{"id":"F2008L02522","name":"AD/DHC-8/137 Amdt 1 - Wing Front Spar to Fuselage Attachment","slug":"ad-dhc-8-137-amdt-1-wing-front-spar-to-fuselage-attachment","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":74493,"registerId":"commonwealth-F2008L02522-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-8/137 Amdt 1 | Wing Front Spar to Fuselage Attachment | 8/2008 |\n| ------------------- | -------------------------------------- | ------ |\n\n| Applicability: | DHC-8 aircraft, Models 400, 401, and 402, serial numbers 4001, and 4003 through 4176.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | Action in accordance with the requirements of Transport Canada Emergency ADCF-2008-11R1.Note: Bombardier Inc. Alert Service Bulletins (ASB) A84-57-19 original issue,A84-57-19 Revision A, and A84-57-19 Revision B, or later Transport Canada approved revisions, refer.                                                                                                                                                                                                                                                                                                                                                                                          |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of31 July 2008.Note: The revised effective date of the original issue of this Directive was8 February 2008.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n|                | This Amendment becomes effective on 31 July 2008.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| Background:    | During scheduled maintenance, an operator found cracks in the DSC228-16 barrel nut at one of the four primary front spar wing to fuselage attachment joints. The investigation determined that the cracks were due to hydrogen embrittlement and the problem is believed to be restricted to a batch of 166 barrel nuts from one supplier. Further inspection by a different operator revealed that cracked barrel nuts were found at three of the four wing front spar to fuselage joints on the same aircraft. All three barrel nuts were from the suspect batch. Failure of the barrel nuts could compromise the integrity of the wing to fuselage attachments. |\n\n|     | Amendment 1 is issued in response to a new Transport Canada AD, which mandates the removal of the affected barrel nuts and the application of corrosion inhibiting compound in accordance with ASB A84-57-19 Revision B, dated 6 March 2008. |\n| --- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n12 June 2008","sortOrder":0},{"sectionNumber":"AD/DHC-8/137 Amdt 1","sectionType":"part","heading":"AD/DHC-8/137 Amdt 1","content":"## AD/DHC-8/137 Amdt 1","sortOrder":1},{"sectionNumber":"Wing Front Spar to Fuselage Attachment","sectionType":"part","heading":"Wing Front Spar to Fuselage Attachment","content":"## Wing Front Spar to Fuselage Attachment","sortOrder":2},{"sectionNumber":"8/2008","sectionType":"part","heading":"8/2008","content":"## 8/2008","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 adopts a new Transport Canada AD and Bombardier ASB revision that mandates removal of the affected barrel nuts and application of corrosion‑inhibiting compound; it also revises the Directive's effective date to 31 July 2008 (see 'Requirement', 'Compliance' and 'Background' sections). The amendment narrows remedial action to removing the suspect batch and prescribing the treatment method specified in ASB A84‑57‑19 Revision B."},"complexity_factors":["Technical cause identified (hydrogen embrittlement of DSC228‑16 barrel nuts) increases technical specificity.","Problem tied to a single suspect batch of 166 nuts, requiring parts traceability and batch screening.","Cross‑jurisdictional reliance on Transport Canada Emergency AD and Bombardier Alert Service Bulletins for mandated procedure.","Operational compliance timing (revised effective date of 31 July 2008) creates scheduling pressure for operators.","Logistical burden: inspection, removal, possible replacement of multiple fasteners per aircraft and application of corrosion inhibitor.","Regulatory clarity is high (specific ASB and AD references) but practical complexity arises from parts supply and maintenance downtime."],"plain_english_summary":"This amendment requires operators of Bombardier DHC‑8 Models 400, 401 and 402 (serials 4001 and 4003–4176) to remove certain DSC228‑16 barrel nuts suspected of hydrogen embrittlement and to apply a corrosion‑inhibiting compound, following Transport Canada Emergency AD CF‑2008‑11R1 and Bombardier ASB A84‑57‑19 Rev B. It becomes effective 31 July 2008.\n\nThe Civil Aviation Safety Authority mandates the action; operators bear inspection, removal and replacement costs, must follow the specified Service Bulletin, and change maintenance practices to prevent compromise of the wing‑to‑fuselage attachments."},"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 an amendment to an existing Airworthiness Directive (AD/DHC-8/137). The amendment updates the compliance requirements to align with a revised Canadian safety bulletin (Revision B) and extends the effective date. The scope remains tightly focused on the original safety issue — faulty barrel nuts in wing-to-fuselage attachments — and has not expanded beyond this specific technical defect."},"complexity_factors":["Short, single-purpose directive (approximately 300 words)","Only 3 defined applicability criteria (aircraft models and serial numbers)","Single cross-reference to Transport Canada Emergency AD CF-2008-11R1","Single technical reference to Bombardier Alert Service Bulletin A84-57-19 Revision B","No nested exceptions or conditional logic — straightforward mandatory action","Technical aviation terminology requires domain knowledge but is clearly explained in context"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of specific Bombardier DHC-8 Series 400 (Models 400, 401, 402; S/N 4001, 4003–4176 — ~176 aircraft) to inspect for and replace barrel nuts joining the wing front spar to the fuselage after cracks from hydrogen embrittlement were found. It mandates compliance with the Canadian service bulletin (ASB A84-57-19 Rev B) to prevent possible wing separation. Amended effective date: 31 July 2008."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-137-amdt-1-wing-front-spar-to-fuselage-attachment","history":"/api/acts/ad-dhc-8-137-amdt-1-wing-front-spar-to-fuselage-attachment/history","analysis":"/api/acts/ad-dhc-8-137-amdt-1-wing-front-spar-to-fuselage-attachment/analysis","conflicts":"/api/acts/ad-dhc-8-137-amdt-1-wing-front-spar-to-fuselage-attachment/conflicts","importantCases":"/api/acts/ad-dhc-8-137-amdt-1-wing-front-spar-to-fuselage-attachment/important-cases","documents":"/api/acts/ad-dhc-8-137-amdt-1-wing-front-spar-to-fuselage-attachment/documents"}}