AD/LYC/98 - Push Rod Inner Diameter Scoring

Overview

The Civil Aviation Regulations 1998, specifically under Part 39 - 106, addresses the safety of civil aviation through a series of airworthiness directives. One such directive, AD/LYC/98, pertains to Textron Lycoming O-235 series engines and was enacted to address a critical issue identified in a subset of these engines. The problem targeted by this directive involves scoring of the push rod inner diameter, which was found to be a precursor to engine failure. This scoring occurred during the extrusion process at the supplier and affected engines shipped between 22 February 1993 and 2 September 1994, as well as those fitted with new push rods since that date. The directive was introduced by the Civil Aviation Safety Authority (CASA) to mitigate risks associated with these identified defects, ensuring that the identified engines are inspected and necessary replacements are made to maintain airworthiness standards. The policy objective is to enhance the safety and reliability of civil aviation operations by proactively addressing potential engine failures through mandatory inspections and component replacements.

Scope and Application

The Civil Aviation Regulations 1998, specifically under Part 39 and the schedule of airworthiness directives, mandates the compliance of all Textron Lycoming O-235 series engines that fall within the period of manufacture from 22 February 1993 to 2 September 1994, or those fitted with new push rods since 22 February 1993, with AD/LYC/98. This directive applies to aircraft operators and owners who must ensure that inspections and replacements of the specified push rods are carried out to maintain airworthiness standards. The requirement to inspect and replace push rods as per Textron Lycoming Mandatory Service Bulletin No. 522 is a response to identified failures stemming from scoring on the push rod tube inner diameter, which was introduced during the manufacturing process. Compliance with this directive is stringent, mandating that inspections be conducted within 10 hours of service or by 1 July 1995, whichever comes first, unless the actions have already been completed and documented in the engine logbook prior to the effective date of 25 May 1995. The directive ensures that only engines meeting these specific criteria are subject to the regulation, excluding those outside the specified manufacturing dates or those not fitted with the identified push rods.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 106, address the safety directives concerning Lycoming Piston Engines through AD/LYC/98. This directive mandates the inspection and replacement of certain push rods in Textron Lycoming O-235 series engines (s. 1). The directive applies to engines shipped between 22 February 1993 and 2 September 1994, and to O-235 engines fitted with new push rods since 22 February 1993 (s. 2). The requirement is to inspect the push rods according to Textron Lycoming Mandatory Service Bulletin No. 522 and replace any push rods identified as P/N 73806 with revision letters "V" or "W" before further flight (s. 3). The directive references FAA Airworthiness Directive 95-03-10 for additional context and compliance (s. 4). Compliance with this directive is effective from 25 May 1995, and must be completed within 10 hours of time in service or before 1 July 1995, whichever comes first (s. 5). The obligations imposed by this directive are clear and stringent. Operators and owners of the specified engines must ensure that the push rods are inspected and, if necessary, replaced according to the guidelines provided in Textron Lycoming Mandatory Service Bulletin No. 522. This involves meticulous record-keeping and verification that the affected engines are compliant with the directive before they are allowed to fly again. Any non-compliance must be documented in the engine log book to demonstrate adherence to the safety requirements (s. 6). Additionally, the directive emphasises the importance of timely action to prevent potential engine failures that could compromise flight safety (s. 7). Failure to comply with this directive can result in serious consequences. The regulations establish that non-compliance is not only a breach of the Civil Aviation Regulations 1998 but also poses significant safety risks. The penalties for such breaches can be severe, including potential civil or criminal liabilities (s. 8). The exact penalties are not specified in the text, but it is clear that the consequences of failing to adhere to these airworthiness directives can include legal action, fines, and possibly more severe sanctions depending on the severity of the non-compliance and its impact on aviation safety (s. 9). Operators must therefore take this directive seriously and ensure full compliance to avoid any adverse outcomes.