{"id":"F2006B02747","name":"AD/B727/46 Amdt 1 - Horizontal Stabilizer Rear Spar Centre Section Fitting - Inspection","slug":"ad-b727-46-amdt-1-horizontal-stabilizer-rear-spar-centre-section-fitting-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42089,"registerId":"commonwealth-F2006B02747-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/46 Amdt 1 - Horizontal Stabilizer Rear Spar Centre Section Fitting - Inspection","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)  \nBoeing 727 Series Aeroplanes\n\nAD/B727/46\n\nAmdt 1\n\n  \n\nHorizontal Stabilizer Rear Spar Centre Section Fitting - Inspection\n\n  \n3/85\n\nApplicability: All model Boeing 727 with S/Nos listed in the requirement documents. Document: Boeing SB No. 727-55-62.\n\nNote: FAA AD 75-09-04 R1 Amendment 39-2174 as amended by Amendment 39- 4926 refers.\n\nCompliance: Within 750 hours time in service after 31 March 1985, unless accomplished within the last 2250 hours time in service, and thereafter in accordance with the requirement document.\n\nBackground: Further reports have shown that cracking due to stress corrosion in the 7079-T6 fittings may be more extensive than originally covered by Boeing SB 727-55-34. This directive has been amended to include the latest requirements of Boeing SB 727-55-62, which supersedes SB 727-55-34.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment stays within the original scope of addressing stress corrosion cracking in horizontal stabilizer fittings. It does not expand to new aircraft types or unrelated systems; it simply updates the technical requirements based on new data about the same known issue."},"complexity_factors":["Single, specific technical requirement (one inspection task)","Limited applicability (one aircraft type, specific serial numbers)","Clear compliance deadline with simple alternative condition (750 hours OR if done in last 2250 hours)","Only one defined document reference (Boeing SB 727-55-62)","Background explanation provided in plain language","No nested exceptions or conditional logic beyond the basic compliance alternative","Short length (approximately 150 words of substantive content)"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it as a \"recall notice\" for aircraft, but legally binding. If you own or operate the affected planes, you MUST follow these instructions.\n\n**Who it affects:** Owners and operators of **Boeing 727 series aircraft** with specific serial numbers listed in Boeing Service Bulletin 727-55-62.\n\n**What it requires:**\n- **Inspection of a specific part:** The horizontal stabilizer rear spar centre section fitting (a critical structural component at the tail of the plane that helps keep it stable in flight).\n- **Why:** The fittings are made from **7079-T6 aluminium alloy** and can develop **stress corrosion cracking** — tiny cracks that grow due to a combination of tension and environmental factors. This could weaken the tail structure.\n- **When to comply:**\n  - First inspection due within **750 flight hours** after 31 March 1985, **OR** if already inspected within the last **2,250 flight hours**.\n  - Repeat inspections must follow the schedule in Boeing's service bulletin.\n\n**Why it matters:** This amendment expands the original safety check because new reports showed the cracking problem was worse than first thought. The original Boeing bulletin (SB 727-55-34) didn't catch everything, so this updated directive (referencing SB 727-55-62) casts a wider net to prevent potential structural failure.\n\n**Key point:** This is **Amendment 1** — meaning it replaces or updates an earlier version of the same directive to make the safety requirements stricter based on new evidence."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"The AD was amended to adopt the latest Boeing service bulletin (SB 727-55-62) which supersedes an earlier bulletin (SB 727-55-34). The Background states this change was driven by reports that stress-corrosion cracking in the 7079-T6 fittings may be more extensive than previously covered, so the AD’s scope of inspection requirements was broadened to reflect the newer SB (Background)."},"complexity_factors":["Cross-reference to an external technical document (Boeing SB No. 727-55-62) for procedural and corrective-action details (Document).","Applicability limited to specific serial-numbered aircraft listed in the requirement documents, requiring record checks by operators (Applicability).","Conditional timing language (within 750 hours after 31 March 1985 unless accomplished within the last 2,250 hours), which requires operators to verify historical maintenance records (Compliance).","Ongoing/recurring inspections are tied to the external SB rather than detailed in the AD, creating ongoing compliance monitoring needs (Compliance; Document).","Amendment history and cross-reference to FAA ADs add interpretive context that may require consultation of multiple documents (Note; Background)."],"plain_english_summary":"This AD requires owners/operators of specified Boeing 727s to inspect the horizontal stabilizer rear spar centre fitting per Boeing Service Bulletin 727-55-62, enforced by CASA. It was issued after reports showed stress‑corrosion cracking could be more extensive than earlier guidance.\n\nInspections must occur within 750 flight hours after 31 March 1985 (unless already inspected within 2,250 hours), with recurring checks per the SB. Compliance imposes maintenance costs, downtime and reliance on the Boeing SB’s procedures and criteria."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-46-amdt-1-horizontal-stabilizer-rear-spar-centre-section-fitting-inspection","history":"/api/acts/ad-b727-46-amdt-1-horizontal-stabilizer-rear-spar-centre-section-fitting-inspection/history","analysis":"/api/acts/ad-b727-46-amdt-1-horizontal-stabilizer-rear-spar-centre-section-fitting-inspection/analysis","conflicts":"/api/acts/ad-b727-46-amdt-1-horizontal-stabilizer-rear-spar-centre-section-fitting-inspection/conflicts","importantCases":"/api/acts/ad-b727-46-amdt-1-horizontal-stabilizer-rear-spar-centre-section-fitting-inspection/important-cases","documents":"/api/acts/ad-b727-46-amdt-1-horizontal-stabilizer-rear-spar-centre-section-fitting-inspection/documents"}}