NTSB Factual Report

On August 14, 2002, at 1011 mountain daylight time, an Air Tractor AT-802A, N91092, was substantially damaged when it exited the left side of the runway at Jeffco Airport (BJC) in Broomfield, Colorado. The commercial pilot, the sole occupant in the airplane, received minor injuries. The U.S.D.A. Forest Service, Broomfield, Colorado, was operating the airplane under Title CFR Part 91. Visual meteorological conditions prevailed for the slurry bomber operation which was originating at the time of the accident. No flight plan was filed for the local flight.

The pilot said the he taxied onto runway 29R, with approximately 700 gallons of fire retardant. He started the takeoff roll and at approximately 800 to 900 feet down the runway he heard a "distinct bang." The airplane immediately started an uncommanded turn to the left, and the pilot, using right rudder and right braking action, could not regain control of the aircraft. The airplane departed the runway and impacted the Visual Approach Slope Indicator box, which sheared the right main landing gear off. Subsequently, the right wing and aileron were bent up.

Postaccident examination of the airplane by maintenance personnel revealed that the left main tire inner seal had separated from the wheel. No determination was made for why this event occurred. A Federal Aviation Administration inspector said he found two black skid marks on the runway; the left one started 10 to 15 feet before the right one.

NTSB Probable Cause

the airplane's left main landing gear tire separated from its wheel during takeoff roll for an undetermined reason. Contributing factors were the pilot's inability to maintain aircraft control during takeoff roll and the subsequent impact with the Visual Approach Slope Indicator box.