{"id":"F2006L02518","name":"AD/DHC-8/128 - Wing Root Electrical Wire Chafing","slug":"ad-dhc-8-128-wing-root-electrical-wire-chafing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":59743,"registerId":"commonwealth-F2006L02518-current","compilationNumber":null,"startDate":"2026-04-02","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-8/128 | Wing Root Electrical Wire Chafing | 9/2006 |\n| ------------ | --------------------------------- | ------ |\n\n| Applicability: | DHC-8 aircraft, Models 102, 103, 106, 201, 202, 301, 311, 314 and 315, Serial Numbers 003 through 606.                                                                                                                                                                                                                                                                               |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | 1. Visually inspect for damage and repair as required the following electrical wiring harness in accordance with the instructions contained in Bombardier Service Bulletin (SB) 8-24-83, Revision A, dated 2 August 2005, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada:                                                                      |\n|                | a. Left electrical cable harness assembly 82440073-001 (DHC-8 Models 100/200) or 82440073-301 (DHC-8 Models 300) located on the left wing root to fuselage aft seal assembly 85350712-001 at station Yw43.00.                                                                                                                                                                        |\n|                | b. Right electrical cable harness assembly 82440074-001 (DHC-8 Models 100/200) or 82440074-301 (DHC-8 Models 300) located on the right wing root to fuselage aft seal assembly 85350711-001 at station Yw43.00.                                                                                                                                                                      |\n|                | Prior inspections of the wiring harnesses and modification of the seal assemblies, before the effective date of this Directive, in accordance with the original issue of Bombardier SB 8-24-83, satisfy the requirements of this Directive.                                                                                                                                          |\n|                | 2. Install Bombardier ModSum 8Y122031 to rework the seal assemblies to create a clearance between the electrical cable assemblies and the edge of the fairing panel. Bombardier SB 8-24-83, Revision A, dated 2 August 2005, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada, contains approved instructions for incorporating Modsum 8Y122031. |\n|                | Incorporation of Bombardier ModSum IS8Q2400005, before the effective date of this Directive, is equivalent to Bombardier ModSum 8Y122031, and satisfies the requirements of this Airworthiness Directive.                                                                                                                                                                            |\n|                | Note: Transport Canada AD CF-2006-15 refers.                                                                                                                                                                                                                                                                                                                                         |\n| Compliance:    | For Requirements 1 and 2 - Within 6 000 hours time in service after the effective date of this Directive.                                                                                                                                                                                                                                                                            |\n|                | This Airworthiness Directive becomes effective on 31 August 2006.                                                                                                                                                                                                                                                                                                                    |\n\n| Background: | Transport Canada has received a report of an incident in which a DHC-8 aircraft encountered an un-commanded propeller feathering during climb, resulting in an emergency landing. Investigation revealed that the wing to fuselage aft seal assembly had chafed through the wires associated with the auto-feather control system. Both the left and right wing to fuselage aft seal assemblies could potentially exhibit this condition. |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | Chafing and/or grounding of the wiring against the aft seal assemblies may interrupt the operation of various aircraft systems, including propeller feather control, AC electrical power, and/or standby hydraulic power, resulting in potential flight safety hazards. This Airworthiness Directive requires that the left and right electrical harness be inspected for chafing and, if necessary, the accomplishment of any repairs.   |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n21 July 2006","sortOrder":0},{"sectionNumber":"AD/DHC-8/128","sectionType":"part","heading":"AD/DHC-8/128","content":"## AD/DHC-8/128","sortOrder":1},{"sectionNumber":"Wing Root Electrical Wire Chafing","sectionType":"part","heading":"Wing Root Electrical Wire Chafing","content":"## Wing Root Electrical Wire Chafing","sortOrder":2},{"sectionNumber":"9/2006","sectionType":"part","heading":"9/2006","content":"## 9/2006","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive remains focused on the original safety concern: eliminating chafing of wing-root wiring that could disable critical systems. It prescribes specific inspections and a particular rework (ModSum) for a defined set of models/serial numbers. Allowing prior-completed work and an equivalent earlier ModSum preserves rather than expands scope; permitting later SB revisions only with Transport Canada approval introduces procedural discretion but does not broaden the substantive対象 (subject) of required actions."},"complexity_factors":["Narrow applicability list but multiple models and a serial-number range (Models 102–315, SN 003–606)","Two main required actions (inspection/repair and ModSum rework) each referencing Bombardier Service Bulletin SB 8-24-83 Revision A","Allowance for prior compliance under the original SB and equivalence of an earlier ModSum (IS8Q2400005) to the required ModSum (8Y122031)","Approval gate: later revisions of the SB may be used only if approved by the Chief, Continuing Airworthiness (regulatory discretion)","Single compliance time condition (6,000 flight hours TIS) — simple but requires tracking","Cross-reference to Transport Canada AD CF-2006-15 (external linkage)"],"plain_english_summary":"**What this instrument does**\n\n- Requires operators of specified De Havilland/Bombardier DHC-8 (Dash 8) aeroplanes to inspect and, if necessary, repair two electrical wiring harnesses located at the wing root where the wing meets the fuselage. (Requirement 1)\n- Requires a physical rework (a ModSum) of the wing root seal assemblies to create clearance so the wiring cannot rub (chafe) against the fairing panel. The required rework is Bombardier ModSum 8Y122031 (or the earlier equivalent ModSum IS8Q2400005). (Requirement 2)\n- Directs compliance with the detailed procedures in Bombardier Service Bulletin SB 8-24-83 Revision A dated 2 August 2005, or later revisions that the Chief, Continuing Airworthiness, Transport Canada approves. (Requirement 1–2)\n- Gives operators 6,000 flight hours time-in-service to complete the inspections and ModSum rework. (Compliance)\n\n**Who is affected**\n\n- Owners/operators of DHC-8 aircraft, Models 102, 103, 106, 201, 202, 301, 311, 314 and 315, with serial numbers 003 through 606. (Applicability)\n- Maintenance organisations and licensed maintenance personnel who will carry out the inspections, repairs and ModSum installation per the Bombardier service instructions.\n\n**Why it matters (safety issue and mechanism)**\n\n- The background supplied by Transport Canada says an incident occurred where chafing of the wing-to-fuselage aft seal assembly had worn through wiring associated with the auto-feather control system, causing an uncommanded propeller feathering and an emergency landing. The directive treats that outcome as a risk to flight safety because similar chafing could interrupt other systems (propeller feather control, AC electrical power, standby hydraulic power). (Background)\n\n**How it works mechanically**\n\n- Inspect the left and right electrical cable harnesses at the wing root (specific part numbers and station locations are given). If chafing or damage is found, repair the wiring according to the Bombardier service bulletin. (Requirement 1)\n- Modify the seal/fairing assemblies by incorporating the specified ModSum so there is physical clearance between the harnesses and the fairing edge, preventing future chafing. (Requirement 2)\n- If the specified earlier work or the earlier ModSum was completed before the effective date, that prior compliance is accepted as satisfying this directive. Similarly, later revisions of the service bulletin may be used if approved by the Chief, Continuing Airworthiness. (Requirement 1; Requirement 2)\n\n**Who pays and who decides**\n\n- Operators pay for inspections, any repairs, and the rework/modification (parts and labour, aircraft downtime). Maintenance providers perform the work under the operator's direction. (Requirements 1–2; Compliance)\n- The regulatory decision to accept later service bulletin revisions or to recognise equivalence of prior ModSums is vested in the Chief, Continuing Airworthiness, Transport Canada. The Civil Aviation Safety Authority delegate issued the directive for Australian operators. (Requirement 1–2)\n\n**Costs, incentives and trade-offs**\n\n- Direct costs: parts, labour, and aircraft out-of-service time to perform inspections and the ModSum rework within 6,000 hours TIS. (Compliance; Requirement 2)\n- Incentive structure: operators have flexibility on timing within the 6,000-hour window; earlier voluntary work reduces immediate safety risk but raises near-term cost. Prior-completed work that matches the required standard avoids repeat expenditure. (Requirement 1; Requirement 2)\n- Implementation risk and practical burden: accessing the wiring at the wing root and accomplishing proper repairs and ModSum installation requires qualified maintenance personnel and may differ in labour time between airframes depending on aircraft condition. Delays or improper repairs could leave the risk unaddressed.\n- Regulatory discretion and substitution: the directive permits use of later revisions of the Bombardier SB only if approved by the Chief, Continuing Airworthiness, creating a single point of regulatory approval for alternative methods. (Requirement 1)\n\n**Bottom-line operational effect**\n\n- Affected operators must schedule and complete an inspection and any required repair of the specified wiring harnesses and implement the specified ModSum rework within the stated compliance window, following the referenced Bombardier service instructions (or approved later revisions). Failure to complete these actions leaves aircraft exposed to the same chafing risk the directive is intended to eliminate. (Requirements; Compliance; Background)\n\n(References: Applicability; Requirement 1 and 2; Compliance; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, targeted Airworthiness Directive addressing a specific safety-of-flight issue identified through incident investigation. The scope remains precisely focused on the identified wiring chafing hazard at the wing root seal assemblies of affected DHC-8 models. There is no evidence of scope creep; the directive does not expand beyond the original safety purpose of preventing wire damage that could disable critical flight systems."},"complexity_factors":["Single, specific technical subject matter (wire chafing at wing root)","Limited applicability (only 9 specific aircraft models within serial number range 003-606)","Two clear requirements with straightforward compliance path","Cross-references to external technical documents (Bombardier Service Bulletin 8-24-83 and ModSum 8Y122031) — operators must obtain these separately","Contains one equivalence provision (prior completion of ModSum IS8Q2400005 satisfies the modification requirement)","Single compliance timeframe (6,000 hours) with one effective date","No nested exceptions or conditional logic beyond the grandfathering clause for prior work"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Bombardier DHC-8-100/200/300 (serials 003–606) registered in Australia to inspect wiring at the wing root for chafing, repair any damage, and modify seal assemblies to prevent recurrence. The work is mandatory within 6,000 flight hours after 31 Aug 2006 because chafed wires have caused in-flight system failures, including an unplanned propeller shutdown."},"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-dhc-8-128-wing-root-electrical-wire-chafing","history":"/api/acts/ad-dhc-8-128-wing-root-electrical-wire-chafing/history","analysis":"/api/acts/ad-dhc-8-128-wing-root-electrical-wire-chafing/analysis","conflicts":"/api/acts/ad-dhc-8-128-wing-root-electrical-wire-chafing/conflicts","importantCases":"/api/acts/ad-dhc-8-128-wing-root-electrical-wire-chafing/important-cases","documents":"/api/acts/ad-dhc-8-128-wing-root-electrical-wire-chafing/documents"}}