AD/DHC-3/20 - Mixture Control Lever Quadrant

Overview

The Civil Aviation Safety Authority (CASA) issued the Civil Aviation Regulations 1998, which include Part 39 - 105, to ensure the safety of civil aviation in Australia. This legislative instrument, specifically the Airworthiness Directive AD/DHC-3/20, addresses the problem of inadequate mixture control lever quadrant markings on DHC-3 (Otter) Series Aeroplanes, which can lead to operational errors. The directive mandates that the mixture control lever quadrant be clearly marked to indicate the "LEAN" and "CUT-OFF" positions, ensuring that pilots can operate the aircraft safely and efficiently. The policy objective behind this directive is to enhance aviation safety by preventing misunderstandings or misoperations of the mixture control lever, which can have serious consequences during flight. Compliance with this directive is required forthwith, ensuring that all applicable aircraft are updated to meet these safety standards as a matter of urgency.

Scope and Application

The Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998, specifically within Part 39 - 105, applies the Airworthiness Directives to DHC-3 (Otter) series aeroplanes. This directive mandates that all models of the DHC-3 series must have their mixture control lever quadrants marked to clearly indicate two specific positions. The first position is the minimum lean position, which must be designated as "LEAN", and the second is the rearmost position, which must be designated as "CUT-OFF". This directive applies to all DHC-3 series aeroplanes, ensuring a uniform standard of safety across the fleet. The requirement to comply with these directives is immediate, necessitating that the specified markings are made forthwith. This legislation, while focusing on a specific aircraft model, forms part of the broader regulatory framework designed to enhance aviation safety across the Commonwealth of Australia.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, establishes the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives. Within this, AD/DHC-3/20 pertains to the DHC-3 (Otter) Series aeroplanes and mandates a specific marking on the mixture control lever quadrant (sections 2/64). According to the directive, the mixture control lever quadrant must be marked to clearly indicate two positions: the "LEAN" position and the "CUT-OFF" position. The "LEAN" position is defined as the rear-most position of the mixture control lever that does not engage the idle cut-off valve. Compliance with this directive is required forthwith. The obligations imposed by this directive include ensuring that all DHC-3 (Otter) Series aeroplanes have their mixture control lever quadrants appropriately marked. This involves identifying and clearly indicating the minimum lean position as "LEAN" and the rearmost position as "CUT-OFF". The directive mandates that these markings must be visible and unambiguous to the pilots, ensuring that they can easily identify these critical positions during flight operations. Failure to comply with the requirements set out in AD/DHC-3/20 could lead to significant consequences. While the specific penalties for non-compliance are not detailed in the text provided, breaches of airworthiness directives typically result in enforcement actions by CASA. Such actions may include fines, orders to rectify the non-compliance, or in severe cases, grounding of the aircraft until compliance is achieved. The potential penalties underscore the importance of adhering to these safety directives to maintain the airworthiness of the aircraft and ensure the safety of all persons on board.