ROBINSON R22 near Miami, FL — 2010-03-28

Probable cause

A loss of main rotor rpm for undetermined reasons.

NTSB narrative

The certificated flight instructor (CFI) and his passenger were flying about 2 miles offshore. The helicopter had just completed a turn at about 100 feet above the water when the low main rotor rpm horn sounded. When an adjustment of the throttle failed to remedy the situation, the CFI entered an autorotation. The tail of the helicopter stuck the water during the flare, which resulted in the helicopter entering an uncontrollable spin. The helicopter immediately sank and at the time of this writing, has not been located or recovered. The helicopter’s flight manual showed that at the time of the accident, the flight was being operated within a region of performance in the height-velocity diagram that the manufacturer recommended avoiding. A review of the helicopter’s maintenance records did not reveal any discrepancies with the helicopter prior to the accident flight.

Analysis

Primary failure mode

Mechanical failure

First missed decision gate

Avoiding low rotor RPM conditions during the 180-degree turn.

NTSB coding

• Loss of lift · Maneuvering-low-alt flying

Evidence available

• 9 docket documents

Docket documents9

• Miscellaneous: Federal Aviation Adminstration Carburetor Icing Information and Chart.form
• Other Pertinent Forms and Reports: Excerpts From the Helicopter's Maintenance Records.form
• Other Pertinent Forms and Reports: Flight Crew Statements to the Federal Aviation Administration Inspector.form
• Other Pertinent Forms and Reports: Flight Crew and HelicopterAcademy.com Agreement.form
• Other Pertinent Forms and Reports: Helicopter Accident/Incident Checklist Supplement.form
• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
• Release of Aircraft Wreckage, NTSB Form 6120.15form
• Miscellaneous: Excerpts from the Helicopter's Pilot's Operating Handbook, Safety Notice Section.other
• Weather Reports and Recordsreport

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