Overview

The Civil Aviation Safety Authority (CASA) introduced the Airworthiness Directive AD/B737/109 Amdt 2 in 2002 to address safety concerns related to the flying control power control unit (PCU) cylinder bores in certain Boeing 737 Series Aeroplanes. This directive was issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998 to ensure that any unsafe conditions identified during investigations into the Boeing 737 flight control system were adequately corrected. The directive applies to specific models and serial numbers of the Boeing 737, requiring the inspection and, if necessary, replacement of PCU manifold cylinder bores that contain chrome plating. The objective is to prevent reduced controllability or uncommanded control inputs that could compromise flight safety. Compliance with this directive is mandatory and must be achieved within specified timeframes or flight hours, depending on the component's serial number.

Scope and Application

This Airworthiness Directive (AD) issued under the Civil Aviation Regulations 1998 applies to specific models of Boeing 737 Series Aeroplanes, namely the 737-100, -200, -300, -400, and -500 series. The directive mandates specific maintenance actions concerning the main rudder power control unit (PCU) and aileron or elevator PCU with certain part numbers, excluding those with specific serial numbers or containing "ss". The AD requires the inspection and replacement of PCU manifold cylinder bores that have chrome plating, as specified in Boeing Service Letter 737-SL-27-30 dated April 1, 1985. Compliance with this AD is required within five years or 15,000 flight hours, whichever occurs first, following specified dates, and before further flight. The AD is applicable throughout the Commonwealth of Australia, as it has been notified in the Commonwealth of Australia Gazette. There are no stated exclusions or exemptions within the text of the AD itself, although the applicability section already excludes certain serial numbers and part numbers. The AD may be extended or restricted through subordinate instruments as necessary.

Key Provisions

The Airworthiness Directive (AD) AD/B737/109 Amdt 2, issued by the Civil Aviation Safety Authority (CASA) delegate, mandates specific actions to address safety concerns related to the power control unit (PCU) of Boeing 737 Series aeroplanes. These actions are outlined in the requirement section (1) of the directive, which specifies that an inspection of the PCU must be conducted to determine if repaired or reworked PCU manifold cylinder bores containing chrome plating are installed, in accordance with Boeing Service Letter 737-SL-27-30 dated April 1, 1985. If chrome plated manifold cylinder bores are identified, they must be replaced according to the same service letter. This directive applies to specific models of the Boeing 737 Series aeroplanes, as detailed in the applicability section (2). The compliance section (3) mandates that these actions be taken within a certain timeframe: within 5 years or 15,000 flight hours, whichever occurs first, after the specified dates for different part numbers of the PCU. Additionally, the directive requires that the actions be completed before any further flight. The AD imposes specific obligations on the parties it governs, primarily the operators and maintainers of Boeing 737 Series aeroplanes. These obligations include conducting a thorough inspection of the PCU to ascertain whether chrome plated manifold cylinder bores are present, as per the outlined service letter. If such bores are found, they must be replaced. These actions must be carried out within the timeframes specified in the compliance section and before any subsequent flight. The AD also mandates that any PCU that has been vibroengraved with "737-SL-27-30" has previously been inspected in accordance with Boeing SL 737-SL-27-120 for chrome plating, ensuring that all necessary inspections and replacements are conducted as per the directive. Failure to comply with the requirements set forth in the AD may result in significant legal and safety consequences. While the specific penalties for non-compliance are not detailed in the text, non-compliance with ADs can generally lead to civil or criminal penalties under the Civil Aviation Act 1988 and the Civil Aviation Regulations 1988. These penalties may include fines and imprisonment, depending on the severity of the breach and the impact on aviation safety. Operators and maintainers are thus required to adhere strictly to the directive to avoid such consequences.