Individually Owned: 150,657
Corporate Owned: 137,281
None Airport
Aircraft Accident/Incident Report
Pocahontas, Arkansas 72455
Tuesady, June 6, 2006 8:00 CDT
NTSB Narrative Summary Released at Completion of Accident
The 18,700-hour pilot was piloting his single-engine experimental airplane at an altitude of 4,500 feet mean sea level (msl) when he started to feel a "slight vibration" or "light buzz" from the engine. The vibrations gradually became more severe until there was a loud bang and the engine seized. The pilot made a forced landing to a hay field. Metallurgical examination of the engine revealed the crankshaft had fractured through the crank cheek, between the #5 and #6 cylinder journals as a result of fatigue cracking. Further examination revealed that the crankshaft was susceptible to early subsurface fatigue failure due to the presence of "honeycomb" structure and microcracking. The mechanical damage was from contact of the connecting rod with the crankshaft thrust faces, and the "honeycomb" structure was most likely a result of overheating during the forging process. The crankshaft had been installed new in the engine in 2001,and two years later was modified with 11:1 compression ratio pistons. As a result of this and other modifications, engine power was increased by 30 percent. Due to the fact that these modifications altered the engine's original certification criteria; the engine was re-classified as an experimental. The serial number of the fractured crankshaft was listed in Lycoming's Mandatory Service Bulletin (SB) 569A, titled Crankshaft Retirement for Certain Lycoming Engines, which recommended the crankshafts be replaced at the first instance the engine crankcase was separated or no later than February 21, 2009. The SB was generated as a result of several subsurface fatigue failures of similar crankshafts used on higher horsepower engines (greater than 300 HP). Those crankshafts were subject to Airworthiness Directive (AD) 2002-04-51, which would have required them to be removed before the date of this accident. Since the engine was classified as experimental, the crankshaft did not have to be removed as a result of this guidance. The AD and SB were issued as a result of a slight change in the specified composition of the crankshaft material, which was a small vanadium addition intended to lower the tempering temperature and reduce warpage; however, this change increased the susceptibility to "honeycomb" and microcracking when slightly over-heated during the forging process. The "honeycomb" and microstructure significantly reduced fatigue properties. The loss of fatigue life was most pronounced in the higher HP applications, and the experimental modifications made to this engine would have made the crankshaft more susceptible to fatigue fracture.
NTSB Probable Cause Narrative
The loss of engine power as a result of a fractured crankshaft due to fatigue. A factor was the engine modifications to increase engine horsepower.
Event Information
| Type of Event | Accident |
| Event Date | 6/6/2006 |
| Event Day of the Week | Tuesday |
| Time of Event | 800 |
| Event Time Zone | Central Daylight Time |
| Event City | Pocahontas |
| Event State | ARKANSAS |
| Event Country | -- |
| Zipcode of the event site | 72455 |
| Event Date Year | 2006 |
| Event Date Month | 6 |
| MidAir Collision Indicator | -- |
| On Ground Collision occurred ? | -- |
| Event Location Latitude | 361426N |
| Event Location Longitude | 0905711W |
| Event Location Airport | None |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | -- |
| 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) | 19 |
| Dew Point at event time (in degress fahrenheit) | 14 |
| Wind Direction (degrees magnetic) | 180 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 10 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30 |
| 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) | 20633 |
| NTSB Notification Source | LIT FSDO |
| NTSB Notification Date | Jun 7 2006 12:00AM |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Nov 29 2006 12:45PM |
| User who most recently changed record | NTSB\johb |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | Little Rock, Arkansas |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N181DM |
| NTSB Number | DFW06LA154 |
| 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 | McClung |
| Aircraft Model | Christian Eagle I |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | M002 |
| Certified Max Gross Weight | 1650 |
| 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 | 1 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Conditional |
| Date of Last Inspection | Mar 1 2006 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | 524.5 |
| ELT Installed | No |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Red Eagle Aviation Incorporated |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Peachtree |
| Aircraft Owner State | GA |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 30269 |
| 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 | JFX |
| Departure City | Jasper |
| Departure State | AL |
| Departure Country | USA |
| Departure Time | 638 |
| Departure Time Zone | CDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | Y76 |
| Destination City | Des Plains |
| Destination State | MO |
| Destination Country | USA |
| Specific Phase of Flight | Cruise - normal |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Sep 6 2006 4:08PM |
| User who most recently changed record | CASH |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | NA |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |