Aspen/Pitkin County Airport
Aircraft Accident/Incident Report

Aspen, Colorado 81611
Wednesday, December 26, 2007 10:00 MST

NTSB Narrative Summary Released at Completion of Accident

During initial climb at 16,000 feet, the pilot noticed oil droplets forming on his windscreen. On seeing the oil, he contacted air traffic control, declared an emergency, and began a standard rate, 180-degree turn, back to the airport. As he completed the turn, he heard a "boom," felt a shutter, and then the windscreen was covered with oil. The pilot said he may have noted a pitch up with the bang, but he immediately got on the best glide speed, 90 knots, and began retracing his ground track via the global positioning system (GPS) back to the airport. The airplane landed uneventfully back to the airport. An examination of the airplane showed minor damage to the front of the cowling, and the engine showed the crankshaft fractured aft of the flange. The propeller and spinner, and the forward part of the crankshaft were missing. Several months after the incident, the separated propeller assembly and crankshaft were located. Examination of the engine revealed the crankshaft was fractured through, aft of the propeller flange. The fracture of the crankshaft was caused by a fatigue crack that stemmed from the aft relief radius of the propeller flange. The surface of the aft radius contained no evidence of mechanical damage and the fatigue crack emanated from multiple origins over a wide area, indicating that a great amount of stress was necessary to initiate the fatigue crack. The reason for the crack initiation could not be determined. The fatigue crack origin area was located in the relief radius in line with the axis of the propeller blades, consistent with forward and aft bending stresses imposed by the blades during flight. The location indicates a possibility that the blades were out of balance while rotating or that the crankshaft was somehow damaged in the past. No evidence of fretting was noted between the faces of the crankshaft propeller flange and the alternator pulley. The propeller assembly was attached firmly to the crankshaft.

NTSB Probable Cause Narrative

The failure of the crankshaft due to fatigue. The fatigue crack initiation was not determined.

Event Information

Type of Event Incident
Event Date 12/26/2007
Event Day of the Week Wednesday
Time of Event 1000
Event Time Zone Mountain Standard Time
Event City Aspen
Event State COLORADO
Event Country --
Zipcode of the event site 81611
Event Date Year 2007
Event Date Month 12
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude 391214N
Event Location Longitude 1065205W
Event Location Airport Aspen/Pitkin County
Event Location Nearest Airport ID ASE
Indicates whether the acc/inc occurred off or on an airport On Airport
Distance from airport in statute miles 0.5
Degrees magnetic from airport --
Airport Elevation 7820
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) --
Dew Point at event time (in degress fahrenheit) --
Wind Direction (degrees magnetic) --
Variable Wind Indicator Wind direction could be determined
Wind Speed (knots) --
Wind Velocity Indicator Light and Variable
Wind Gust Indicator Gusting
Wind Gust (knots) --
Altimeter Setting at event time (in. Hg) --
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 4
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 24430
NTSB Notification Source FAA-Northwest Mountain Region
NTSB Notification Date Dec 26 2007 12:00AM
NTSB Notification Time --
Fiche Number and/or location -used to find docket information --
Date of most recent change to record Oct 7 2008 2:29PM
User who most recently changed record saua
Basic weather conditions Visual Meteorological Cond
FAA District Office Denver, Colorado FSDO

Aircraft Involved

Aircraft #1

Aircraft Registration Number N47BC
NTSB Number DEN08IA044
Missing Aircraft Indicator --
Federal Aviation Reg. Part Part 91: General Aviation
Type of Flight Plan filed IFR
Flight plan Was Activated? Yes
Damage Minor
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name PIPER
Aircraft Model PA-46-310P
Aircraft Series Identifier --
Aircraft Serial Number 4608129
Certified Max Gross Weight 4100
Aircraft Category Airplane
Aircraft Registration Class --
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 6
Number of Engines 1
Fixed gear or retractable gear Retractable
Aircraft, Type of Last Inspection Annual
Date of Last Inspection May 1 2007 12:00AM
Airframe hours since last inspection --
Airframe Hours 3638
ELT Installed Yes
ELT Activated No
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name Bretton International LTD
Aircraft Owner Street Address 3747 S. Cox Rd
Aircraft Owner City Springfield
Aircraft Owner State MO
Aircraft Owner Country USA
Aircraft Owner Zipcode 65807
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 USA
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 --
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 ASE
Departure City Aspen
Departure State CO
Departure Country USA
Departure Time 945
Departure Time Zone MST
Destination Same as Local Flt --
Destination Airport Code DEN
Destination City Denver
Destination State CO
Destination Country USA
Specific Phase of Flight Climb
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Oct 7 2008 1:15PM
User who most recently changed record saua
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 --