The FAA is superseding an Airworthiness Directive which applied to all Air Tractor Models AT-802 and AT-802A with the Wipaire SA01795CH Supplemental Type Certificate (STC) installed.

The original AD 2023-15-07 required repetitive 200 hour Time in Service (TIS) inspections of the left and right forward horizontal stabilizer spars for cracks, replacing any forward horizontal stabilizer spar found cracked, and reporting inspection results to the FAA.

As a result of the reports of the inspections additional cracks have been found in the forward horizontal stabilizer spar, including cracks found before the airplane accumulated their 200 hours TIS after installation of the STC. The FAA determined that reducing the inspection interval is necessary. In addition, based on a new fatigue analysis, the FAA determined that there is the potential for cracks in the rear horizontal stabilizer spar.

Wipaire has developed a change to its STC, which incorporates an improved design that includes modification kits to install bathtub fittings on the horizontal stabilizer spars to mitigate this condition by improving the structural load path and more accessible repetitive inspection intervals of 110 hours TIS.