Airworthiness Directive · Amendment 39-14563 · Air Tractor, Inc. Models AT-400; AT-401, AT-401B, AT-402, AT-402A, and AT-402B Airplanes
Air Tractor, Inc. Models AT-400; AT-401, AT-401B, AT-402, AT-402A, and AT-402B Airplanes
Superseded. A later AD replaced this one: AD 2006-08-08 R1. Comply with the one in force.
This AD applies to certain Models AT-400, AT-401, AT-401B, AT-402, AT-402A, and AT-402B airplanes that are certificated in any category. Use paragraph (c)(1) of this AD for affected airplanes that do not incorporate and never have incorporated Marburger winglets. Use paragraph (c)(3) of this AD for airplanes that have been modified to install lower spar caps, part number (P/N) 21058-1, and P/N 21058-2. Use paragraph (c)(4) of this AD for certain Models AT-401, AT-401B, AT-402, AT-402A, and AT-402B 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:
| Model | Serial Nos. | Wing lower spar cap safe life |
|---|---|---|
| AT-400 | All beginning with 0416 | 13,300 hours TIS. |
| AT-401 | 0662 through 0951 | 10,757 hours TIS. |
| AT-401B | 0952 through 1020, except 1015 | 6,948 hours TIS. |
| AT-401B | 1015 and all beginning with 1021 | 7,777 hours TIS. |
| AT-402 | 0694 through 0951 | 7,440 hours TIS. |
| AT-402A | 0738 through 0951 | 7,440 hours TIS. |
| AT-402A | 0952 through 1020 | 2,000 hours TIS. |
| AT-402A | All beginning with 1021 | 2,300 hours TIS. |
| AT-402B | 0966 through 1020, except 1015 | 2,000 hours TIS. |
| AT-402B | 1015 and all beginning with 1021 | 2,300 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) If you have an aircraft that has been modified by installing lower spar caps, P/N 21058-1 and P/N 21058-2, you must use a wing lower spar cap life of 9,800 hours TIS. No inspections are required to reach this life.
(i) Airplanes that have been modified with replacement spar caps, P/N 21058-1 and P/N 21058-2, are not eligible to have Supplemental Type Certificate (STC) No. SA00490LA, Marburger winglets, installed.
(ii) If your airplanes currently has spar caps, P/N 21058-1 and P/N 21058-2, and winglets installed, then you must remove the winglets before further flight and you must contact the FAA at the address in paragraph (l)(1) of this AD for a new safe life.
(iii) Installation of Marburger winglets on airplanes that have been modified with replacement spar caps, P/N 21058-1 and P/N 21058-2, will require additional fatigue-data substantiating an appropriate safe life. If you have replacement spar caps and wish to install winglets, you must contact the FAA at the address in paragraph (l)(1) of this AD for additional information.
(4) The following table applies to airplanes that incorporate or have incorporated Marburger winglets. These winglets are installed following STC No. SA00490LA. Use the winglet usage factor in Table 2 of this paragraph, the wing lower spar cap 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:
| Model | Serial Nos. | Winglet usage factor |
|---|---|---|
| AT-401 | 0662 through 0951 | 1.6 |
| AT-401B | 0952 through 1020, except 1015 | 1.1 |
| AT-401B | 1015 and all beginning with 1021 | 1.1 |
| AT-402 | 0694 through 0951 | 1.6 |
| AT-402A | 0738 through 0951 | 1.6 |
| AT-402A | 0952 through 1020 | 1.1 |
| AT-402A | All beginning with 1021 | 1.1 |
| AT-402B | 0966 through 1020, except 1015 | 1.1 |
| AT-402B | 1015 and all beginning with 1021 | 1.1 |
The FAA is adopting a new airworthiness directive (AD) for certain Air Tractor, Inc. (Air Tractor) Models AT-400, AT-401, AT-401B, AT-402, AT-402A, and AT-402B airplanes. This AD requires you to lower the safe life for the wing lower spar cap for certain Models AT-402A and AT-402B airplanes and those that incorporate or have incorporated Marburger Enterprises, Inc. (Marburger) winglets. For Models AT-400, AT-401, AT-401B, AT-402, and certain AT-402A, airplanes, this AD requires you to repetitively inspect the wing lower spar cap in order to reach the safe life. We also developed an alternative method of compliance (AMOC) to the requirements of this Ad for certain Models AT- 402A and AT-402B airplanes. The AMOC includes repetitive eddy current inspections, modification of the center splice connection, and lower spar cap replacement. This AD is the result of reports of cracks in the \3/8\-inch bolt hole of the wing lower spar cap before reaching the approved safe life. We are issuing this AD to prevent fatigue cracks from occurring in the wing lower spar cap before the originally established safe life is reached. Fatigue cracks in the wing lower spar cap, if not detected and corrected, could result in wing separation and loss of control of the airplane.
