64-03-02\tBOEING: Amdt. 681 Part 507 Federal Register February 7, 1964. Applies to All Models 707 and 720 Series Aircraft. \n\n\tCompliance required at the next terminal where adequate facilities and personnel are available but not to exceed 25 hours' time in service after the effective date of this AD, unless already accomplished in accordance with Boeing Alert Service Bulletins Nos. 1964 and 1964A. \n\n\tAs a result of recently discovered cracking in the wing structure accomplish the following inspection external to the wing fuel tanks: \n\n\t(a)\tOn all Models 707-300 and -400 Series aircraft, visually inspect the left and right wing upper rear spar chord for evidence of cracking of the vertical leg of the chord member in the vicinity of wing Station 208. \n\n\t(b)\tOn all Models 707 and 720 Series aircraft, visually inspect the left and right wing upper and lower front spar chord for evidence of longitudinal cracking of the vertical leg adjacent to the fillet between the vertical and horizontal legs of the chord in the vicinity of Wing Station 727 outboard to the production splice station. \n\n\t(c)\tRepair any cracked chord member before further flight, in accordance with technical data approved by the Engineering and Manufacturing Branch, FAA Western Region. \n\n\t(Boeing Alert Service Bulletins Nos. 1964 and 1964A cover this same subject.) \n\n\tThis directive effective upon publication in the Federal Register for all persons except those to whom it was made effective immediately by telegram dated January 24, 1964.