Individually Owned: 150,657
Corporate Owned: 137,281
Boulder Municipal Airport
Aircraft Accident/Incident Report
Boulder, Colorado 80301
Tuesady, November 9, 1999 11:00 MST
NTSB Narrative Summary Released at Completion of Accident
The pilot said that as he descended to 6,500 feet mean sea level, the left engine of the twin-engine airplane failed. The pilot landed the airplane without further incident. The engine had 23.5 hours on it since major overhaul. An engine teardown revealed that the #6 connecting rod had failed. Examination of the #6 cylinder parts found preexisting fractures on both the rod cap and the connecting rod. The fatigue features displayed on the rod cap are suggestive of lower stress propagation than those stress propagation marks on the connecting rod. It appeared that the engine failure-initiating event was the failure of the rod cap. Examination of the #6 connecting rod bolts indicated that they fractured as a result of overstress.
NTSB Probable Cause Narrative
The fatigue failure of the #6 cylinder connecting rod cap.
Event Information
| Type of Event | Incident |
| Event Date | 11/9/1999 |
| Event Day of the Week | Tuesday |
| Time of Event | 1100 |
| Event Time Zone | Mountain Standard Time |
| Event City | BOULDER |
| Event State | COLORADO |
| Event Country | -- |
| Zipcode of the event site | 80301 |
| Event Date Year | 1999 |
| Event Date Month | 11 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | BOULDER MUNICIPAL AIRPORT |
| Event Location Nearest Airport ID | 1V5 |
| 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 | 5288 |
| Weather Briefing Completeness | Unknown |
| Investigator's weather source | Pilot |
| Time of the weather observation | 0 |
| Direction of event from weather observation facility (degrees) | 0 |
| Weather Observation Facility ID | |
| Elevation of weather observation facility | 0 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 18 |
| Dew Point at event time (in degress fahrenheit) | -1 |
| Wind Direction (degrees magnetic) | 270 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 5 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 29 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 1 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 5030 |
| NTSB Notification Source | |
| NTSB Notification Date | Apr 11 2000 12:00AM |
| NTSB Notification Time | 1000 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Apr 9 2001 8:54AM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N457DA |
| NTSB Number | DEN00IA075 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Minor |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Beech |
| Aircraft Model | A60 |
| Aircraft Series Identifier | A60 |
| Aircraft Serial Number | P-166 |
| Certified Max Gross Weight | 6500 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 6 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Jun 1 1999 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | 6117 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | BOULDER COUNTY SHERIFFS DEPT |
| Aircraft Owner Street Address | 1777 6TH STREET |
| Aircraft Owner City | BOULDER |
| Aircraft Owner State | CO |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 80302 |
| Operator is an individual? | -- |
| 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? | No |
| Certified for Part 133 or 137 Operation | Unknown |
| 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) | Public Use |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | APA |
| Departure City | ENGLEWOOD |
| Departure State | CO |
| Departure Country | |
| Departure Time | 1040 |
| Departure Time Zone | MST |
| Destination Same as Local Flt | crash at destination city |
| Destination Airport Code | 1V5 |
| Destination City | |
| Destination State | |
| Destination Country | |
| Specific Phase of Flight | Descent |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Apr 9 2001 8:54AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 26 |
| Runway Length | 4100 |
| Runway Width | 75 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |