Airworthiness Directives; Air Tractor, Inc. Models AT-300, AT-301, AT-302, AT-400, and AT-400A Airplanes

This amendment supersedes Airworthiness Directive (AD) 2002- 13-02, which applies to all Air Tractor, Inc. (Air Tractor) Models AT- 300, AT-301, AT-302, and AT-400A airplanes that have aluminum spar caps; certain Air Tractor Models AT-400 airplanes that have aluminum spar caps; and all Models AT-300 and AT-301 airplanes that have aluminum spar caps and are or have been converted to turbine power. AD 2002-13-02 currently requires you to inspect (one-time) the wing centerline splice joint for cracks and, if any crack is found, replace the affected wing spar lower cap; requires you to report the results of the inspection to the Federal Aviation Administration (FAA); and requires you to replace the wing spar lower caps after a certain amount of usage. Based upon the inspection results from AD 2002-13-02, FAA has determined that the mandatory wing spar lower cap replacement times should be reduced. This AD maintains the wing spar lower cap replacement and reporting requirements from AD 2002-13-02 and reduces the compliance time of these replacements. The actions specified by this AD are intended to detect and correct cracks in the wing centerline splice joint. If not detected and corrected, these cracks could eventually result in the wing separating from the airplane during flight.