COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 170, 172, F172, FR172 and 175 Series Aeroplanes AD/CESSNA 170/19 Amdt 1 Pneumatic Stall Warning System 6/83 Applicability: All models with pneumatic stall warning systems not incorporating horn reed assembly P/N 0413483-2, P/N 0713348-1 or subsequent and protective screens over the horn bell and stall warning system opening on the left wing. Requirement: 1. Check the pneumatic stall warning system for correct operation by applying a slight suction with the mouth at the stall warning opening in the left wing. A properly functioning horn will provide a sound that is clearly audible. It may be advisable to first cover the opening with a clean piece of cloth. Cessna 100 Series Service Manual 1963 to 1967 Section 16 refers. Note: This check may be performed and certified by the pilot. 2. Install the following placard in full view of the pilot: "PRE-FLIGHT TEST THE PNEUMATIC STALL WARNING SYSTEM". 3. The requirements of paragraphs 1 and 2 may be removed by incorporation of the following modifications. Replace the stall warning reed assembly P/N 0413028-1 with reed assembly P/N 0413483-2, P/N 0713348-1 or subsequent and install an 18 x 14 or 18 x 16 mesh screen over the exposed horn bell inside the cabin and over the left wing opening. Flight test the aircraft to assure the stall warning horn sounds at 5 to 10 knots above the stalling speed. Compliance: For para. 1 - Before each flight. For para. 2 - Within 25 hours time in service after 3 September 1968. Background: This amendment reflects latest Cessna Part Number change.