Airworthiness Directive · Amendment 39-21457 · Te flap control system
Air Tractor, Inc., Airplanes
This AD applies to Air Tractor, Inc., (Air Tractor), Models AT-250, AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-401A, AT-401B, AT402, AT-402A, AT-402B, AT-501, AT-502, AT-502A, AT-502B, AT-503, AT-503A, AT-504, AT-602, AT-802, and AT-802A airplanes, all serial numbers, certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for all Air Tractor, Inc., (Air Tractor) Models AT-250, AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-401A, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, AT-502A, AT-502B, AT-503, AT-503A, AT-504, AT-602, AT- 802, and AT-802A airplanes. This AD was prompted by reports of cracks in the flap torque tube actuator attachment brackets that may cause the flap actuator to detach from the flap torque tube. This AD requires repetitive visual and dye penetrant inspections of the flap actuator attachment bracket welds for cracks and replacement if cracks are identified. The FAA is issuing this AD to address the unsafe condition on these products.
(1) Within 300 hours time-in-service (TIS) after the effective date of this AD and thereafter at intervals not to exceed 900 hours TIS, perform a dye penetrant inspection of each flap torque tube actuator attachment bracket for cracks in accordance with steps 4B(2) through (7) of Air Tractor, Inc., Service Letter #347, Revision A, dated December 9, 2019 (Air Tractor SL #347, Rev A).
(i) If there is a crack, before further flight, replace the flap torque tube with a flap torque tube that has zero hours TIS or a part that has been inspected in accordance with paragraph (g)(1) of this AD and passed the inspection.
(ii) If there are no cracks, before further flight, complete the actions in steps 4B(9) and (10) of Air Tractor SL #347, Rev A.
(2) Within 345 hours TIS after the inspection required by paragraph (g)(1) of this AD and thereafter at intervals not to exceed 345 hours TIS, visually inspect each flap torque tube actuator attachment bracket for cracks in accordance with steps 4A(1) through (3) of Air Tractor SL #347, Rev A. If there is a crack, before further flight, replace the flap torque tube with a flap torque tube that has zero hours TIS or with a flap torque tube that has been inspected in accordance with paragraph (g)(1) of this AD and passed the inspection.
(3) Replacing a flap torque tube does not terminate any of the inspections required by this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
