AD/INST/42 - KSA 470 Autopilot Servo Actuator

Overview

The Commonwealth of Australia enacted the Civil Aviation Regulations 1998 to ensure the safety of civil aviation and to address issues concerning aircraft airworthiness. This legislation was introduced to fill the gap by providing a comprehensive framework to maintain and improve aviation safety standards. Enacted by the Australian Parliament, the policy objective of these regulations is to safeguard the public by ensuring that civil aircraft meet the required safety standards. A specific example of this is the regulation addressing the issue of faulty autopilot servo actuators that can lead to serious safety hazards. The regulations mandate the replacement of certain autopilot servo actuators to prevent potential control failures, thereby ensuring that aircraft remain airworthy and safe for operation.

Scope and Application

The Civil Aviation Safety Authority (CASA) has issued an airworthiness directive under the Civil Aviation Regulations 1998, specifically in PART 39 - 107, concerning the Allied Signal Bendix/King Model KSA-470 autopilot servo actuators with part numbers 065-0076-10 through 065-0076-15 and serial numbers 0001 through 3081 inclusive. This directive applies to these particular servo actuators installed on various aircraft models, including Raytheon (Beech) 400, 200, and 300 Series, Dassault Falcon 20, Fairchild C26A/C26B, SA227-AC/AT/BC/CC/DC, Learjet 31A, Lockheed (Grumman) S-2 Tracker, and Piper 400LS and PA-42-1000. The requirement is to replace the affected servo actuators with those that incorporate Modification 3 (Mod 3), as detailed in the applicable maintenance manual. Any aircraft with an unmodified actuator installed after the directive's effective date is not compliant. The directive mandates compliance within 100 hours of the directive's effective date of 18 June 1998, or as of the effective date, depending on the compliance action. This directive aims to mitigate the risk of loose roll pins within the servo housing, which could potentially cause loss of control of the affected flight control axis.

Key Provisions

The Civil Aviation Safety Authority (CASA) has issued an airworthiness directive (AD) under the Civil Aviation Regulations 1998, Part 39, Section 107, which specifically mandates the replacement of certain autopilot servo actuators (sections 1 and 2). The AD applies to Allied Signal Bendix/King Model KSA-470 autopilot servo actuators with part numbers ranging from 065-0076-10 through 065-0076-15 and serial numbers from 0001 to 3081 inclusive. These actuators are commonly fitted to various aircraft, including the Raytheon (Beech) 400, 200, and 300 Series, Dassault Falcon 20, Fairchild C26A/C26B, SA227-AC/AT/BC/CC/DC, Learjet 31A, Lockheed (Grumman) S-2 Tracker, and Piper 400LS and PA-42-1000. The directive requires the replacement of these actuators with ones that incorporate Modification 3 (Mod 3) and specifies that any unmodified actuators should not be installed in any aeroplane. The AD imposes specific obligations on aircraft owners, operators, and maintenance personnel to ensure compliance. Owners and operators must replace the affected servo actuators with the modified versions within 100 hours of the directive's effective date or as of the effective date if the aircraft is already in service. Maintenance personnel must follow the procedures outlined in the applicable maintenance manual to perform the replacement. Furthermore, it is strictly prohibited to install any unmodified actuators on any aeroplane, as stipulated in section 2 of the AD. Failure to comply with this airworthiness directive can result in significant consequences. Non-compliance may lead to potential safety hazards, including the risk of the autopilot servo actuator's roll pins becoming loose, which could lodge in the output shaft and prevent disengagement. Such a malfunction could increase the pilot's effort to control the aircraft and potentially result in the loss of control over the affected flight control axis. Regulatory action may be taken against the aircraft owner or operator, and the aircraft may be grounded until the required modifications are made. There are no specific penalties mentioned in the directive, but civil or criminal penalties could be imposed under broader aviation safety regulations if non-compliance leads to an accident or other safety incidents.