Aircraft Accident/Incident Report

Provo, Utah 84601
Thursday, February 3, 2005 8:00 MST

NTSB Narrative Summary Released at Completion of Accident

According to the pilot, while approximately 4 feet above the ground, he applied power for the landing and felt an "unusual" vibration in both tail rotor pedals and the helicopter's airframe. He stated that he increased the power and brought the helicopter up to a 10-foot hover to reposition approximately 20 feet away. While repositioning, the vibrations and noise became worse. As he attempted the second landing, he heard a "clanking" sound. He immediately lost all tail rotor authority. He decreased the power and executed an autorotation. The helicopter spun to the right approximately 200 degrees as it settled upright into a 1foot deep layer of snow. One of the passengers stated that they were landing on a down slope. As they approached the landing zone, he noticed the nose of the helicopter "elevate slightly" and then he felt something in the rear of the helicopter "hit" the snow. He said that the pilot lifted the helicopter up about 10 to 15 feet as it began to spin and then they touched down facing to the west. He stated that he noticed a mark in the snow where the pilot first attempted to land. The mark was approximately 30 feet away and was about 10 feet in length. He stated that he watched the pilot walk away from the helicopter, in the direction of the mark, and he watched him walk directly through the mark in the snow. A visual examination revealed a 3 inch by 4 inch tear on the aft right side of the fuselage, and that the tail rotor shaft was fractured. No tail rotor blade damage was noted. According to the Boeing representative, the tail rotor drive shaft had a "rotational/torsion fracture" near fuselage station 170.0, and exhibited a degree of "shaft wind-up" normally associated with a "sudden stoppage to the tail rotor system." According to a metallurgist who examined the fractured tail rotor drive shaft, the fractured surfaces exhibited "extensive torsional deformation on both sides of the aft fracture." The indicated direction of torsion, as viewed looking aft, was "as if the forward portion of the shaft rotated clockwise," relative to the aft portion of the shaft. This fracture was largely circumferential and was at a location where the exterior surface of the shaft contained mechanical rubbing and rotational contact damage. Several other areas of rotational damage were noted on the shaft surface between the forward and aft fractures. A detailed examination of the fracture surfaces in the shaft revealed clean fractures on a 45-degree slant plane, "typical of recent overstress fracture under tension or tearing loads." No evidence of preexisting fracture such as fatigue cracking was noted.

NTSB Probable Cause Narrative

the pilot's improper in-flight planning and decision making, his failure to maintain terrain clearance, and the total failure of the tail rotor drive shaft as a result of the tail rotor strike.

Event Information

Type of Event Accident
Event Date 2/3/2005
Event Day of the Week Thursday
Time of Event 800
Event Time Zone Mountain Standard Time
Event City Provo
Event State UTAH
Event Country --
Zipcode of the event site 84601
Event Date Year 2005
Event Date Month 2
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude --
Event Location Longitude --
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 815 Mountain Standard Time
Direction of event from weather observation facility (degrees) 225
Weather Observation Facility ID KPVU
Elevation of weather observation facility 4494
Distance of event from weather observation facility (units?) 9
Time Zone of the weather observation MST
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) -7
Dew Point at event time (in degress fahrenheit) -5
Wind Direction (degrees magnetic) 0
Variable Wind Indicator Wind direction could be determined
Wind Speed (knots) 0
Wind Velocity Indicator --
Wind Gust Indicator Gusting
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 30.47
Density Altitude (feet) --
Intensity of Precipitation --
METAR weather report --
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 3
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 18236
NTSB Notification Source FAA Comm Ctr
NTSB Notification Date Feb 16 2005 12:00AM
NTSB Notification Time 1707
Fiche Number and/or location -used to find docket information DMS
Date of most recent change to record Sep 13 2005 12:54PM
User who most recently changed record NTSB\JOHB
Basic weather conditions Visual Meteorological Cond
FAA District Office Salt Lake City FSDO

Aircraft Involved

Aircraft #1

Aircraft Registration Number N9118F
NTSB Number DEN05LA056
Missing Aircraft Indicator --
Federal Aviation Reg. Part Part 135: Air Taxi & Commuter
Type of Flight Plan filed None
Flight plan Was Activated? No
Damage Substantial
Aircraft Fire --
Aircraft Explosion --
Aircraft Manufacturer's Full Name Hughes
Aircraft Model 369HS
Aircraft Series Identifier --
Aircraft Serial Number 720397S
Certified Max Gross Weight 3200
Aircraft Category Helicopter
Aircraft Registration Class --
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 5
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection 100 Hour
Date of Last Inspection Sep 1 2004 12:00AM
Airframe hours since last inspection 2913.5
Airframe Hours 2970.4
ELT Installed Yes
ELT Activated No
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name W. Enterprises, Inc.
Aircraft Owner Street Address --
Aircraft Owner City Park City
Aircraft Owner State UT
Aircraft Owner Country USA
Aircraft Owner Zipcode 84060
Operator is an individual? No
Operator Name --
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? Yes
Operator Street Address --
Operator City --
Operator State --
Operator Country --
Operator Zip code --
Operator Code W9EA
Owner has at least one certificate None
Other Operator of large aircraft? --
Certified for Part 133 or 137 Operation --
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Non-scheduled
Indicates Domestic or International Flight Domestic
Operator carrying Pax/Cargo/Mail Passenger Only
Type of Flying (Per_Bus / Primary) --
Second Pilot on Board No
Departure Point Same as Event No
Departure Airport Code --
Departure City Park City
Departure State UT
Departure Country USA
Departure Time 730
Departure Time Zone MST
Destination Same as Local Flt crash at destination city
Destination Airport Code --
Destination City Provo
Destination State UT
Destination Country USA
Specific Phase of Flight Landing - flare/touchdown
Report sent to ICAO? No
Evacuation occurred No
Date of most recent change to record Jun 21 2005 11:14AM
User who most recently changed record MCBM
Since inspection or accident Time of Accident
Event Location Runway Number and Location --
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --