ASN Wikibase Occurrence # 357024
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| Date: | Friday 19 July 1996 |
| Time: | 10:34 LT |
| Type: |  Robinson R22B |
| Owner/operator: | Takai Hiroyasu |
| Registration: | N730SH |
| MSN: | 1730 |
| Year of manufacture: | 1991 |
| Total airframe hrs: | 3951 hours |
| Engine model: | Lycoming O-320-B2C |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Morgan Hill, CA -
 United States of America
|
| Phase: | En route |
| Nature: | Training |
| Departure airport: | San Martin, CA (Q99) |
| San Jose, CA (KRHV) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot reported that the helicopter was in cruise flight at 1,000 feet agl when he noticed that both the engine and main rotor were at 110 percent on the dual tachometer. He then entered an autorotation because he believed the engine might quit. The student stated that at touchdown the helicopter had a nose low attitude with some forward speed remaining and the skids dug into the ground, rolling the helicopter over. Through a translator, the pilot reported that the engine/main rotor governor was not working properly. Robinson Helicopter Company reported that the governor unit senses main rotor speed through a sending unit on the engine to transmission shaft. An electronic computer maintains the speed within the normal operating range through a servo motor which actuates the throttle on the collective by means of a clutch assembly. The unit can be turned off by a toggle switch on the collective control, and can be overridden by twisting the throttle. The entire governor assembly, including the speed sensing unit, computer, servo, clutch, and collective/throttle were removed from the helicopter and taken to Robinson Helicopter Company by a Safety Board investigator. All components of the unit were functionally tested and performed within factory new unit acceptance criteria.
Probable Cause: The student's improper reaction to an engine/main rotor overspeed condition, and his failure to achieve the proper zero airspeed nose high attitude during a touchdown from an autorotation.
Accident investigation:
 |
|
Sources:
NTSB LAX96LA277
History of this aircraft
Other occurrences involving this aircraft
| 11 July 1991 | N730SH | Hiro Takai & Fred Farnsworth | 0 | San Jose, CA | |
sub |
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Mar-2024 13:20 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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