COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Gates Learjet 24 & 25 Series Aeroplanes AD/LEARJET/5 Airspeed - Machmeter Indicator Presentation - Modification Applicability: Learjet Model 24D S/Nos. 266 and 279. 6/74 Requirement: Inspect and where necessary modify airspeed-machmeters to ensure that the Vmo limit is marked on the dial either by a red radial line at 306 knots for instruments without coloured sectors, or by a red arc extending from 306 knots to 700 knots for instruments with coloured sectors. All other limit marks or coloured sectors above 306 knots shall be removed. Note 1: Arrange with DoT to amend the Aircraft Flight Manual to comply with the aircraft installation if any change is necessary. Note 2: If the airspeed-machmeters have presentations identical to that shown on the Gates Learjet 24D Flight Manual Page 1-16 FAA-approved 6.25.70 Change 7, this page will be used in the Flight Manual. Such a presentation is without coloured sectors and has radial red lines at 306 knots and at .82 mach. Compliance: Within 300 hours time in service after 28 June 1974.