COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Cessna 400 Series Aeroplanes
AD/CESSNA 400/95 Pilot’s Instruments Air System 11/88
Applicability: Models 425 equipped with pneumatic gyro instruments in the left instrument panel and approved for IFR operations.
Requirement: Action in accordance with CESSNA Service Bulletin CQB 88-9 and Service Kit SK425-41.
Compliance: Not later than 31 March 1989.
Background: The existing instrument air pressure regulator by itself is not capable of operating at high overpressure conditions and may close and shut off airflow to the attitude and directional gyros. In the event an overpressure condition failure occurs, the additional regulator installed per this AD is designed to provide reduced air pressure at an acceptable value to the inlet of the existing regulator to assist it in operating normally.