AD/DC4/1 - Vacuum System - Modification

Overview

The Civil Aviation Regulations 1998, as amended by the legislative instrument F2006B08814, introduced specific Airworthiness Directives to ensure the safety and operational integrity of the Douglas DC4 series aeroplanes. Enacted by the Commonwealth of Australia, this regulation targets a critical safety issue concerning the vacuum system of these aircraft. The policy objective is to prevent potential failures in the vacuum system that could compromise the aircraft's operational safety. This legislation mandates the rework of the vacuum system, either by replacing the existing oil separator with a specified Genesco model that includes a pressure relief valve or by installing a fusible plug in the vacuum pump discharge port. The directive aims to standardise modifications across all models of the Douglas DC4 series to ensure consistent safety measures are adhered to.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to Airworthiness Directives issued by the Civil Aviation Safety Authority (CASA) and applies to all persons and entities involved in the operation and maintenance of the Douglas DC4 series aeroplanes. These regulations mandate the modification of the vacuum system to ensure airworthiness and safety, which is applicable nationally within Australia. The directive requires the rework of the vacuum system by either replacing the existing oil separator with a Genesco No. 40081 separator, which includes a pressure relief valve and can be disassembled for cleaning, or by installing a fusible plug in the side of the vacuum pump discharge port. This directive applies to all models of Douglas DC4 series aeroplanes and does not specify any exclusions or exemptions within the provided text. The regulation extends its application through subordinate instruments, such as the FAA AD 49-46-1 and ANO 105.1.16.0.1.1, which provide further detailed instructions and compliance requirements.

Key Provisions

The Civil Aviation Regulations 1998 (CAR), particularly Part 39 - 105, contain the Civil Aviation Safety Authority’s (CASA) Schedule of Airworthiness Directives (AD) for various aircraft models. One such directive, AD/DC4/1, pertains specifically to the Douglas DC4 series aeroplanes and mandates modifications to the vacuum system. According to section 105 of CAR Part 39, all models of the Douglas DC4 series must have their vacuum systems reworked (CAR 39-105). The directive provides two acceptable modifications: either replacing the existing oil separator with a Genesco No. 40081 separator, which includes a pressure relief valve and can be dismantled for cleaning, or installing a fusible plug in the side of the vacuum pump discharge port at right angles to the axis of the discharge port boss. For pumps that have a plugged hole in the discharge port, this can be enlarged to a 3/8 in. NPT tapped hole to accommodate the fusible plug, which should use an AN-840-8D fitting with a binary eutectic mixture of 68 per cent tin and 32 per cent cadmium, melting at 351°F. Operators and owners of Douglas DC4 series aeroplanes are obligated to ensure compliance with these ADs. This involves either replacing the current vacuum system components as specified or installing the requisite fusible plug in the discharge port of the vacuum pump. Such modifications are crucial for maintaining the airworthiness of the aircraft and ensuring the safety of its operation. Furthermore, operators must keep records of all modifications carried out in accordance with the ADs, and these records must be made available for inspection by CASA upon request. Failure to comply with the ADs outlined in CAR Part 39 - 105, specifically AD/DC4/1, can result in significant consequences. Non-compliance with these airworthiness directives may lead to enforcement actions under the Civil Aviation Act 1988. This can include fines and other penalties imposed by CASA. The severity of these penalties can vary depending on the nature and extent of the non-compliance, but they underscore the importance of adhering to the specified modifications to ensure the safety and airworthiness of the aircraft.