AD/LA-4/10 Amdt 2 - Aircraft Structure - Inspection for Corrosion

Overview

The Airworthiness Directive AD/LA-4/10 Amdt 2 was issued by the Civil Aviation Safety Authority (CASA) in 2005 to address safety concerns identified in the Consolidated Aeronautics, Colonial and LA-4 Series Aeroplanes. This amendment was enacted to rectify a gap in the original AD/LA-4/10 Amdt 1 by updating the referenced requirements document from Service Bulletin No. 25 to Service Letter No. 25, and to mandate more stringent inspections for corrosion in the aircraft structure. This was prompted by an incident where extensive corrosion in an elevator control push rod joint caused a failure in flight, which was not detectable through standard visual inspections. The policy objective behind this directive is to ensure the airworthiness of these aircraft by mandating regular and thorough inspections to prevent structural failures due to corrosion. The AD requires aircraft owners and operators to inspect their aircraft structure in accordance with Lake Aircraft Service Letter No. 25, with a particular focus on inspecting all control system push pull rods for corrosion. The directive specifies that if corrosion is suspected under rivet heads, certain methods should be used to determine the extent of corrosion and the integrity of the joints. If corrosion is found, all affected rivets must be replaced, and the control push rod tube and end fitting must be inspected and repaired as necessary. The AD mandates these inspections to occur within 100 hours of time in service after specific dates and at intervals not exceeding one year, ensuring ongoing compliance with airworthiness standards. This directive became effective on 20 January 2005, reinforcing CASA’s commitment to maintaining high safety standards in aviation.

Scope and Application

The Airworthiness Directive issued under the Civil Aviation Safety Regulations 1998 applies specifically to all models of Consolidated Aeronautics, Colonial, and LA-4 Series Aeroplanes. This legislative instrument mandates that the action outlined in the directive, which is considered necessary to rectify the identified unsafe condition, must be undertaken in accordance with the detailed requirements specified. The directive applies to aircraft structures and control system push-pull rods, necessitating inspections for corrosion as per Lake Aircraft Service Letter No.25 and the replacement of corroded or damaged rivets where necessary. The geographic reach of this directive is nationwide, as it is issued by the Civil Aviation Safety Authority, a Commonwealth authority. Compliance with this directive is mandatory for all applicable aircraft, with inspections mandated within specific intervals after certain dates and under certain conditions. The directive does not specify any exclusions or exemptions, implying that it applies universally to the targeted aircraft models within the stipulated timeframes and conditions.

Key Provisions

The Airworthiness Directive (AD) AD/LA-4/10 Amdt 2, issued by the Civil Aviation Safety Authority (CASA) delegate, primarily mandates specific inspection and maintenance requirements for Consolidated Aeronautics, Colonial, and LA-4 Series Aeroplanes to address corrosion issues. Section (1) of the AD specifies that the aircraft structure must be inspected in accordance with Lake Aircraft Service Letter No. 25. Section (2) requires a detailed inspection of all control system push-pull rods for corrosion, particularly under rivet heads. If corrosion is suspected, Section (2) allows for the use of methods such as attempting to remove rivet heads with a blunt aluminium tool or rotating the control tube while holding the end fitting still to determine if rivet integrity has been lost. Section (3) stipulates the procedure to follow if rivets in any control system push-pull rod need to be replaced, including removing all rivets, inspecting and repairing the control push rod tube and end fitting, and reassembling the control rod in accordance with approved data. Additionally, it is recommended to use a jointing compound during reassembly to protect the rivets from future corrosion. The AD imposes several obligations on the operators and maintainers of these aircraft. Firstly, they must conduct inspections of the aircraft structure in compliance with Lake Aircraft Service Letter No. 25. Secondly, they must inspect all control system push-pull rods for corrosion, and if corrosion is suspected, they must follow the specified methods to determine if rivet integrity has been lost. If any corrosion is found, they must replace the affected rivets and ensure that the control push rod tube and end fitting are inspected, repaired, and reassembled according to approved data. Operators and maintainers must also ensure that inspections are performed within the specified intervals: within 100 hours time in service after 30 April 1974 and thereafter at intervals not exceeding one year, and within 100 hours time in service after 5 November 2003 and thereafter at intervals not exceeding one year. Furthermore, if any rivets are found damaged or corroded, inspections must be conducted without delay. Failure to comply with the requirements of this AD can result in serious safety issues, as the directive aims to correct the unsafe condition identified in previous incidents. While the AD does not explicitly state specific penalties for non-compliance, the CASA delegate has the authority to enforce compliance and may impose administrative or legal actions under the Civil Aviation Act 1988. Non-compliance could potentially lead to enforcement actions, including fines and other civil or criminal penalties, depending on the severity of the breach and its impact on aviation safety. The specific penalties would be determined in accordance with relevant aviation regulations and any applicable civil or criminal laws.