AD 2002-11-05 Airworthiness Directives; Air Tractor, Inc. Model AT-501 Airplanes

Models named: AT-501. Read the applicability below — it usually turns on serial or part numbers too.

(c) This AD applies to Model AT-501 airplanes that are certificated in any category. Use Table 1 in paragraph (c)(1) of this AD for AT-501 airplanes that do not incorporate and never have incorporated Marburger winglets and use Table 2 in paragraph (c)(3) of this AD for AT-501 airplanes that incorporate or have incorporated Marburger winglets. (1) The following table applies to airplanes that do not incorporate and never have incorporated Marburger winglets along with the safe life (presented in hours time-in-service (TIS)) of the wing lower spar cap for all affected airplane models and serial numbers: Table 1.—Safe Life for Airplanes That Do Not Incorporate and Never Have Incorporated Marburger Winglets Model Serial Nos. Wing lower spar cap safe line AT-501 0002 through 0061 4,531 hours TIS. AT-501 All beginning with 0062 7,693 hours TIS. (2) If piston-powered aircraft have been converted to turbine power, you must use the limits for the corresponding serial number turbine-powered aircraft. (3) The following table applies to airplanes that incorporate or have incorporated Marburger winglets. These winglets are installed in accordance with Supplemental Type Certificate (STC) No. SA00490LA. Use the winglet usage factor in Table 2 of this paragraph, the safe life specified in Table 1 in paragraph (c)(1) of this Ad, and the instructions included in Appendix 1 to this AD to determine the new safe life of airplanes that incorporate or have incorporated Marburger winglets: Table 2.—Winglet Usage Factor To Determine the Safe Life for Airplanes That Incorporate or Have Incorporated Marburger Winglets Per STC No. SA00490LA Model Serial Nos. Winglet usage factor AT-501 0002 through 0061 1.6 AT-501 all serial numbers beginning with 0062 1.6

(e) To address this problem, you must do the following: Table 3.—Actions/Compliance/Procedures Actions Compliance Procedures (1) Modify the applicable aircraft records as follows to show the reduced safe life for the wing lower spar cap (use the information from table in paragraph (c)(1) of this AD and utilize the information in paragraph (c)(3) of this AD and the Appendix to this AD, as applicable). (i) Incorporate the following into the Aircraft Logbook “In accordance with AD 2002-11-05, the wing lower spar cap is life limited to ___.” Insert the applicable safe life number from the applicable tables in paragraphs (c)(1) and (c)(3) of this AD and the Appendix of this AD. (ii) If, as of the time of the logbook entry requirement of paragraph (e)(1) of this AD, your airplane is over or within 10 hours of the safe life, an additional 10 hours TIS after July 12, 2002 (the effective date of this AD) is allowed to do the replacement. Do the logbook entry within the next 10 hours TIS after July 12, 2002 (the effective date of AD 2002-11-05), unless already done. The logbook language is referenced as AD 2002-11-05 instead of AD 2002-2002-11-05 R1 to maintain continuity and to assure that no additional action is necessary. The owner/operator holding at least a private pilot certificate as authorized by section 43.7 of the Federal Aviation Regulations (14 CFR 43.7) may modify the aircraft records as specified in paragraphs (e)(1) of this AD. Make an entry into the aircraft records showing compliance with this portion of the following section 43.9 of the Federal Aviation Regulations (14 CFR 43.9). Do the replacement when the safe life is reached following Snow Engineering Service Letters #197 or #205, both revised March 26, 2001, as applicable. The owner/operator may not do the replacement unless he/she holds the proper mechanic authorization. (2) If you have ordered parts from the factory when it is time to replace the wing lower spar cap (as required when you reach the established safe life), but the parts are not available, you may eddy-current inspect the wing lower spar cap. These inspections are allowed until one of the following occurs, at which time the replacement must be done: (i) Crack(s) is/are found; (ii) Parts become available from the manufacturer; or (iii) Not more than three inspections or 1,200 hours TIS go by: the first inspection would have to be done upon accumulating the safe life; the second inspection would have to be done within 400 hours TIS after accumulating the safe life; the third inspection would have to be done 400 hours TIS after the second inspection; and the replacement would have to be done within 400 hours TIS after the third inspection (maximum elapsed time would be 1,200 hours TIS). Inspect before further flight after ordering the parts and thereafter at intervals not to exceed 400 hours TIS until one of the criteria in paragraphs (e)(2)(i), (e)(2)(ii), and (e)(2)(iii) of this AD is met. Following the procedures in Snow Engineering Service Letter #197, pages 1 and 2, revised March 26, 2001, and page 3, dated June 13, 2000; and Snow Engineering Service Letter #205, pages 1, 2, and 4, revised March 26, 2001, and page 3, dated October 25, 2000 as applicable. (3) Eddy-current inspect the wing lower spar cap in order to detect any crack before it extends to the modified center section of the wing and repair that crack or replace the wing section. The inspection must be done by one of the following: (i) a Level 2 or Level 3 inspector that is certified for eddy-current inspection using the guidelines established by the American Society for Nondestructive Testing or MIL-STD-410; or (ii) A person authorized to perform AD work who has completed and passed the Air Tractor, Inc. training course on Eddy Current Inspection on wing lower spar caps. Immediately before the replacement/modification required when you reach the new safe life. For airplanes that had this replacement done in accordance with either AD 2001-10-04 or AD 2001-10-04 R1, do this inspection and any necessary corrective action within the next 400 hours TIS after July 12, 2002 (the effective date of AD 2002-11-05), unless already done (have the mechanic who did the work mark the logbook accordingly). Following the procedures in Snow Engineering Service Letter #197, pages 1 and 2, revised March 26, 2001, and page 3, dated June 13, 2000; and Snow Engineering Service Letter #205, pages 1, 2, and 4, revised March 26, 2001, and page 3, dated October 25, 2000, as applicable.

(d) This AD is the result of service reports and analysis done on wing lower spar caps of Air Tractor airplanes. The actions specified in this AD are intended to prevent fatigue cracks from occurring in the wing lower spar cap before the established safe life is reached. Fatigue cracks in the wing lower spar cap, if not detected and corrected, could result in failure of the spar cap and lead to wing separation and loss of control of the airplane.