COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Sikorsky S-76 Series Helicopters
AD/S-76/29
Amdt 4
Vertical Pylon Forward Spar 3/94
Applicability: All Sikorsky S-76A helicopters without Sikorsky Modification Kit 76070-20086 (steel straps which reinforce the aluminium cap angles of the vertical pylon forward spar; referred to in Sikorsky Alert Service Bulletin No. 76-55-12).
Requirement: 1. Inspect for cracks in the cap angles, web, and web doubler of the vertical pylon forward spar, and in repairs and reinforcements near the tail rotor shaft cut-out in the vertical pylon forward spar, or near the fuselage shear deck, as follows:
(a) Remove the tail rotor drive shaft fairings near the vertical pylon, exposing the shear deck and vertical pylon forward spar;
(b) Using a clean cloth and a suitable solvent, clean all accessible areas of the spar around the cut-out for the tail rotor drive shaft;
(c) Using a light, visually inspect the forward side of the spar for cracks near where the shear deck attaches to the spar web, and web doubler;
(d) Using a light and mirror, and looking through the tail rotor drive shaft cut-out, visually inspect the aft side of the spar for cracks.
2. Retire from service the cap angles of the vertical pylon forward spar.
Note: FAA ADs 91-08-03 and 91-24-13 refer.
Compliance: 1. Inspect every 50 hours or less.
2. Retire before 1420 hours component time in service. This amendment is effective from 3 March 1994.
Background: The vertical pylon forward spar has a long history of cracking. This directive allows operation for a limited period, with frequent inspections, but eventually the cap angles must be replaced or reinforced before the inspections become unreliable in the face of widespread multiple site fatigue damage. For convenience, the requirements of AD/S76/56 are now included in this directive. The main change introduced in Amendment 4 is the exemption of helicopters fitted with Mod Kit 76070-20086, since Sikorsky’s analysis suggests that the steel spar straps, and the doubler which joins the web and shear deck, should impart a long fatigue life.
The earlier mod kits in Sikorsky Customer Service Notice No. 76-141 have proved unsuccessful, so are not exempt.
Overview
The Civil Aviation Regulations 1998, specifically within Part 39, contains provisions aimed at ensuring the airworthiness of aircraft operating in Australia. One such regulation is AD/S-76/29, introduced in 1994 by the Civil Aviation Safety Authority (CASA), addressing issues related to the structural integrity of the vertical pylon forward spar in Sikorsky S-76 series helicopters. The regulation was enacted to rectify a known problem of cracking in the vertical pylon forward spar, which posed significant safety risks. The policy objective behind AD/S-76/29 is to mitigate these risks through mandated inspections and eventual replacement of the affected components, ensuring that the aircraft remain airworthy and safe for operation. This directive applies to all Sikorsky S-76A helicopters unless they are fitted with a specific modification kit that reinforces the spar, thereby extending the safe operational life of the affected components.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105, encompasses the Civil Aviation Safety Authority's Schedule of Airworthiness Directives, including AD/S-76/29 Amendment 4 for Sikorsky S-76 Series Helicopters. This directive applies to all Sikorsky S-76A helicopters that do not have Sikorsky Modification Kit 76070-20086 installed. The legislation mandates the inspection and subsequent retirement of certain components of the vertical pylon forward spar to ensure the safety and airworthiness of these helicopters. The directive requires regular inspections for cracks in specified parts of the vertical pylon forward spar and mandates the removal of the cap angles of the vertical pylon forward spar from service before they reach 1420 hours of component time in service. Compliance with these requirements involves detailed inspection procedures, including cleaning and visual inspections of the spar using appropriate tools and techniques. This legislation is effective from 3 March 1994 and includes provisions from previous directives, with the notable exemption for helicopters equipped with the specified modification kit, which has been identified as sufficiently mitigating the identified risks.
Key Provisions
The Civil Aviation Regulations 1998, specifically under Part 39, Section 105, contains a schedule of airworthiness directives (AD) which mandate certain actions to be taken for aircraft to ensure their continued airworthiness. One such directive, AD/S-76/29, pertains to the Sikorsky S-76 Series helicopters and is aimed at addressing known structural issues with the vertical pylon forward spar (section 1). This directive applies to all Sikorsky S-76A helicopters that do not have the Sikorsky Modification Kit 76070-20086 installed (section 2). The directive requires two main actions: firstly, a comprehensive inspection of the vertical pylon forward spar for any cracks in the cap angles, web, and web doubler, and in repairs and reinforcements near the tail rotor shaft cut-out or the fuselage shear deck (section 3(a)–(d)). Secondly, it mandates the retirement of the cap angles of the vertical pylon forward spar from service (section 3). These inspections must be conducted every 50 hours or less, and the cap angles must be retired before the component reaches 1420 hours of service time (section 4).
Operators of Sikorsky S-76A helicopters must ensure compliance with these directives to maintain the airworthiness of their aircraft. This involves meticulous inspection protocols as outlined in the directive. Operators must remove the tail rotor drive shaft fairings near the vertical pylon to expose the shear deck and vertical pylon forward spar. They must then clean all accessible areas of the spar using a suitable solvent and a clean cloth, and visually inspect the spar for cracks from both the forward and aft sides (section 3(a)–(d)). Moreover, operators are required to retire the cap angles of the vertical pylon forward spar before they accumulate 1420 hours of service time (section 4). Failure to adhere to these requirements could result in the aircraft being deemed unairworthy, leading to potential grounding of the helicopter.
Breaching the provisions of the AD/S-76/29 could have serious legal and operational consequences. The Civil Aviation Safety Authority (CASA) has the authority to enforce compliance with airworthiness directives. If an operator fails to conduct the required inspections or does not retire the cap angles of the vertical pylon forward spar within the stipulated timeframe, CASA may take enforcement actions. These could include issuing a Notice of Proposed Civil Penalty or initiating legal proceedings. The penalties for non-compliance can be substantial, including fines and potential criminal charges if the non-compliance results in an aviation accident or incident. The specific penalties are determined by the severity of the breach and the potential risk posed to aviation safety. Operators must, therefore, take these directives seriously to avoid the severe consequences associated with non-compliance.