COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES British Aerospace BAe 125 Series Aeroplanes AD/HS 125/112 Water System 11/90 Applicability: Model 125-600A, 125-700A, and 125-800A series equipped with a cabin interior and aft lavatory water system installed in accordance with STC SA 2271 SW. Requirement: Drain all water from the aft lavatory water system reservoir, deactivate the water system pressure pump by pulling the circuit breaker located beneath the vanity in the aft lavatory, and install a tie wrap on the circuit beaker to prevent it from being reset. Note 1: FAA AD 90-08-07 Amdt 39-6600 refers. Note 2: Reactivation will be dependent upon the design of a modification that is acceptable to the Authority. Compliance: Prior to the issue of a Certificate of Airworthiness. Background: This Airworthiness Directive is raised in response to a FAA report of an aft lavatory water system leak, which caused the aileron control system to jam due to the resulting ice formation on the aileron control cables and fairleads.