COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pilatus PC-12 Series Aeroplanes AD/PC-12/22 Electrical Power - Suppression Filters 13/99 TX Applicability: All Model PC-12 and PC-12/45 with Manufacturers Serial Numbers MSN 101 up to and including MSN 289. Requirement: 1. Remove suppression filter (A250) part number (P/N) 524.52.12.358 and install suppression filter (A250) P/N 524.52.12.502 in accordance with Pilatus PC-12 Service Bulletin (SB) No.24-014 dated 27 October 1999. Note: The new suppression filter can be positively identified by the part number and a black placard with a yellow A250 marked on it. 2. Perform system test in accordance with Pilatus PC-12 SB No.24-014 paragraph 3(D). Note: FOCA Switzerland AD HB 99-542 refers. Compliance: 1. Within the next 10 flights after the effective date of this directive. 2. Prior to further flight after Requirement 1. This Airworthiness Directive becomes effective on 8 November 1999. Background: After installation of SB 24-012 and electrical power activation, circuit breaker CB 235, which protects the GEN 2 circuit, tripped. Investigation revealed the suppression diode in the suppression filter (A250) P/N 524.52.12.358 was shorted. The diode is not capable of carrying the operational loads in this installation and can melt, resulting in a short circuit. Overheat damage to electrical wiring can result.