AD/MU-2/40 - Placard - Use of Reverse Thrust

Overview

The Civil Aviation Regulations 1998, specifically Part 39 - 105, were enacted by the Australian Government to regulate civil aviation safety and ensure compliance with international standards. This legislative instrument, known as Airworthiness Directive AD/MU-2/40, was introduced to address the specific safety issue related to the Mitsubishi MU-2 series aeroplanes fitted with Garrett TPE-331 turboprop engines and Hartzell model HC-B4(T,M)N-5 propellers. The problem this directive sought to resolve was the failure of the pitch change rod P/N B-3018S-2 in these propellers, which occurred during ground operation when full reverse pitch was applied. Such failures could lead to severe asymmetric thrust conditions or engine overtemperature, posing significant safety risks. The policy objective of this directive, as stipulated in the Civil Aviation Regulations, is to mandate the installation of a placard in the cockpit of affected aircraft to warn pilots against using full reverse pitch until the propellers are modified to Hartzell SB 153 specifications. Compliance with this directive was required by 30 October 1987, ensuring that operators of these aircraft were promptly informed of the necessary safety measures to mitigate the identified risks.

Scope and Application

The Civil Aviation Regulations 1998, under Part 39 - 105, specifically addresses the airworthiness directives for Mitsubishi MU-2 Series Aeroplanes, particularly those equipped with Garrett TPE-331 turboprop engines and Hartzell model HC-B4(T,M)N-5 propellers. This legislation applies to all such aircraft, mandating the installation of a temporary placard in the cockpit to caution pilots against using full reverse pitch until the propellers are modified in accordance with Hartzell Service Bulletin 153. This directive is aimed at preventing failures of the pitch change rod, which have been noted during ground operations when full reverse pitch is applied, potentially leading to severe asymmetric thrust conditions or engine overtemperature. Compliance with this airworthiness directive is required by 30 October 1987, ensuring that all affected aircraft meet the specified safety standards. The jurisdictional reach of these regulations is nationwide, overseen by the Civil Aviation Safety Authority, ensuring uniform application across the Commonwealth of Australia. This legislation does not specify any exclusions or exemptions, and compliance is mandatory for all relevant aircraft operators within the designated timeframe.

Key Provisions

The Civil Aviation Regulations 1998, under Part 39 - 105, establish the Civil Aviation Safety Authority's (CASA) schedule of airworthiness directives for various aircraft types, including the Mitsubishi MU-2 series aeroplanes. One such directive, AD/MU-2/40, pertains to the use of reverse thrust on MU-2 aeroplanes fitted with specific turboprop engines and propellers. According to this directive (section 10/87 DM), all MU-2 models equipped with Garrett TPE-331 turboprop engines and Hartzell model HC-B4(T,M)N-5 propellers must comply with certain safety measures. The directive requires the installation of a temporary placard in a conspicuous location within the cockpit. This placard must contain the following wording: “Until propellers are modified to Hartzell SB 153, avoid the use of full reverse pitch” (section 10/87 DM). This measure is aimed at preventing potential hazards associated with the use of full reverse pitch, which has been linked to failures in the pitch change rod. Specifically, such failures have occurred during ground operations when full reverse pitch was applied, potentially leading to severe asymmetric thrust conditions or engine overtemperature situations. Entities governed by these regulations, particularly operators and maintenance providers of Mitsubishi MU-2 aeroplanes, must ensure compliance with the directive by installing the required placard by the specified date of 30 October 1987. Failure to adhere to this requirement may result in safety risks and potential regulatory action. Operators must also ensure that pilots are aware of the placard's message and understand the operational limitations it imposes until the propellers are modified. Non-compliance with the airworthiness directive could lead to serious consequences. Under the Civil Aviation Act 1988, CASA has the authority to enforce these regulations and can impose penalties for breaches. The maximum penalties for non-compliance can include substantial fines and, in severe cases, prosecution under civil or criminal law. Such enforcement actions are intended to maintain the high safety standards expected in civil aviation operations, ensuring the safety of all personnel and passengers involved.