{"id":"F2006L00743","name":"AD/DHC-8/113 - Fuel & Hydraulic Tubes Chafing","slug":"ad-dhc-8-113-fuel-hydraulic-tubes-chafing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":136766,"registerId":"commonwealth-F2006L00743-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bombardier (Boeing Canada/De Havilland) ","sectionType":"division","heading":"Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes","content":"### Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes\n\n| AD/DHC-8/113 | Fuel & Hydraulic Tubes Chafing | 4/2006 |\n| ------------ | ------------------------------ | ------ |\n\n| Applicability: | Bombardier Inc. DHC-8 Series 400 aircraft serial numbers 4003 through 4089.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. For aircraft without Bombardier Systems Drawings SYD 84-28-002, Issue 1, or later approved revisions, and SYD 84-29-006, Issue 1, or later approved revisions incorporated; orFor aircraft without Modsum 4-184079 and Modsum 4-184081 incorporated:Install Bombardier Modsum 4-113438 (modified fairlead plate assemblies). Bombardier Service Bulletin (SB) 84-54-09, dated 23 January 2004, or later revisions approved by Transport Canada.2. For aircraft with Bombardier Systems Drawings SYD 84-28-002, Issue 1, or later approved revisions, and SYD 84-29-006, Issue 1, or later approved revisions incorporated; orFor aircraft with Modsum 4-184079 and Modsum 4-184081 incorporated;Install Bombardier Modsum 4-113438 (modified fairlead plate assemblies). Bombardier (SB) 84-54-09, or later revisions approved by Transport Canada.Note: Transport Canada AD CF-2004-07 refers. |\n| Compliance:    | 1. Within 500 hours time in service after the effective date of this directive.2. Within 4,000 hours time in service after the effective date of this directive:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n|                | This Airworthiness Directive becomes effective on 13 April 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n| Background:    | Service difficulty reports indicate there is a potential for chafing of fuel and hydraulic tubes with the fairlead plate where the tubes pass through the firewall. Titanium plates attached to the fairleads have close tolerance holes to provide isolation between fire zones. If the tubes are not centred in the fairlead plate, nacelle flexing can cause a fouling condition, which may cause chafing of the tubes, leading to leakage of fluid creating an unsafe condition.                                                                                                                                                                                                                                                                                                                                                                                                               |\n\n|     | Bombardier Inc. has issued System Drawings SYD 84-28-002 (for the fuel tubes), and SYD 84 29 006 (for the hydraulic tubes), to provide temporary rework instructions (to enlarge the tolerance holes) for the fairlead plates, in order to avoid chafing with the tubes which pass through the fairlead plates. Production rework Modsum 4-184079 (for the hydraulic tubes) and Modsum 4-184081 (for the fuel tubes) were issued to introduce the intent of SYDs 84-28-002 and 84-29-006 for production aircraft. In addition, Bombardier Inc. Service Bulletin (SB) 84-54-09 was issued to introduce modified fairlead plate assemblies to rectify the fuel and hydraulic tubes chafing problem. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nJayaprakashan Ambali  \nDelegate of the Civil Aviation Safety Authority\n\n21 February 2006","sortOrder":0},{"sectionNumber":"AD/DHC-8/113","sectionType":"part","heading":"AD/DHC-8/113","content":"## AD/DHC-8/113","sortOrder":1},{"sectionNumber":"Fuel & Hydraulic Tubes Chafing","sectionType":"part","heading":"Fuel & Hydraulic Tubes Chafing","content":"## Fuel & Hydraulic Tubes Chafing","sortOrder":2},{"sectionNumber":"4/2006","sectionType":"part","heading":"4/2006","content":"## 4/2006","sortOrder":3}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with a clear, narrow scope: addressing a specific mechanical chafing issue on a defined subset of aircraft (DHC-8-400, serials 4003-4089). The scope remains tightly focused on the original safety issue without expansion into unrelated systems or aircraft types."},"complexity_factors":["Two-tier compliance structure based on aircraft modification status (500 hours vs 4,000 hours)","Multiple technical reference documents (Modsums, System Drawings, Service Bulletins) with specific issue numbers","Nested conditional logic: 'without X OR without Y' vs 'with X OR with Y' creates four possible aircraft configurations","Cross-reference to Canadian aviation authority (Transport Canada AD CF-2004-07)","Technical aviation terminology requiring domain knowledge (Modsum, fairlead, nacelle flexing, time in service)"],"plain_english_summary":"CASA’s Airworthiness Directive requires owners/operators of Bombardier DHC‑8 Series 400 (serials 4003–4089) to install modified fairlead plate assemblies to stop fuel and hydraulic tubes chafing the firewall plates—a condition that can cause leaks and fire. Aircraft without specific factory mods must comply within 500 flight hours; those with the mods have 4,000 flight hours. The fix follows Bombardier Service Bulletin 84‑54‑09 (Transport Canada approved). Effective 13 April 2006."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive implements remedial hardware changes for the specific DHC-8 Series 400 serial-number range to address identified chafing. It applies only to the aircraft set out in the Applicability and prescribes installation of Modsum 4-113438 per SB 84-54-09 within set flight-hour limits. It does not broaden scope beyond those aircraft or the stated unsafe condition; it references earlier temporary rework and production mods as background."},"complexity_factors":["Applicability limited to a specific serial-number range (4003–4089), requiring operators to identify affected airframes (Applicability).","Conditional compliance paths depending on whether Systems Drawings SYD 84-28-002 and SYD 84-29-006 or Modsum 4-184079 and 4-184081 are already incorporated (Requirement).","Mandated installation of Modsum 4-113438 via Bombardier Service Bulletin 84-54-09, with only Transport Canada–approved later revisions permitted (Requirement).","Two separate compliance timeframes (within 500 hours TIS and within 4,000 hours TIS) after the effective date, creating scheduling constraints (Compliance).","Technical intervention: modification of fairlead plates to prevent chafing caused by nacelle flexing and off-centred tubes (Background), requiring hands-on maintenance and parts.","Reference to prior Transport Canada AD (CF-2004-07) and reliance on manufacturer drawings and modsum history increases paperwork and traceability needs (Background/Compliance).","Operational costs and downtime are borne by operators and their maintenance providers; regulatory approval governs permissible methods, adding administrative discretion."],"plain_english_summary":"This directive requires Bombardier DHC-8 Series 400 aircraft (serials 4003–4089) to have modified fairlead plate assemblies fitted to stop fuel and hydraulic tubes chafing where they pass through the firewall. Operators must install Bombardier Modsum 4-113438 per Service Bulletin 84-54-09 (Transport Canada–approved) within the specified flying-hour deadlines. The work and parts are the operators’ responsibility; approval controls which revisions are acceptable."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-113-fuel-hydraulic-tubes-chafing","history":"/api/acts/ad-dhc-8-113-fuel-hydraulic-tubes-chafing/history","analysis":"/api/acts/ad-dhc-8-113-fuel-hydraulic-tubes-chafing/analysis","conflicts":"/api/acts/ad-dhc-8-113-fuel-hydraulic-tubes-chafing/conflicts","importantCases":"/api/acts/ad-dhc-8-113-fuel-hydraulic-tubes-chafing/important-cases","documents":"/api/acts/ad-dhc-8-113-fuel-hydraulic-tubes-chafing/documents"}}