COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 737 Series Aeroplanes AD/B737/60 Crew Call Horn 7/91 Applicability: All model 737 series as listed in the Requirement Document. Requirement: Action in accordance with the Technical Requirements of FAA AD 91-09-05. Note: SB 737-23-1059 also refers. Compliance: Prior to 30 November 1991. Background: This AD is prompted by reports of overheated printed circuit cards caused by horn failures. This condition, if not corrected, could result in damage to adjacent circuitry, smoke and possible fire.