# NTSB LAX96LA277: Robinson R22B, N730SH, Morgan Hill, CA, July 19, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 19, 1996, 10:34 local (17:34 UTC) - Place: Morgan Hill, CA - Coordinates: 37.169818, -121.649192 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.1698&lon=-121.6492&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 16, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 29512 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX96LA277 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29512/pdf - Page: https://openairdocs.org/ntsb/LAX96LA277 ## 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. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Miscellaneous/other, cruise - remedial action - improper, pilot in command (cause) - throttle/power control - not used, pilot in command (cause) - Forced landing, emergency descent/landing - autorotation - attempted, pilot in command - Roll over, landing - flare/touchdown - rotorcraft flight controls - improper use of, pilot in command (cause) - flare - inadequate, pilot in command (cause) ## Analysis 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. ## Factual narrative On July 19, 1996, at 1034 hours Pacific daylight time, a Robinson R22B helicopter, N730SH, rolled over on landing from an autorotation near Morgan Hill, California. According to the pilot, the autorotation was precipitated by an engine and main rotor overspeed situation on the engine-rotor tach which the pilot could not resolve. The helicopter was operated by Nice Air of San Jose, California, and rented by the student pilot for a local area solo instructional flight. Visual meteorological conditions prevailed and included calm winds. No flight plan was filed for the operation. The helicopter sustained substantial damage. The student pilot, the sole occupant, was not injured. The flight originated from the Reid-Hillview Airport, San Jose, on the morning of the accident and had made an en route stop at the South County Airport, San Martin, California. The pilot reported in his written statement 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. ## Aircraft - Registration: [N730SH](https://openairdocs.org/deregistered/N730SH-2013-07-11), registration cancelled 2013-07-11, S/N 1730, built 1991 (OpenAirDocs) - Reported make and model: Robinson R22B - Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 1730 - Airframe hours: 3951 - Engines: Lycoming O-320-B2C 160 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Takai Hiroyasu - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, July 8, 1996, 50 hours before - Departed: Q99, SAN MARTIN, CA - Destination: RHV, SAN JOSE, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 24; student; medical: class 3, valid medical--w/ waivers/lim; seat: right; flight hours: 55 total, 55 in this make and model, 8 as pilot in command, 55 in the last 90 days, 48 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 68 °F, dew point 50 °F - Altimeter: 30.00 inHg - Observed at: SJC, 22 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19960719041689A](https://openairdocs.org/incident/19960719041689A), Jul 19, 1996: Robsin R22BETA, Morgan Hill, CA, Substantial damage. Beleived overspeed both engine and rotors. Autorotated. Nose low run on landing. Skids dug in. Rolled. No anomalies ## Other investigations on N730SH (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB LAX91LA305](https://openairdocs.org/ntsb/LAX91LA305), Jul 11, 1991: Robinson R-22-B (N730SH), San Jose, CA, substantial damage. Probable cause: THE STUDENT PILOT'S FAILURE TO UNLOCK THE CYCLIC TRIM AND TO MAINTAIN HIS HOVER ALTITUDE. HIS LACK OF EXPERIENCE WITH THE AIRCRAFT, INADEQUATE PREFLIGHT, AND THE UNCONTROLLED DESCENT WERE FACTORS IN… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.