AD 97-14-05 Airworthiness Directives; Air Tractor Incorporated Models AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT-502 Airplanes

The following airplane Models and serial numbers fitted with a \3/16\-inch fin front spar fitting that do not have the modification in Snow Engineering Company Report No. 138, dated July 29, 1995, revised August 7, 1996, incorporated, certificated in any category: Note 1: The modification in Snow Engineering Company Report No. 138, dated July 29, 1995, revised August 7, 1996, and AD 95-20-06 required the airplanes to replace 3/16-inch thick fin front spar attach fittings with \1/4\-inch thick fin front spar attach fittings. ------------------------------------------------------------------------ Models Serial numbers ------------------------------------------------------------------------ AT-301 and AT-401...................... 301-0261 through 301-0736, and 401-0662 through 401-0736 that have been converted to turbine powerplants and equipped with the all metal rudder, part number (P/N) 30456-1. AT-302................................. All aircraft equipped with the all metal rudder, P/N 30456-1. AT-400 and AT-400A..................... All aircraft equipped with the all metal rudder, P/N 30456-1. AT-402................................. 402-0694 and 402-0695 through 402-0736. AT-501................................. 501-0002 through 501-0030 that have been converted to turbine powerplants and equipped with the all metal rudder, P/N 30456-1. AT-502................................. AT-502 502-0002 through 502- 0030. ------------------------------------------------------------------------ Note 2: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Required initially within the next 25 hours time-in- service (TIS) after the effective date of this AD, unless already accomplished, and thereafter as indicated in the body of this AD. To prevent in-flight vertical fin cracking, which, if not detected and corrected, could result in structural failure of the front spar attachments and eventually the rear spar attachment and cause loss of directional control of the airplane, accomplish the following: (a) Inspect the fin front spar attachment fittings for fatigue cracks in accordance with the INSTRUCTIONS section of the Snow Engineering Report (SER) number (No.) 138, dated July 29, 1995, Revised August 7, 1996. (b) If no cracks are found during the initial inspection, repeat the inspection required by paragraph (a) of this AD at intervals not to exceed 25 hours TIS thereafter in accordance with the INSTRUCTIONS section of the SER No. 138, Revised August 7, 1996. (c) If cracks are found during any inspections required by this AD, prior to further flight, modify the fin front spar attachment fittings in accordance with the [[Page 38447]] INSTRUCTIONS section of the SER No. 138, dated July 29, 1995, Revised August 7, 1996. (d) Incorporating the modification specified in paragraph (c) of this AD is considered terminating action for the repetitive inspection requirements of this AD. (e) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. (f) An alternative method of compliance or adjustment of the compliance times that provides an equivalent level of safety may be approved by the Manager, Fort Worth Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Fort Worth Airplane Certification Office. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from Fort Worth Airplane Certification Office. (g) The inspection and modification required by this AD shall be done in accordance with Snow Engineering Report No. 138, dated July 29, 1995, Revised August 7, 1996. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Air Tractor Incorporated, P.O. Box 485, Olney, Texas 76374. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (h) This amendment supersedes AD 95-20-06, Amendment 39-9384. (i) This amendment (39-10063) becomes effective on August 25, 1997. Issued in Kansas City, Missouri, on June 26, 1997. James E. Jackson, Acting Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-17533 Filed 7-17-97; 8:45 am] BILLING CODE 4910-13-U