61-19-01\tBOEING: Amdt. 332 Part 507 Federal Register September 14, 1961. Applies to All Model 720 Series Aircraft Which Have Not Previously Been Modified By Installation of Micro P/N 5EN11-6B. \n\n\tCompliance required as indicated. \n\n\tFaults occurring in the fuel dump chute safety switch of the retractable dump chute system have caused burning of the lead wires at the switch and, in one case, caused a fuel dump valve to cycle open and close allowing fuel to enter the fuel dump manifold and leak out through the dump chute secondary seal. To prevent this, the following inspection and modification shall be accomplished: \n\n\t(a)\tCommencing within 10 days after the effective date of this AD unless the lead wire insulation has been reinforced by wrapping with suitable electrical tape at the switch, conduct daily inspections of the fuel dump chute safety switch (Micro P/N 5EN11-6) to determine if the wires are burned or charred where they protrude. If wires are found burned or charred,prior to further flight replace safety switch with improved type Micro P/N 5EN11-6B, after which the daily inspection can be discontinued.\n \n\t(b)\tUnless already accomplished in accordance with paragraph (a), within the next 350 hours' time in service after the effective date of this AD, replace fuel dump valve safety switches Micro P/N 5EN11-6 with switch Micro P/N 5EN11-6B, using standard Boeing Maintenance Manual procedures. Upon installation of switch Micro P/N 5EN11-6B the daily inspection required by (a) can be discontinued. \n\n\t(c)\tUpon request of the operator, an FAA maintenance inspector, subject to approval of the Chief, Engineering and Manufacturing Branch, FAA Western Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator. \n\n\t(Boeing Service Bulletin No. 1305, dated May 22, 1961, covers thismodification.) \n\n\tThis directive effective September 14, 1961.