Overview

The Airworthiness Directive AD/ENST 28/38, issued under the Civil Aviation Act 1988, was enacted to address safety concerns identified in the main rotor hub plates of Enstrom F-28 Series Helicopters. This legislative instrument aims to ensure that the specified hub plates are replaced after accumulating 5,000 hours of service, thereby mitigating the risk of hub plate failure, loss of control of the main rotor, and subsequent loss of control of the helicopter. The directive was issued by the Civil Aviation Safety Authority (CASA) in response to a reliability-based stress analysis conducted by the Federal Aviation Administration (FAA) in the United States, which prompted the imposition of a 5,000-hour life limit on certain hub plates to prevent unsafe conditions. The policy objective of this directive is to enhance aviation safety by enforcing stringent maintenance protocols for critical components of helicopters.

Scope and Application

The Airworthiness Directive issued by the Civil Aviation Safety Authority (CASA) applies specifically to the Enstrom F-28 Series helicopters, namely the TH-28 and 480 models, that are equipped with particular main rotor hub plates, specifically part numbers 28-14280-1 and 28-14281-1. This directive mandates that operators of these aircraft must create a detailed component history card or equivalent record for these hub plates and track their total hours in service. The directive sets a life limit of 5,000 hours for these hub plates, after which they must be replaced with specified new part numbers depending on the installed main rotor damper part number. This requirement aims to ensure the continued airworthiness and safety of these helicopters by preventing potential failures that could lead to loss of control. The directive is applicable nationwide across Australia, and it extends its requirements to all operators of the specified Enstrom F-28 Series helicopters within the country. The directive, which is effective from 18 March 2004, also includes provisions for compliance and establishes a timeframe within which the specified actions must be completed.

Key Provisions

This Airworthiness Directive (AD), AD/ENST 28/38, issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations (CASR) 1998, applies to Enstrom F-28 Series Helicopters, specifically the TH-28 and 480 models, equipped with the main rotor upper hub plate part number 28-14280-1 and the lower hub plate part number 28-14281-1. The AD mandates the creation of a component history card or an equivalent record for these hub plates to monitor their total hours in service (section 1(a)). Once the total hours in service have been determined, each hub plate must be replaced after accumulating 5,000 hours of service. The replacement hub plates, part number 28-14280-3 and 28-14281-3, should be installed on helicopters with main rotor damper part number 28-14375-8, while hub plates part number 28-14280-5 and 28-14281-5 should be installed on helicopters with main rotor damper part number 28-14375-10 (section 1(b)). The AD imposes specific obligations on the parties and entities it governs. It requires the creation of a component history card or equivalent record for the upper and lower hub plates to track their total hours in service. The AD also mandates the replacement of these hub plates after they accumulate 5,000 hours of service. Additionally, the AD requires updating the Limitations section of the applicable maintenance manual to establish the life limit of 5,000 hours for these hub plates (section 1). The AD also references FAA AD 2001-25-02 Amdt 39-12554 for additional context and background. Failure to comply with this AD may result in various consequences. The compliance period for the actions outlined in the AD begins 30 days after the effective date of the AD, which is 18 March 2004, unless the actions have already been completed (section 2). Any non-compliance with the AD may lead to safety risks and potential legal ramifications. However, the specific penalties or consequences for non-compliance are not explicitly stated in the AD. It is essential for the governed parties and entities to adhere to the AD to maintain airworthiness and safety standards.