Safe Life Record: For all affected airplanes, modify the applicable aircraft records (logbook) as follows to show the safe life for the wing lower spar cap listed in this AD (use the information from paragraph (c) of this AD and Appendix 1 to this AD, as applicable).
(1) Incorporate the following into the Aircraft Logbook: “Following AD 2006-08-08 the wing lower spar cap is life limited to __ hours time-in-service (TIS).” Insert the applicable safe life number from the applicable tables in paragraph (c) of this AD and Appendix 1 to this AD.
(i) Do the logbook entry within the next 10 hours TIS after April 21, 2006 (the effective date of this AD).
(ii) 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. Make an entry into the aircraft records showing compliance with this portion of the AD following section 43.9 of the Federal Aviation Regulations (14 CFR 43.9).
(2) Wing Spar Replacement: For all affected airplanes, replace the wing lower spar cap following Snow Engineering Drawing Number 21088, dated November 3, 2004. Replace upon accumulating the safe life used in paragraph (e)(1) of this AD or within the next 50 hours TIS after [date] (the effective date of this AD), whichever occurs later. The owner/operator may not do the spar cap replacement, unless he/she holds the proper mechanic's authorization.
(f) Inspection Requirements: For all affected airplanes, except Model AT-402A, all serial numbers beginning with 0952, and except Model AT-402B, all serial numbers beginning with 0966: Do the initial inspection of the outboard two lower spar cap bolt holes following Snow Engineering Co. Process Specification #197, page 1, revised June 4, 2002, pages 2 through 4, dated February 23, 2001, and page 5, dated May 3, 2002; and using the wing spar lower cap TIS schedules listed in the following table. After the initial inspection, perform repetitive inspections using the same procedure as the initial inspection at the repetitive inspection intervals listed in the following table. If not already done, install access panels at the time of the first inspection following Snow Engineering Service Letter #202, page 3, dated October 16, 2000.
Note 1: Hours listed in the table are in hours TIS and the phrase “within __ hours” refers to “within __ hours after [date] (the effective date of this AD).”
| Model | Serial Nos. | Current wing spar lower cap TIS hours | Initial inspection | Repetitive inspection interval |
|---|---|---|---|---|
| AT-400 | All beginning with 0416 | Greater than 7,750 | Within 50 hours or upon the accumulation of 8,000 hours, whichever is later | 900 hours. |
| AT-401 | 0662-0951 | Greater than 6,250 | Within 50 hours or upon the accumulation of 6,500 hours, whichever is later | 700 hours. |
| AT-401 | 0662-0951 | Greater than 4,350 but less than or equal to 6,250 | Within 250 hours or upon the accumulation of 4,850 hours, whichever is later | 700 hours. |
| AT-401 | 0662-0951 | Greater than 2,750 but less than or equal to 4,350 | Within 500 hours | 700 hours. |
| AT-401 | 0662-0951 | Less than or equal to 2,750 | Upon the accumulation of 3,250 | 700 hours. |
| AT-401B | 0952-1020 except 1015 | Greater than 3,950 | Within 50 hours or upon the accumulation of 4,200 hours, whichever is later | 600 hours. |
| AT-401B | 0952-1020 except 1015 | Greater than 2,650 but less than or equal to 3,950 | Within 250 hours or upon the accumulation of 3,150 hours, whichever is later | 600 hours. |
| AT-401B | 0952-1020 except 1015 | Greater than 1,600 but less than or equal to 2,650 | Within 500 hours | 600 hours. |
| AT-401B | 0952-1020 except 1015 | Less than or equal to 1,600 | Upon the accumulation of 2,100 hours | 600 hours. |
