AD/ATR 42/3 - Propeller Pitch Change System Components

The instrument is short and concentrated on a single technical concept: contamination of the Propeller Control Unit (PCU) servo ball screw on Hamilton Sundstrand 14SF5 propellers can cause hang-up, loss of efficiency and ultimately contribute to propeller pitch lock. The AD supplies three interlocking concepts: applicability, required action, and compliance timing. Applicability restricts the directive to "ATR 42-200, -300 and -320 series aircraft" (Applicability). The required action is prescriptive: ultrasonic cleaning of the PCU servo ball screw and doing this "in accordance with Hamilton Sundstrand Component Maintenance Manual 61-21-07" (Requirement). The compliance concept defines when the action must be carried out: either at a flight-hour threshold (10,500 flight hours since new or since last critical inspection) or immediately where contamination or anomalies are discovered (Compliance).

The background paragraph sets out the causal logic the regulator uses to justify the maintenance requirement: three cases of propeller pitch lock occurred during final approach; in two incidents crews did not recognise the resulting asymmetric power, which then contributed to runway excursion after reverse selection while the "Low Pitch" condition was not effective; investigation pointed to "significant anomalies of the pitch control unit ball screw" and "ball screw contamination" observed on test bench with hang-up and loss of efficiency (Background). The AD therefore links a discrete physical failure mode (ball screw contamination) to an operational hazard (reduced controllability during landing). The stated countermeasure is mechanical cleaning, executed by ultrasonic process per the manufacturer's CMM.

Two further procedural concepts are embedded but not developed in the text: reference to an external regulator’s AD (DGAC AD 2002-070-090(B) R1) and the authoritative maintenance document to be used (Hamilton Sundstrand CMM 61-21-07). The AD presumes that following the referenced CMM specifies the technical details of the ultrasonic cleaning process, while the AD itself establishes the regulatory obligation to perform that cleaning at the specified triggers.

In operational terms, the instrument creates conditional immediate obligations ("Before further flight" in the case of contamination or anomalies) and a scheduled obligation based on a flight-hour threshold. Those two forms of timing convert an identified technical risk into enforceable maintenance actions that must be integrated into the operator’s maintenance planning and production acceptance processes.

The AD explicitly applies to operators and owners of ATR 42-200, -300 and -320 series aircraft that have Hamilton Sundstrand 14SF5 propellers fitted, because the Requirement targets the "Propeller Control Unit servo ball screw on Hamilton Sundstrand 14SF5 propellers" and the Applicability clause names those ATR 42 variants (Applicability, Requirement). Therefore the primary economic actors affected are aircraft operators, owners, and their maintenance organisations responsible for ATR 42-200/-300/-320 aircraft with the specified propeller model. The maintenance providers who carry out work in accordance with Hamilton Sundstrand Component Maintenance Manual 61-21-07 are an immediate secondary group; the AD mandates that the cleaning be performed "in accordance with" that CMM (Requirement). Production organisations that conduct acceptance tests for these aircraft are also affected because the AD requires cleaning "before further flight" where anomalies are found during production acceptance tests (Compliance).

Manufacturers and suppliers are implicated only insofar as the AD invokes the Hamilton Sundstrand CMM as the procedural authority for the cleaning. The AD also notes a related DGAC AD (Note), suggesting regulators and airworthiness authorities who coordinate on airworthiness directives may be indirectly implicated. The AD’s Background documents operational incidents that occurred during landing, which identifies pilot recognition of asymmetric power as an associated operational risk, but the AD itself imposes the maintenance obligation on operators rather than specific crewing or operational conduct.

Financially, the direct costs fall to the operators/owners who must schedule and pay for the ultrasonic cleaning and any associated downtime. Operationally, the phrase "Before further flight" for contamination or production anomalies imposes an immediate action requirement that can prevent the affected aircraft from departing until the cleaning is completed. That has scheduling and potentially passenger or cargo impact costs for operators. Maintenance-programme administrators must also record and track flight hours to determine when the 10,500 flight hours threshold is reached "since new or since last critical inspection" (Compliance), so record-keeping and inspection protocols are put on the affected parties.

The AD is signed "David Punshon, Delegate of the Civil Aviation Safety Authority" with an effective date, indicating it was issued under the authority of the Australian regulator and therefore binding on Australian-registered aircraft of the specified types from the effective date. The instrument does not specify exemptions, alternative procedures, or compensation mechanics; it prescribes a single cleaning method per the manufacturer's CMM.

Duties

• Perform ultrasonic cleaning of the Propeller Control Unit servo ball screw on Hamilton Sundstrand 14SF5 propellers, and do so "in accordance with Hamilton Sundstrand Component Maintenance Manual 61-21-07" (Requirement). The AD prescribes the procedural source for the cleaning rather than specifying cleaning steps itself.
• Observe the stated compliance timing: undertake the cleaning before reaching 10,500 flight hours since new or since last critical inspection; or undertake it "Before further flight" where contamination is detected; or "Before further flight" where anomalies are found during production acceptance tests (Compliance). Those three triggers define when the duty becomes due.
• Integrate the AD into maintenance planning, production acceptance testing, and critical-inspection scheduling, because the AD ties a compliance threshold to flight hours "since new or since last critical inspection" (Compliance). That requires operators to track those counters against each relevant PCU assembly and related inspection schedules.

