AD/FU24/31 Amdt 1 - Elevator Hinge and Attachment Fittings

Overview

The Civil Aviation Regulations 1998, specifically under Part 39, establish stringent safety standards to ensure the airworthiness of aircraft. Within this framework, Airworthiness Directive AD/FU24/31 Amendment 1 pertains to the FU 24 Series Aeroplanes manufactured by Airparts (NZ) Ltd. This directive was enacted to address the identified problem of cracking and corrosion in elevator hinge and attachment fittings, particularly those with part numbers 242220 and 243008. The policy objective behind this directive is to enhance the safety of in-service aircraft by mandating regular inspections to detect and prevent the onset of structural failures in these critical components. This directive was issued by the Civil Aviation Safety Authority (CASA) and is aimed at ensuring that all affected aircraft are maintained to the highest safety standards, particularly in environments prone to corrosion such as agricultural operations. This directive underscores the importance of maintaining the original protective treatments on these parts to mitigate the risk of intercrystalline corrosion and subsequent structural failure. By specifying inspection intervals not exceeding 500 hours of service time, the directive ensures that the safety of these aircraft is continuously monitored and maintained. The requirement for these inspections remains unchanged since the initial issuance of the directive, with Amendment 1, effective from 20 July 1995, further refining the scope of applicability to aircraft equipped with specific aluminium fittings.

Scope and Application

The Civil Aviation Safety Authority's Schedule of Airworthiness Directives under the Civil Aviation Regulations 1998 governs the airworthiness and maintenance of aircraft within Australian airspace, with a specific focus on ensuring the safety and reliability of air travel. One such directive, AD/FU24/31 Amendment 1, pertains to elevator hinge and attachment fittings for FU 24 Series Aeroplanes manufactured by Airparts (NZ) Ltd. This directive applies to all models equipped with specific elevator hinge fitting and attachment fitting part numbers, specifically part numbers 242220 and 243008, respectively. The directive mandates that these fittings be examined for cracking and corrosion, particularly in critical areas such as rivet holes in the transverse flange and hinge bolt holes. This directive aims to prevent intercrystalline corrosion and subsequent failure due to stress corrosion by emphasising the preservation of original protective treatments on these parts, especially in corrosive environments typical of agricultural aircraft. Compliance with this directive requires inspections at intervals not exceeding 500 hours of time in service. This specific airworthiness directive was prompted by in-service experience of cracking and is effective from 20 July 1995, with Amendment 1 further restricting its applicability to aircraft with aluminium fittings installed.

Key Provisions

The key provisions of this Airworthiness Directive (AD) pertain to the inspection of specific elevator fittings on FU 24 Series Aeroplanes (section 1). This AD applies to all models equipped with elevator hinge fitting part number 242220 and/or elevator attachment fitting part number 243008 (section 1). The main requirement (section 1.1) is that these fittings must be examined for cracking and corrosion, with a particular focus on the rivet holes in the transverse flange for the elevator attachment fittings and the vicinity of the hinge bolt holes for the elevator hinge fittings. This examination is critical to preventing the onset of intercrystalline corrosion and subsequent failures due to stress corrosion, especially in the corrosive environment typical of agricultural aircraft. Compliance with this AD involves conducting the specified inspections at intervals not exceeding 500 hours of time in service (section 1). This directive mandates that the protective treatments on these parts be preserved to mitigate the risk of corrosion and stress-related failures. The directive's initial compliance remains unchanged, and this amendment is effective from 20 July 1995. The impetus for this amendment stems from in-service experiences of cracking in these fittings (Background), which led to a restriction of the directive's applicability to aircraft with aluminium fittings installed. The AD imposes specific obligations on aircraft operators and maintenance personnel to ensure that the required inspections are conducted within the stipulated intervals. These inspections are critical for maintaining the structural integrity of the elevator fittings and preventing potential catastrophic failures. Operators must ensure that the protective treatments are maintained on the fittings, and any signs of cracking or corrosion must be addressed according to the manufacturer's guidelines and any applicable regulatory requirements. Failure to comply with these obligations could result in the aircraft being grounded until the required inspections and repairs are completed. Breach of the requirements outlined in this AD could result in serious safety implications, potentially leading to structural failure of the elevator fittings in flight. The AD does not explicitly state penalties for non-compliance, but non-compliance could lead to enforcement actions by the Civil Aviation Safety Authority (CASA). These actions may include fines, operational restrictions, or other regulatory penalties. The severity of the consequences will depend on the specific circumstances of the non-compliance and the impact on aviation safety. It is imperative for operators to adhere strictly to the inspection intervals and requirements to avoid any adverse outcomes.