Aircraft Accident/Incident Report

Eagle Nest, New Mexico 87718
Thursday, March 14, 2013 14:45 MDT

NTSB Narrative Summary Released at Completion of Accident

The flight instructor and student pilot were cruising about 800 feet above ground level when they heard a loud “bang,” followed immediately by the low rotor rpm horn, a warning light illumination, and a rapid decrease in rotor rpm indication. In response, the instructor initiated an autorotation by lowering the collective, and the engine immediately lost power. The helicopter touched down and then rocked forward due to soft and downward-sloping terrain. The instructor applied slight aft cyclic to prevent the main rotor blades from contacting the ground; however, the main rotor blades struck and severed the tail boom. The engine was functionally tested, and it operated normally. However, one of the magnets used to provide rotor rpm indications was missing from the rotating transmission yoke and was found affixed to a bolt just aft of the yoke. It likely had become loose in flight, and its movement was the bang heard by the pilots. Scarring was found on one of the sensors opposite the magnet, indicating that the magnet had contacted the sensor. The separation of the magnet caused the rotor rpm indication to drop and the low rotor rpm warning horn and light to activate. Due to the control linkage between the collective and the throttle, when the instructor lowered the collective, the throttle closed rapidly. According to Robinson Helicopters, rapid throttle changes can result in a fuel-air ratio becoming too rich or too lean to sustain engine operation and result in an engine failure.

NTSB Probable Cause Narrative

A total loss of engine power due to a rapid throttle change during autorotation, which the flight instructor initiated in response to a low rotor rpm warning, which resulted from the separation of one of the magnets used to provide rotor rpm indications from the rotating transmission yoke. Contributing to the accident was the flight instructor's aft cyclic input upon landing.

Event Information

Type of Event Accident
Event Date 3/14/2013
Event Day of the Week Thursday
Time of Event 1445
Event Time Zone Mountain Daylight Time
Event City Eagle Nest
Event State NEW MEXICO
Event Country --
Zipcode of the event site 87718
Event Date Year 2013
Event Date Month 3
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude 363326N
Event Location Longitude 1051519W
Event Location Airport --
Event Location Nearest Airport ID --
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness --
Investigator's weather source Weather Observation Facility
Time of the weather observation 1440 Mountain Daylight Time
Direction of event from weather observation facility (degrees) 20
Weather Observation Facility ID AXX
Elevation of weather observation facility 8380
Distance of event from weather observation facility (units?) 13
Time Zone of the weather observation MDT
Lighting Conditions Day
Lowest Ceiling Height --
Lowest Non-Ceiling Height --
Sky/Lowest/Cloud Conditions Clear
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) --
Visibility Runway Visual Value (Statute Miles) --
Visibility (Statute Miles) 10
Air Temperature at event time (in degrees celsius) 13
Dew Point at event time (in degress fahrenheit) -6
Wind Direction (degrees magnetic) 180
Variable Wind Indicator Wind direction could be determined
Wind Speed (knots) 7
Wind Velocity Indicator --
Wind Gust Indicator Not Gusting
Wind Gust (knots) --
Altimeter Setting at event time (in. Hg) 30.41
Density Altitude (feet) --
Intensity of Precipitation --
METAR weather report KAXX 141955Z AUTO 22004KT 10SM CLR 13/M07 A3042
Event Highest Injury None
On Ground, Fatal Injuries --
On Ground, Minor Injuries --
On Ground, Serious Injuries --
Injury Total Fatal --
Injury Total Minor --
Injury Total None 2
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 31269
NTSB Notification Source FAA Operations Center
NTSB Notification Date --
NTSB Notification Time --
Fiche Number and/or location -used to find docket information --
Date of most recent change to record Apr 11 2013 12:48PM
User who most recently changed record scoa
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N392GP
NTSB Number CEN13LA194
Missing Aircraft Indicator --
Federal Aviation Reg. Part Part 91: General Aviation
Type of Flight Plan filed None
Flight plan Was Activated? No
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name ROBINSON HELICOPTER COMPANY
Aircraft Model R44 II
Aircraft Series Identifier --
Aircraft Serial Number 11238
Certified Max Gross Weight 6100
Aircraft Category Helicopter
Aircraft Registration Class --
Aircraft is a homebuilt? No
Flight Crew Seats 2
Cabin Crew Seats --
Passenger Seats 2
Total number of seats on the aircraft 4
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection 100 Hour
Date of Last Inspection Feb 13 2013 12:00AM
Airframe hours since last inspection 63
Airframe Hours 2167
ELT Installed No
ELT Activated Unknown
ELT Aided Location of Event Site Unknown
ELT Type --
Aircraft Owner Name Global Positioning Services, Inc.
Aircraft Owner Street Address --
Aircraft Owner City Anchorage
Aircraft Owner State AK
Aircraft Owner Country USA
Aircraft Owner Zipcode 99503-2673
Operator is an individual? No
Operator Name Leading Edge Aviation, Inc.
Operator Same as Owner? No
Operator Is Doing Business As --
Operator Address Same as Owner? No
Operator Street Address --
Operator City Bend
Operator State OR
Operator Country USA
Operator Zip code 97701
Operator Code --
Owner has at least one certificate None
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation --
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not --
Indicates Domestic or International Flight --
Operator carrying Pax/Cargo/Mail --
Type of Flying (Per_Bus / Primary) Instructional
Second Pilot on Board Yes
Departure Point Same as Event No
Departure Airport Code KDHT
Departure City Dalhart
Departure State TX
Departure Country USA
Departure Time 1315
Departure Time Zone MDT
Destination Same as Local Flt --
Destination Airport Code KMVI
Destination City Monte Vista
Destination State CO
Destination Country USA
Specific Phase of Flight --
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Apr 9 2013 4:10PM
User who most recently changed record scoa
Since inspection or accident Last Inspection
Event Location Runway Number and Location N/A
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --