ASN Wikibase Occurrence # 353495
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Friday 11 December 1998 |
| Time: | 18:45 LT |
| Type: |  Bell 47G-2 |
| Owner/operator: | Private |
| Registration: | N9021R |
| MSN: | CCI-165 |
| Total airframe hrs: | 7898 hours |
| Engine model: | Lycoming VO-435-A1B |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Helendale, CA -
 United States of America
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Kramer's Jct, CA |
| Helendale, CA | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Probable Cause: The pilot's failure to follow proper procedures to recover from main rotor blade aerodynamic retreating blade stall.
Accident investigation:
 |
|
Sources:
NTSB LAX99LA047
History of this aircraft
Other occurrences involving this aircraft
| 12 August 1997 | N9021R | National Test Pilot School | 0 | Mojave, CA | |
sub |
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 10-Mar-2024 07:24 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation