{"id":"F2006B09778","name":"AD/F28/42 Amdt 1 - Horizontal Stabiliser Hinge Bolt Retention - Inspection and Modification","slug":"ad-f28-42-amdt-1-horizontal-stabiliser-hinge-bolt-retention-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54690,"registerId":"commonwealth-F2006B09778-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F28/42 Amdt 1 - Horizontal Stabiliser Hinge Bolt Retention - Inspection and Modification","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)  \nFokker F28 Series Aeroplanes\n\nAD/F28/42\n\nAmdt 1\n\n  \n\nHorizontal Stabiliser Hinge Bolt Retention \\- Inspection and Modification\n\n  \n8/80\n\nApplicability: All models F28 with S/Nos. 11003 to 11145, 11147, 11150, 11151, 11991 and 11992.\n\nRequirement: 1. Inspect the retention of the horizontal stabiliser hinge bolts in accordance with RLD AD No. 79-89-55, or Fokker F28 SB No. F28/55-20.\n\n2. Modify the retention of the horizontal Stabiliser hinge bolts in accordance with RLD AD No. 80-37-55, OR Fokker SB No. F28/55-21.\n\nCompliance: 1. Before 1 June 1980.\n\n2. Before 1 November 1980.\n\nAn overseas operator experienced migration of a horizontal stabiliser hinge bolt after loss of the retaining pin. This AD amendment adds a modification to provide back-up to bolt retention.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment expands the original directive by adding a mandatory modification to provide back-up retention of the horizontal stabiliser hinge bolts in addition to the inspection requirement. The AD therefore moves from inspection-only to inspection-plus-modification for the listed F28 serial numbers, and sets separate compliance deadlines for each action (Requirement; Compliance; explanatory sentence)."},"complexity_factors":["References external technical documents (RLD AD Nos. 79-89-55 and 80-37-55, and Fokker SBs F28/55-20 and F28/55-21) rather than setting out technical steps in the AD itself, requiring operators to obtain and interpret those documents.","Applicability limited to a set of specific serial numbers, requiring rostered checks of fleet records.","Two separate mandatory actions (inspection then modification) with distinct compliance deadlines.","Technical work (inspection and modification) requires qualified maintenance personnel and possible parts procurement, introducing operational scheduling complexity for operators.","Limited text; legal requirements are straightforward but rely on cross-references, which increases practical complexity despite simple legal structure."],"plain_english_summary":"This AD requires listed Fokker F28s to inspect horizontal stabiliser hinge‑bolt retention and install a back‑up retention modification per the referenced RLD ADs or Fokker service bulletins, with inspections due by 1 June 1980 and modifications by 1 November 1980. It applies only to the specified serial numbers; owners/operators fund and schedule the work. The aim is to prevent hinge‑bolt migration after retaining‑pin loss, trading maintenance cost and downtime for improved safety."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is an amendment to an existing Airworthiness Directive (AD/F28/42), but it does not represent scope creep. The amendment adds a required modification to address the same safety issue (hinge bolt retention) that prompted the original inspection requirement. The scope remains tightly focused on the specific mechanical defect identified after an incident overseas."},"complexity_factors":["Very short document (approximately 150 words)","Only 2 defined compliance actions with clear deadlines","Single applicability criterion (specific aircraft serial numbers)","No nested exceptions or conditional logic","References to external technical documents (Service Bulletins and foreign ADs) but does not reproduce their content","Straightforward temporal compliance structure (two fixed dates)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance actions on certain aircraft.\n\n**What it does:**\nThis directive orders owners and operators of specific Fokker F28 series aircraft to inspect and modify how the horizontal stabiliser hinge bolts are held in place. The horizontal stabiliser is the small wing at the tail of the aircraft that controls pitch (up and down movement). The hinge bolts are critical structural fasteners that hold this component to the fuselage.\n\n**Who it affects:**\n- Owners and operators of Fokker F28 aircraft with specific serial numbers (11003 to 11145, plus 11147, 11150, 11151, 11991, and 11992)\n- Maintenance organisations servicing these aircraft\n\n**What must be done:**\n1. **Inspection:** Check the retention of the horizontal stabiliser hinge bolts by 1 June 1980, following either Dutch aviation authority guidelines (RLD AD No. 79-89-55) or Fokker's Service Bulletin F28/55-20\n2. **Modification:** Install a backup retention system for these bolts by 1 November 1980, following either RLD AD No. 80-37-55 or Fokker Service Bulletin F28/55-21\n\n**Why it matters:**\nAn overseas operator discovered that a hinge bolt had started to move out of position after its retaining pin fell out. This could lead to loss of control of the aircraft. This amendment adds a mandatory modification to create a backup safety system, ensuring that even if the primary retention fails, the bolt cannot migrate and cause catastrophic structural failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f28-42-amdt-1-horizontal-stabiliser-hinge-bolt-retention-inspection-and-modification","history":"/api/acts/ad-f28-42-amdt-1-horizontal-stabiliser-hinge-bolt-retention-inspection-and-modification/history","analysis":"/api/acts/ad-f28-42-amdt-1-horizontal-stabiliser-hinge-bolt-retention-inspection-and-modification/analysis","conflicts":"/api/acts/ad-f28-42-amdt-1-horizontal-stabiliser-hinge-bolt-retention-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-f28-42-amdt-1-horizontal-stabiliser-hinge-bolt-retention-inspection-and-modification/important-cases","documents":"/api/acts/ad-f28-42-amdt-1-horizontal-stabiliser-hinge-bolt-retention-inspection-and-modification/documents"}}