{"id":"F2006B06165","name":"AD/PDH/6 - Bracket Type Propellers - Modification","slug":"ad-pdh-6-bracket-type-propellers-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46997,"registerId":"commonwealth-F2006B06165-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PDH/6 - Bracket Type Propellers - Modification","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 - 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Propellers - Variable Pitch - De Havilland\n\n \n\nAD/PDH/6 Bracket Type Propellers - Modification 6/67\n\nApplicability: All model PD28/212/1, PD51/212/1, PD92/212/1, PD136/212 /1, PD170/212/1 and PD175/212/1 propellers.\n\n \n\nDocument: DeHavilland MNS No. 81 (Modification 5226).\n\n \n\nCompliance: Before installation in an aircraft following next overhaul completed after 15 July 1967.\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\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"This directive imposes a new mandatory modification requirement on the listed De Havilland bracket‑type propellers as a condition of reinstalling them after overhaul. Mechanically, it changes the permissible state of those propellers at the point of installation by requiring the specific modification described in DeHavilland MNS No. 81 (Modification 5226) to have been applied before installation following the next overhaul completed on or after 15 July 1967 (Applicability; Document; Compliance)."},"complexity_factors":["Narrow, clearly enumerated applicability to six specific propeller models (Applicability).","Single, discrete required action referenced (DeHavilland MNS No. 81 / Modification 5226) rather than multiple alternatives or conditional steps (Document).","Compliance trigger tied to a plainly stated operational milestone (installation after next overhaul completed after 15 July 1967), which is straightforward to identify (Compliance).","Reference to an external technical document creates a modest administrative task to obtain and follow that document (Document).","The directive text does not set out reporting, recordkeeping, or enforcement procedures, which reduces procedural complexity in the instrument itself but requires implementers to rely on existing regulatory practice (implicit from Document and Compliance)."],"plain_english_summary":"This directive makes a specific De Havilland modification (MNS No. 81 / Modification 5226) mandatory for listed De Havilland variable‑pitch bracket‑type propellers (PD28/51/92/136/170/175). It affects aircraft owners/operators and the maintenance organisations that overhaul or install those propellers.\n\nEach affected propeller must have the referenced modification applied before it is installed following its next overhaul completed on or after 15 July 1967; implementers must obtain and follow the De Havilland document."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1967 addressing a specific mechanical modification. It has not expanded beyond its original purpose of mandating a safety modification to specific De Havilland propeller models."},"complexity_factors":["Extremely short document (approximately 150 words of substantive content)","Only 6 specific propeller models listed in applicability section","Single compliance requirement with clear deadline (post-15 July 1967 overhaul)","References only one external technical document (DeHavilland MNS No. 81)","No defined terms section, no cross-references to other legislation, no conditional logic or exceptions","Straightforward temporal trigger (\"following next overhaul completed after 15 July 1967\")"],"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 like a compulsory recall notice, but for aircraft parts rather than cars.\n\n**What it does:** It requires a specific modification to be made to certain De Havilland \"bracket type\" variable-pitch propellers. The modification (called \"Modification 5226\") must be carried out according to De Havilland Maintenance Note Service (MNS) No. 81.\n\n**Who it affects:** Anyone who owns, operates, or maintains aircraft fitted with these specific De Havilland propeller models:\n- PD28/212/1\n- PD51/212/1  \n- PD92/212/1\n- PD136/212/1\n- PD170/212/1\n- PD175/212/1\n\n**When it must be done:** The modification is required **before** any of these propellers can be installed in an aircraft, but only after the propeller's next overhaul that occurs **after 15 July 1967**.\n\n**Why it matters:** Airworthiness Directives exist to prevent accidents. This particular directive (dating from 1967) addresses a safety issue with the bracket-type design of these propellers. The modification likely fixes a structural or mechanical defect that could cause propeller failure in flight — a catastrophic event. Compliance is **legally mandatory**; flying with non-compliant equipment violates civil aviation law and puts lives at risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pdh-6-bracket-type-propellers-modification","history":"/api/acts/ad-pdh-6-bracket-type-propellers-modification/history","analysis":"/api/acts/ad-pdh-6-bracket-type-propellers-modification/analysis","conflicts":"/api/acts/ad-pdh-6-bracket-type-propellers-modification/conflicts","importantCases":"/api/acts/ad-pdh-6-bracket-type-propellers-modification/important-cases","documents":"/api/acts/ad-pdh-6-bracket-type-propellers-modification/documents"}}