{"id":"F2005L03889","name":"AD/PMC/48 - Propeller Hub Socket Retention Threads","slug":"ad-pmc-48-propeller-hub-socket-retention-threads","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":39657,"registerId":"commonwealth-F2005L03889-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Propellers - Variable Pitch - McCauley","sectionType":"division","heading":"Propellers - Variable Pitch - McCauley","content":"### Propellers - Variable Pitch - McCauley\n\n| AD/PMC/48 | Propeller Hub Socket Retention Threads | 1/2006 DM |\n| --------- | -------------------------------------- | --------- |\n\n```html\n

Applicability:

McCauley Propeller Systems propeller assemblies, models 2D34C53/74E-X; D2A34C58/90AT-X; 3AF32C87/82NC-X; D3AF32C87/82NC-X;
D3A32C88/82NC-X; D3A32C90/82NC-X; and 3AF34C92/ 90LF-X, with propeller hubs listed by serial number in Table 1 of this AD:

Table 1.

Hub model

Hub serial number

C58, C34, C49, C78, C98

030725, 030726, 030727, 030728, 030729, 030730, 030748, 030749, 030750, 030751, 030752, 030753, 030754, 030755, 030756, 030757, 030758, 030759, 030760, 050403, 050407, 050408, 050410, 050475, 050477

C53

050389

C79, C90

042206, 042207, 042208

C77, C88

042201, 042202

C87 blank index, C72, C93

042239, 042524, 042527, 042528, 042529, 050071, 050073

C92, C74, C86

050866

C87 D index

050934

Note 1: Because a propeller hub can be interchanged and re-identified as a different model with the installation of different studs or adapters, any of the affected hubs could have been re-identified as a different model. Each propeller hub model listed in Table 1 of this AD is the original hub configuration when shipped from McCauley.

Note 2: A list of aeroplanes that these hubs can be fitted to can be found in Table 2 of FAA AD 2005-24-09.

