Aircraft Accident/Incident Report

Springtown, Texas 76082
Friday, February 26, 1999 9:10 CST

NTSB Narrative Summary Released at Completion of Accident

While at cruise altitude, the helicopter's engine began to surge. The pilot initiated an autorotation to an open field. During the downwind forced landing, the skids dug into the ground, and the helicopter nosed over and came to rest on its left side. An examination of the engine revealed that the P3 air pipe, which supplies air to the fuel control, was broken close to the fitting on the combustion chamber casing. Examination of the P3 pipe revealed that its fracture was 'consecutive to the propagation of a fatigue fissure,' as a result of the pipe being 'subjected to an excessive vibratory excitation.' Engine vibration tests were conducted and two main excitation sources were identified. The two sources were the starter-generator and the breather gear assembly. The proposed solution to correct for this vibration consists of fitting an attachment clamp at mid-length of the P3 pipe, 'which moves the natural frequencies out of engine power ratings.'

NTSB Probable Cause Narrative

The improper touchdown executed by the pilot. Factors were the tail wind condition, and the manufacturer's inadequate design of the P3 pipe supports, which resulted in a fatigue fracture of the P3 pipe.

Event Information

Type of Event Accident
Event Date 2/26/1999
Event Day of the Week Friday
Time of Event 910
Event Time Zone Central Standard Time
Event City SPRINGTOWN
Event State TEXAS
Event Country --
Zipcode of the event site 76082
Event Date Year 1999
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 Not pertinent
Investigator's weather source Weather Observation Facility
Time of the weather observation 953 Central Standard Time
Direction of event from weather observation facility (degrees) 40
Weather Observation Facility ID AFW
Elevation of weather observation facility 722
Distance of event from weather observation facility (units?) 19
Time Zone of the weather observation CST
Lighting Conditions Day
Lowest Ceiling Height 2200
Lowest Non-Ceiling Height 1200
Sky/Lowest/Cloud Conditions Scattered
Sky Condition for Lowest Ceiling Broken
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 5
Air Temperature at event time (in degrees celsius) 19
Dew Point at event time (in degress fahrenheit) 18
Wind Direction (degrees magnetic) 180
Variable Wind Indicator Unknown
Wind Speed (knots) 11
Wind Velocity Indicator Unknown
Wind Gust Indicator Not Gusting
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 29
Density Altitude (feet) --
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury Minor
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor 1
Injury Total None --
Injury Total Serious --
Injury Total All 1
Investigating Agency NTSB
NTSB Docket Number (internal use) 1070
NTSB Notification Source --
NTSB Notification Date Feb 26 1999 12:00AM
NTSB Notification Time 930
Fiche Number and/or location -used to find docket information IMAGE
Date of most recent change to record Dec 12 2000 11:20AM
User who most recently changed record dbo
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N122TH
NTSB Number FTW99LA085
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 91: General Aviation
Type of Flight Plan filed VFR
Flight plan Was Activated? --
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name Eurocopter
Aircraft Model COLIBRI EC120B
Aircraft Series Identifier COLIBRI EC
Aircraft Serial Number 1017
Certified Max Gross Weight 3700
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 5
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection Annual
Date of Last Inspection Feb 20 1999 12:00AM
Airframe hours since last inspection 14
Airframe Hours 22
ELT Installed Yes
ELT Activated Yes
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name AMERICAN EUROCOPTER CORP.
Aircraft Owner Street Address
Aircraft Owner City
Aircraft Owner State
Aircraft Owner Country
Aircraft Owner Zipcode
Operator is an individual? --
Operator Name
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? No
Operator Street Address 2701 FORUM DR.
Operator City GRAND PRAIRIE
Operator State TX
Operator Country
Operator Zip code 75052
Operator Code
Owner has at least one certificate None
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Unknown
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) Business
Second Pilot on Board No
Departure Point Same as Event No
Departure Airport Code GPM
Departure City GRAND PRAIRIE
Departure State TX
Departure Country
Departure Time 845
Departure Time Zone CST
Destination Same as Local Flt --
Destination Airport Code TDW
Destination City AMARILLO
Destination State TX
Destination Country
Specific Phase of Flight Cruise
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Jan 2 2001 10:34AM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --