COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/195 Leading Edge Flaps - Prevention of Uncommanded Retraction 2/99 Applicability: Model 747-400 series aeroplanes, having cumulative line number (C/L) 696 through 1090 inclusive. Requirement: 1. For Groups 1 and 2 aircraft as identified in Boeing Service Bulletin 747-27A2356, Revision 1, dated 13 August 1998, replace the cam assembly, cam bellcrank assembly and thrust reverser control switch actuator on all four thrust levers with new components in accordance with the reference Boeing Service Bulletin. 2. For Groups 3 and 4 aircraft as identified in Boeing Service Bulletin 747-27A2356, Revision 1, dated 13 August 1998, replace the cam bellcrank assembly and thrust reverser control switch actuator on all four thrust levers with new components in accordance with the reference Boeing Service Bulletin.. Note: FAA AD 98-24-26 amendment 39-10913 refers. Compliance: Unless already accomplished, within 18 months of the effective date of this Directive. This Airworthiness Directive becomes effective on 25 February 1999. Background: This Directive is issued to mandate actions deemed necessary to prevent the uncommanded automatic retraction of the leading edge flaps during take-off which would seriously degrade lift off and climb capabilities and could result in near stall conditions.