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. Gippsland Aeronautics GA8 Series Aeroplanes AD/GA8/11 Solenoid (Relay) Box Electrical Bonding 24/2023 Applicability: GA8 aircraft - all serial numbers up to and including GA8-20-262. GA8-TC 320 aircraft - all serial numbers up to and including GA8-TC 320-20-261. Requirement: Accomplish the requirements of Gippsland Aeronautics mandatory service bulletin SB-GA8-2023-216 Issue 1, dated 24 February 2023, as in force at the date of this AD. Compliance: Unless previously accomplished, within 100 hours flight time or 12 months, whichever occurs first, from the effective date of this AD. Effective date This AD commences on 23 December 2023. Background: Operators have reported intermittent system discrepancies that have been attributed to poor electrical bonding of the solenoid (relay) box assembly. GA8 aircraft without a dedicated solenoid box electrical bonding connection may suffer degraded performance, errors, or intermittent failures of equipment connected to electrical Bus 1, Bus 2, associated electrical control, and protective devices fitted within or attached to the solenoid box. For the majority of GA8 and GA8-TC 320 aircraft manufactured before July 2019 the solenoid box assembly was electrically bonded to the aircraft through the solenoid box attachment screws. Aircraft produced after July 2019 should be fitted with a dedicated electrical bonding connection. David Punshon Delegate of the Civil Aviation Safety Authority 21 November 2023