AD/DHC-6/8 Amdt 1 - Airspeed Placard Installation and Left Elevator Trim Tab - Inspection

Overview

The Civil Aviation Regulations 1998 were enacted by the Parliament of Australia to regulate and ensure the safety of civil aviation within Australia, thereby addressing the need for comprehensive airworthiness standards and directives. Part 39 - 105 of these regulations, specifically concerning the Civil Aviation Safety Authority's schedule of airworthiness directives for DHC-6 (Twin Otter) Series Aeroplanes, introduces the requirement for specific modifications and inspections to ensure compliance with safety standards. The policy objective is to mandate the installation of an airspeed placard and the inspection and adjustment of the left elevator trim tab, ensuring that these aircraft meet the necessary safety criteria. This legislative instrument, F2006B09162, provides clear directives aimed at maintaining the safety and reliability of DHC-6 series aeroplanes through specified compliance actions.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, mandates that the Airworthiness Directives apply to all DHC-6 (Twin Otter) Series Aeroplanes that do not include the De Havilland of Canada Modification Bulletins 6/1120, 6/1135, and 6/1142. This legislative instrument is enforced by the Civil Aviation Safety Authority (CASA) and has a national reach across Australia, impacting aircraft operators and maintenance personnel within the country. The directive requires immediate compliance for the installation of a specific placard and adjustments to the elevator trim tab assembly, while also mandating a visual inspection of the elevator trim tab skins before each flight. The directive does not explicitly state any exclusions or thresholds but is enforced through subordinate instruments that may further clarify specific implementation details.

Key Provisions

The Civil Aviation Regulations 1998 (Cth), Part 39 – 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives, specifically addresses the DHC-6 (Twin Otter) series aeroplanes with Amendment 1, focusing on airspeed placard installation and the left elevator trim tab inspection (sections 1/68). The primary requirement is the installation of an airspeed placard in full view of the pilot, stating "SPEED SHALL NOT EXCEED 125 KTS, I.A.S." (section 1). Additionally, there are specific instructions regarding the left elevator trim tab assembly. The bolt between the push rod and the elevator tab operating lever must be removed, and the tab cockpit control must be operated until the screw jack in the elevator is fully retracted. After this, the push rod should be adjusted to allow the re-insertion of the bolt in the lowered tab without exerting pressure on the tab (section 2). It is also essential that the total free play measured adjacent to the operating lever with the trim tab in the neutral position does not exceed 0.1 inch at the trailing edge of the tab (section 3). Lastly, a visual inspection of the elevator trim tab top and bottom skins must be conducted to ascertain there is no diagonal buckling or concavity other than manufactured flutes (section 4). Entities governed by these regulations must adhere to strict compliance requirements. For paragraphs 1, 2, and 3, compliance must be achieved forthwith. This means that the airspeed placard must be installed immediately, and the adjustments to the left elevator trim tab must be performed without delay. For paragraph 4, the visual inspection of the elevator trim tab must be conducted before each flight to ensure the safety and airworthiness of the aircraft. Non-compliance with these requirements can lead to severe consequences, including the potential for flight safety risks and regulatory penalties. The Civil Aviation Regulations impose significant obligations on the parties and entities involved. Failure to install the airspeed placard as required, or to perform the necessary adjustments to the left elevator trim tab, could result in a breach of the regulations. Such breaches can lead to enforcement actions by the Civil Aviation Safety Authority (CASA), including the imposition of fines and other penalties. The visual inspection requirement before each flight is a critical safety measure, and failure to conduct it can compromise the safety of the aircraft and its occupants, leading to potential criminal charges and civil liabilities for the responsible parties. In terms of penalties and consequences, the Civil Aviation Regulations do not specify maximum penalties for breaches of the airworthiness directives within the provided text. However, general provisions within the Civil Aviation Act 1988 (Cth) outline that serious breaches of civil aviation safety regulations can result in significant fines and, in some cases, imprisonment. Additionally, non-compliance with airworthiness directives can lead to the grounding of the aircraft, further operational restrictions, and potential revocation of airworthiness certificates, which would severely impact the operational capabilities of the affected entities.