\n```\n\n| Requirement: | 1. Remove from service propeller assemblies with affected propeller hubs, listed in Table 1 of this AD.2. Propeller assemblies with affected propeller hubs listed in Table 1 of this AD must be disassembled, inspected, and have the propeller hub replaced with a serviceable propeller hub.3. For retention nuts that were removed from an affected propeller hub, visually inspect the retention nut threads with a 10- power magnifier before assembly into a replacement propeller hub. Reject the nut for any signs of galling, heavy localized loading, thread deformation, or chipped threads that may have been caused by thread interference in the propeller hub.4. Report the findings of any propeller hub removed during Requirement 1 of this AD to:Manager,New Technologies and Systems SectionManufacturing, Certification and New Technologies OfficeCivil Aviation Safety Authority,GPO Box 2005, Canberra, ACT 2601Fax (02) 6217 1903 or (02) 6217 1442Email: airworthiness.directives@casa.gov.au5. Do not install hubs listed in Table 1 of this AD.Note 3: McCauley Alert Service Bulletin No. ASB251A, dated 28 September, 2005 pertains to this AD.Note 4: FAA AD 2005-24-09 Amdt 39-14389 refers. |\n| ------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | For Requirements 1, 2 and 3: Within 10 flight hours or 10 calendar days after the effective date of this AD whichever occurs first.For Requirement 4: Within 10 calendar days after the completion of the inspection detailed in Requirement 2 of this AD.For Requirement 5: After the effective date of this AD. |\n| | This Airworthiness Directive becomes effective on 15 December 2005. |\n\n| Background: | In August of 2005, McCauley Propeller Systems reported to the FAA that a repair facility had found a single, new, unused propeller hub with improperly machined socket retention threads. Further investigation revealed that McCauley Propeller Systems had improperly machined socket retention threads on 40 propeller hubs, manufactured in 2004 and 2005. Using a propeller hub with improperly machined socket retention threads could cause concentrated loading on the threads, resulting in cracking of the hub and blade separation. This condition, if not corrected, could result in failure of the propeller hub, blade separation, and loss of control of the aeroplane. |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n1 December 2005","sortOrder":0},{"sectionNumber":"AD/PMC/48","sectionType":"part","heading":"AD/PMC/48","content":"## AD/PMC/48","sortOrder":1},{"sectionNumber":"Propeller Hub Socket Retention Threads","sectionType":"part","heading":"Propeller Hub Socket Retention Threads","content":"## Propeller Hub Socket Retention Threads","sortOrder":2},{"sectionNumber":"1/2006 DM","sectionType":"part","heading":"1/2006 DM","content":"## 1/2006 DM","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive remains narrowly scoped to the original safety problem: hubs with improperly machined socket retention threads. The requirements (remove, inspect/replace, inspect nuts, report, and forbid installation) are corrective and proportionate to the described defect and do not expand beyond that safety remediation purpose."},"complexity_factors":["Single focused safety directive with five numbered requirements (clear structure)","Table 1 contains multiple hub models and many serial numbers that must be checked against individual aircraft records","Three different compliance timings (Requirements 1–3: 10 flight hours or 10 days; Requirement 4: 10 calendar days after inspection; Requirement 5: immediate prohibition) creating conditional deadlines","Cross‑references to external documents (McCauley ASB251A and FAA AD 2005‑24‑09) for context and affected aeroplane lists","Note that hubs can be re‑identified after interchange (adds tracing/recordkeeping complexity)","A subjective inspection criterion (visual inspection with 10× magnifier) that may be interpreted variably by maintenance personnel"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- Orders owners/operators to remove from service specific McCauley variable‑pitch propeller assemblies whose hubs are listed by model and serial number in Table 1 of the directive (Requirement 1). \n- Requires the removed propeller assemblies to be disassembled, inspected and have the propeller hub replaced with a serviceable hub (Requirement 2). \n- Requires visual inspection of any retention nuts removed from the affected hubs using a 10‑power magnifier; nuts showing galling, heavy local loading, thread deformation or chipped threads must be rejected (Requirement 3). \n- Requires reporting the findings from any hub removed under Requirement 1 to CASA (Requirement 4), giving contact details and a 10‑day deadline for that report. \n- Prohibits installation of any of the hubs listed in Table 1 (Requirement 5). \n\n**Who this affects**\n\n- Aircraft owners and operators that have McCauley propeller assemblies of the listed models and serial numbers fitted to their aeroplanes. \n- Maintenance organisations and repair facilities that service, inspect or install these propeller hubs and retention nuts. \n- Parts suppliers, because the listed hubs must not be re‑installed and replacement serviceable hubs will be required. \n\n**Why it matters (safety risk and mechanics)**\n\n- The stated reason (from McCauley and the AD) is that some hubs were manufactured with improperly machined socket retention threads. That defect can concentrate load on the threads, potentially causing hub cracks, blade separation and loss of aircraft control. The AD's measures are targeted to remove affected hubs and prevent re‑use of potentially damaged retention nuts. (Background and Notes: McCauley Alert Service Bulletin No. ASB251A and FAA AD 2005‑24‑09 are referenced.)