COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 550 (Citation II) Series Aeroplanes AD/CESSNA 550/15 Amdt 1 Flap Drain Holes 10/88 Applicability: S550 and 552 S/N S550-0001 to S550-0153 and 552-0001 to 552-0017. Requirement: 1. Action in accordance with Cessna Service Letter SLA S550-57-01. 2. Repairs, if necessary, in accordance with Cessna SB S550-57-5. Note: FAA AD 88-11-07 refers. Compliance: 1. Prior to further flight after 13 June 1988. 2. Must be accomplished prior to further flight for aeroplanes identified as having no drain holes or obstructed drain holes in the flaps by Service Letter SLA S550-57-01. Background: There has been an incident where the outboard flap shattered in flight. Investigation revealed that the flap had no drain/vent holes which led to pressurization at altitude. Subsequently, other flaps have been found without drain/vent holes. Amendment 1 states SB that provides repair instructions and spares stock affected.