AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Boeing 727 Series Aeroplanes
AD/B727/184 Autopilot Pitch Control Computer 8/2003
Applicability: Model 727-100 and 727-200 series aeroplanes, as listed in Boeing Alert Service Bulletin (ASB) 727-22A0093 dated 20 December 2000; excluding aeroplanes equipped with radio altimeter-based autopilots.
Requirement: 1. For any aeroplane on which autopilot coupled ILS approaches with time-based glideslope gain programming are used, revise the Limitations Section, under AUTOPILOT/FLIGHT DIRECTOR SYSTEM, of the Aircraft Flight Manual (AFM) by adding the following (this may be accomplished by inserting a copy of this AD into the AFM):
Coupled ILS approaches are prohibited unless the autopilot has been modified in accordance with AD/B727/184.
CAT II autopilot coupled ILS approach shall not be performed if the Middle Marker (ground or airborne system) is inoperative or nonexistent.
Disconnect the autopilot at, or prior to, 80 ft. (above the runway's touchdown- zone elevation) during coupled ILS CAT II approaches.
2. Unless previously accomplished, modify the existing SP-50 or SP-150 single- channel autopilot in accordance with ASB 727-22A0093.
Note 1: Modification may have been previously carried out in accordance with Sperry Service Bulletin (SB) 21-1132-121, dated 23 November 1982 (for SP-50 autopilots); or SB 21-1132-122, dated 7 February 1983 (for SP-150 autopilots).
3. Perform a one-time test procedure of the modified autopilot, in accordance with Sperry SB 21-1132-121 or SB 21-1132-122, as applicable.
Testing carried out before the effective date of this Directive in accordance with Component Maintena nce Manual (CMM) test procedures is also acceptable, provided that the procedures implement all the CMM changes and test steps described in the applicable Sperry service bulletin. For autopilot units manufactured with the actions of the applicable Sperry service bulletin already incorporated, testing is not required.
Boeing 727 Series Aeroplanes
AD/B727/184 (continued)
4. Autopilot pitch control computers may not be installed on any aeroplane as a replacement part unless modified in accordance with this Directive.
Note 2: FAA AD 2003-11-19 Amdt 39-13178 refers.
Compliance: For Requirement 1 - Within 6 months after the effective date of this Directive. For Requirement 2 - Within 18 months after the effective date of this Directive.
For Requirement 3 - Before reinstallation of the autopilot unit after the modification required by Requirement 2.
For Requirement 4 - After 7 February 2004.
This Airworthiness Directive becomes effective on 7 August 2003.
Background: This Directive requires, under certain conditions, replacement of the autopilot pitch control computer with a modified computer, testing of the modified system and revision of the AFM. These actions are intended to prevent undesirable and potentially dangerous pitch oscillations during coupled instrument landing system (ILS) approaches.
Jim Coyne
Delegate of the Civil Aviation Safety Authority 26 June 2003
The above AD is notified in the Commonwealth of Australia Gazette on 16 July 2003.
Overview
The Airworthiness Directive issued by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Safety Regulations (CASR) 1998, is titled "Boeing 727 Series Aeroplanes AD/B727/184" and was enacted on 7 August 2003. This directive addresses the identified issue of potentially dangerous pitch oscillations that could occur during coupled instrument landing system (ILS) approaches in Boeing 727-100 and 727-200 series aeroplanes. The directive aims to enhance the safety of these aircraft by mandating modifications to the autopilot pitch control computer, revisions to the Aircraft Flight Manual, and specific testing procedures. This legislative instrument was developed to ensure compliance with safety standards and mitigate the risks associated with autopilot-coupled ILS approaches, ultimately contributing to the overall safety of aviation operations in Australia.
Scope and Application
This Airworthiness Directive applies to Boeing 727 series aeroplanes, specifically the 727-100 and 727-200 models, excluding those equipped with radio altimeter-based autopilots. The AD mandates modifications to the autopilot pitch control computer and updates to the Aircraft Flight Manual to address the risk of pitch oscillations during coupled ILS approaches. The directive applies to operators of the specified Boeing 727 models and requires compliance with the outlined modifications and documentation updates within specified timeframes. It extends its application nationally and is notified under the Civil Aviation Safety Authority (CASA). The directive does not apply to aeroplanes equipped with radio altimeter-based autopilots and is applicable to aeroplanes engaged in operations involving autopilot coupled ILS approaches. Compliance with subordinate instruments, such as service bulletins and maintenance manuals, is necessary to implement the required modifications and testing.
Key Provisions
The Airworthiness Directive (AD) AD/B727/184 applies to Boeing 727-100 and 727-200 series aeroplanes, excluding those equipped with radio altimeter-based autopilots (Section Applicability). The AD mandates several actions to address an unsafe condition related to autopilot pitch control during instrument landing system (ILS) approaches (Section Requirement). Firstly, operators must revise the Limitations Section of the Aircraft Flight Manual (AFM) to prohibit autopilot coupled ILS approaches unless the conditions specified in the AD are met (Requirement 1). Secondly, any existing SP-50 or SP-150 single-channel autopilots must be modified according to Boeing Alert Service Bulletin (ASB) 727-22A0093 (Requirement 2). Thirdly, a one-time test procedure of the modified autopilot must be performed, as outlined in the applicable Sperry service bulletin (Requirement 3). Lastly, any autopilot pitch control computers installed as replacements must be modified in accordance with this AD (Requirement 4).
The AD imposes several obligations on the operators of the specified Boeing 727 series aeroplanes. Operators must ensure that the AFM is updated as required by Requirement 1. They must also modify any existing autopilots in accordance with Requirement 2, perform the specified testing as outlined in Requirement 3, and ensure that any replacement autopilot pitch control computers are modified as per Requirement 4. Operators must adhere to the specified compliance timelines: within 6 months for Requirement 1, within 18 months for Requirement 2, before reinstallation for Requirement 3, and after 7 February 2004 for Requirement 4 (Section Compliance).
Failure to comply with the AD may result in serious safety risks, including potentially dangerous pitch oscillations during ILS approaches. Although the AD itself does not specify offences, penalties, or civil/criminal consequences for non-compliance, such failure could lead to regulatory action by the Civil Aviation Safety Authority (CASA). This may include enforcement actions, fines, or other penalties under the Civil Aviation Act 1988 or other relevant legislation. The severity of any penalties would depend on the specific circumstances of the non-compliance and any subsequent regulatory action taken by CASA.