Airworthiness Directive · Amendment 39-15518 · Air Tractor, Inc. AT-400, AT-500, AT-600, and AT-800 Series Airplanes
Air Tractor, Inc. AT-400, AT-500, AT-600, and AT-800 Series Airplanes
Superseded. A later AD replaced this one: AD 2009-11-05. Comply with the one in force.
This AD applies to the following airplane models and serial numbers that are certificated in any category:
| Models | Serial Nos. |
|---|---|
| AT-400, AT-400A, AT-402, AT-402A, and AT-402B | -0001 through -1175. |
| AT-502, AT-502A, AT-502B, and AT-503A | -0001 through -2597. |
| AT-602 | -0001 through -1141. |
| AT-802 and AT-802A | -0001 through -0227. |
We are adopting a new airworthiness directive (AD) to supersede AD 2007-13-17, which applies to certain Air Tractor, Inc. (Air Tractor) Models AT-602, AT-802, and AT-802A airplanes. AD 2007-13- 17 currently requires you to repetitively inspect the engine mount for any cracks, repair or replace any cracked engine mount, and report any cracks found to the FAA. Since we issued AD 2007-13-17, Air Tractor has learned of a Model AT-502B with a crack located where the lower engine mount tube is welded to the engine mount ring. In addition, Air Tractor has developed gussets that, when installed according to their service letter, terminate the repetitive inspection requirement. Consequently, this AD would retain the inspection actions of AD 2007-13-17 for Model AT-602, AT-802, and AT-802A airplanes, including the compliance times and effective dates; establish new inspection actions for the AT-400 and AT-500 series airplanes; incorporate a mandatory terminating action for all airplanes; and terminate the reporting requirement of AD 2007- 13-17. We are issuing this AD to detect and correct cracks in the engine mount, which could result in failure of the engine mount. Such failure could lead to separation of the engine from the airplane.
To address this problem, you must do the following, unless already done:
(1) For all airplanes with less than 5,000 hours total TIS that do not have gussets installed on the engine mount in accordance with Snow Engineering Co. Service Letter #253 Rev. A, dated October 16, 2007; Snow Engineering Co. Service Letter #253 Rev. B, dated November 30, 2007; or Snow Engineering Co. Service Letter #253 Rev. C, dated April 17, 2008: Visually inspect the engine mount as follows:
| Affected airplanes | Compliance | Procedures |
|---|---|---|
| (i) For all Models AT-602, AT-802, and AT-802A airplanes | Initially before the airplane reaches a total of 1,300 hours TIS or within the next 100 hours TIS after August 10, 2007 (the effective date of AD 2007-13-17), whichever occurs later. Repetitively thereafter at intervals not to exceed 300 hours TIS. | Follow one of the following: (A) Snow Engineering Co. Service Letter #253, Rev. C, dated April 17, 2008; (B) Snow Engineering Co. Service Letter #253, Rev. B, dated November 30, 2007; (C) Snow Engineering Co. Service Letter #253, Rev. A, dated October 16, 2007; |
| or | ||
| (D) Snow Engineering Co. Service Letter #253, revised January 22, 2007. | ||
| (ii) For all Model AT-502A airplanes | Initially before the airplane reaches a total of 1,300 hours TIS or within the next 100 hours TIS after June 12, 2008 (the effective date of this AD), whichever occurs later. Repetitively thereafter at intervals not to exceed 300 hours TIS. | Follow one of the following: (A) Snow Engineering Co. Service Letter #253, Rev. C, dated April 17, 2008; or (B) Snow Engineering Co. Service Letter #253, Rev. B, dated November 30, 2007. |
| (iii) For all Models AT-400, AT-400A, AT-402, AT-402A, AT-402B, AT-502, AT-502B, and AT-503A airplanes | Initially within the next 12 months after June 12, 2008 (the effective date of this AD). Repetitively thereafter at intervals not to exceed 12 months. | Follow one of the following: (A) Snow Engineering Co. Service Letter #253, Rev. C, dated April 17, 2008; or (B) Snow Engineering Co. Service Letter #253, Rev. B, dated November 30, 2007. |
(2) For all airplanes: Before further flight after any inspection required by paragraph (e)(1) of this AD where crack damage is found, repair and modify the engine mount by installing gussets following Snow Engineering Co. Service Letter #253, Rev. C, dated April 17, 2008; or Snow Engineering Co. Service Letter #253, Rev. B, dated November 30, 2007. This modification terminates the repetitive inspections required in paragraphs (e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of this AD.
(3) For all airplanes: Unless already done (mandated by paragraph (e)(2) of this AD when crack damage was found) inspect, repair if cracked, and modify the engine mount by installing gussets following Snow Engineering Co. Service Letter #253, Rev. C, dated April 17, 2008; or Snow Engineering Co. Service Letter #253, Rev. B, dated November 30, 2007, at whichever of the following compliance times that occurs later. This modification terminates the repetitive inspections required in paragraphs (e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of this AD.
(i) Before the airplane reaches 5,000 hours total TIS; or
(ii) Within the next 100 hours TIS after June 12, 2008 (the effective date of this AD).
(4) For all airplanes: You may delay the modification specified in paragraph (e)(3) above until April 30, 2009, provided you do the following in accordance with the service information provided in the Procedures column of the table presented in paragraph (e)(1) of this AD:
(i) Initially inspect upon reaching the applicable time in paragraph (e)(3)(i) or (e)(3)(ii) of this AD, unless already done within the last 100 hours TIS;
(ii) Repetitively inspect thereafter at intervals not to exceed 100 hours TIS; and
(iii) If cracks are found during any inspection, before further flight, repair the cracked part and install the gussets.
Note: As a terminating action to the repetitive inspections required in paragraphs (e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of this AD, you may install the gussets before finding cracks or reaching the times specified above provided you inspect to assure the area is crack free before installing the gussets.
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.
