47-27-02 DOUGLAS: (Was Service Note 4 of AD-762-7.) Applies to All C-54-DC Series and DC-4 Airplanes. \n\n\tInspection required at intervals not to exceed 170 hours. \n\n\tOpen the quick-opening type inspection doors in the bottom of the outer wing and center wing section surfaces forward of the front spar and aft of the center spar. Inspect spar web structure for loose rivets, cracks, or other irregularities. Pay particular attention in the fuel tank areas for evidence of fuel leaks which will indicate cracked spar webs or rivets and seam leaks. \n\n\tAll spar web cracks which are found after accomplishment of AD 46-27-01 (Service Bulletin C-54-205. "Rework - Integral Fuel Tanks") or cracks that are located in areas to which the Service Bulletin C-54-205 does not apply, should be repaired in accordance with Douglas Drawing No. 5354811, "Service Rework-Station 463, Outer Wing, Center Spar", and No. 3344236, "Repair-Integral Tank Spar Web Crack". \n\n\tRevised March 21, 1961.