Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Del Valle, Texas 78617
Monday, June 27, 2011 12:23 CDT
NTSB Narrative Summary Released at Completion of Accident
The helicopter was flying across a river when witnesses heard a loud "pop" or "bang" and saw something fall from the helicopter into the river. They heard the helicopter crash, saw smoke, and ran to the crash site. One main rotor blade was found approximately 780 feet from the wreckage. The other main rotor blade was found approximately 975 feet from the wreckage in the opposite direction. Both blades had separated from the main rotor hub at their coning hinges. All components of the helicopter were accounted for with the exception of portions of both coning bolts. The investigation was unable to locate the object observed falling from the helicopter or determine what it was. Examination of the rotor head components, including the recovered portions of the coning bolts, revealed fracture features consistent with overload failure and mechanical damage indicative of mast bumping (contact between the main rotor blades and the mast). The main rotor blade pitch links and attaching hardware displayed compression buckling and bending overload features consistent with an out-of-control main rotor that had diverged from its normal plane of rotation. The helicopter manufacturer reported that the damage signatures were consistent with both low-G mast bumping and low rotor rpm rotor stall. Low-G mast bumping is a phenomenon specific to two-bladed teetering rotor systems in which the rotor disc becomes unloaded, typically due to a cyclic pushover. Low rotor rpm rotor stall is a different phenomenon in which the main rotor blades experience an aerodynamic stall due to low rotor rpm caused either by the pilot raising the collective too much or by a loss of engine power followed by the pilot lowering the collective too slowly. Rotor blade stall can lead to mast bumping. The pilot’s control inputs leading up to the event are unknown, and, therefore, the reason for the main rotor divergence could not be determined.
NTSB Probable Cause Narrative
The divergence of the main rotor from its normal plane of rotation for reasons that cannot be determined because the pilot’s control inputs leading up to the event are unknown, resulting in mast bumping and main rotor blade separation.
Event Information
| Type of Event | Accident |
| Event Date | 6/27/2011 |
| Event Day of the Week | Monday |
| Time of Event | 1223 |
| Event Time Zone | Central Daylight Time |
| Event City | Del Valle |
| Event State | TEXAS |
| Event Country | -- |
| Zipcode of the event site | 78617 |
| Event Date Year | 2011 |
| Event Date Month | 6 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 343007N |
| Event Location Longitude | 0973338W |
| 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 | 1153 Central Daylight Time |
| Direction of event from weather observation facility (degrees) | 275 |
| Weather Observation Facility ID | AUS |
| Elevation of weather observation facility | 542 |
| Distance of event from weather observation facility (units?) | 7 |
| Time Zone of the weather observation | CDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | 3600 |
| 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) | 10 |
| Air Temperature at event time (in degrees celsius) | 34 |
| Dew Point at event time (in degress fahrenheit) | 22 |
| Wind Direction (degrees magnetic) | 190 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 12 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Gusting |
| Wind Gust (knots) | 19 |
| Altimeter Setting at event time (in. Hg) | 29.93 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | KAUS 271653Z 19012G19KT 10SM SCT036 34/22 A2993 |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | 1 |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 1 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 31388 |
| NTSB Notification Source | ASW ROC |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Aug 6 2013 12:37PM |
| User who most recently changed record | coln |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N7779M |
| NTSB Number | CEN11FA422 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | Ground |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | ROBINSON |
| Aircraft Model | R22 BETA |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 1229 |
| Certified Max Gross Weight | 1370 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | 2 |
| 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 | Dec 30 2010 12:00AM |
| Airframe hours since last inspection | 20 |
| Airframe Hours | 2295 |
| ELT Installed | No |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | Don S. Arsenault |
| Aircraft Owner Street Address | 1107 Cool Lake Cv. |
| Aircraft Owner City | Round Rock |
| Aircraft Owner State | TX |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 78664-5618 |
| Operator is an individual? | No |
| Operator Name | Don S. Arsenault |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | Round Rock |
| Operator State | TX |
| Operator Country | USA |
| Operator Zip code | 78664-5618 |
| 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 | No |
| Departure Airport Code | KT74 |
| Departure City | Taylor |
| Departure State | TX |
| Departure Country | USA |
| Departure Time | 1205 |
| Departure Time Zone | CDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | -- |
| Destination City | Luling |
| Destination State | TX |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Apr 6 2013 1:34AM |
| User who most recently changed record | scoa |
| 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 | -- |