Altus Municipal Airport
Aircraft Accident/Incident Report

Altus, Oklahoma 73521
Sunday, May 23, 2004 13:00 CDT

NTSB Narrative Summary Released at Completion of Accident

The pilot was performing aerobatic maneuvers when he noticed the fabric on the top right wing was separating and departing the airplane. The pilot reduced the engine power, airspeed, and altitude, and then returned to the airport. Examination of the airplane revealed the wing rib stitching had failed, and approximately 5 feet of the top right wing fabric and approximately 3 feet of the top right wing lower fabric was separated. According to a fabric manufacturer technical bulletin, "When light weight fabric is installed on an aircraft with a high horsepower engine and inadequate fabric forming structural spacing, coating fatigue cracks develop very rapidly...We recommend fabric weighing less than 2.4 [ounces] per [square yard] be used only on aircraft with engines up to 145 [horsepower]." The fabric covering weight on the airplane was 1.7 ounces per square yard, and the airplane was equipped with a 300-horsepower engine.

NTSB Probable Cause Narrative

The partial in-flight separation of the wing fabric and rib structure due to an inadequate material installed by the airplane builder.

Event Information

Type of Event Accident
Event Date 5/23/2004
Event Day of the Week Sunday
Time of Event 1300
Event Time Zone Central Daylight Time
Event City Altus
Event State OKLAHOMA
Event Country --
Zipcode of the event site 73521
Event Date Year 2004
Event Date Month 5
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude 344155N
Event Location Longitude 0992017W
Event Location Airport Altus Municipal
Event Location Nearest Airport ID AXS
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 1433
Weather Briefing Completeness --
Investigator's weather source Weather Observation Facility
Time of the weather observation 1253 Central Daylight Time
Direction of event from weather observation facility (degrees) 30
Weather Observation Facility ID HBR
Elevation of weather observation facility 1564
Distance of event from weather observation facility (units?) 22
Time Zone of the weather observation CDT
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) 34
Dew Point at event time (in degress fahrenheit) 2
Wind Direction (degrees magnetic) 200
Variable Wind Indicator Wind direction could be determined
Wind Speed (knots) 6
Wind Velocity Indicator --
Wind Gust Indicator Not Gusting
Wind Gust (knots) --
Altimeter Setting at event time (in. Hg) 29.73
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 2
Injury Total Serious --
Injury Total All --
Investigating Agency --
NTSB Docket Number (internal use) 16285
NTSB Notification Source OKC FSDO
NTSB Notification Date --
NTSB Notification Time --
Fiche Number and/or location -used to find docket information DMS
Date of most recent change to record Sep 29 2004 1:02PM
User who most recently changed record NTSB\MONR
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N25BM
NTSB Number FTW04LA148
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 Bruce Moore
Aircraft Model Skybolt
Aircraft Series Identifier --
Aircraft Serial Number S-BM-001
Certified Max Gross Weight --
Aircraft Category Airplane
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? Yes
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 Unknown
Date of Last Inspection --
Airframe hours since last inspection --
Airframe Hours --
ELT Installed Unknown
ELT Activated Unknown
ELT Aided Location of Event Site Unknown
ELT Type --
Aircraft Owner Name Clark A. Murray
Aircraft Owner Street Address 3109 Mallard Ct.
Aircraft Owner City Altus
Aircraft Owner State OK
Aircraft Owner Country USA
Aircraft Owner Zipcode 73521
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) Personal
Second Pilot on Board No
Departure Point Same as Event Yes
Departure Airport Code AXS
Departure City Altus
Departure State OK
Departure Country USA
Departure Time --
Departure Time Zone CDT
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 --
Report sent to ICAO? --
Evacuation occurred No
Date of most recent change to record Jul 29 2004 3:09PM
User who most recently changed record CASH
Since inspection or accident --
Event Location Runway Number and Location --
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --