Individually Owned: 150,657
Corporate Owned: 137,281
Twin Lakes Ranch Airport
Aircraft Accident/Incident Report
Granite, Oklahoma 73547
Sunday, October 10, 1999 19:05 CDT
NTSB Narrative Summary Released at Completion of Accident
The airplane was destroyed upon impact with terrain following a loss of control during the takeoff/initial climb. Severe corrosion was found at two structural tube clusters (one with a windshield pillar) located directly below the right wing forward and aft attach fittings. The portion of the forward structure available for carrying loads prior to the accident was less than 30% of the circumference of the pillar tube. Deformation associated with the separation of the pillar tube indicates that the pillar failed under compression loads. The manufacturer's representative stated that the 'windshield pillar is normally subjected to a tensile load during flight.' It is possible that compression loads generated during the takeoff roll led to a compression failure of the pillar. This failure would have changed the lift characteristics of the wing since the separation point was directly below the right wing forward attach fitting. The most recent annual inspection was performed in January 1999; the maintenance entry for the annual stated, in part, 'treated steel tubing as required.' In June 1999, a major repair was made to a tube cluster in the aft fuselage area 'due to external rust through from past acid spill.'
NTSB Probable Cause Narrative
Corrosion failure of the fuselage support tubing below the right wing forward attach fitting due to inadequate maintenance.
Event Information
| Type of Event | Accident |
| Event Date | 10/10/1999 |
| Event Day of the Week | Sunday |
| Time of Event | 1905 |
| Event Time Zone | Central Daylight Time |
| Event City | GRANITE |
| Event State | OKLAHOMA |
| Event Country | -- |
| Zipcode of the event site | 73547 |
| Event Date Year | 1999 |
| Event Date Month | 10 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | TWIN LAKES RANCH AIRPORT |
| Event Location Nearest Airport ID | 810K |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | 1630 |
| Weather Briefing Completeness | Unknown |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1753 Central Daylight Time |
| Direction of event from weather observation facility (degrees) | 120 |
| Weather Observation Facility ID | HBR |
| Elevation of weather observation facility | 1630 |
| Distance of event from weather observation facility (units?) | 16 |
| Time Zone of the weather observation | CDT |
| Lighting Conditions | Night/Bright |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 26 |
| Dew Point at event time (in degress fahrenheit) | 18 |
| Wind Direction (degrees magnetic) | 180 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 5 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 30 |
| Density Altitude (feet) | 3097 |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | Serious |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | 2 |
| Injury Total All | 2 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 1397 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Oct 10 1999 12:00AM |
| NTSB Notification Time | 2217 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Jan 10 2001 9:57AM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N4473A |
| NTSB Number | FTW00LA010 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Piper |
| Aircraft Model | PA-18-150 |
| Aircraft Series Identifier | PA-18-150 |
| Aircraft Serial Number | 18-4828 |
| Certified Max Gross Weight | 1750 |
| Aircraft Category | Airplane |
| 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 | Annual |
| Date of Last Inspection | Jan 12 1999 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | -- |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | GREAT PLAINS AVIATION LLC |
| Aircraft Owner Street Address | RR1 BOX 199 |
| Aircraft Owner City | GRANITE |
| Aircraft Owner State | OK |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 73547 |
| Operator is an individual? | -- |
| 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? | 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) | Personal |
| Second Pilot on Board | No |
| Departure Point Same as Event | Yes |
| Departure Airport Code | 810K |
| Departure City | |
| Departure State | |
| Departure Country | |
| Departure Time | 1905 |
| 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 | Takeoff |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 10 2001 12:27PM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 34 |
| Runway Length | 2200 |
| Runway Width | 35 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |