COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Aerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes AD/TB20/36 Propeller Governor Control 13/99 Applicability: TB20 aircraft, S/Nos. 1899, 1904 through 1909, TB21 aircraft, S/No 1911, and all TB20 and TB21 aircraft fitted with a propeller governor control delivered by SOCATA between 22 March 1999 and 31 August 1999. Requirement: Replace affected propeller governor controls in accordance with SOCATA mandatory Service Bulletin No. SB 10-112-61 dated August 1999. Note: DGAC AD 1999-386(A) also refers. Compliance: No later than 31 January 2000. This Airworthiness Directive becomes effective on 30 December 1999. Background: This directive is prompted by advice that faulty propeller governor controls have been released to the field. Failure of a non conforming control will lead to jamming of the propeller governor.