{"id":"F2006B02542","name":"AD/AT/13 - Wing Spar Cap Corrosion","slug":"ad-at-13-wing-spar-cap-corrosion","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41798,"registerId":"commonwealth-F2006B02542-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AT/13 - Wing Spar Cap Corrosion","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Airtractor AT-300, 400 and 500 Series Aeroplanes\n\n \n\nAD/AT/13 Wing Spar Cap Corrosion 7/92\n\nApplicability: Models AT-300, AT-301, & AT-302 with S/N’s 300-0001 through 301-0688; Model AT-400 with S/N’s 400-0244 through400-0415; & Model AT-400A all S/N’s.\n\n \n\nRequirement: Action in accordance with Air Tractor Inc. Service Letter No. 90.\n\n \n\nNote: FAA AD 92-07-14 Amdt 39-8210 refers.\n\n \n\nCompliance: Prior to 30 September 1992; and thereafter at intervals not to exceed 12 calendar months.\n\n \n\nBackground:  The FAA has received three reports of badly corroded wing spar caps on the affected aircraft. The actions specified by this Directive are intended to prevent failure of the wing structure.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive’s scope is explicit in the text: it applies to the listed models and serial-number ranges and requires actions in the manufacturer’s Service Letter with an initial deadline and 12‑month recurrence (Applicability; Requirement; Compliance). The AD text does not indicate any alteration of that scope from an earlier version within the provided document."},"complexity_factors":["Narrow technical scope limited to specific models and serial-number ranges (Applicability).","Compliance is recurring (annual) with a fixed initial deadline, creating an ongoing administrative burden (Compliance).","Practical implementation depends on an external document (Air Tractor Inc. Service Letter No. 90) rather than detailed procedures in the AD itself (Requirement).","Safety justification is factual but brief (three reports cited), leaving limited detail about inspection standards or repair thresholds (Background)."],"plain_english_summary":"Owners/operators of specified Air Tractor AT‑300/301/302/400/400A aircraft must follow Air Tractor Service Letter No. 90 to inspect for and correct corroded wing spar caps before 30 September 1992 and then at least annually. This AD shifts implementation to the manufacturer’s procedure, imposes recurring inspection and repair costs and downtime on owners, and aims to prevent wing-structure failure."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow airworthiness directive focused on a specific safety issue (wing spar corrosion) in a specific aircraft type. It has not expanded beyond its original purpose of mandating inspections to prevent structural failure."},"complexity_factors":["Very short document (approximately 200 words)","Only 4 defined elements: specific aircraft models and serial number ranges","Single requirement referencing an external document (Air Tractor Service Letter No. 90)","Simple compliance structure: one-time deadline plus recurring annual requirement","No nested conditions, exceptions, or cross-references to other legislation beyond a single FAA AD reference","Straightforward applicability test based on model and serial number"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nRequires owners and operators of certain **Air Tractor crop-dusting planes** (models AT-300, AT-301, AT-302, AT-400, and AT-400A) to inspect their aircraft for **corrosion in the wing spar caps** — that's the metal structure at the top and bottom of the wing that bears most of the load during flight.\n\n**Who it affects:**\n- Owners and operators of specific Air Tractor agricultural aircraft with particular serial numbers\n- Anyone maintaining these aircraft in Australia\n\n**What must be done:**\n- Follow the procedures in **Air Tractor Service Letter No. 90** (the manufacturer's official instructions)\n- Complete the first inspection **before 30 September 1992**\n- Repeat the inspection **every 12 months** thereafter\n\n**Why it matters:**\nThe US Federal Aviation Administration (FAA) found **three cases of severe corrosion** in these wing components. If left unchecked, this corrosion could cause the **wing structure to fail in flight** — potentially catastrophic for agricultural pilots flying low and heavy with chemical loads.\n\nThis directive is designed to catch the problem before it causes accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-at-13-wing-spar-cap-corrosion","history":"/api/acts/ad-at-13-wing-spar-cap-corrosion/history","analysis":"/api/acts/ad-at-13-wing-spar-cap-corrosion/analysis","conflicts":"/api/acts/ad-at-13-wing-spar-cap-corrosion/conflicts","importantCases":"/api/acts/ad-at-13-wing-spar-cap-corrosion/important-cases","documents":"/api/acts/ad-at-13-wing-spar-cap-corrosion/documents"}}