Airworthiness Directive · Amendment 39-15692 · Air Tractor, Inc. Models AT-402, AT-402A, and AT-402B Airplanes
Air Tractor, Inc. Models AT-402, AT-402A, and AT-402B Airplanes
This AD applies to Models AT-402, AT-402A, and AT-402B airplanes, serial numbers 0694 through 1176, that are certificated in any category.
We are adopting a new airworthiness directive (AD) for certain Air Tractor, Inc. (Air Tractor) Models AT-402, AT-402A, and AT-402B airplanes. This AD requires you to repetitively visually inspect the rudder and vertical fin hinge attaching structure for loose fasteners and inspect the rudder or vertical fin skins, spars, hinges, or brackets for cracks and/or corrosion. This AD also requires you to replace any damaged parts found as a result of the inspections and install an external doubler at the upper rudder hinge. Installation of the external doubler at the upper rudder hinge is terminating action for the repetitive inspection requirements. This AD results from a report of a Model AT-402 airplane with a loose upper rudder hinge caused by fatigue. We are issuing this AD to detect and correct loose fasteners; any cracks in the rudder or vertical fin skins, spars, hinges, or brackets; or corrosion of the rudder and vertical fin hinge attaching structure. Hinge failure adversely affects ability to control yaw and has led to the rudder folding over in flight. This condition could allow the rudder to contact the elevator and affect ability to control pitch with consequent loss of control.
To address this problem, you must do the following, unless already done:
| Actions | Compliance | Procedures |
|---|---|---|
| (1) Inspect visually the rudder and vertical fin hinge attachment for loose fasteners; and inspect the rudder or vertical fin skins, spars, hinges, and brackets for cracks and/or corrosion | Initially inspect when the airplane reaches a total of 3,500 hours time-in-service (TIS) or within the next 100 hours TIS after November 20, 2008 (the effective date of this AD), whichever occurs later. Thereafter, repetitively inspect at intervals not to exceed every 100 hours TIS. Installation of the external doubler at the upper rudder hinge required by paragraph (e)(2)(ii) or (e)(3) of this AD is terminating action for the repetitive inspections required by this AD | Follow Snow Engineering Co. Service Letter #247, revised June 2, 2008. |
| (2) If you find any damage as a result of any inspection required by paragraph (e)(1) of this AD, you must: | ||
| (i) Replace any damaged parts with new parts; and | ||
| (ii) Do the installation of the external doubler at the upper rudder hinge. | Before further flight after any inspection required by paragraph (e)(1) of this AD where you find any damaged parts. The installation of the external doubler at the upper rudder hinge required by paragraph (e)(2)(ii) or (e)(3) of this AD terminates the repetitive inspections required by this AD | Follow Snow Engineering Co. Service Letter #247, revised June 2, 2008; and Snow Engineering Co. Process Specification Number 145, dated December 6, 1991. |
| (3) Do the installation of the external doubler at the upper rudder hinge | When the airplane reaches a total of 5,000 hours TIS after November 20, 2008 (the effective date of this AD) or within the next 100 hours TIS after November 20, 2008 (the effective date of this AD), whichever occurs later. The installation of the external doubler at the upper rudder hinge required by paragraph (e)(2)(ii) or (e)(3) of this AD terminates the repetitive inspections required by this AD | Follow Snow Engineering Co. Service Letter #247, revised June 2, 2008; and Snow Engineering Co. Process Specification Number 145, dated December 6, 1991. |
| (4) Do not install any rudder without the external doubler at the upper rudder hinge required by paragraph (e)(3) of this AD | As of November 20, 2008 (the effective date of this AD) | Not Applicable. |
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.
