Individually Owned: 150,657
Corporate Owned: 137,281
Jefferson County Airport
Aircraft Accident/Incident Report
Broomfield, Colorado 80021
Sunday, May 1, 1994 12:20 MDT
NTSB Narrative Summary Released at Completion of Accident
SHORTLY AFTER TAKEOFF, THE PILOT REQUESTED CLEARANCE TO RETURN FOR AN IMMEDIATE LANDING. A WITNESS SAID THAT HE HEARD A METALLIC NOISE FROM THE PLANE AS IT PASSED OVERHEAD. HE SAID THE PILOT MADE A STEEP RIGHT BANK TO LAND ON RUNWAY 29L; HOWEVER, THE PLANE IMPACTED BETWEEN THE PARALLEL RUNWAYS. AN EXAM OF THE ENGINE REVEALED 2 FINGER-TIGHT CYLINDER BASE NUTS & UNDERTORQUED BASE NUTS & CRANKCASE THROUGH-NUTS. A TEARDOWN REVEALED THE CRANKSHAFT HAD FAILED FROM FATIGUE BETWEEN THE #3 & #4 CONNECTING ROD JOURNALS. A METALLURGICAL EXAM OF THE CRANKSHAFT REVEALED HIGH LOCALIZED STRESS-INDUCED FATIGUE CRACKS. THE ENGINE HAD ACCUMULATED 266 HRS OF FLIGHT TIME SINCE MAJOR OVERHAUL ON 1/11/91. THE PLANE HAD BEEN MODIFIED WITH 2 STC'S, 1 FOR INSTALLATION OF A RAYJAY TURBOCHARGER, ANOTHER FOR INSTALLATION OF A 'BLACKMAC' PROPELLER. THE HOLDER OF THE PROPELLER STC REPORTED THE COMPANY WOULD NOT HAVE INSTALLED THE PROPELLER ON A TURBOCHARGED ENGINE, SINCE CERTIFICATION VIBRATORY TESTS WERE ONLY MADE ON NORMALLY ASPIRATED ENGINES. AFTER INSTALLATION ON 1/17/91, THE PROPELLER WAS REMOVED ON 3/19/91 FOR STATIC BALANCE & 'RE-INDEX PROP #1 BLADE 180 DEGREES;' ON 3/28/91, IT WAS REMOVED FOR A BLADE ANGLE CHECK; AND ON 5/23/91, IT RECEIVED A DYNAMIC BALANCE.
NTSB Probable Cause Narrative
FATIGUE FAILURE OF THE ENGINE CRANKSHAFT; AND FAILURE OF THE PILOT TO MAINTAIN ADEQUATE AIRSPEED, WHILE MANEUVERING TO LAND, WHICH RESULTED IN A STALL AND COLLISION WITH THE TERRAIN. FACTORS RELATED TO THE ACCIDENT WERE: THE UNDESIRABLE ENGINE/PROPELLER VIBRATION, AND THE LOOSE CRANKCASE AND CYLINDER BASE NUTS.
Event Information
| Type of Event | Accident |
| Event Date | 5/1/1994 |
| Event Day of the Week | Sunday |
| Time of Event | 1220 |
| Event Time Zone | Mountain Daylight Time |
| Event City | BROOMFIELD |
| Event State | COLORADO |
| Event Country | -- |
| Zipcode of the event site | 80021 |
| Event Date Year | 1994 |
| Event Date Month | 5 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | JEFFERSON COUNTY |
| Event Location Nearest Airport ID | BJC |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | 5657 |
| Weather Briefing Completeness | Partial - limited by pilot |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1229 Mountain Daylight Time |
| Direction of event from weather observation facility (degrees) | 0 |
| Weather Observation Facility ID | BJC |
| Elevation of weather observation facility | 5671 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | MDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 20000 |
| Lowest Non-Ceiling Height | 7000 |
| Sky/Lowest/Cloud Conditions | Scattered |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 60 |
| Air Temperature at event time (in degrees celsius) | 14 |
| Dew Point at event time (in degress fahrenheit) | -1 |
| Wind Direction (degrees magnetic) | 190 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 7 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 29 |
| Density Altitude (feet) | 6821 |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | 2 |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 2 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 653 |
| NTSB Notification Source | -- |
| NTSB Notification Date | May 1 1994 12:00AM |
| NTSB Notification Time | 1305 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Dec 6 2000 11:12AM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N1905Y |
| NTSB Number | FTW94FA141 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Destroyed |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | MOONEY |
| Aircraft Model | M20E |
| Aircraft Series Identifier | M20E |
| Aircraft Serial Number | 288 |
| Certified Max Gross Weight | 2575 |
| 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 | 4 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | 100 Hour |
| Date of Last Inspection | Mar 25 1994 12:00AM |
| Airframe hours since last inspection | 11 |
| Airframe Hours | 4412 |
| ELT Installed | Yes |
| ELT Activated | Yes |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | VERBOSH, GEORGE M. |
| Aircraft Owner Street Address | 13462 SHILOH DR., P.O. BOX 689 |
| Aircraft Owner City | CONIFER |
| Aircraft Owner State | CO |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 80433 |
| 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) | Personal |
| Second Pilot on Board | No |
| Departure Point Same as Event | Yes |
| Departure Airport Code | BJC |
| Departure City | |
| Departure State | |
| Departure Country | |
| Departure Time | 1218 |
| Departure Time Zone | MDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | BJC |
| Destination City | |
| Destination State | |
| Destination Country | |
| Specific Phase of Flight | Maneuvering |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:34AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 29L |
| Runway Length | 7000 |
| Runway Width | 75 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |