COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Embraer EMB-120 (Brasilia) Series Aeroplanes AD/EMB-120/3 Amdt 1 Autopilot Disengagement Logic 12/91 Applicability: As detailed in the requirement document. Requirement: Action in accordance with the technical requirements of Brazilian AD 91-03-02 R2. Compliance: Parts I and II of the requirement document must be actioned in accordance with the original issue of this AD which required compliance within 300 hours time in service after 2 April 1991, or prior to 13 August 1991. Part III of the requirement document must be complied with prior to 31 December 1991. Background: Advice has been received of an elevator trim runaway during descent which caused a deep pitch down of the aeroplane. As a result, the crew experienced great difficulty maintaining control of the aircraft. This AD introduces a modification which will allow the crew to quickly disconnect power from the affected servo motor by disengaging the autopilot when the "AP DISCONNECT" button is activated. Note: Amendment 1 to this AD is issued to require compliance with Part III of Brazilian AD 91-03-02R2 which was introduced with Revision 2 to the Brazilian AD.