Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Helendale, California 92342
Friday, December 11, 1998 16:45 PST
NTSB Narrative Summary Released at Completion of Accident
The pilot encountered retreating blade stall while flying at 100 mph. He reported that the helicopter began to shake and it felt like an 'out of balance feeling, like when the washing machine gets unbalanced.' The rotor rpm began to decay. When he reduced power and stabilized the airspeed to about 60 to 65 mph, the shaking stopped. The pilot stated that he was not able to maintain lift, so he entered an autorotation over the hilly terrain. The tail rotor blades impacted an embankment and the main rotor blades severed the tail boom. The pilot's manual for the Bell 47G2 indicates that the 'never-exceed speed' (Vne) for the helicopter is 100 mph. According to the FAA's Basic Helicopter Handbook, the recovery procedure for retreating blade stall is to reduce the collective pitch, increase rotor rpm, reduce forward airspeed, and minimize maneuvering.
NTSB Probable Cause Narrative
The pilot's failure to follow proper procedures to recover from main rotor blade aerodynamic retreating blade stall.
Event Information
| Type of Event | Accident |
| Event Date | 12/11/1998 |
| Event Day of the Week | Friday |
| Time of Event | 1645 |
| Event Time Zone | Pacific Standard Time |
| Event City | HELENDALE |
| Event State | CALIFORNIA |
| Event Country | -- |
| Zipcode of the event site | 92342 |
| Event Date Year | 1998 |
| Event Date Month | 12 |
| 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 | 1653 Pacific Standard Time |
| Direction of event from weather observation facility (degrees) | 260 |
| Weather Observation Facility ID | PMD |
| Elevation of weather observation facility | 2543 |
| Distance of event from weather observation facility (units?) | 39 |
| Time Zone of the weather observation | PST |
| 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) | 11 |
| Dew Point at event time (in degress fahrenheit) | -16 |
| Wind Direction (degrees magnetic) | 10 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 3 |
| 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 | 1 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 1624 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Dec 11 1998 12:00AM |
| NTSB Notification Time | 1815 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Dec 11 2000 11:55AM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N9021R |
| NTSB Number | LAX99LA047 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Bell |
| Aircraft Model | 47G2 |
| Aircraft Series Identifier | 47G2 |
| Aircraft Serial Number | CCI-165 |
| Certified Max Gross Weight | 2450 |
| Aircraft Category | Helicopter |
| 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 | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | 100 Hour |
| Date of Last Inspection | Oct 22 1998 12:00AM |
| Airframe hours since last inspection | 38 |
| Airframe Hours | 7898 |
| ELT Installed | Unknown |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | RAY F. HUNT |
| Aircraft Owner Street Address | P.O. BOX 301 |
| Aircraft Owner City | HELENDALE |
| Aircraft Owner State | CA |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 92342 |
| 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 | |
| Owner has at least one certificate | None |
| 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 | -- |
| 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 | |
| Departure City | KRAMER'S JCT |
| Departure State | CA |
| Departure Country | |
| Departure Time | 1630 |
| Departure Time Zone | PST |
| Destination Same as Local Flt | -- |
| Destination Airport Code | |
| Destination City | HELENDALE |
| Destination State | CA |
| Destination Country | |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:34AM |
| 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 | -- |