AD 83-18-01

83-18-01 AIR TRACTOR: Amendment 39-4717. Applies to Model AT-300, AT-301, AT-302 (Serial Numbers 0001 through 0240) airplanes certificated in any category.

Compliance: Required as indicated, unless already accomplished.

To prevent failure of the vertical fin front spar fuselage attach fittings, accomplish the following:

a) On airplanes having less than 2,000 hours time-in-service on the effective date of this AD, within the next 25 hours time-in-service, or 100 hours time-in-service since the last inspection per Snow Engineering Company Service Letter No. 26, dated February 2, 1978, whichever occurs later, and within each 100 hours time- in-service thereafter, inspect the vertical fin front spar fuselage attach fittings using dye penetrant procedures at the locations specified in Snow Engineering Company Service Letter No. 26, dated February 2, 1978.

b) On airplanes having more than 2,000 hours time-in-service on the effective date of this AD within the next25 hours time-in-service, or 50 hours time-in-service since compliance with paragraph a), or the last inspection per Snow Engineering Company Service Letter No. 26 dated February 2, 1978, whichever occurs later, and each 50 hours time-in-service thereafter, inspect the vertical fin front spar fuselage attach fittings using dye penetrant procedures at the locations specified in Snow Engineering Service Letter No. 26, dated February 2, 1978.

c) Prior to further flight, replace any cracked fittings found during the inspections required by paragraphs a) and b) of this AD with a new 10398-3 fitting in accordance with Snow Engineering Company Service Letter No. 47, dated February 12, 1983.

d) On or before December 31, 1983, or upon reaching 2,000 hours time-in-service, whichever occurs later, replace existing sheet metal vertical fin front spar fuselage attach fittings with a new part number 10398-3 fitting, in accordance with Snow Engineering Company Service Letter No. 47 dated February 12, 1983.

e) The other requirements of this AD are no longer required when the 10398-3 fittings are installed.

f) The interval between the repetitive inspections required by this AD may be adjusted up to 10 percent of the specified interval to allow accomplishing these inspections concurrent with other scheduled maintenance of the airplane.

g) Airplanes may be flown in accordance with FAR 21.197 to a location where this AD can be accomplished.

h) Any equivalent means of compliance with this AD may be used, if approved, by the Manager, Aircraft Certification Division, ASW-100, FAA, P.O. Box 1689, Fort Worth, Texas 76101.

This amendment becomes effective on September 6, 1983.