67-23-02\tBOEING: Amdt. 39-462, Part 39, Federal Register August 11, 1967. Applies to Model 707 and 720 Series Airplanes, except 707-300B and -300C Series. \n\n\tCompliance required within the next 7,000 hours' time in service after the effective date of this AD unless already accomplished. \n\n\tTo prevent explosion of fuel vapors in the fuel tanks as a result of lightning-induced ignition at the fuel tank vent outlet, accomplish one of the following, or an equivalent, approved by the Chief, Aircraft Engineering Division, FAA Western Region \n\n\t(a)\tInstall a flame and explosion suppression system in the fuel tank vent outlet system to prevent flame propagation through the vent system following ignition of vapor by lightning at the vent outlet; or \n\n\t(b)\tInstall an auxiliary vent tube with flame arrester, to the vent system surge tank to provide, during flight, continuous airflow inward through the existing outlet and outward through the protected auxiliary tube. \n\n\tThis amendmenteffective September 10, 1967.