73-17-02: Corrosion of Wing Spars

73-17-02 SLINGSBY: Amdt. 39-1702. Applies to all Model T.51 Dart Gliders which have metal reinforced wing spars. Compliance is required as indicated. To prevent possible loss of wing structural integrity due to corrosion of the wing spars, accomplish the following: Before July 14, 1973, unless already accomplished within the last year, and thereafter at intervals not to exceed one year since the last inspection - (a) Cut seven inspection holes in the lower surface skin of each wing in accordance with Slingsby Technical Instruction No. 58, Issue 1, dated May, 1973, or an FAA-approved equivalent; (b) Visually inspect the metal portion of the spars for corrosion; NOTE: During the inspection required by paragraph (b), particular attention should be directed to the bolted joints and rib attachment areas. (c) If corroded areas are found during an inspection required by paragraph (b), measure the depth of the corrosion in the affected areas; (d) If corrosion is found which exceeds a depth of 0.007 of an inch, before further flight, repair the corroded areas, or replace the corroded parts with serviceable identical parts or FAA-approved equivalent; and (e) Close the inspection holes cut in accordance with paragraph (a). (f) Notification in writing must be sent to the Chief, Aircraft Certification Staff, FAA, Europe, Africa, and Middle East Region, American Embassy, APO New York, N.Y. 09667, stating the results, positive or negative, of each inspection required by this AD, within 10 days after such inspections. (Reporting approved by the Bureau of the Budget under BOB No. 04-R0174). This amendment is effective upon publication in the Federal Register as to all persons except those persons to whom it was made immediately effective upon receipt of the airmail letter dated June 27, 1973, which contained this amendment.