60-24-01 LOCKHEED: Amdt. 222 Part 507 Federal Register November 15, 1960. Applies to All 188 Aircraft.
Compliance required within 5,000 hours' time in service after the effective date of this directive.
To provide protection against possible over-pressurization of fuel tanks during refueling, the following modification is required unless already accomplished:
Install pressure relief overflow valves in each fuel tank. Lockheed overflow valves P/N 634114-7 or -9 are satisfactory for this purpose. (Lockheed Service Bulletin 188/SB-422 covers this subject.)
This directive effective December 13, 1960.