{"id":"F2006B02380","name":"AD/AMD 50/13 - Water Heater Overheat","slug":"ad-amd-50-13-water-heater-overheat","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41610,"registerId":"commonwealth-F2006B02380-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AMD 50/13 - Water Heater Overheat","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAMD Falcon 50 and 900 Series Aeroplanes\n\nAD/AMD 50/13 Water Heater Overheat 3/97\n\nApplicability: All Mystere Falcon 900 aeroplanes equipped with L’HOTELLIER water system gauges part numbers 5250, 5251, 5250-1 and 5251-1.\n\nRequirement: Accomplish the following actions in accordance with Dassault Aviation Mandatory Service Bulletin F900-181 dated 4 December 1996:\n\n    replace the water heater control relays with relays having high-power contactors,\n\n    b. install a testing and monitoring circuit for each relay, and\n\n    c. improve the electrical bonding of the drinking water tank.\n\nNote: DGAC AD 96-279-018(B) refers.\n\nCompliance: Either prior to 31 August 1997 or prior to accumulation of 300 hours time in service after 27 February 1997, whichever occurs first.\n\nThis Airworthiness Directive takes effect on 27 February 1997.\n\nBackground: Actions specified by this Directive are designed to prevent overheating of the water heaters caused by incorrect operation of the heater control relays.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of mandating a manufacturer-recommended fix for water heater overheating risks."},"complexity_factors":["Very short document (under 200 words)","Only 4 defined elements: specific aircraft model, 4 part numbers, one referenced service bulletin, and one referenced foreign AD","Single unconditional requirement with 3 discrete, non-technical action items described in plain language","Simple compliance deadline structure (date OR flight hours, whichever first)","No cross-references to other legislation, regulations, or conditional exceptions","No nested definitions or interpretive provisions"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain **Mystere Falcon 900 business jets** to fix a potentially dangerous flaw in the onboard water heating system. The problem is that the water heater control relays can malfunction, causing the heaters to overheat — a fire risk.\n\n**Who must act:**\nAnyone operating a Falcon 900 aircraft fitted with specific L'HOTELLIER water system gauges (part numbers 5250, 5251, 5250-1, and 5251-1).\n\n**What must be done:**\nThree specific repairs must be carried out following instructions from the manufacturer (Dassault Aviation):\n- **Replace** the water heater control relays with upgraded versions that have high-power contactors (electrical switches that can handle more current without failing)\n- **Install** a testing and monitoring circuit for each relay (so crews can check if the relays are working properly)\n- **Improve** the electrical bonding of the drinking water tank (ensuring proper electrical grounding to prevent sparks or electrical faults)\n\n**When it must be done:**\nBy **31 August 1997** OR before the aircraft clocks up **300 flight hours** after 27 February 1997 — whichever comes first.\n\n**Why it matters:**\nFaulty relays can cause water heaters to overheat, creating a fire hazard in the aircraft. This AD forces a fix before a serious incident occurs. It references a French aviation safety directive (DGAC AD 96-279-018(B)), showing this was an international safety concern."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope remains focused and unchanged: the directive applies only to Mystere Falcon 900 aeroplanes fitted with the listed L'HOTELLIER gauge part numbers and prescribes specified hardware and wiring changes to address relay-caused water-heater overheating, consistent with the Background and Requirement sections."},"complexity_factors":["Targeted applicability to aircraft with specific part numbers (Applicability).","Three separate technical modifications required: relay replacement, monitoring circuit installation, and improved tank electrical bonding (Requirement).","Mandate to follow an external manufacturer document: Dassault Aviation Mandatory Service Bulletin F900-181 (Requirement).","Dual compliance trigger: calendar date or accumulation of 300 hours time in service after the effective date (Compliance).","Reference to a foreign airworthiness directive (DGAC AD 96-279-018(B)) adds an external cross-reference (Note)."],"plain_english_summary":"**What it changes:** Requires replacing the water-heater control relays with high-power contactors, adding a testing/monitoring circuit for each relay, and improving the electrical bonding of the drinking-water tank on specified Mystere Falcon 900 aeroplanes. \n\n**Who it affects and why it matters:** Applies to Falcon 900 aircraft fitted with L'HOTELLIER gauges (parts 5250, 5251, 5250-1, 5251-1); operators must complete the work per Dassault Mandatory Service Bulletin F900-181 by 31 August 1997 or within 300 hours' service after 27 February 1997 to prevent water-heater overheating caused by incorrect relay operation."}},"importantCases":[],"_links":{"self":"/api/acts/ad-amd-50-13-water-heater-overheat","history":"/api/acts/ad-amd-50-13-water-heater-overheat/history","analysis":"/api/acts/ad-amd-50-13-water-heater-overheat/analysis","conflicts":"/api/acts/ad-amd-50-13-water-heater-overheat/conflicts","importantCases":"/api/acts/ad-amd-50-13-water-heater-overheat/important-cases","documents":"/api/acts/ad-amd-50-13-water-heater-overheat/documents"}}