COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES PZL 104 (Wilga) Series Aeroplanes AD/WILGA/2 Stall Warning System 2/95 Applicability: All PZL-104 `Wilga 80' aircraft. Requirement: Install a guard on the Stall Warning System automatic switch in accordance with PZL-Warszawa-Okecie Mandatory Service Bulletin 10493023. Note: This Service Bulletin has been classified as Mandatory by the General Inspectorate of Civil Aviation Poland. Compliance: Prior to 1 August 1995. Background: This Directive introduces measures whereby the Stall Warning System cannot be inadvertently switched off, preventing the operation of the acoustic warning horn.