COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 737 Series Aeroplanes
AD/B737/107 Aileron and Elevator Power Control Unit Replacement
7/97
Applicability: Model 737 series airplanes equipped with aileron or elevator power control unit (PCU) having part number (P/N) 65-45180-29, serial numbers 182 through 1297 inclusive.
Note: PCUs part number 65-45180-29 may also be identified by the serial numbers of the PCU sub-assembly part number 65-44761-21. These serial numbers are listed in the FAA AD 97-05-09 Amendment 39-9953.
Requirement: Replace the flow restrictors P/N JETA 1875500D on the subject PCUs in accordance with Boeing Service Letter 737-SL-27-71-A dated June 19 1992, including Attachment 1.
Note: FAA AD 97-05-09, Amendment 39-9953 refers.
Compliance: Within 5 years of the effective date of this directive.
This Airworthiness Directive becomes effective on 19 June 1997.
Background: As part of the recent Design Review of the Boeing 737 flight control system, it was decided that the filter screens in the flow restrictors in the aileron and elevator PCUs could, under certain extreme conditions, break up and cause a blockage. Due to the extreme conditions necessary to cause this possible defect, the FAA agreed to extend the period of compliance from 18 months to five years. No in-service failure of these screens has ever been recorded.
Overview
The Civil Aviation Regulations 1998, as amended by the Legislative instrument F2006B02811, include specific Airworthiness Directives to address safety concerns in civil aviation, particularly regarding aircraft design and maintenance. This particular directive, AD/B737/107, was enacted in 1997 and targets the Boeing 737 series aeroplanes equipped with specific aileron or elevator power control units (PCUs). The directive was introduced to address the potential risk of filter screens in the PCUs breaking up under extreme conditions and causing blockages, which could compromise flight safety. The directive mandates the replacement of the flow restrictors on the specified PCUs within five years from the effective date of the directive. The objective of this legislative action is to ensure the continued airworthiness and safety of the Boeing 737 series aeroplanes by mitigating the identified risk.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105 and the Airworthiness Directive AD/B737/107, apply to all Boeing 737 series airplanes that are equipped with aileron or elevator power control units (PCUs) identified by part number 65-45180-29 and serial numbers ranging from 182 to 1297 inclusive. This regulation is a Commonwealth legislative instrument that mandates the replacement of the flow restrictors P/N JETA 1875500D on the specified PCUs, as per Boeing Service Letter 737-SL-27-71-A dated 19 June 1992, including its attachment. The directive is designed to mitigate the risk of filter screens in the flow restrictors breaking up and causing blockages under certain extreme conditions, although no such in-service failures have been recorded to date. Compliance with this directive is required within five years of its effective date of 19 June 1997. The regulation applies nationally and is subject to extension or restriction through subordinate instruments as deemed necessary by the Civil Aviation Safety Authority.
Key Provisions
The Civil Aviation Regulations 1998, particularly Part 39 - 105, mandate specific maintenance and safety measures for certain Boeing 737 series aeroplanes. Section AD/B737/107 focuses on aileron and elevator power control units (PCUs) and requires the replacement of flow restrictors in these units to mitigate potential risks. Specifically, this directive applies to Model 737 series airplanes equipped with aileron or elevator PCUs bearing part number (P/N) 65-45180-29, and serial numbers 182 through 1297 inclusive (1). This requirement includes replacing the flow restrictors P/N JETA 1875500D as per Boeing Service Letter 737-SL-27-71-A dated June 19, 1992, including Attachment 1 (1).
The obligations imposed by this directive include ensuring that the replacement of the flow restrictors is carried out strictly in accordance with the specified Boeing Service Letter and its attachments. Operators must ensure that these modifications are implemented within a specified period of five years from the directive's effective date, which is June 19, 1997 (1). Failure to comply with these requirements can lead to significant safety risks, as the flow restrictors' filter screens could potentially break up and cause blockages under certain extreme conditions, even though no such in-service failures have been recorded to date.
Breaching the requirements outlined in this Airworthiness Directive can result in severe consequences. While the specific penalties are not detailed in the provided text, non-compliance with airworthiness directives is generally taken very seriously under Australian aviation law. Such breaches can lead to enforcement actions by the Civil Aviation Safety Authority (CASA), including fines, suspension or revocation of airworthiness certificates, and potential criminal charges against the responsible parties. The exact penalties would depend on the severity and impact of the non-compliance, but they are designed to ensure the highest standards of aviation safety are maintained.