NTSB Identification: LAX93LA308.
The docket is stored on NTSB microfiche number 51605.
Accident occurred Friday, July 30, 1993 in VERDI, NV
Probable Cause Approval Date: 11/15/1993
Aircraft: ROBINSON R-22, registration: N549SM
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

THE HELICOPTER WAS ONE OF A FLIGHT OF FOUR HELICOPTERS CONDUCTING A MOUNTAIN FLYING COURSE WHICH CONSISTED OF EXECUTING PINNACLE LANDINGS AND TAKEOFFS. THE CFI ALLOWED THE DUAL STUDENT TO FOLLOW ANOTHER HELICOPTER ON ITS DEPARTURE FROM THE PINNACLE. THE HELICOPTER ENCOUNTERED THE PRECEDING HELICOPTER'S ROTOR WASH AND IMMEDIATELY TURNED RIGHT. THE STUDENT APPLIED LEFT PEDAL CORRECTIVE ACTION, BUT THE MAIN ROTOR RPM'S BEGAN TO DECAY. THE CFI ASSUMED THE CONTROLS AND IMMEDIATELY LOWERED THE COLLECTIVE AND APPLIED FULL THROTTLE, BUT THE REAR SKIDS STRUCK THE GROUND. THE CFI WAS ABLE TO REGAIN A LEVEL ATTITUDE, BUT THE HELICOPTER STRUCK SOME ROCKS AND CRASHED.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

THE INSTRUCTOR'S IMPROPER SUPERVISION OF THE FLIGHT; THE DUAL STUDENT'S IMPROPER IN-FLIGHT DECISION TO FOLLOW ANOTHER HELICOPTER ON DEPARTURE AND THE DUAL STUDENTS DELAY IN CORRECTING THE INADVERTENT YAW. FACTORS RELATED TO THIS ACCIDENT WAS THE INADVERTENT ENCOUNTER WITH THE WAKE TURBULENCE FROM THE PRECEDING DEPARTING HELICOPTER; THE DUAL STUDENT'S IMPROPER USE OF THE THROTTLE AND THE DUAL STUDENTS FAILURE TO MAINTAIN ADEQUATE ROTOR RPM.

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