\n\n**Timing and compliance mechanics**\n\n- Requirements 1–3: must be done within 10 flight hours or 10 calendar days after the effective date of the AD, whichever occurs first. \n- Requirement 4 (reporting): within 10 calendar days after completing the inspection required by Requirement 2. \n- Requirement 5 (do not install): applies after the AD becomes effective. \n- The AD notes that hubs may have been re‑identified after interchange (i.e. a hub can be fitted with studs/adapters and re‑marked), so operators must trace the hub's original McCauley serial/model history when determining applicability (Note 1). \n\n**Practical effects on behaviour and costs**\n\n- Operators must ground or take affected propeller assemblies out of service quickly, disassemble and replace hubs, inspect and possibly reject retention nuts, and submit a report to CASA. \n- Direct costs fall on aircraft owners/operators: aircraft downtime, labour for disassembly/inspection/reassembly, and the cost and lead time to obtain serviceable replacement hubs and possibly replacement nuts. \n- Maintenance providers will carry out inspections and replacements and must apply the inspection standard described (10x magnifier). \n\n**Implementation, compliance and operational risks**\n\n- Tracking affected hubs can be difficult because hubs may have been re‑identified after interchange; operators must check original McCauley serial/model records (Table 1 + Note 1). \n- The inspection standard is a visual check with a 10× magnifier; this is straightforward but may miss sub‑surface or fatigue defects that require more advanced inspection methods. \n- The compliance window (10 flight hours or 10 days) is short and may cause operational disruption if replacement hubs are not readily available. \n\n**References in the AD**\n\n- Table 1 lists the affected hub models and serial numbers. \n- The AD refers to McCauley Alert Service Bulletin ASB251A (28 Sep 2005) and FAA AD 2005‑24‑09 (Amdt 39‑14389).\n\n**Net summary sentence**\n\nThis AD mandates the prompt removal, inspection and replacement of specified McCauley propeller hubs that may have improperly machined retention threads, requires visual inspection of removed retention nuts, prohibits re‑installation of the listed hubs, and requires reporting findings to CASA; the measures shift inspection, replacement and reporting costs to aircraft owners/operators and create short‑term operational and parts‑supply burdens while targeting a specific structural safety defect."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a targeted emergency airworthiness directive addressing a specific manufacturing defect in 40 identified propeller hubs. The scope remains precisely limited to the identified safety issue without expansion into broader regulatory matters."},"complexity_factors":["Highly technical subject matter requiring aviation engineering knowledge to fully assess","Precise serial number tracking across multiple hub models (C58, C34, C49, C78, C98, C53, C79, C90, C77, C88, C87, C72, C93, C92, C74, C86) with specific serial numbers for each","Cross-reference to external documents: FAA AD 2005-24-09 and McCauley Alert Service Bulletin ASB251A","Conditional applicability note warning that hubs may have been re-identified as different models through parts interchange","Multiple compliance deadlines with different triggers (flight hours vs calendar days vs effective date)","Specific inspection methodology requiring 10-power magnification and criteria for thread rejection (galling, localized loading, deformation, chipping)","Reporting requirement with specific CASA contact details and 10-day deadline"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific McCauley aircraft propellers to immediately ground and replace certain faulty propeller hubs.\n\n**What the problem is:**\nIn 2005, McCauley discovered that 40 propeller hubs manufactured in 2004–2005 had **improperly machined threads** in the socket retention area. These threads hold critical parts of the propeller together. If they fail, the propeller hub can crack, blades can separate from the aircraft, and the pilot can lose control of the plane.\n\n**Who must act:**\nAnyone operating aircraft with specific McCauley variable-pitch propeller models, **but only those with specific hub serial numbers** listed in Table 1 of the directive. The affected models include:\n- 2D34C53/74E-X\n- D2A34C58/90AT-X \n- 3AF32C87/82NC-X and variants\n- D3A32C88/82NC-X and variants\n- 3AF34C92/90LF-X\n\n**What must be done:**\n- **Immediately remove** affected propellers from service (within 10 flight hours or 10 days)\n- **Disassemble and inspect** the propeller, replacing the faulty hub with a serviceable one\n- **Inspect retention nuts** under 10× magnification for damage before reusing them\n- **Report findings** to CASA within 10 days of inspection\n- **Never reinstall** the listed faulty hubs\n\n**Why it matters:**\nThis is an emergency safety measure. The defect could cause catastrophic failure mid-flight. The directive leaves no discretion — compliance is mandatory and time-critical."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-pmc-48-propeller-hub-socket-retention-threads","history":"/api/acts/ad-pmc-48-propeller-hub-socket-retention-threads/history","analysis":"/api/acts/ad-pmc-48-propeller-hub-socket-retention-threads/analysis","conflicts":"/api/acts/ad-pmc-48-propeller-hub-socket-retention-threads/conflicts","importantCases":"/api/acts/ad-pmc-48-propeller-hub-socket-retention-threads/important-cases","documents":"/api/acts/ad-pmc-48-propeller-hub-socket-retention-threads/documents"}}