Individually Owned: 150,657
Corporate Owned: 137,281
Denver International Airport
Aircraft Accident/Incident Report
Denver International Airport, Colorado 80249
Friday, February 17, 2012 8:30 MST
NTSB Narrative Summary Released at Completion of Accident
During a post flight inspection the pilot discovered a hydraulic leak on the nose landing gear that was emanating from a crack in the nose landing gear end cap. The end cap was examined and found to have failed in fatigue that initiated from multiple origins at an internal diameter. The fatigue had propagated significantly into the wall thickness of the end cap and through the thickness at one location. The striation count revealed that the fatigue crack had initiated and been growing in the end cap for at least 15,305 cycles. The end cap had been inspected using an ultrasonic method recommended by the manufacturer 337 cycles prior to the incident. The crack was present at the time of the inspection which indicated that the inspection method was ineffective in detecting the crack. The timing of the end cap inspection was in compliance with the manufacturer’s recommendation. Examination of the microstructure of the material revealed that the longitudinal grain direction was oriented parallel to the shuttle valve bore in the end cap. Resistance to fatigue can be improved by aligning the principle tension stresses in the end cap with the longitudinal grain direction. It is probable that the manufacturer had determined that the grain direction was a contributing factor to fatigue failure in the end cap and revised the end cap drawing to require a grain direction along the longitudinal axis of the end cap in February 2010. No engineering data to support the drawing revision was made available.
NTSB Probable Cause Narrative
A failure of the nose landing gear end cap due to fatigue. Contributing to the failure were the ineffective inspection and the unknown effect of grain direction on fatigue life.
Event Information
| Type of Event | Incident |
| Event Date | 2/17/2012 |
| Event Day of the Week | Friday |
| Time of Event | 830 |
| Event Time Zone | Mountain Standard Time |
| Event City | Denver International Airport |
| Event State | COLORADO |
| Event Country | -- |
| Zipcode of the event site | 80249 |
| Event Date Year | 2012 |
| Event Date Month | 2 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | Denver International Airport |
| Event Location Nearest Airport ID | KDEN |
| 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 | 5434 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Unknown |
| 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 | -- |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | -- |
| Sky Condition for Lowest Ceiling | -- |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | -- |
| Air Temperature at event time (in degrees celsius) | -- |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | -- |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | -- |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | -- |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | -- |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 31706 |
| NTSB Notification Source | Great Lakes Airlines |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Mar 15 2013 10:46AM |
| User who most recently changed record | croc |
| Basic weather conditions | -- |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N210GL |
| NTSB Number | ENG12IA014 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | Yes |
| Damage | Minor |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BEECH |
| Aircraft Model | 1900D |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | UE-210 |
| Certified Max Gross Weight | -- |
| 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 | 19 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | -- |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | -- |
| Airframe Hours | 32365 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | Unknown |
| Aircraft Owner Name | GREAT LAKES AVIATION INC |
| Aircraft Owner Street Address | 1022 AIRPORT PARKWAY |
| Aircraft Owner City | CHEYENNE |
| Aircraft Owner State | WY |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 82001 |
| Operator is an individual? | No |
| Operator Name | Great Lakes Airlines |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | 1022 AIRPORT PARKWAY |
| Operator City | CHEYENNE |
| Operator State | WY |
| Operator Country | USA |
| Operator Zip code | 82001 |
| Operator Code | GLBA |
| Owner has at least one certificate | Yes - certificate holder |
| 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 | Scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | -- |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | KLAR |
| Departure City | Laramie |
| Departure State | WY |
| Departure Country | USA |
| Departure Time | 700 |
| Departure Time Zone | MST |
| Destination Same as Local Flt | -- |
| Destination Airport Code | KDEN |
| Destination City | Denver |
| Destination State | CO |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Mar 15 2013 10:46AM |
| User who most recently changed record | croc |
| 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 | -- |