AD/AC/85 Amdt 1 - Flight in Icing Conditions

Overview

The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, serve as the primary legislative framework governing civil aviation safety across the nation. One of the amendments within this extensive regulatory body, specifically under Part 39 - 105, addresses Airworthiness Directives for particular aircraft series, including the Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600, and 700) aeroplanes. This particular directive, AD/AC/85 Amendment 1, was introduced on 7/95 to mitigate the risk of engine flameout during flights in icing conditions for certain aircraft not equipped with an automatic engine ignition relight system as per Gulfstream Aerospace Custom Kit 138 or 139. The objective is to ensure the continued airworthiness and safety of these aircraft by enforcing specific inspection and placarding requirements, as well as updating engine maintenance programs and aircraft flight manuals accordingly. Compliance with this directive must be achieved within 25 hours of the aircraft being in service after 22 June 1995, or before the aircraft is flown into actual or forecast icing conditions, whichever comes first.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105 concerning Airworthiness Directives, mandates specific requirements for Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600, and 700) series aeroplanes, focusing on flight operations in icing conditions. This directive applies to all aircraft models 690, 690A, 690B, 690C, 690D, 695, 695A, and 695B that do not have an automatic engine ignition relight system as per Gulfstream Aerospace Custom Kits 138 or 139. The directive is applicable nationally within Australia and is enforced by the Civil Aviation Safety Authority. It sets forth mandatory inspections and modifications to ensure aircraft safety during flight in icing conditions, including detailed checks on engine ignition units and anti-ice shield assemblies. Non-compliance with these requirements results in a mandatory placard warning pilots against flying in actual or forecast icing conditions, which can only be removed once the specified modifications are completed. This directive also necessitates adjustments to engine maintenance programs and amendments to the Aircraft Flight Manual to incorporate updated ignition system duty cycles.

Key Provisions

The Civil Aviation Regulations 1998, specifically under Part 39 - 105, mandate certain safety directives for Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600 and 700) series aeroplanes to ensure their airworthiness. One such directive, AD/AC/85 Amendment 1, focuses on flight operations in icing conditions for aircraft models that do not have an automatic engine ignition relight system as per Gulfstream Aerospace Custom Kits 138 or 139. This directive applies to all aircraft with specific serial numbers, including 690, 690A, 690B, 690C, 690D, 695, 695A, and 695B. The directive outlines several key requirements. Firstly, it mandates an inspection of both engines to confirm that they meet specific standards: the engine ignition units must comply with AlliedSignal Service Bulletin TPE/TSE331-74-0003 and the anti-ice shield assemblies with TPE/TSE331-75-0004. The part numbers of these components must be logged in both the aircraft log book and each engine log book. Secondly, the configuration details of the ignition unit and anti-ice shield must be made readily available to the flight crew for reference during flight. Lastly, if the inspection reveals non-compliance with the specified service bulletins, a placard must be affixed to the aircraft instrument panel stating in capital letters: "THIS AIRCRAFT IS PROHIBITED FROM FLIGHT INTO ACTUAL OR FORECAST ICING CONDITIONS." This placard must be removed only if the aircraft is modified to include the specified automatic engine ignition relight system or if both engines comply fully with the service bulletins. The obligations imposed by the directive are clear and include ensuring the engines meet specified standards, logging the relevant details, making configuration information available to the flight crew, and affixing a placard in cases of non-compliance. Maintenance programs must also be revised to incorporate these requirements whenever an engine or ignition unit is replaced. Furthermore, if the Aircraft Flight Manual does not already include the Ignition Override Time Limits associated with the ignition unit and anti-ice shield configurations, an approved amendment must be incorporated. Failure to comply with these directives can result in severe consequences. The directive is designed to prevent engine flameouts in icing conditions, which could be catastrophic. While the specific penalties are not detailed within the directive, non-compliance with Civil Aviation Regulations can generally lead to enforcement actions by the Civil Aviation Safety Authority, including fines, enforcement notices, and potential grounding of the aircraft until compliance is achieved. The severity of penalties may depend on the extent and impact of the non-compliance.