{"id":"F2006B09802","name":"AD/F28/68 - Fuselage Lap Joint at Stringer 73","slug":"ad-f28-68-fuselage-lap-joint-at-stringer-73","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54723,"registerId":"commonwealth-F2006B09802-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F28/68 - Fuselage Lap Joint at Stringer 73","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/F28/68 Fuselage Lap Joint at Stringer 73 12/91\n\nApplicability: All model F28 with serial numbers referenced in the Requirement Document. Requirement: Modify the fuselage lap joint in accordance with the Technical Requirements of RLD\n\nAD 90-006 issue 2.\n\nCompliance: As specified in the Requirement Document.\n\nBackground: Investigation following the discovery of cracks in a fuselage lap joint on two aircraft prompted the requirement for a low frequency eddy current inspection, which has now been incorporated into the F28 Structural Integrity Program (S.I.P). The Dutch airworthiness authority has since determined that safety cannot be reliably maintained by inspection, hence this Directive provides for a permanent repair/modification of the affected lap joint.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating repair of the Stringer 73 lap joint."},"complexity_factors":["Short, single-issue directive (approximately 150 words)","Only 1 defined reference (RLD AD 90-006 issue 2) — technical details outsourced to external document","No nested exceptions or conditional logic — simple applicability rule (specific aircraft serial numbers)","Single compliance pathway with no alternatives","Background provided for context but not legally operative"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nOrders owners and operators of **Fokker F28 series aircraft** to permanently repair or modify a specific structural weak point — the **fuselage lap joint at Stringer 73** (a seam where two sections of the aircraft's body join together, near a structural support called \"Stringer 73\").\n\n**Why it matters:**\nCracks were found in this joint on two aircraft. Initially, regulators required regular inspections to catch cracks early. However, the Dutch aviation authority (RLD — now part of the Netherlands' civil aviation authority) decided inspections alone weren't reliable enough to keep planes safe. This directive replaces the inspection requirement with a **permanent fix**.\n\n**Who must comply:**\nAnyone operating Fokker F28 aircraft with specific serial numbers listed in the accompanying technical document.\n\n**How to comply:**\nFollow the technical instructions in **RLD AD 90-006 issue 2** (the Dutch authority's safety directive). The exact deadline for completing the work is set out in that same document."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"The directive changes scope from a monitoring/inspection approach to a mandatory permanent repair for the affected lap joint. Previously a low-frequency eddy-current inspection had been incorporated into the F28 Structural Integrity Program; the Dutch authority concluded inspection alone was insufficient and the directive replaces that option with a required modification for the serial-numbered aircraft listed in the Requirement Document (Background; Requirement; Applicability)."},"complexity_factors":["Technical nature of work: structural fuselage modification (lap joint at stringer 73) requiring specialised maintenance skills and parts (Requirement).","External document dependence: key details (serial numbers, method, timing) are in the Requirement Document and RLD technical requirements rather than the directive text itself (Applicability; Requirement; Compliance).","Change in compliance regime: moves from inspection-based management (eddy-current S.I.P.) to mandatory modification, altering operational decision-making and cost timing (Background).","Traceability and verification: enforcement and proof of compliance depend on following and documenting an external Requirement Document (Compliance).","Identification of affected fleet: applicability limited to specified serial numbers, requiring accurate records and fleet checks by operators (Applicability).","International regulatory input: the Dutch authority’s determination influenced the move from inspection to repair, adding cross-jurisdictional evidence and precedent (Background)."],"plain_english_summary":"This AD mandates a permanent repair to the fuselage lap joint at stringer 73 on specific Fokker F28 airframes (by serial number), replacing the prior inspection regime. It affects the listed aircraft owners/operators, who must fund and schedule the modification, while technical methods and timing are set by the Responsible Local Design authority and the referenced Requirement Document."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f28-68-fuselage-lap-joint-at-stringer-73","history":"/api/acts/ad-f28-68-fuselage-lap-joint-at-stringer-73/history","analysis":"/api/acts/ad-f28-68-fuselage-lap-joint-at-stringer-73/analysis","conflicts":"/api/acts/ad-f28-68-fuselage-lap-joint-at-stringer-73/conflicts","importantCases":"/api/acts/ad-f28-68-fuselage-lap-joint-at-stringer-73/important-cases","documents":"/api/acts/ad-f28-68-fuselage-lap-joint-at-stringer-73/documents"}}