{"id":"F2007L02165","name":"AD/G1159/50 - Water Drain/Supply Valves","slug":"ad-g1159-50-water-drain-supply-valves","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":67368,"registerId":"commonwealth-F2007L02165-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Gulfstream (Grumman) G1159 and G-IV Seri","sectionType":"division","heading":"Gulfstream (Grumman) G1159 and G-IV Series Aeroplanes","content":"### Gulfstream (Grumman) G1159 and G-IV Series Aeroplanes\n\n| AD/G1159/50 | Water Drain/Supply Valves | 9/2007 DM |\n| ----------- | ------------------------- | --------- |\n\n```html\n

Applicability:

Gulfstream Model GIV-X, GV, and GV-SP series aeroplanes, as identified in the alert customer bulletins specified in Table 1 of this AD.

Table 1. - Gulfstream Alert Customer Bulletins

Aeroplane Model

Alert Customer Bulletin

Date

GIV-X

G350 Number 5

11 April, 2007

G450 Number 5

11 April, 2007

GV

GV Number 26

11 April, 2007

GV-SP

G500 Number 7

11 April, 2007

G550 Number 7

11 April, 2007

Requirement:

1. Revise the Normal Procedures section of the AFMs to include the information in the applicable AFM supplement identified in Table 2 of this AD. This may be done by inserting a copy of the supplement into the AFM.

