COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Electrical Equipment AD/ELECT/55 Amdt 2 Texas Instruments Circuit Breakers 8/93 Applicability: Texas Instruments three phase circuit breakers models 6TC6-7.5; 6TC6-10; 6TC20- 7.5 and 6TC20-10 date coded 8150 or earlier. Note: Aircraft known to have these circuit breakers installed include, but are not limited to, aircraft manufactured by Boeing Commercial Airplanes and Lockheed Corporation. Requirement: If not previously accomplished inspect the circuit breakers listed above to determine the date code. If the date code is 8150 or earlier, replace the circuit breaker. Note: FAA AD 90-09-10, Boeing SBs 747-24-2135, 757-24-0054, 767-24-0060, and Lockheed SB 093-24-134 refer. Compliance: The Compliance for the previous issue of this Directive was prior to 12 November 1990. Compliance for this issue is prior to 22 October 1993. Background: Some aircraft have experienced inflight fires which have been attributed to overheating of Texas Instruments circuit breakers. Compliance with this AD is considered necessary to prevent potential overheating of these affected circuit breakers which could result in an onboard fire. Amendment 1 to this Directive was issued to correct a typographical error only. Amendment 2 is issued to correct errors in the reference documentation and to clarify the requirement.