| AT-401B | 1015 and 1021-1124 | Greater than 4,450 | Within 50 hours or upon the accumulation of 4,700, whichever is later | 400 hours. |
| AT-401B | 1015 and 1021-1124 | Greater than 3,000 but less than or equal to 4,450 | Within 250 hours or upon the accumulation of 3,500 hours, whichever is later | 400 hours. |
| AT-401B | 1015 and 1021-1124 | Greater than 1,850 but less than or equal to 3,000 | Within 500 hours | 400 hours. |
| AT-401B | 1015 and 1021-1124 | Less than or equal to 1,850 | Upon the accumulation of 2,350 | 400 hours. |
| AT-401B | All beginning with 1125 | Greater than 4,450 | Within 50 hours or upon the accumulation of 4,700 hours, whichever is later | 1,000 hours. |
| AT-401B | All beginning with 1125 | Greater than 3,000 but less than or equal to 4,450 | Within 250 hours or upon the accumulation of 3,500 hours, whichever is later | 1,000 hours. |
| AT-401B | All beginning with 1125 | Greater than 1,850 but less than or equal to 3,000 | Within 500 hours | 1,000 hours. |
| AT-401B | All beginning with 1125 | Less than or equal to 1,850 | Upon the accumulation of 2,350 | 1,000 hours. |
| AT-402/4 02A | 0694-0951 | Greater than 4,250 | Within 50 hours or upon the accumulation of 4,500, whichever is later | 700 hours. |
| AT-402/4 02A | 0694-0951 | Greater than 2,850 but less than or equal to 4,250 | Within 250 hours or upon the accumulation of 3,350, whichever is later | 700 hours. |
| AT-402/4 02A | 0694-0951 | Greater than 1,750 but less than or equal to 2,850 | Within 500 hours | 700 hours. |
| AT-402/4 02A | 0694-0951 | Less than or equal to 1,750 | Upon the accumulation of 2,250 | 700 hours. |
(g) For all affected airplanes: Replace any cracked wing lower spar cap following Snow Engineering Drawing Number 21088, dated November 3, 2004, before further flight after the inspection in which cracks are found.
(h) For all affected airplanes, except Model AT-402A, all serial numbers beginning with 0952, and except Model AT-402B, all serial numbers beginning with 0966: Report to the FAA any cracks detected as the result of each inspection required by paragraph (f) of this AD on the form in Figure 1 of this AD.
(1) Only if cracks are found, send the report within 10 days after the inspection required in paragraph (f) of this AD.
(2) The Office of Management and Budget (OMB) approved the information collection requirements contained in this regulation under the provisions of the Paperwork Reduction Act and assigned OMB Control Number 2120-0056.
(i) For all affected airplanes: Upon the accumulation of the life used in paragraph (e)(1) of this AD or within the next 50 hours TIS after [date] (the effective date of this AD), whichever occurs later, you must replace your wing lower spar cap before further flight following Snow Engineering Drawing Number 21088, dated November 3, 2004.
(j) For Model AT-402A airplanes, all serial numbers beginning with 0952; and Model AT-402B airplanes, all serial numbers beginning with 0966: In lieu of the safe life used in paragraph (e)(1) of this AD, you may eddy-current inspect and modify the wing lower spar cap. The inspection schedule and modification procedures are included in Appendix 2 to this AD.
(k) For all affected airplanes (those complying with the actions in the AD or AMOC): One of the following must do the inspection:
(1) A level 2 or 3 inspector certified in eddy current inspection using the guidelines established by the American Society for Nondestructive Testing or MIL-STD-410; or
(2) A person authorized to perform AD work and who has completed and passed the Air Tractor, Inc. training course on Eddy Current Inspection on wing lower spar caps.
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.