Table 2. - AFM Supplements

Aeroplane Model

AFM Supplement

Date

GIV-X

G350-2007-01

12 April, 2007

G450-2007-02

12 April, 2007

GV

GV-2007-04

12 April, 2007

GV-SP

G500-2007-03

12 April, 2007

G550-2007-05

12 April, 2007

\n```\n\n| | 2. Perform a functional check of the forward water system water drain/supply valves and do applicable corrective actions, in accordance with the applicable AFM supplement identified in Table 2 of this AD.Either the cockpit flight crew or certificated maintenance personnel may perform these functional checks. If the water system has been deactivated as part of the corrective actions, the functional checks need not be performed again until the water system is reactivated. Doing the optional terminating action specified below ends the requirement for the repetitive functional checks.3. No person may install a water supply valve having P/N 4E4151-1, or a water drain valve having P/N 4E4151-3, on any aeroplane.Optional Terminating ActionDoing the following actions described below, as applicable, of this AD terminates the functional checks detailed in Requirement 2 of this AD. After the actions specified in (1) and (2) below have been done, the applicable AFM supplement specified in Requirement 1 of this AD may be removed from the AFM.(1) Inspect to determine the part numbers of the forward water drain/supply valves, in accordance with Part II of the Accomplishment Instructions of the applicable alert customer bulletin identified in Table 1 of this AD. A review of aeroplane maintenance records is acceptable in lieu of this inspection if the part numbers of the drain/supply valves can be conclusively determined from that review.(2) Replace any water supply valve having part number (P/N) 4E4151-1 with a new, improved water supply valve having P/N 4E4491- 1, and any water drain valve having P/N 4E4151-3 with a new, improved water drain valve having P/N 4E4493-1; in accordance with Part III of the Accomplishment Instructions of the applicable alert customer bulletin identified in Table 1 of this AD. If the P/N of any water drain/supply valve is missing or cannot be determined, replace the water drain/supply valve with a new, improved water drain/supply valve, as applicable.Note 1: Help is available from Gulfstream for determining a missing or otherwise indeterminate part number of any water drain/ supply valve.Note 2: FAA AD 2007-12-25 Amdt 39-15104 dated 8 June 2007 refers. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | 1. Within 20 flight hours after the effective date of this AD, unless previously accomplished. |\n\n| | 2. Before further flight following accomplishment of the AFM revision required by Requirement 1 of this AD at the following intervals:(a) Before the first flight of the day.(b) Before further flight when the aeroplane is exposed to freezing conditions on the ground after the aeroplane has been powered down.3. From the effective date of this AD. |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| | This Airworthiness Directive becomes effective on 10 July 2007. |\n| Background: | This AD results from reports of failed forward water drain/ supply valves on numerous aeroplanes, and reports of ice striking the wing-to-body fairings and engine nose cowls of several aeroplanes. The issuing of this AD is intended to prevent leakage from failed water drain/ supply valves allowing the build-up of ice on the aeroplane, which could separate and strike the aeroplane structure aft of the failed valves; become ingested by a propulsion engine; or become a hazard to persons or property on the ground. |\n\n![](image.001.png) \nDavid Punshon \nDelegate of the Civil Aviation Safety Authority\n\n4 July 2007","sortOrder":0},{"sectionNumber":"AD/G1159/50","sectionType":"part","heading":"AD/G1159/50","content":"## AD/G1159/50","sortOrder":1},{"sectionNumber":"Water Drain/Supply Valves","sectionType":"part","heading":"Water Drain/Supply Valves","content":"## Water Drain/Supply Valves","sortOrder":2},{"sectionNumber":"9/2007 DM","sectionType":"part","heading":"9/2007 DM","content":"## 9/2007 DM","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The AD's scope aligns with the stated safety concern in the Background: it targets failed forward water drain/supply valves that can cause ice build‑up and downstream hazards. The instrument confines measures to AFM changes, repetitive checks, a ban on two valve P/Ns, and replacement with specified improved P/Ns as a terminating action; there is no indication in the text that the AD expands beyond that original intent."},"complexity_factors":["Cross-references to model‑specific Alert Customer Bulletins (Table 1) and AFM supplements (Table 2) increase traceability and record‑checking complexity.","Multiple, timed compliance actions: AFM revision within 20 flight hours; repetitive functional checks before first flight of the day and after on‑ground freezing exposure (Requirement 1 & 2).","Permitted performers: either cockpit flight crew or certificated maintenance personnel may perform functional checks (Requirement 2) — this expands who can satisfy the requirement but creates potential variability in procedure execution and training burden.","Optional terminating action requires inspection or review of maintenance records to determine valve P/Ns, or unconditional replacement where P/Ns are indeterminate (Optional Terminating Action ¶(1)–(2)).","Parts control rule: absolute prohibition on installing specific P/Ns (P/N 4E4151‑1 and 4E4151‑3) on any aeroplane (Requirement 3) imposes supply‑chain and procurement constraints.","Replacement mandate uses specific replacement P/Ns (P/N 4E4491‑1 and 4E4493‑1) — enforces a hardware fix as an alternative to ongoing procedural checks (Optional Terminating Action ¶(2)).","AFM administrative burden: AFM supplements may be inserted and later removed after terminating action, requiring document control and operator compliance monitoring.","Reliance on manufacturer support for part identification where P/Ns are missing (Note 1) creates operational dependence on Gulfstream for technical assistance.","Interplay of inspections, record reviews, and procedural changes creates mixed compliance pathways (procedural vs hardware), increasing implementation choices and enforcement complexity."],"plain_english_summary":"This Airworthiness Directive requires operators of Gulfstream GIV‑X, GV and GV‑SP series aeroplanes to update their Aircraft Flight Manuals and carry out repeated functional checks of the forward water drain/supply valves, prohibits installing two specified valve part numbers, and allows replacing those valves with improved parts to stop the recurring checks. It affects aircraft operators, maintenance organisations and flight crews, who bear the cost and operational burden of manual changes, inspections and any valve replacements to reduce the risk of ice build-up and related hazards."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope addressing a specific mechanical defect in water valves on specific Gulfstream aircraft models. The optional terminating action and alternative compliance methods (maintenance records review vs physical inspection) are standard regulatory flexibility mechanisms rather than scope expansion."},"complexity_factors":["Multiple nested tables cross-referencing aircraft models to specific manufacturer bulletins and flight manual supplements","Conditional logic: different requirements apply depending on whether terminating action is taken, whether water system is deactivated, or whether part numbers can be determined from records","Specific part number tracking required (P/N 4E4151-1, 4E4151-3, 4E4491-1, 4E4493-1) with consequences for indeterminate part numbers","Dual compliance paths: repetitive functional checks OR one-time replacement with optional terminating action","Cross-reference to US FAA AD 2007-12-25 for additional context","Multiple effective dates and compliance windows (20 flight hours, before further flight, from effective date)"],"plain_english_summary":"This CASA Airworthiness Directive targets faulty forward water drain and supply valves on certain Gulfstream GIV‑X, GV and GV‑SP series jets that can leak and freeze into hazardous ice. It requires inserting an AFM supplement, daily and post‑freeze checks of the valves, and prohibits installing specified defective part numbers. Operators may stop repetitive checks by identifying and replacing affected valves with approved improved parts."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-g1159-50-water-drain-supply-valves","history":"/api/acts/ad-g1159-50-water-drain-supply-valves/history","analysis":"/api/acts/ad-g1159-50-water-drain-supply-valves/analysis","conflicts":"/api/acts/ad-g1159-50-water-drain-supply-valves/conflicts","importantCases":"/api/acts/ad-g1159-50-water-drain-supply-valves/important-cases","documents":"/api/acts/ad-g1159-50-water-drain-supply-valves/documents"}}