{"id":"F2007L02137","name":"AD/ATR 42/3 - Propeller Pitch Change System Components","slug":"ad-atr-42-3-propeller-pitch-change-system-components","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":67304,"registerId":"commonwealth-F2007L02137-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Avions de Transport Regional ATR 42 Seri","sectionType":"division","heading":"Avions de Transport Regional ATR 42 Series Aeroplanes","content":"### Avions de Transport Regional ATR 42 Series Aeroplanes\n\n| AD/ATR 42/3 | Propeller Pitch Change System Components | 8/2007 |\n| ----------- | ---------------------------------------- | ------ |\n\n| Applicability: | ATR 42-200, -300 and -320 series aircraft. |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | Carry out ultrasonic cleaning of the Propeller Control Unit servo ball screw on Hamilton Sundstrand 14SF5 propellers in accordance with Hamilton Sundstrand Component Maintenance Manual 61-21-07.Note: DGAC AD 2002-070-090(B) R1 dated 15 May 2002 refers. |\n| Compliance: | Before reaching 10,500 flight hours since new or since last critical inspection; orBefore further flight, in the case of contamination; orBefore further flight, in the case of anomalies found during production acceptance tests. |\n| | This Airworthiness Directive becomes effective on 2 August 2007. |\n| Background: | Three cases of propeller pitch lock during final approach have been experienced on ATR aircraft. During two of these events the asymmetric power resulting from the propeller pitch lock was not recognized by the crew during landing and the aircraft veered off the runway after selection of reverse power while the “Low Pitch” condition was not effective for both engines.On one case the investigation led on the suspected components of the propeller pitch control system showed significant anomalies of the pitch control unit ball screw. The hang up and the loss of efficiency noted on the test bench are due to ball screw contamination. These anomalies could contribute to a pitch lock condition when the combine with another propeller component failure of the pitch control system.The actions detailed in the AD are intended to clean the ball screw and avoid the propeller lock situation which could lead to reduced controllability of the aircraft during landing. |\n\n![](image.001.png) \nDavid Punshon \nDelegate of the Civil Aviation Safety Authority\n\n21 June 2007","sortOrder":0},{"sectionNumber":"AD/ATR 42/3","sectionType":"part","heading":"AD/ATR 42/3","content":"## AD/ATR 42/3","sortOrder":1},{"sectionNumber":"Propeller Pitch Change System Components","sectionType":"part","heading":"Propeller Pitch Change System Components","content":"## Propeller Pitch Change System Components","sortOrder":2},{"sectionNumber":"8/2007","sectionType":"part","heading":"8/2007","content":"## 8/2007","sortOrder":3}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a narrow, specific safety purpose. It addresses a defined mechanical issue (propeller pitch lock due to contamination) with a targeted remedy (cleaning of the ball screw). The scope remains tightly focused on the original safety concern without expansion into broader operational or regulatory matters."},"complexity_factors":["Single, specific mechanical requirement (ultrasonic cleaning of one component)","No defined terms section or interpretation provisions","Straightforward applicability (three specific aircraft series)","Simple conditional compliance structure (three alternative triggers)","No cross-references to other legislation beyond a reference to a French aviation authority directive (DGAC AD 2002-070-090(B) R1) and a maintenance manual","Short, single-purpose document with clear technical background"],"plain_english_summary":"This AD mandates ultrasonic cleaning of the servo ball screw in the Propeller Control Unit on ATR 42-200/-300/-320 aircraft (per the maintenance manual) because contamination has caused propeller lockups during landing approaches, leading to runway excursions. Operators must clean before the propeller reaches 10,500 flight hours, or immediately if contamination is found or testing shows problems. It’s a required safety action to prevent loss of propeller control."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive remains narrowly focused on cleaning the servo ball screw of the Hamilton Sundstrand 14SF5 propeller control unit to prevent propeller pitch lock. It does not broaden regulatory obligations beyond this targeted maintenance action, introduce new certification requirements, nor create ongoing monitoring regimes beyond the stated compliance triggers. Therefore the scope has not expanded beyond the original safety-driven purpose described in the AD."