COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AMD Falcon 50 and 900 Series Aeroplanes AD/AMD 50/13 Water Heater Overheat 3/97 Applicability: All Mystere Falcon 900 aeroplanes equipped with L'HOTELLIER water system gauges part numbers 5250, 5251, 5250-1 and 5251-1. Requirement: Accomplish the following actions in accordance with Dassault Aviation Mandatory Service Bulletin F900-181 dated 4 December 1996: 1. replace the water heater control relays with relays having high-power contactors, b. install a testing and monitoring circuit for each relay, and c. improve the electrical bonding of the drinking water tank. Note: DGAC AD 96-279-018(B) refers. Compliance: Either prior to 31 August 1997 or prior to accumulation of 300 hours time in service after 27 February 1997, whichever occurs first. This Airworthiness Directive takes effect on 27 February 1997. Background: Actions specified by this Directive are designed to prevent overheating of the water heaters caused by incorrect operation of the heater control relays.