{"id":"F2006B06297","name":"AD/PMC/42 - Oil Filled Hubs for Agricultural Aircraft","slug":"ad-pmc-42-oil-filled-hubs-for-agricultural-aircraft","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47387,"registerId":"commonwealth-F2006B06297-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PMC/42 - Oil Filled Hubs for Agricultural Aircraft","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPropellers \\- Variable Pitch \\- McCauley\n\nAD/PMC/42 Oil Filled Hubs for Agricultural Aircraft 13/88\n\nApplicability: All model D2A34C58, D2A34C98 and D3A32C90 series propellers fitted to agricultural aircraft.\n\nRequirement: Modify all propeller hubs to dye oil filled standard in accordance with McCauley Service Manual 720415 Supplement No 1. Service Bulletins 122 and 138C refer.\n\nNote: FAA AD 78-20-01 and 85-08-08 refer.\n\nCompliance: At next propeller overhaul or by 1 December 1989, whichever occurs first. Background: Further hub failures have occurred since revision of the threaded hub dye inspection\n\nAD. Due to the load cycles imposed in a hub during agricultural operations and to\n\nassist in early detection of hub cracks dye oil filling is being introduced. Propeller TBO has also been reduced to 1200 hours.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical failure mode in specific equipment. It has not expanded beyond its original purpose of preventing propeller hub failures through improved crack detection."},"complexity_factors":["Single, specific technical requirement (dye oil filling)","Limited applicability (three specific propeller models on agricultural aircraft only)","Clear compliance deadline with simple alternative trigger (overhaul or date)","No nested exceptions or conditional logic","Minimal cross-referencing (only to specific service manuals and bulletins)","Short document (approximately 150 words)","Only one defined term implied ('agricultural aircraft')"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority that requires specific modifications to propellers used on agricultural aircraft.\n\n**What it does:**\n- Requires owners/operators to modify certain McCauley propeller hubs so they are filled with dyed oil\n- This dye helps reveal cracks in the hub during inspections\n- Also reduces the Time Between Overhauls (TBO) — how often the propeller must be serviced — to 1,200 hours\n\n**Who it affects:**\n- Owners and operators of agricultural aircraft fitted with specific McCauley propeller models: D2A34C58, D2A34C98, and D3A32C90 series\n- Maintenance organisations servicing these aircraft\n\n**Why it matters:**\n- **Safety critical:** Hub failures on propellers can be catastrophic\n- Agricultural operations put heavy stress on propeller hubs (frequent takeoffs, low-altitude flying, heavy loads)\n- The dyed oil acts as an early warning system — cracks allow oil to leak, making them visible before the hub fails completely\n- Previous inspection methods weren't catching cracks early enough, leading to actual failures\n\n**When compliance is required:**\n- By 1 December 1989, or at the next propeller overhaul — whichever comes first\n\n**Key documents referenced:**\n- McCauley Service Manual 720415 Supplement No 1\n- Service Bulletins 122 and 138C\n- Related US FAA directives (78-20-01 and 85-08-08)"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This directive moves from an inspection-based regime (the prior threaded hub dye inspection AD mentioned in Background) to a mandatory physical modification (dye oil filling) of the hub and also reduces propeller TBO to 1,200 hours. The instrument therefore changes the required remedial action and the maintenance interval: operators must implement a conversion per the manufacturer's service manual and plan for more frequent overhauls or replacements. (Requirement; Background; Compliance)"},"complexity_factors":["Narrow technical scope: applies to three specific propeller model series (Applicability).","Technical implementation relies on external manufacturer documents (McCauley Service Manual 720415 Supplement No 1; Service Bulletins 122 and 138C) which adds dependency but not regulatory complexity (Requirement).","Fixed compliance deadline plus alternative of 'next overhaul' creates a simple scheduling constraint (Compliance).","Includes an operational change to TBO (1200 hours) which has ongoing maintenance and cost implications (Background).","Cross-reference to foreign ADs (FAA AD 78-20-01 and 85-08-08) adds normative context but no additional procedural steps in this instrument (Note)."],"plain_english_summary":"The directive requires owners of specified McCauley variable‑pitch propellers on agricultural aircraft to have hubs modified to be filled with dye‑detecting oil per McCauley Service Manual and referenced bulletins, and reduces propeller TBO to 1,200 hours. The Civil Aviation Safety Authority prescribes compliance by the next overhaul or by 1 December 1989; operators bear modification and increased overhaul costs."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pmc-42-oil-filled-hubs-for-agricultural-aircraft","history":"/api/acts/ad-pmc-42-oil-filled-hubs-for-agricultural-aircraft/history","analysis":"/api/acts/ad-pmc-42-oil-filled-hubs-for-agricultural-aircraft/analysis","conflicts":"/api/acts/ad-pmc-42-oil-filled-hubs-for-agricultural-aircraft/conflicts","importantCases":"/api/acts/ad-pmc-42-oil-filled-hubs-for-agricultural-aircraft/important-cases","documents":"/api/acts/ad-pmc-42-oil-filled-hubs-for-agricultural-aircraft/documents"}}