},"complexity_factors":["Single, focused requirement (ultrasonic cleaning of one specific component)","Clear applicability list limited to ATR 42-200, -300 and -320 series","Reference to one external document: Hamilton Sundstrand CMM 61-21-07","Three discrete compliance triggers (before 10,500 flight hours; before further flight if contamination; before further flight if anomalies on production testing)","Short background narrative explaining the safety concern","One cross-reference to a foreign AD (DGAC AD 2002-070-090(B) R1)"],"plain_english_summary":"**What this instrument does (mechanical change first)**\n\n- Requires ultrasonic cleaning of the servo ball screw inside the Propeller Control Unit (the part that moves the propeller blades) on Hamilton Sundstrand 14SF5 propellers fitted to ATR 42-200, -300 and -320 aeroplanes. The cleaning must be done following the Hamilton Sundstrand Component Maintenance Manual (CMM) 61-21-07.\n\n**Who it affects**\n\n- Aircraft operators and owners of ATR 42-200, -300 and -320 series aeroplanes that use Hamilton Sundstrand 14SF5 propellers.\n- Maintenance organisations and licensed engineers who perform the prescribed cleaning and inspections.\n\n**When the work must be done (compliance timing)**\n\n- Before the propeller has accumulated 10,500 flight hours since new or since its last critical inspection; or\n- Immediately (before the next flight) if contamination is found; or\n- Immediately (before the next flight) if anomalies are detected during production acceptance testing.\n\n**Why the rule was issued (official rationale)**\n\n- The background given is that three events of propeller pitch lock occurred during final approach. In one investigation, the ball screw of the pitch control unit exhibited significant anomalies caused by contamination. Contaminated ball screws can hang up or lose efficiency and, especially combined with another pitch control failure, may lead to a pitch lock condition that can reduce aircraft controllability during landing. The AD’s stated purpose is to remove contamination by ultrasonic cleaning to reduce the risk of pitch lock.\n\n**Practical effects, costs and incentives (analyst testing of the stated purpose)**\n\n- Who pays: aircraft operators pay for the cleaning (labour, any parts, and aircraft out-of-service time). If maintenance providers charge separately, those firms receive payment for the work.\n- Who decides: the Civil Aviation Safety Authority (CASA) issued the AD; compliance is implemented by operators and maintenance organisations who must follow the Hamilton Sundstrand CMM procedure referenced in the AD.\n- Behavioural change required: operators must schedule ultrasonic cleaning of the specified ball screw at or before the hour limit, and must inspect and remove contaminated units immediately when contamination or anomalies are found. Maintenance practices must follow the referenced CMM.\n- Direct costs: labour, consumables, possible replacement of units if cleaning does not restore function, and aircraft downtime (loss of revenue while the aircraft is in maintenance). Those are predictable, concentrated costs on affected operators.\n- Benefits: reduction in the risk of propeller pitch lock during critical flight phases (landing), which is a safety benefit for operators, passengers and crew. This is a concentrated benefit for the affected fleet.\n- Trade-offs and opportunity costs: time spent on cleaning and inspections competes with other maintenance or utilisation (flight hours lost). Operators may choose to perform cleaning at scheduled heavy maintenance to reduce incremental downtime, but the AD’s hour limit constrains timing.\n- Implementation risk and compliance burden: the AD relies on accurate detection of contamination and correct performance of ultrasonic cleaning per the CMM. Potential implementation risks include inconsistent cleaning technique, inadequate inspection to detect early contamination, or administrative failures to track hours to the 10,500‑hour threshold. These are standard maintenance-compliance risks.\n- Effects on market competition and private choice: the measure applies uniformly to all operators of the specified models and propellers, so it does not favour particular firms. It imposes a compliance cost that may be slightly larger for smaller operators with less maintenance capacity. There is no new subsidy, certification change, or market-entry barrier introduced by this AD.\n\n**Cross-reference and provenance**\n\n- The AD explicitly points maintenance engineers to Hamilton Sundstrand CMM 61-21-07 for the cleaning procedure. It also notes a related French DGAC AD (2002-070-090(B) R1), which indicates the issue has been recognised by another regulator.\n\n**Net practical effect**\n\n- Mechanically, the AD mandates a specific maintenance action (ultrasonic cleaning of the ball screw) within a specified time window or immediately if contamination/anomalies are found. Practically, operators will incur maintenance costs and scheduling impacts in exchange for a targeted reduction in the risk of propeller pitch lock during landing."}},"importantCases":[],"_links":{"self":"/api/acts/ad-atr-42-3-propeller-pitch-change-system-components","history":"/api/acts/ad-atr-42-3-propeller-pitch-change-system-components/history","analysis":"/api/acts/ad-atr-42-3-propeller-pitch-change-system-components/analysis","conflicts":"/api/acts/ad-atr-42-3-propeller-pitch-change-system-components/conflicts","importantCases":"/api/acts/ad-atr-42-3-propeller-pitch-change-system-components/important-cases","documents":"/api/acts/ad-atr-42-3-propeller-pitch-change-system-components/documents"}}