/rate of climb test with the new propeller, he smelled a wood burning smell followed by a "real bad vibration." The pilot initiated a forced landing to an open field. During the landing roll on the soft terrain, the landing gear sheared off. After the accident, the pilot noted that one of the blades of the wooden propeller was missing. The remaining blades and two hub plates were sent to the NTSB Materials Laboratory for examination. The metallurgist reported that the fretting observed on the hub plates suggested that the hub mounting bolts were not as tight as required allowing the hub to oscillate on its mounting flange. The motion in the pitch block of both blades produced the heat that charred the wood and softened the pitch block material allowing it to be displaced and imprinted with the pattern of the wood plies. The compression failure and the frictional features on the hub portion in the pitch block indicated a fatigue-like failure in wood which propagated until the remaining wood could not withstand the stresses of operation and subsequently failed in a tensile mode.
NTSB Probable Cause Narrative
Undertorqued mounting bolts which resulted in fatigue to the wooden propeller blade and subsequent in flight separation of one of the blades while in cruise flight. An improper installation of the propeller assembly and soft terrain encountered during the landing roll were factors.
Event Information
| Type of Event | Accident |
| Event Date | 7/12/2002 |
| Event Day of the Week | Friday |
| Time of Event | 1020 |
| Event Time Zone | Mountain Daylight Time |
| Event City | Laurel |
| Event State | MONTANA |
| Event Country | -- |
| Zipcode of the event site | 59044 |
| Event Date Year | 2002 |
| Event Date Month | 7 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 453900N |
| Event Location Longitude | 1085216W |
| Event Location Airport | -- |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | -- |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Unknown |
| Investigator's weather source | Pilot |
| Time of the weather observation | |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | -- |
| Elevation of weather observation facility | -- |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | -- |
| 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) | 28 |
| Dew Point at event time (in degress fahrenheit) | 7 |
| Wind Direction (degrees magnetic) | 270 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 5 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30.07 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 1 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 14487 |
| NTSB Notification Source | FAA Regional Operations Center |
| NTSB Notification Date | Jul 12 2002 12:00AM |
| NTSB Notification Time | 1311 |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Nov 25 2003 11:36AM |
| User who most recently changed record | NTSB\MONR |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | Helena, Montana |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N9104S |
| NTSB Number | SEA02LA130 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | No |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Thurmond |
| Aircraft Model | Moni |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | PJT-00048 |
| Certified Max Gross Weight | 560 |
| Aircraft Category | Glider |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | Yes |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 1 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Jun 2 2002 12:00AM |
| Airframe hours since last inspection | 5 |
| Airframe Hours | 151 |
| ELT Installed | No |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Paul J. Thurmond |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Huntley |
| Aircraft Owner State | MT |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 59037 |
| Operator is an individual? | No |
| Operator Name | -- |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | -- |
| Operator State | -- |
| Operator Country | -- |
| Operator Zip code | -- |
| Operator Code | -- |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | -- |
| 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 | 6S8 |
| Departure City | Laurel |
| Departure State | MT |
| Departure Country | USA |
| Departure Time | 1000 |
| Departure Time Zone | MDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | -- |
| Destination City | -- |
| Destination State | -- |
| Destination Country | -- |
| Specific Phase of Flight | Cruise |
| Report sent to ICAO? | No |
| Evacuation occurred | No |
| Date of most recent change to record | Sep 29 2003 2:25PM |
| User who most recently changed record | STAM |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | -- |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |