{"id":"F2006B11404","name":"AD/MUSTANG/1 Amdt 2 - Wing Front Spar","slug":"ad-mustang-1-amdt-2-wing-front-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57305,"registerId":"commonwealth-F2006B11404-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/MUSTANG/1 Amdt 2 - Wing Front Spar","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)  \nC.A.C. CA-18 (Mustang) Series Aeroplanes\n\nAD/MUSTANG/1\n\nAmdt 2\n\n  \nWing Front Spar 4/86\n\nApplicability: As detailed in the Requirements.\n\nRequirement: 1. Remove the wing fuel tank covers and carry out a visual inspection of the lower portion of the wing front spar.\n\n    2. Inspect the lower portion of the wing front spar for cracking at and near wing station 27 port and starboard.\n\n    3. For aircraft in which the cutout in the wing main spar lower boom flange at the wing root extends beyond wing station 2, inspect the lower portion of the spar for cracking at and near the end of the cutout port and starboard.\n\nCompliance: At intervals not exceeding 240 hours time in service.\n\nBackground: This Directive has been amended to clarify the inspection requirements on the wing spar tension boom flange. In addition, the interval between inspections has been extended to 240 hours time in service.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a straightforward amendment to an existing Airworthiness Directive. The changes are minor clarifications: making inspection requirements clearer and extending the inspection interval based on operational data. The scope remains tightly focused on wing spar inspections for a specific aircraft type, with no expansion into unrelated areas."},"complexity_factors":["Very short document (approximately 200 words)","Only 3 specific inspection requirements with clear sequential numbering","Single conditional clause (Requirement 3) applying only to aircraft with specific spar cutout characteristics","No defined terms section — technical terms (wing station, port/starboard, boom flange) are standard aviation terminology","No cross-references to other legislation or regulations beyond the enabling citation (Civil Aviation Regulations 1998, Part 39)","Simple compliance trigger: time-based interval (240 hours) with no exceptions or alternative compliance methods"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) that tells aircraft owners and operators they must perform specific maintenance checks.\n\n**What it does:** This AD applies specifically to **CAC CA-18 Mustang series aeroplanes** (Australian-built versions of the famous P-51 Mustang fighter aircraft). It requires owners/operators to:\n\n- **Remove the wing fuel tank covers** and visually inspect the lower part of the wing's front spar (the main structural beam that runs through the wing)\n- **Check for cracks** at specific locations near \"wing station 27\" on both left (port) and right (starboard) sides\n- **For certain aircraft only:** If the cutout in the wing spar's lower boom flange extends past \"wing station 2,\" also check for cracks at the end of that cutout on both sides\n\n**How often:** These inspections must be done **every 240 hours of flight time** (\"time in service\" means actual flying hours, not just calendar time).\n\n**Why it matters:** Cracks in wing spars are extremely serious — the spar is essentially the backbone of the wing. If it fails, the wing can separate from the aircraft. This AD was updated (Amendment 2) to make the inspection instructions clearer and extend the interval between checks from a shorter period to 240 hours, based on operational experience showing this was safe.\n\n**Who must comply:** Anyone operating or maintaining a CAC CA-18 Mustang aircraft in Australia."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The Directive was amended to clarify inspection requirements on the wing spar tension boom flange and to extend the inspection interval to 240 hours time in service. (Background; Compliance; Requirement)"},"complexity_factors":["Requires removal of wing fuel tank covers before inspection (increases preparatory work and access requirements).","Multiple specific inspection locations: lower front spar at wing station 27 port and starboard, and conditionally at the end of a cutout near wing root (adds inspection points).","Inspection method is \"visual inspection,\" which leaves scope for inspector judgement and possible variability in findings.","Compliance frequency is recurring (every 240 hours TIS), creating ongoing scheduling and maintenance planning obligations.","Applicability phrase \"As detailed in the Requirements\" and conditional language about the cutout create some practical ambiguity about which airframes or configurations are subject to the extra inspection point."],"plain_english_summary":"The Civil Aviation Safety Authority requires operators of C.A.C. CA‑18 (Mustang) aeroplanes to remove wing fuel tank covers and perform recurring visual inspections of the lower wing front spar (focusing on wing station 27 and certain wing‑root cutout ends) to detect cracking, now at intervals not exceeding 240 hours time in service. This directive affects aircraft owners and maintenance providers by adding recurring inspection work, potential repair costs and altered maintenance scheduling, while leaving inspection technique and judgement to competent personnel."}},"importantCases":[],"_links":{"self":"/api/acts/ad-mustang-1-amdt-2-wing-front-spar","history":"/api/acts/ad-mustang-1-amdt-2-wing-front-spar/history","analysis":"/api/acts/ad-mustang-1-amdt-2-wing-front-spar/analysis","conflicts":"/api/acts/ad-mustang-1-amdt-2-wing-front-spar/conflicts","importantCases":"/api/acts/ad-mustang-1-amdt-2-wing-front-spar/important-cases","documents":"/api/acts/ad-mustang-1-amdt-2-wing-front-spar/documents"}}