Individually Owned: 150,657
Corporate Owned: 137,281
Rocky Mountain Metro Airport
Aircraft Accident/Incident Report
Denver, Colorado 80021
Saturday, June 2, 2012 11:35 MDT
NTSB Narrative Summary Released at Completion of Accident
The pilot reported that, during an introductory flight, he was conducting a 2-foot hover in the helicopter. An airplane started to taxi in front of the helicopter, so the pilot set the helicopter back down on the ground, left skid first and then the right. The helicopter drifted right as the skid made contact, and the pilot added left cyclic input to remedy the drift as he also lowered the collective. As the skids started to settle apart, the pilot noticed a low frequency vibration that immediately got worse. He determined that the helicopter was entering ground resonance, but the engine and collective parameters were too low to lift the helicopter off of the ground, as indicated in the helicopter's operating procedures. The pilot reduced the throttle to idle and "within seconds, the helicopter had shaken itself apart."
Postaccident testing revealed that all four landing gear dampers failed to meet the manufacturer's serviceable testing specifications, and two dampers were overcharged. Maintenance records indicated that the front dampers had been replaced with overhauled units about 10 months and about 534 flight hours before the accident. The aft dampers had been replaced with overhauled units about 7 months and about 280 flight hours before the accident. A review of the manufacturer's overhaul procedure for the landing gear dampers revealed that the procedure used by the overhaul facility did not include functional testing of the dampers following overhaul, which would have identified the out-of-specification condition before installation. Maintenance procedures required periodic inspection of the landing gear dampers, and the operator stated that the 100-hour inspection procedure was accomplished about 1 month before the accident. The mechanic who accomplished this inspection reported that he used the manufacturer's procedures to complete the inspection. However, the out-of-specification damper conditions were not detected.
As a result of this and a similar accident (CEN12LA353), the helicopter manufacturer has committed to revising the overhaul manual to include testing procedures and criteria for overhauled landing gear dampers.
NTSB Probable Cause Narrative
The inadequately overhauled landing gear dampers that allowed initiation of a ground resonance event from which the pilot was unable to recover. Contributing to the accident was the overhaul facility's failure to identify the overcharged dampers and a lack of any published acceptance testing criteria for the dampers in the manufacturer's overhaul procedure manual, resulting in the out-of-specification dampers being provided to the operator. Also contributing was the ineffective damper inspection conducted by the operator's maintenance personnel.
Event Information
| Type of Event | Accident |
| Event Date | 6/2/2012 |
| Event Day of the Week | Saturday |
| Time of Event | 1135 |
| Event Time Zone | Mountain Daylight Time |
| Event City | Denver |
| Event State | COLORADO |
| Event Country | -- |
| Zipcode of the event site | 80021 |
| Event Date Year | 2012 |
| Event Date Month | 6 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 395448N |
| Event Location Longitude | 1050636W |
| Event Location Airport | Rocky Mountain Metro Airport |
| 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 | 0 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 5673 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1050 Mountain Daylight Time |
| Direction of event from weather observation facility (degrees) | 202 |
| Weather Observation Facility ID | KBJC |
| Elevation of weather observation facility | 5670 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | MDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | 7000 |
| Sky/Lowest/Cloud Conditions | Scattered |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 50 |
| Air Temperature at event time (in degrees celsius) | 23 |
| Dew Point at event time (in degress fahrenheit) | 4 |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | Variable |
| Wind Speed (knots) | 4 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | METAR KBJC 021650Z VRB04KT 50SM SCT070 SCT200 23/0 |
| 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 | 2 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 32186 |
| NTSB Notification Source | ANM-FAA-ROC |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Sep 19 2013 6:03PM |
| User who most recently changed record | male |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N2196F |
| NTSB Number | CEN12LA343 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | Company VFR |
| Flight plan Was Activated? | Yes |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | SCHWEIZER |
| Aircraft Model | 269C |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | S1647 |
| Certified Max Gross Weight | -- |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 3 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | 100 Hour |
| Date of Last Inspection | May 17 2012 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | 1720 |
| ELT Installed | No |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | TOP FLIGHT ROTORS LLC |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | THORNTON |
| Aircraft Owner State | CO |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 80233 |
| Operator is an individual? | No |
| Operator Name | TYJ Global |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | -- |
| Operator City | Broomfield |
| Operator State | CO |
| Operator Country | USA |
| Operator Zip code | 80021 |
| 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) | Instructional |
| Second Pilot on Board | No |
| Departure Point Same as Event | Yes |
| Departure Airport Code | BJC |
| Departure City | Denver |
| Departure State | CO |
| Departure Country | USA |
| Departure Time | 1135 |
| Departure Time Zone | MDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | BJC |
| 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 | Jun 12 2012 6:46PM |
| User who most recently changed record | male |
| 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 | -- |