Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Lohn, Texas 76852
Sunday, January 1, 2012 14:00 CST
NTSB Narrative Summary Released at Completion of Accident
The pilot performed a preflight inspection of the helicopter to include checking the tail rotor oil level through its sight glass. He had flown the helicopter for more than an hour when the tail yawed to the left, slowly at first then rapidly. The pilot “cut” the throttle, flew the helicopter “to the ground as fast as possible,”and impacted terrain. A postaccident examination of the wreckage revealed that the tail rotor gearbox did not operate when it was rotated. A teardown revealed that the interior surfaces of the gearbox were covered with a black oily substance consistent with residual lubricating oil contaminated with liberated metal particles. The oil level sight glass exhibited no discoloration or other hindrance to normal oil level detection in service.
Examination of the ring and pinion gears revealed that the teeth on the pinion gear were deformed and worn almost down to the tooth root in some locations. Wear was observed on the top land and drive faces of the ring gear. Wear patterns were noted on the coast faces of the ring and pinion gear teeth. The observation of wear on the coast faces of the gear teeth is most probably an indication that the spacing between the gears was too tight as a result of improper alignment during installation, causing accelerated wear. A logbook entry showed that the helicopter’s last annual inspection was completed about 6 months before the accident during which the tail rotor gearbox was overhauled and installed.
NTSB Probable Cause Narrative
The improper installation of the tail rotor gearbox by maintenance personnel, which led to accelerated wear of the ring and pinion gears, resulting in the loss of tail rotor effectiveness and subsequent forced landing.
Event Information
| Type of Event | Accident |
| Event Date | 1/1/2012 |
| Event Day of the Week | Sunday |
| Time of Event | 1400 |
| Event Time Zone | Central Standard Time |
| Event City | Lohn |
| Event State | TEXAS |
| Event Country | -- |
| Zipcode of the event site | 76852 |
| Event Date Year | 2012 |
| Event Date Month | 1 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 311930N |
| Event Location Longitude | 0992430W |
| 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 | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1535 Central Standard Time |
| Direction of event from weather observation facility (degrees) | 162 |
| Weather Observation Facility ID | BBD |
| Elevation of weather observation facility | 1827 |
| Distance of event from weather observation facility (units?) | 12 |
| Time Zone of the weather observation | CST |
| 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) | 13 |
| Dew Point at event time (in degress fahrenheit) | -6 |
| Wind Direction (degrees magnetic) | 340 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 12 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30.52 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | KBBD 012135Z AUTO 34012KT 10SM CLR 13/M06 A3052 |
| Event Highest Injury | Serious |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | 2 |
| Injury Total All | 2 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 31603 |
| NTSB Notification Source | -- |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Sep 3 2013 11:51AM |
| User who most recently changed record | coln |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N9021R |
| NTSB Number | CEN12LA120 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | No |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | CONTINENTAL COPTERS INC. |
| Aircraft Model | 47G2 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | CCI-165 |
| Certified Max Gross Weight | 2350 |
| 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 | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Jul 13 2011 12:00AM |
| Airframe hours since last inspection | 68 |
| Airframe Hours | 9057 |
| ELT Installed | No |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | SKY HORSE HELICOPTERS INC |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | BRADY |
| Aircraft Owner State | TX |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 76825-1328 |
| Operator is an individual? | No |
| Operator Name | SKY HORSE HELICOPTERS INC |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | BRADY |
| Operator State | TX |
| Operator Country | USA |
| Operator Zip code | 76825-1328 |
| 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) | Aerial Observation |
| Second Pilot on Board | No |
| Departure Point Same as Event | Yes |
| Departure Airport Code | -- |
| Departure City | Lohn |
| Departure State | TX |
| Departure Country | USA |
| Departure Time | 1300 |
| Departure Time Zone | CST |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | -- |
| Destination City | Lohn |
| Destination State | TX |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jul 1 2013 2:11PM |
| 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 | -- |