{"id":"F2006B09211","name":"AD/DHC-8/55 - Horizontal Stabiliser Skin Disbonding Follow-up","slug":"ad-dhc-8-55-horizontal-stabiliser-skin-disbonding-follow-up","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53051,"registerId":"commonwealth-F2006B09211-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-8/55 - Horizontal Stabiliser Skin Disbonding Follow-up","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)  \nBombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes\n\nAD/DHC-8/55 Horizontal Stabiliser Skin Disbonding Follow-up 12/98\n\nApplicability: All DHC-8, Series 100 and 300 aircraft which have horizontal stabilisers, serial numbers CAP 003 through CAP 214 fitted.\n\nRequirement: 1. For Horizontal Stabilisers, Serial Numbers CAP 003 through CAP 050:\n\nPerform an Ultrasonic Bond Inspection of the upper and lower skin panels (part number 85510025 and 85510026) for disbonding as outlined in de Havilland Non Destructive Testing Manual, PSM 1-8-7A, Part 5, Section 55-00-01.\n\n2. For Horizontal Stabilisers, Serial Numbers CAP 003 through CAP 214:\n\nThe inspection interval in the Airworthiness Limitations List (AWL) is reduced from 3 years to 2 years in accordance with Temporary Revision (TR) No. AWL 63 of the AWL in the Maintenance Program Manual PSM 1-8-7 (for Series 100 aircraft) and TR No. AWL 3-70 of the AWL in the Maintenance Program Manual PSM 1-83-7 (for Series 300 aircraft). These inspections are to be phased in as specified in Compliance paragraph 2.\n\nDisbonds beyond the local disbond limits defined in de Havilland document PSM 1- 8-7A, Part 5, Section 55-00-01 shall be repaired before further flight.\n\nNote: Transport Canada AD CF-98-24 refers.\n\nCompliance: 1 Unless already accomplished within the last 3 months, before 5 December 1998; repeat between 12 and 14 months after the initial inspection.\n\n2. a. For Horizontal Stabilisers Serial Number CAP 003 through CAP 050:\n\nFollowing the Compliance 1 repeat inspection, inspect within the next 2 years and thereafter at intervals not to exceed 2 years.\n\n    2. b. For Horizontal Stabilisers Serial Numbers CAP 051 through CAP 214:\n\n    Where the next inspection falls due in 1998, unless already accomplished, perform the inspection as scheduled and repeat thereafter at intervals not to exceed 2 years.\n\n    ii. Where the next inspection falls due in 1999, unless already accomplished, perform the inspection no later than 31 December 1998 and repeat thereafter at intervals not to exceed 2 years.\n\n    iii. Where the next inspection falls due after 1 January 2001, perform the inspection 1 year earlier and repeat thereafter at intervals not to exceed 2 years.\n\nThis Airworthiness Directive becomes effective on 5 November 1998.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nBackground: As a result of the inspection required by AD/DHC-8/51, a total of four aircraft with serial numbers close together were determined to have disbonds of the doublers and stringers on the upper and lower skin panels of the horizontal stabiliser. This discovery indicates that the bonding process was defective on a single batch of skins. The follow-up inspections of this Directive will ensure that no further problems exist in the above single batch or other batches of the bonded skin panels.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Yes. Compared with the prior AWL schedule and the earlier AD action that discovered defects, this AD widens and accelerates mandatory activity: it mandates ultrasonic inspections for the specified batch range, reduces the AWL inspection interval from 3 years to 2 years, and imposes phased, serial-numbered compliance deadlines and a repair-before-flight requirement (see Requirement 1–2 and Compliance)."},"complexity_factors":["Technical inspection standard: requires ultrasonic bond inspection per de Havilland NDT manual (Requirement 1).","Part/serial-number specificity: applies only to horizontal stabilisers CAP 003–CAP 214 (Applicability).","Phased compliance schedule with different rules by serial-number ranges and calendar-year triggers (Compliance 2 a–b i–iii).","Modification of maintenance program AWL intervals from 3 years to 2 years (Requirement 2), affecting scheduled maintenance planning.","Repair-before-flight mandate for disbonds beyond manufacturer limits (Requirement 1; Repair note).","Dependence on external documents and revisions: references manufacturer manuals, AWL Temporary Revisions, and Transport Canada AD CF-98-24 (Requirement 1–2; Note).","Effective-date and short initial deadlines introduce immediate operational pressures (Compliance; Effective date 5 Nov 1998)."],"plain_english_summary":"This directive requires operators of Bombardier DHC‑8 Series 100 and 300 aeroplanes with horizontal stabilisers CAP 003–CAP 214 to carry out ultrasonic inspections of the upper and lower stabiliser skins and to repair any disbonds beyond the manufacturer's local limits before further flight. It also shortens the mandated inspection interval in the Airworthiness Limitations List from 3 years to 2 years.\n\nOperators pay for inspections and repairs; inspections must follow the manufacturer's NDT procedures and are phased by serial number with specified initial and repeat deadlines. The measure follows discovery of a defective bonding batch and takes effect 5 November 1998."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope: addressing a specific manufacturing defect in horizontal stabiliser skin bonding on specific DHC-8 aircraft. The follow-up nature references earlier directive AD/DHC-8/51 but does not expand beyond the original safety concern."},"complexity_factors":["Multiple serial number ranges with different compliance requirements (CAP 003–050 vs CAP 051–214)","Phased compliance schedule with four distinct deadline scenarios based on existing inspection dates","Cross-references to external technical documents (PSM 1-8-7A, Temporary Revisions AWL 63 and AWL 3-70)","Nested conditional logic: different rules apply depending on when the next inspection was due (1998, 1999, or post-2001)","Technical aviation terminology requiring specialist knowledge (disbonding, ultrasonic bond inspection, doublers, stringers, Airworthiness Limitations List)"],"plain_english_summary":"This safety order requires urgent ultrasonic inspections for disbonding of the horizontal stabiliser on Bombardier DHC‑8 Series 100 and 300 aircraft with stabilisers CAP 003–214, shortens recurring inspection intervals, and mandates repair before flight if disbonding exceeds limits. \n\nIt affects airlines/operators and maintenance crews servicing these Dash 8s after four aircraft were found with dangerous bonded‑skin separation traced to a defective manufacturing batch."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-55-horizontal-stabiliser-skin-disbonding-follow-up","history":"/api/acts/ad-dhc-8-55-horizontal-stabiliser-skin-disbonding-follow-up/history","analysis":"/api/acts/ad-dhc-8-55-horizontal-stabiliser-skin-disbonding-follow-up/analysis","conflicts":"/api/acts/ad-dhc-8-55-horizontal-stabiliser-skin-disbonding-follow-up/conflicts","importantCases":"/api/acts/ad-dhc-8-55-horizontal-stabiliser-skin-disbonding-follow-up/important-cases","documents":"/api/acts/ad-dhc-8-55-horizontal-stabiliser-skin-disbonding-follow-up/documents"}}