COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Lycoming Piston Engines
AD/LYC/78
Amdt 5
Thermostatic Oil Cooler Bypass Valve 6/95
Applicability: All Textron Lycoming engines fitted with thermostatic bypass valve P/N 53E19600, 75944, LW-13230 or 53E19980.
Requirement: Carry out a physical inspection of the thermostatic bypass valve in accordance with the procedure detailed in Textron Lycoming Mandatory Service Bulletin No. 518B.
Note: Textron Lycoming Mandatory Service Bulletin No. 518 has been amended to delete reference to a crimp nut dimension.
Compliance: Effective 25 May 1995: Unless previously accomplished in accordance with a previous issue of this Directive;
- Dual magneto engines; within 25 hours time in service from 25 May 1995 and thereafter at intervals not to exceed 300 hours time in service.
2. Non dual magneto engines; within 25 hours time in service after 25 May 1995 and thereafter at intervals not to exceed 600 hours time in service.
Background: This Directive requires an inspection of the oil cooler thermostatic bypass valve for security of the crimp nut on the valve shaft. This amendment reflects the release of Textron Lycoming Mandatory Service Bulletin No. 518B. The original issue of MSB 518 included a dimension check of the valve crimp nut in addition to a requirement to inspect the crimp nut for security on the shaft. Following in-service experience, the service bulletin was amended to increase the crimp nut dimension limits. A further amendment of the service bulletin now removes the dimension check entirely.
Overview
The Civil Aviation Regulations 1998, as amended through F2006B11204, introduced an Airworthiness Directive (AD) aimed at addressing safety issues associated with Textron Lycoming engines equipped with specific thermostatic bypass valves. This legislative instrument was enacted to ensure that these engines, particularly those fitted with bypass valve part numbers 53E19600, 75944, LW-13230, or 53E19980, are regularly inspected for potential safety hazards. The AD mandates a physical inspection of these valves to verify the security of the crimp nut on the valve shaft, aligning with the procedure outlined in Textron Lycoming Mandatory Service Bulletin No. 518B. This amendment responds to in-service experiences and updates in the service bulletin, ensuring that compliance with the directive reflects current safety standards. The objective is to maintain the airworthiness of these engines by mitigating risks associated with the thermostatic bypass valve.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 106, includes Airworthiness Directives (AD) issued by the Civil Aviation Safety Authority (CASA) to ensure the safety of civil aviation operations. One such directive, AD/LYC/78 Amendment 5, applies to all Textron Lycoming engines equipped with specific thermostatic bypass valves, namely P/N 53E19600, 75944, LW-13230, or 53E19980. The directive mandates that a physical inspection of the thermostatic bypass valve must be conducted in accordance with the procedure outlined in Textron Lycoming's Mandatory Service Bulletin No. 518B, which has been amended to remove the reference to a crimp nut dimension. Compliance with this directive is required for dual magneto engines within 25 hours of time in service after 25 May 1995, and thereafter at intervals not exceeding 300 hours. For non-dual magneto engines, the inspection must be carried out within 25 hours of time in service after 25 May 1995 and subsequently at intervals not exceeding 600 hours. The directive applies across the Commonwealth of Australia and extends its reach to any entity operating aircraft with the specified engines, ensuring uniform safety standards across the nation.
Key Provisions
The Civil Aviation Regulations 1998, specifically in Part 39 - 106 under the Civil Aviation Safety Authority Schedule of Airworthiness Directives, detail the requirements for the maintenance and inspection of Textron Lycoming piston engines fitted with certain thermostatic bypass valves. This directive, identified as AD/LYC/78 Amendment 5, applies to all Textron Lycoming engines equipped with thermostatic bypass valves of specified part numbers (Section 1). The directive mandates a physical inspection of the thermostatic bypass valve as per the procedure outlined in Textron Lycoming Mandatory Service Bulletin No. 518B (Section 1). It is important to note that the original service bulletin has undergone amendments, particularly removing the requirement to check the crimp nut dimensions, which was previously included in an earlier version.
Operators and owners of aircraft equipped with the specified Textron Lycoming engines are required to ensure that the inspection of the thermostatic bypass valve is conducted as per the directive (Section 1). For dual magneto engines, this inspection must occur within 25 hours of time in service from 25 May 1995 and then at intervals not exceeding 300 hours (Section 2(1)). For non-dual magneto engines, the inspection must be done within 25 hours after 25 May 1995 and thereafter at intervals not exceeding 600 hours (Section 2(2)). Compliance with these inspection requirements is essential to maintain airworthiness standards and ensure the safety of the aircraft.
Failure to comply with the provisions set out in this Airworthiness Directive may result in serious safety implications, as the directive is critical for the maintenance of engine integrity. While the Civil Aviation Regulations do not explicitly state penalties for non-compliance with Airworthiness Directives, non-compliance could lead to enforcement actions by the Civil Aviation Safety Authority (CASA). Such actions might include grounding of the aircraft, fines, or other administrative penalties. The severity of the consequences would depend on the specific circumstances of the non-compliance and the impact on aviation safety.