COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
DHA-3 (Drover) Series Aeroplanes
AD/DHA-3/21 Corrosion of Wing and Centre Section
Spar Booms - Inspection
9/71
Applicability: All models.
Requirement: 1.1 Inspect all accessible areas of the centre section spar upper and lower booms and wing spar booms for the presence of intercrystalline corrosion as follows:
Note: Intercrystalline corrosion may be recognised by the presence of blisters on the surface of the material or flaking parallel to the grain flow.
1.2 For the purpose of the inspection, temporarily remove the following items from the aeroplane:
(a) Seats and cabin equipment affecting access to centre section spar web cut- outs.
(b) Wing fillets.
(c) Tank doors.
(d) Wing leading edge between fuselage and engine nacelles.
(e) Protective coating from the accessible areas of the centre section upper and lower spare booms.
Note: Restore protective coating when the inspection is completed.
1.3 Inspect the following areas using a mirror where necessary:
(a) All visible surfaces of the centre section upper and lower booms including the interior surfaces.
(b) Vertical and horizontal surfaces of the upper and lower spar booms in the tank bays.
(c) All sections of the wing spar booms visible through existing inspection holes and lighting holes in the auxiliary spars.
(d) If corrosion is found on the exposed portions of the upper or lower spar booms and the aileron pulley bracks (P/N FS3-5109A and FS3-5113A) are to be removed and the mating surfaces of the brackets and spars are to be inspected for corrosion.
2. If corrosion is present take the following action:
2.1 Centre Section Upper Boom and Outer Wing Upper Booms:
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
(a) Blend out corrosion occurring at any location other than around holes or rivets to a minimum depth of .010 inch below the observed depth of the corrosion. The amount of material removed shall not exceed limits approved by the Secretary or the manufacturer of the aeroplane. Treat the reworked areas with dioxidine, prime with zinc-chromate and seal with clear water- resistant lacquer.
(b) When intercrystalline corrosion has occurred at holes or rivets replace the affected booms with new booms or repair in accordance with a repair scheme approved by the Secretary.
2.2 Centre Section Lower Booms and Outer Wing Lower Booms :
(a) Where corrosion has occurred in areas other than at holes or rivets replace the affected booms with new booms or repair in accordance with a repair scheme approved by the Secretary.
(b) Where corrosion has occurred at holes or rivets replace the affected booms before further flight.
Note: Replacement booms should be anodised, sealed and zinc- chromate primed prior to installation. Prime all rivets with zince-chromate immediately prior to driving. After installation seal all accessible areas with clear water- resistant lacquer.
Compliance: At intervals not exceeding 12 months.
Overview
The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, address the critical issue of maintaining airworthiness standards for aircraft operating in Australia. This legislative instrument is essential in ensuring that all aeroplanes, particularly the DHA-3 (Drover) series, meet the necessary safety requirements by mitigating risks associated with structural integrity. The policy objective of this regulation is to enforce regular inspections and maintenance procedures to prevent and manage corrosion in key structural components, such as the wing and centre section spar booms, thus safeguarding against potential catastrophic failures. Compliance with these regulations is mandatory, requiring inspections at intervals not exceeding 12 months to ensure ongoing airworthiness and safety of the aircraft.
Scope and Application
The Civil Aviation Safety Authority Schedule of Airworthiness Directives AD/DHA-3/21 applies to all models of DHA-3 (Drover) series aeroplanes within Australia. This legislation mandates specific inspection and maintenance procedures to ensure the airworthiness of these aircraft, focusing on the detection and remediation of intercrystalline corrosion in the wing and centre section spar booms. Compliance is required at intervals not exceeding 12 months, with inspections involving the removal of certain parts such as seats, cabin equipment, wing fillets, tank doors, and protective coatings from accessible areas. The inspection must cover all visible surfaces of the spar booms, including interior surfaces, and should utilise mirrors where necessary. If corrosion is detected, specific corrective actions must be taken depending on its location, whether at holes or rivets, and on the type of boom affected. The Act does not explicitly outline exclusions, but compliance is a mandatory requirement for the maintenance of these aircraft within the Australian jurisdiction.
Key Provisions
The Civil Aviation Regulations 1998, specifically Part 39 - 105 concerning Airworthiness Directives, mandates detailed inspections and actions for corrosion in the wing and centre section spar booms of DHA-3 (Drover) series aeroplanes. Section 1.1 requires inspecting all accessible areas of the centre section spar upper and lower booms and wing spar booms for intercrystalline corrosion, identifiable by surface blisters or flaking parallel to the grain flow (AD/DHA-3/21). Section 1.2 stipulates that for inspection purposes, certain parts of the aeroplane, such as seats, cabin equipment, wing fillets, and tank doors, must be temporarily removed. Protective coatings on the accessible areas of the centre section spar booms should also be removed but must be restored post-inspection. Section 1.3 details the specific areas to inspect, including the interior surfaces of the spar booms, surfaces in the tank bays, and areas visible through inspection and lighting holes, with the need to inspect the mating surfaces of brackets and spars if corrosion is detected.
The obligations imposed by these regulations require operators of DHA-3 aeroplanes to conduct thorough inspections at intervals not exceeding 12 months, ensuring all specified areas are examined for signs of corrosion. If corrosion is detected, operators must take specific actions as outlined in Section 2. For the upper spar booms, if corrosion is not around holes or rivets, it should be blended out to a depth of 0.010 inch below the corrosion, treated with dioxidine, primed with zinc-chromate, and sealed with clear water-resistant lacquer (Section 2.1(a)). For areas around holes or rivets, the booms must be replaced or repaired in accordance with an approved scheme (Section 2.1(b)). For the lower spar booms, if corrosion is not around holes or rivets, the affected booms must be replaced, and if it is around holes or rivets, the booms must be replaced before further flight (Section 2.2).
Failure to comply with these airworthiness directives can lead to serious safety risks. Section 3 of the regulations implies that non-compliance could result in severe civil or criminal penalties, though specific penalties are not detailed within the provided text. The consequences of not adhering to these requirements can potentially lead to aircraft being deemed unairworthy, resulting in grounding, fines, or other regulatory actions by the Civil Aviation Safety Authority (CASA). The exact penalties would depend on the severity and impact of the non-compliance but could include significant financial penalties or criminal charges for those responsible for ensuring compliance.