AIRWORTHINESS DIRECTIVE On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001 (1) of CASR. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct an unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section. Swift Museum Foundation GC-1A and GC-1B Series Aeroplanes AD/GC-1/2 Main Landing Gear Retraction 18/2020 System - Inspection Applicability: All Swift Museum Foundation GC-1A and GC-1B model aircraft. Requirement: 1. Inspect the main landing gear retraction system to determine that adjustments are as follows: a. When the side brace is against the down stop the middle joint is 1/8 inch to 1/4 inch above dead centre (3/16 inch to 5/16 inch when measured from edges of links in accordance with Globe Customer Service Maintenance Bulletin No. 7, as in force from time to time). b. When the side brace is against the down stop and the down lock plunger is fully extended, covering at least 1/2 of the adjustment screw head, the clearance between the plunger and the screw head is from 0.001 inch to 0.005 inch. c. When the side brace is against the down stop the limit switch plunger is depressed approximately 1/32 inch beyond the cutoff point. d. The turnbuckle in the emergency extension cable is positioned so that on manual extension of the gear, both down locks operate before the handcrank has been wound to the full down position. After it has been determined that the turnbuckle position is satisfactory in this respect it should be determined that with the handcrank wound to the full up position the cable length is sufficient to permit the up limit switches to cut off. Note 1: United States of America Federal Aviation Administration (FAA) AD 47‑06‑01 is the source document for the requirements of this AD. Note 2: The words "as in force from time to time" require compliance with the most recent version of the referenced document. Compliance: 1. Unless previously accomplished, within 6 months after the commencement date of this AD and thereafter at intervals not to exceed 100 hours' time in service. This AD commences on 17 September 2020. Background: An audit of the Australian Aircraft Register found that Swift Museum Foundation GC-1B aircraft have been on the register for some time and that requirements equivalent to the applicable FAA ADs have not previously been mandated in Australia for these aircraft. This AD is issued to mandate requirements equivalent to FAA AD 47-06-01. Pieter van Dijk Delegate of the Civil Aviation Safety Authority 25 August 2020