AD/F50/21 - Forward Fuselage - Stringers and Frame 5775

Overview

The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority, are designed to ensure the safe operation of aircraft within Australia. Specifically, Part 39 - 105 of these regulations contains Airworthiness Directives aimed at maintaining and enhancing the safety of civil aviation. One such directive, AD/F50/21, was introduced to address a safety concern identified in Fokker F50 (F27 Mk 50) Series Aeroplanes, where full-scale fatigue testing revealed a potential for cracks in the forward fuselage due to insufficient connection between the frame and stringers. The directive mandates that these connections be reinforced by installing connecting angles as specified in Fokker Service Bulletin F50-53-004, dated 14 October 1988, to ensure compliance before the aircraft accumulates 10,000 flight cycles. This policy objective is to mitigate the risk of structural failure, thereby enhancing the overall safety of the affected aircraft.

Scope and Application

The Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives under the Civil Aviation Regulations 1998 applies specifically to Fokker F50 (F27 Mk 50) series aeroplanes identified by certain serial numbers, namely 20103 through 20108 and 20110 through 20121. The requirement outlined in this directive mandates the reinforcement of the fuselage frame to stringer connection by installing connecting angles, as specified in Fokker Service Bulletin F50-53-004 dated 14 October 1988, to address the identified risk of cracks due to insufficient connection strength. This directive must be complied with prior to the aircraft accumulating 10,000 flight cycles. The directive is a national measure enforced by CASA and applies throughout Australia, ensuring that the specified modifications are implemented to maintain the airworthiness of the affected aircraft. The directive references Netherlands AD 88-81, indicating alignment with international standards and practices in addressing the identified safety concern.

Key Provisions

The Civil Aviation Regulations 1998, specifically in Part 39 - 105, under the Civil Aviation Safety Authority's schedule of airworthiness directives, addresses the Fokker F50 (F27 Mk 50) series aeroplanes through AD/F50/21. This directive pertains to the forward fuselage, focusing on stringers and frame 5775 (Section 1). The requirement outlined in this directive mandates the reinforcement of the fuselage frame to stringer connection by installing connecting angles in accordance with Fokker Service Bulletin F50-53-004 dated 14 October 1988 (Section 2). This reinforcement is crucial to prevent potential cracks that may occur due to insufficient connections in the specified area, as indicated by full-scale fatigue testing (Section 3). The obligations imposed by this directive are primarily on the operators of Fokker F50 series aeroplanes within the specified serial number range (20103 through 20108 and 20110 through 20121) (Section 4). These operators must ensure that the required reinforcement is completed prior to the aircraft accumulating 10,000 flight cycles (Section 5). This directive is informed by the Netherlands AD 88-81, which likely provided the impetus for the structural improvements recommended by Fokker (Section 6). Failure to comply with the airworthiness directive AD/F50/21 may result in significant legal consequences. Civil penalties can be imposed under the Civil Aviation Act 1988 for non-compliance with airworthiness directives, and in severe cases, criminal penalties may apply, depending on the circumstances and the extent of the non-compliance (Section 7). The maximum penalties for such breaches can include substantial fines and, in cases of criminal negligence, imprisonment (Section 8). These penalties underscore the importance of adhering to the directive to ensure the safety and airworthiness of the Fokker F50 series aeroplanes.