Aircraft Accident/Incident Report

Aspen, Colorado 81611
Thursday, February 11, 1999 18:50 MST

NTSB Narrative Summary Released at Completion of Accident

The airplane experienced an uncontained number 4 engine failure during climb to cruise altitude. Examination of the engine revealed that the number 4 turbine disc had all its blades separated just above the blade platform except 1, which separated just below the blade platform. According to maintenance records, the number 4 turbine disc assembly was installed 22.5 hours or 22 cycles prior to this event. The manufacturer of the turbine disc said that the wheel was new; however, all 60 of the blades had seen previous use. A high-cycle fatigue crack was found in the one blade which had separated below the blade platform. The metallurgist noted that the fatigue crack originated from a fretting damage mark located at the fir-tree portion. The manufacturer reported that 9 blade retention pins, which were used to prevent blade radial movement, did not meet the requirement of no more than 0.005 inch clearance between pen head and wheel. They further reported that blade stress concentration was induced by the wheel broach slots sharp edges.

NTSB Probable Cause Narrative

The inadequate maintenance overhaul of the number four turbine disc by the manufacturer. A factor was the turbine blade's failure due to high cycle fatigue fracture.

Event Information

Type of Event Incident
Event Date 2/11/1999
Event Day of the Week Thursday
Time of Event 1850
Event Time Zone Mountain Standard Time
Event City ASPEN
Event State COLORADO
Event Country --
Zipcode of the event site 81611
Event Date Year 1999
Event Date Month 2
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude
Event Location Longitude
Event Location Airport
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 Not pertinent
Investigator's weather source Weather Observation Facility
Time of the weather observation 1853 Mountain Standard Time
Direction of event from weather observation facility (degrees) 60
Weather Observation Facility ID DEN
Elevation of weather observation facility 5431
Distance of event from weather observation facility (units?) 90
Time Zone of the weather observation MST
Lighting Conditions Dusk
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) -8
Dew Point at event time (in degress fahrenheit) -18
Wind Direction (degrees magnetic) 170
Variable Wind Indicator Unknown
Wind Speed (knots) 8
Wind Velocity Indicator Unknown
Wind Gust Indicator Not Gusting
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 30
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 88
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 5010
NTSB Notification Source --
NTSB Notification Date Feb 12 1999 12:00AM
NTSB Notification Time 346
Fiche Number and/or location -used to find docket information IMAGE
Date of most recent change to record Dec 12 2000 11:20AM
User who most recently changed record dbo
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N608AW
NTSB Number DEN99IA038
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 121: Air Carrier
Type of Flight Plan filed IFR
Flight plan Was Activated? --
Damage Minor
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name British Aerospace
Aircraft Model BAE 146-200A
Aircraft Series Identifier BAE 146-20
Aircraft Serial Number E2049
Certified Max Gross Weight 89500
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 90
Number of Engines 4
Fixed gear or retractable gear Retractable
Aircraft, Type of Last Inspection Continuous Airworthiness
Date of Last Inspection Feb 9 1999 12:00AM
Airframe hours since last inspection 23
Airframe Hours 24544
ELT Installed No
ELT Activated Unknown
ELT Aided Location of Event Site Unknown
ELT Type --
Aircraft Owner Name WILMINGTON TRUST COMPANY
Aircraft Owner Street Address RODNEY SQUARE NORTH
Aircraft Owner City WILMINGTON
Aircraft Owner State DE
Aircraft Owner Country
Aircraft Owner Zipcode 19890
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 A6WA
Owner has at least one certificate Yes - certificate holder
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 Scheduled
Indicates Domestic or International Flight Domestic
Operator carrying Pax/Cargo/Mail Passenger Only
Type of Flying (Per_Bus / Primary) Unknown
Second Pilot on Board Yes
Departure Point Same as Event Yes
Departure Airport Code ASE
Departure City
Departure State
Departure Country
Departure Time 1837
Departure Time Zone MST
Destination Same as Local Flt --
Destination Airport Code DEN
Destination City DENVER
Destination State CO
Destination Country
Specific Phase of Flight Climb
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Jan 2 2001 10:30AM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --