Airworthiness Directives; Viking Air Limited Model (Caribou) DHC-4 and (Caribou) DHC-4A Airplanes; and Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP Series Airplanes

The FAA is correcting typographical errors in three existing airworthiness directives (ADs) that were published in the Federal Register on January 8, 2008 (73 FR 1269); January 7, 2008 (73 FR 1052); and January 7, 2008 (73 FR 1055). The errors resulted in incorrect docket numbers. One AD applies to all Viking Air Limited Model (Caribou) DHC-4 and (Caribou) DHC-4A airplanes. The other two ADs apply to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747- 200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes. The Viking Air AD requires doing a fluorescent penetrant inspection for cracking of certain upper engine mount bracket assemblies, and corrective actions if necessary. One of the Boeing ADs requires revising the FAA-approved maintenance inspection program to include inspections that will give no less than the required damage tolerance rating for each structural significant item, and repair of cracked structure. The other Boeing AD requires implementing a corrosion prevention and control program.