{"id":"F2006B09689","name":"AD/F27/122 Amdt 1 - MLG Upper Member","slug":"ad-f27-122-amdt-1-mlg-upper-member","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115841,"registerId":"commonwealth-F2006B09689-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/122 Amdt 1 - MLG Upper Member","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 F27 Series Aeroplanes\n\nAD/F27/122\n\nAmdt 1\n\n  \nMLG Upper Member 12/91\n\nApplicability: Model F27 series with serial numbers 10102 through 10684, 10686 and 10687, 10689\n\nthrough 10692.\n\nRequirement: Inspect and modify in accordance with Fokker SB F27/32-162.\n\nNote: RLD AD 91-041 refers.\n\nCompliance: Before 1 January 1992. (Same as previous issue of this Directive.)\n\nBackground: Several main undercarriage upper members were found on inspection to have a fatigue crack at the intersection of the side face and the cross bore. Therefore Fokker is calling for a one time inspection of the rest of the fleet, and a rework to radius the edge of the cross bore to prevent further cracking.\n\nAmendment 1 is raised to align this Directive with the related RLD AD, which calls up the above Fokker bulletin, and in doing so now includes the Mk 500.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"Amendment 1 expands the Directive’s scope by bringing it into alignment with the related RLD airworthiness directive and, in doing so, adds the Mk 500 to the aircraft captured by the requirement (Amendment 1; Note). Mechanically the core obligation (inspect and modify per Fokker SB F27/32-162 by 1 January 1992) remains the same, but the pool of affected aircraft increased."},"complexity_factors":["Technical specificity: refers to a manufacturer service bulletin (Fokker SB F27/32-162) that contains the procedural and engineering detail required to comply (Requirement).","Serial-numbered applicability: applicability is limited to a discrete list of serial numbers (Applicability), requiring operators to check applicability precisely.","Fixed compliance deadline: a single mandatory date (before 1 January 1992) concentrates workload and scheduling pressure (Compliance).","Cross-reference to another regulator’s AD (RLD AD) and the amendment that expands scope to include an additional mark (Mk 500), adding a layer of cross-document consistency to check (Note; Amendment 1).","Regulatory formality: the instrument is an airworthiness directive, which creates an enforceable obligation rather than guidance (Requirement; Compliance)."],"plain_english_summary":"Operators of specified Fokker F27 series aeroplanes (listed serials, amendment adding Mk 500) must carry out a one‑time inspection and radius rework of the main landing‑gear upper member per Fokker SB F27/32‑162 before 1 January 1992. The action addresses fatigue cracking found at a cross‑bore edge; costs and downtime fall to aircraft owners, while the regulator enforces compliance."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":true,"description":"Amendment 1 expanded the original directive's scope to include the Fokker F27 Mk 500 variant, aligning it with the related Dutch aviation safety directive (RLD AD 91-041). This represents a modest expansion of the original safety measure to cover an additional aircraft variant."},"complexity_factors":["Single, specific technical requirement (inspect and modify per manufacturer bulletin)","Limited applicability (specific aircraft serial numbers plus one variant)","No nested exceptions or conditional logic","Only one defined term implicitly referenced (MLG = Main Landing Gear)","Short document (approximately 150 words)","Simple amendment purpose (expanding scope to include Mk 500 variant)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires aircraft owners or operators to take specific action to fix a known safety problem.\n\n**What it does:**\n- Orders inspections and modifications to the **main landing gear (MLG) upper member** on certain Fokker F27 aircraft.\n- The problem: fatigue cracks were found where the side face meets the cross bore of this component. If left unchecked, this could lead to landing gear failure.\n- The fix: a one-time inspection of the fleet, plus reworking (rounding off) the edge of the cross bore to prevent future cracking.\n\n**Who it affects:**\n- Owners and operators of Fokker F27 series aircraft with specific serial numbers (10102–10684, 10686–10687, and 10689–10692).\n- Amendment 1 expands this to include the **Mk 500** variant, bringing it in line with a related Dutch aviation safety directive.\n\n**Why it matters:**\nLanding gear failure is catastrophic. This directive prevents accidents by catching cracks before they cause structural failure. The compliance deadline was tight (before 1 January 1992), reflecting the urgency of the safety risk.\n\n**Key terms explained:**\n- **Airworthiness Directive (AD):** A legally enforceable instruction to fix an unsafe condition in an aircraft.\n- **Service Bulletin (SB):** Technical instructions from the manufacturer (here, Fokker) on how to inspect or repair aircraft.\n- **RLD AD 91-041:** A corresponding safety order from the Dutch aviation authority (Rijksluchtvaartdienst), the country where Fokker was based."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-122-amdt-1-mlg-upper-member","history":"/api/acts/ad-f27-122-amdt-1-mlg-upper-member/history","analysis":"/api/acts/ad-f27-122-amdt-1-mlg-upper-member/analysis","conflicts":"/api/acts/ad-f27-122-amdt-1-mlg-upper-member/conflicts","importantCases":"/api/acts/ad-f27-122-amdt-1-mlg-upper-member/important-cases","documents":"/api/acts/ad-f27-122-amdt-1-mlg-upper-member/documents"}}