64-22-02\tBOEING: Amdt. 816 Part 507 Federal Register September 24, 1964. Applies to Models 707, 720 and 727 Series Aircraft Having Fluorescent Cabin Cove Lights with Day-Ray Ballasts Type 62-37 With Serial Numbers Below 5639, or Servo Mechanism Ballast Type 562859. \n\n\tCompliance required within 50 hours' time in service after the effective date of this AD unless already accomplished. \n\n\tTo prevent overheating of the cove light ballast units, accomplish the following: \n\n\t(a)\tDeactivate all cabin fluorescent cove light systems by securing the circuit breakers for the cove light systems in the off position with a clip-on guard. \n\n\t(b)\tThe cove light systems may be reactivated upon installation of Day-Ray ballasts type 62-37, Serial Numbers 5639 and above, or Servo mechanism ballasts type 563116, or by an equivalent approved by the Aircraft Engineering Division, FAA Western Region. \n\n\tThis directive effective September 24, 1964.