Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Anchorage, Alaska 99502
Saturday, March 19, 2005 16:15 AST
NTSB Narrative Summary Released at Completion of Accident
The private certificated pilot was conducting short-field landings with the wheels extended on a frozen lake in a wheel/ski-equipped airplane. On the ninth landing, the main landing gear collapsed, and the airplane settled onto its belly. The pilot said both landing gear A-frame type gear assemblies rotated outward and upward, as the airplane settled onto the ice. He said that the touchdown was not hard, and the common point of failure was at the center, fuselage-mounted spring shock assembly. Each landing gear assembly has an extended arm that attaches in the center of the fuselage to the bottom end of a vertically mounted oleo shock. The left gear arm attaches to the oleo lug by a clevis bolt that is installed front-to-back. The bolt also retains the top end of two oval-shaped metal link plates that are positioned vertically at the front and aft side of the oleo attach lug. A clevis bolt, through the bottom hole of each link, retains a spacer and the right landing gear extended attaching arm. Each clevis bolt uses a tension castle nut, with a cotter pin for security. The aft link plate had extensive elongation of the upper bolt hole radius. The forward link plate upper bolt hole was fractured, and had opening and elongation of a segment of the bolt hole radius. The upper clevis bolt was found at the scene, but its castle nut and cotter pin were not located. The clevis bolt was bent along its span. The threaded portion of the bolt had flattening of the threads about 1/3 of its circumference, and partial threads on the remaining 2/3 of its circumference, with slight necking of the bolt end. An FAA aerospace engineer examined the recovered parts and reported, in part, that: "...the cotter pin failed in service, or was never installed, and the shear nut loosened and fell off the aft end of the upper bolt, or was never installed." The airplane had accrued 11 hours since the most recent annual inspection.
NTSB Probable Cause Narrative
A main landing gear collapse during the landing touch down due to a non-secured clevis bolt at the common attach point on the landing gear oleo shock.
Event Information
| Type of Event | Accident |
| Event Date | 3/19/2005 |
| Event Day of the Week | Saturday |
| Time of Event | 1615 |
| Event Time Zone | Atlantic Standard Time |
| Event City | Anchorage |
| Event State | ALASKA |
| Event Country | -- |
| Zipcode of the event site | 99502 |
| Event Date Year | 2005 |
| Event Date Month | 3 |
| MidAir Collision Indicator | -- |
| On Ground Collision occurred ? | -- |
| Event Location Latitude | 611830N |
| Event Location Longitude | 1502719W |
| 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 | Pilot |
| Time of the weather observation | |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | -- |
| Elevation of weather observation facility | -- |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | -- |
| 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) | 20 |
| Air Temperature at event time (in degrees celsius) | 3 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | -- |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | Calm |
| Wind Gust Indicator | Unknown |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | -- |
| 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 |
| NTSB Docket Number (internal use) | 18720 |
| NTSB Notification Source | FAA Regional Operations Center |
| NTSB Notification Date | Mar 19 2005 12:00AM |
| NTSB Notification Time | 1710 |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Dec 20 2005 6:27AM |
| User who most recently changed record | NTSB\JOHB |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | FAA-AL-ANC FSDO 03 |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N67AT |
| NTSB Number | ANC05LA051 |
| 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 | Arctic Aircraft Company |
| Aircraft Model | S-1B2 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 1018 |
| Certified Max Gross Weight | 1650 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| 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 | Aug 1 2004 12:00AM |
| Airframe hours since last inspection | 11 |
| Airframe Hours | 1131 |
| ELT Installed | Yes |
| ELT Activated | Yes |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Bill L. Brown |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Anchorage |
| Aircraft Owner State | AK |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 99516 |
| 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 | PAMR |
| Departure City | Anchorage |
| Departure State | AK |
| Departure Country | USA |
| Departure Time | 1555 |
| Departure Time Zone | AST |
| 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 | Landing - roll |
| Report sent to ICAO? | No |
| Evacuation occurred | -- |
| Date of most recent change to record | Sep 23 2005 2:29PM |
| User who most recently changed record | PETL |
| 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 | -- |