AD 2008-10-12 Airworthiness Directives; Air Tractor, Inc. AT-400, AT-500, AT-600, and AT-800 Series Airplanes

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.

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. Alternative Methods of Compliance (AMOCs) (f) The Manager, Fort Worth Airplane Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Andy McAnaul, Aerospace Engineer, ASW-150, FAA San Antonio MIDO-43, 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; phone: (210) 308-3365; fax: (210) 308-3370. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. Material Incorporated by Reference (g) You must use Snow Engineering Co. Service Letter #253, Rev. C, dated April 17, 2008; Snow Engineering Co. Service Letter #253, Rev. B, dated November 30, 2007; Snow Engineering Co. Service Letter #253, Rev. A, dated October 16, 2007; or Snow Engineering Co. Service Letter #253, revised January 22, 2007, to do the actions required by this AD, unless the AD specifies otherwise. (1) The Director of the Federal Register approved the incorporation by reference of Snow Engineering Co. Service Letter #253, Rev. C, dated April 17, 2008; Snow Engineering Co. Service Letter #253, Rev. B, dated November 30, 2007; and Snow Engineering Co. Service Letter #253 Rev. A, dated October 16, 2007, under 5 U.S.C. 552(a) and 1 CFR part 51. (2) On August 10, 2007 (72 FR 36863, July 6, 2007), the Director of the Federal Register approved the incorporation by reference of Snow Engineering Co. Service Letter #253, revised January 22, 2007. (3) For service information identified in this AD, contact Air Tractor Inc., P.O. Box 485, Olney, Texas 76374; telephone: (940) 564-5616; fax: (940) 564-5612. (4) You may review copies at the FAA, Central Region, Office of the Regional Counsel, 901 Locust, Kansas City, Missouri 64106; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html . Issued in Kansas City, Missouri, on April 30, 2008. Patrick R. Mullen, Acting Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. E8-9925 Filed 5-7-08; 8:45 am] BILLING CODE 4910-13-P

This AD results from a report of a Model AT-502B airplane with a crack located where the lower engine mount tube is welded to the engine mount ring. The airplane had 8,436 total hours time-in-service (TIS). 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.