Robinson R22B N730SH

Summary

On 19 July 1996 at about 17:34 local time, a Robinson R22B registered N730SH was involved in an accident near Morgan Hill, California, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

19 July 1996 at 17:34

Classification

Accident

Location

Morgan Hill, California, United States

Coordinates

37.1698, -121.6492

Aircraft

Robinson R22B

Registration

N730SH

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

San Martin → San Jose

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX96LA277

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.