AD/AL 250/49 - N2 Overspeed Control System - Disarming

Overview

The Civil Aviation Regulations 1998, enacted by the Australian Government, play a crucial role in ensuring the safety and regulation of civil aviation activities within Australia. Specifically, Part 39 - 106 of these regulations concerns the Civil Aviation Safety Authority's (CASA) schedule of airworthiness directives. One such directive, AD/AL 250/49, addresses the issue of N2 overspeed control system disarming in Allison Turbine Engines of the 250 series, particularly the Allison 250-C28B. This directive was introduced to mitigate the risk of intermittent and spurious activations of the N2 overspeed control system, which could potentially lead to engine spooling down during flight. The policy objective is to enhance the safety of aircraft operations by ensuring that such incidents do not recur, thereby maintaining the integrity of flight operations. This directive mandates compliance with specific technical bulletins or FAA airworthiness directives to prevent further instances of N2 overspeed control system-related issues post 2 March 1982. CASA’s role in issuing these directives ensures that all stakeholders adhere to the necessary safety standards, thereby upholding the high safety benchmarks required in the aviation industry.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 – 106, which pertains to the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, applies to the Allison 250 Series turbine engines, particularly the Allison 250-C28B model. The regulation mandates compliance with the directives outlined in specific engine bulletins or Federal Aviation Administration (FAA) Airworthiness Directives, such as the Detroit Diesel Allison Commercial Engine Bulletin 250-C28B CEB-A-73-2020 or the FAA AD 82-03-02 Detroit Diesel Allison Amendment 39-4305. These directives must be adhered to before any further flight operations are conducted after 2 March 1982, in response to incidents where the N2 Overspeed Control System caused unexpected power reductions or shut-downs during flight. This regulation is intended to ensure the continued safety and airworthiness of the Allison 250-C28B engines by addressing the identified issues with the N2 Overspeed Control System.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 106, address the scheduling of airworthiness directives. Section AD/AL 250/49 pertains to the N2 Overspeed Control System for Allison 250 Series turbine engines. This section mandates that operators of Allison 250-C28B engines comply with certain directives to prevent issues such as spooling downs in flight caused by the N2 Overspeed Control System. The applicable documents for compliance are either Detroit Diesel Allison Commercial Engine Bulletin 250-C28B CEB-A-73-2020 or FAA AD 82-03-02 Detroit Diesel Allison Amendment 39-4305. Compliance is required before any further flight after 2 March 1982. The obligations imposed on the parties governed by this directive are stringent. Operators of Allison 250-C28B engines must ensure that the N2 Overspeed Control System is correctly configured and functioning as intended. This involves following the specific instructions outlined in either the referenced commercial engine bulletin or the FAA amendment. The aim is to prevent any spurious activation of the system that could lead to power reductions or shut-downs during flight, thereby ensuring the safety and reliability of the aircraft. Operators must also maintain records of compliance and any actions taken to address the issue, ensuring that all flights are conducted in accordance with the directive. Failure to comply with the requirements set out in the Civil Aviation Regulations 1998 can result in significant penalties and consequences. If an operator fails to adhere to the provisions of AD/AL 250/49, they may face enforcement actions by the Civil Aviation Safety Authority (CASA). Potential outcomes include fines, orders for corrective action, or even suspension or revocation of the aircraft’s airworthiness certificate. In severe cases, where non-compliance leads to an incident or accident, criminal charges may be brought against the operator or responsible individuals, leading to imprisonment or substantial fines. The specific penalties depend on the nature and severity of the breach, but the overarching intent is to ensure strict adherence to safety standards to protect passengers and crew.