COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES FLS Aerospace OA7 Optica Series Aeroplanes AD/OPTICA/3 A51 Fan Replacement 13/94 DM Applicability: All model OA7 Optica series aircraft. Requirement: Action in accordance with Brookland Aerospace Mandatory SB No 0A7/SB/0042 Issue 1. Note: UK CAA AD 004-05-90 refers. Compliance: Prior to issue of Certificate of Airworthiness. Background: FLS Aerospace (Lovaux) Light Aircraft Division has advised that the A51 fan originally fitted to the OA7 Optica has suffered fatigue failure due to the fundamentally flawed design of the fan assembly. The A51 fan is therefore considered unsuitable for use on the aircraft.