Aircraft Accident/Incident Report

Chandler, Arizona 85226
Monday, April 1, 2002 9:55 MST

NTSB Narrative Summary Released at Completion of Accident

The helicopter collided with the ground following a loss of tail rotor drive during a steep approach. After performing various maneuvers, the certified flight instructor (CFI) and the student began traffic patterns to a landing zone (LZ). On short final, approximately 40 feet agl, and 40 mph, the helicopter yawed left slowly. When the helicopter had reached a 45-degree left yaw, the CFI took the controls. As the helicopter approached a 90-degree left yaw, the CFI had applied full right pedal. Simultaneously, he lowered the collective and reduced power. The helicopter rotated 360 degrees about 3 times before impact. Post accident inspection revealed incorrect installation of the forward end of the intermediate drive belt on the intermediate pulley group. The tail rotor drive system uses three belts, interconnected via pulleys at various points within the tail boom, to drive the tail rotor. The forward and aft belts and pulleys were normal. The intermediate belt was found shredded, burned, and separated. The aft end of the intermediate belt was positioned correctly on the rear pulley; however, the forward end was around the wrong pulley, the one meant for the forward belt, which induced a large misalignment of the intermediate belt and consequent rub between it and the pulley side. All pulleys were installed with specified tightness and with fore/aft play as stated in the maintenance manual. Maintenance records for the helicopter indicated that the belts were replaced twice in the past 8 months, both times by the manufacturer. The first time was in August 2001, for a heavy maintenance rebuild. The second time was in November 2001 following a tail rotor strike. The belts had about 200 hours operating time since their last replacement in November.

NTSB Probable Cause Narrative

The tail rotor drive system failure as a result of incorrect installation procedures by the manufacturer's personnel.

Event Information

Type of Event Accident
Event Date 4/1/2002
Event Day of the Week Monday
Time of Event 955
Event Time Zone Mountain Standard Time
Event City Chandler
Event State ARIZONA
Event Country --
Zipcode of the event site 85226
Event Date Year 2002
Event Date Month 4
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude 331609N
Event Location Longitude 1114840W
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 Not pertinent
Investigator's weather source Weather Observation Facility
Time of the weather observation 947 Mountain Standard Time
Direction of event from weather observation facility (degrees) 60
Weather Observation Facility ID KCHD
Elevation of weather observation facility 1243
Distance of event from weather observation facility (units?) 8
Time Zone of the weather observation MST
Lighting Conditions Day
Lowest Ceiling Height --
Lowest Non-Ceiling Height 20000
Sky/Lowest/Cloud Conditions Scattered
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) --
Visibility Runway Visual Value (Statute Miles) --
Visibility (Statute Miles) 35
Air Temperature at event time (in degrees celsius) 23
Dew Point at event time (in degress fahrenheit) 1
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) 29.87
Density Altitude (feet) 2531
Intensity of Precipitation --
METAR weather report --
Event Highest Injury Serious
On Ground, Fatal Injuries --
On Ground, Minor Injuries --
On Ground, Serious Injuries --
Injury Total Fatal --
Injury Total Minor 1
Injury Total None --
Injury Total Serious 1
Injury Total All 2
Investigating Agency NTSB
NTSB Docket Number (internal use) 14730
NTSB Notification Source FAA
NTSB Notification Date Apr 1 2002 12:00AM
NTSB Notification Time 910
Fiche Number and/or location -used to find docket information DMS
Date of most recent change to record Feb 5 2004 4:26PM
User who most recently changed record NTSB\MONR
Basic weather conditions Visual Meteorological Cond
FAA District Office WP-FSDO-Scottsdale, AZ

Aircraft Involved

Aircraft #1

Aircraft Registration Number N21901
NTSB Number LAX02LA121
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 Rotorway
Aircraft Model Exec 165F
Aircraft Series Identifier --
Aircraft Serial Number 6035
Certified Max Gross Weight 1500
Aircraft Category Helicopter
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 2
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection Continuous Airworthiness
Date of Last Inspection Mar 18 2002 12:00AM
Airframe hours since last inspection 12
Airframe Hours 1776
ELT Installed Yes
ELT Activated No
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name Cobb International, Inc.
Aircraft Owner Street Address 44140 W. Mercury Way
Aircraft Owner City Chandler
Aircraft Owner State AZ
Aircraft Owner Country USA
Aircraft Owner Zipcode 85266
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 --
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 --
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 Yes
Departure Airport Code P19
Departure City Chandler
Departure State AZ
Departure Country USA
Departure Time 900
Departure Time Zone TL
Destination Same as Local Flt dest & departure same, accident can occur anywhere
Destination Airport Code --
Destination City --
Destination State --
Destination Country --
Specific Phase of Flight Cruise
Report sent to ICAO? No
Evacuation occurred No
Date of most recent change to record Nov 21 2003 4:58PM
User who most recently changed record COOS
Since inspection or accident Last Inspection
Event Location Runway Number and Location --
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --