{"id":"F2006B06282","name":"AD/PMC/25 - Propeller Hub and Blade - Modification or Replacement (Shot Peening of Hub Retention Threads and Blade Shank Threads)","slug":"ad-pmc-25-propeller-hub-and-blade-modification-or-replacement-shot-peening-of-hub-retention-threads-","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47338,"registerId":"commonwealth-F2006B06282-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PMC/25 - Propeller Hub and Blade - Modification or Replacement (Shot Peening of Hub Retention Threads and Blade Shank Threads)","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/25 Propeller Hub and Blade - Modification or Replacement (Shot Peening of Hub Retention\n\nThreads and Blade Shank Threads)\n\n  \n1/73\n\nApplicability: Hubs on propeller models E2A34C64 and C64A, and E2A34C73, C73A, C73J and C73K with S/Nos. 64000 thru 699999 not incorporating shot peened blade retention threads. Ref. AD.PMC/20 (SB No. 88). All 90AT-8 blades used with above propeller models, and not incorporating shot peened shank threads. Ref. AD/PMC/24 (SB No. 81).\n\nDocument: McCauley SB No. 100.\n\nCompliance: For propellers that have completed 775 or more hours total time in service \\- within 25 hours time in service after 31 January 1973. For propellers that have completed less than 700 hours total time in service \\- before achieving 800 hours total time in service.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a vintage 1973 Airworthiness Directive that remains focused on its original narrow purpose: mandating shot peening treatment for specific McCauley propeller models to address a known fatigue failure mode. The scope has not expanded beyond this specific safety issue."},"complexity_factors":["Single, specific technical requirement (shot peening) with clear applicability criteria","Two-tier compliance schedule based on flight hours (775+ hours vs. <700 hours)","Cross-references to two other Airworthiness Directives (AD.PMC/20 and AD/PMC/24) and one Service Bulletin (McCauley SB No. 100)","Specific serial number ranges and model numbers limit applicability clearly","No nested exceptions or conditional logic — straightforward mandate","Very short document (approximately 150 words of substantive text)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires specific maintenance on certain McCauley aircraft propellers to prevent mechanical failure.\n\n**What it does:**\n- Orders owners/operators to modify or replace parts on specific McCauley variable-pitch propeller models\n- Requires **shot peening** (a surface treatment that bombards metal with tiny spheres to strengthen it and prevent cracks) on two critical areas:\n  - The **hub retention threads** (where the propeller hub grips the blade)\n  - The **blade shank threads** (the threaded portion of the blade itself)\n\n**Who it affects:**\n- Owners and operators of aircraft with specific McCauley propeller models: E2A34C64, C64A, E2A34C73, C73A, C73J, and C73K\n- Specifically those with serial numbers 64000 through 699999 that haven't already been shot peened\n- Also applies to 90AT-8 blades used with these propellers\n\n**Why it matters:**\nThread failures in propeller hubs can cause catastrophic blade separation during flight. This AD mandates a proven fatigue-prevention treatment to avoid accidents. The compliance deadlines are based on flight hours — urgent for high-time propellers (must fix within 25 hours after January 31, 1973), less urgent for low-time ones (must fix before reaching 800 total hours).\n\n**Key compliance dates:**\n- High-time propellers (775+ hours): Within 25 hours of flying time after January 31, 1973\n- Low-time propellers (<700 hours): Before hitting 800 total flight hours"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD, as supplied, targets hubs and blades that do not incorporate shot-peened threads and prescribes modification or replacement using McCauley SB No. 100 with specified compliance times (Applicability; Document; Compliance). The text references earlier ADs (AD.PMC/20 and AD/PMC/24) in relation to parts that do not incorporate shot-peened threads but does not, within the supplied text, expand or narrow the listed applicability or otherwise alter the population of affected parts beyond those identified. Therefore, based on the supplied instrument alone, the scope as written does not appear to change from the population identified within this AD; it prescribes the remedial action and timing for that population rather than redefining who is covered. (Applicability; Document; Compliance)"},"complexity_factors":["Technical specificity of the required action (shot peening of hub retention threads and blade shank threads). (Document)","Selective applicability limited to particular propeller models and a defined serial-number range (S/Nos. 64000–699999) and to blades of a particular type (90AT-8). (Applicability)","Differentiated compliance windows tied to total time-in-service thresholds (>=775 hours with 25 hours after 31 Jan 1973; <700 hours before 800 hours). (Compliance)","Dependency on an external technical procedure (McCauley Service Bulletin No. 100) for implementation. (Document)","Operational burdens: need to track serial numbers and service hours, arrange shot-peening or parts replacement, and manage aircraft downtime. (Applicability; Compliance)"],"plain_english_summary":"This AD requires certain McCauley variable‑pitch propeller hubs and their 90AT‑8 blades that do not have shot‑peened retention/shank threads to be modified (shot peened) or replaced per McCauley SB No.100. It affects owners/operators of the listed propellers/serials, imposes short compliance windows for higher‑time units, and shifts costs and downtime to those operators while regulators enforce compliance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pmc-25-propeller-hub-and-blade-modification-or-replacement-shot-peening-of-hub-retention-threads-","history":"/api/acts/ad-pmc-25-propeller-hub-and-blade-modification-or-replacement-shot-peening-of-hub-retention-threads-/history","analysis":"/api/acts/ad-pmc-25-propeller-hub-and-blade-modification-or-replacement-shot-peening-of-hub-retention-threads-/analysis","conflicts":"/api/acts/ad-pmc-25-propeller-hub-and-blade-modification-or-replacement-shot-peening-of-hub-retention-threads-/conflicts","importantCases":"/api/acts/ad-pmc-25-propeller-hub-and-blade-modification-or-replacement-shot-peening-of-hub-retention-threads-/important-cases","documents":"/api/acts/ad-pmc-25-propeller-hub-and-blade-modification-or-replacement-shot-peening-of-hub-retention-threads-/documents"}}