Rights and procedural notes in the text

• The AD does not set out any formal appeals, exemptions, or alternative method of compliance (AMOC) within the text supplied. The only procedural reference is to comply "in accordance with Hamilton Sundstrand Component Maintenance Manual 61-21-07" (Requirement) and a reference to the DGAC AD (Note). The instrument does not explicitly provide for exceptions or for alternative compliance methods within its text.
• The AD provides the operative date ("becomes effective on 2 August 2007") and is signed by a CASA delegate (signature block). This establishes an authoritative regulatory instruction with an effective date for duty-bearers.

Operational consequences implied by duties

• The "Before further flight" phrasing for contamination or production anomalies imposes an immediate suspension of flight pending completion of the cleaning action and any necessary verification. That converts an inspection finding into a near-certain temporary operational restriction until compliance is achieved, and therefore creates an immediate operational duty on the operator to complete the cleaning promptly.
• The flight-hour trigger (10,500 hours) imposes a scheduled maintenance obligation to be accommodated within maintenance cycles and critical-inspection intervals; duty-bearers must ensure flight-hour tracking and planning accommodates the cleaning before that threshold is reached.

Limitations in the text

• The AD does not detail enforcement mechanisms, penalties, or the wider regulatory consequences of non-compliance; it does not state whether non-compliance renders the aircraft unairworthy or the specific regulatory sanctions that flow from failing to comply. Those enforcement arrangements, if they exist, are not contained within this instrument as supplied.

The AD text, as provided, does not specify statutory penalties, sanctions, or the enforcement mechanism that will be applied for non-compliance. The instrument states that it "becomes effective on 2 August 2007" and is signed by "David Punshon, Delegate of the Civil Aviation Safety Authority" (signature and effective date lines), which establishes the regulator’s authorship and the date when the directive takes effect. However, the AD does not itself include any express enforcement provisions, penalty clauses, or procedural steps for enforcement actions.

Because the text does not state enforcement measures, the instrument leaves unarticulated within its body how non-compliance will be detected, recorded, or sanctioned. The AD requires specific maintenance work and timing (Requirement and Compliance), but the AD does not explain whether an inspector will audit maintenance records, how reporting is to occur, or what administrative or civil penalties would be applied for failure to comply. The absence of explicit penalty language in the AD means the AD itself focuses on the substantive maintenance obligation rather than on enforcement modalities.

Operationally, the "Before further flight" formulation in the Compliance section effectively creates a contemporaneous operational constraint: if contamination or anomalies are detected, the operator must perform cleaning before flying again. That phrasing functions as an immediate operational control because it ties the finding to a pre-flight prohibition until the specified action is complete. The AD does not elaborate on the approved method for documenting that the cleaning is complete or how an inspector would verify compliance in a post-event audit. The AD likewise does not state any procedures for seeking approval of an alternative method of compliance.

The AD includes a "Note" pointing to a DGAC AD (DGAC AD 2002-070-090(B) R1 dated 15 May 2002), but does not set out whether that foreign AD creates reciprocal enforcement obligations, nor does it describe coordination between authorities. The AD therefore establishes the maintenance content and timing obligations, but is silent in the text on formal enforcement mechanisms and penalties; any enforcement procedures or sanctions would need to be sought in the regulator’s wider enforcement framework or other legislative instruments outside this AD, none of which are contained in the supplied text.

The AD itself explicitly references an earlier foreign airworthiness directive and incorporates a manufacturer's maintenance manual as the technical compliance standard. The "Note" states: "DGAC AD 2002-070-090(B) R1 dated 15 May 2002 refers" (Note). That cross-reference indicates that the Australian AD recognises a related action previously taken by the French national authority (DGAC), but the AD text does not elaborate how the two instruments interlock operationally or legally. The AD also makes the Hamilton Sundstrand Component Maintenance Manual 61-21-07 the procedural source for the ultrasonic cleaning ("in accordance with Hamilton Sundstrand Component Maintenance Manual 61-21-07", Requirement). This means the AD operates by imposing a regulatory duty that must be executed using a manufacturer's specified procedure, thereby directly interacting with the operator’s maintenance regime and any obligations to follow approved maintenance data.

Operationally, the AD interacts with existing maintenance and inspection frameworks because the timing of the cleaning event is tied to flight hours "since new or since last critical inspection". That creates a dependency on how "critical inspection" is defined and scheduled within the operator’s maintenance programme and any overarching maintenance standards applicable to Australian-registered aircraft. The AD therefore has a practical intersection with maintenance scheduling rules and record-keeping requirements: operators must track flight hours and the status of last critical inspections to know when the AD-required cleaning becomes due.

The AD does not, within its text, state how it interacts with regulatory provisions governing airworthiness certifications, maintenance release procedures, acceptance testing paperwork, or alternative compliance mechanisms. It does not state whether adherence to the Hamilton Sundstrand CMM suffices to meet general maintenance data requirements imposed under other regulatory instruments. The AD similarly does not state whether an operator may seek approval for an alternative procedure or whether satisfying the DGAC AD would be taken as satisfying this AD. Those interactions are not spelled out in the AD, so any practical cross-references or mutual recognition would have to be inferred or determined from the regulator’s broader policy and legal framework outside the document.

Finally, the AD’s background narrative describing incidents and test bench findings establishes the technical rationale for the maintenance duty, but it does not itself change other provisions of law. The AD therefore functions as a focused, operational amendment to the maintenance obligations applying to the specified aircraft and propeller configuration; any legal enforcement or reciprocal recognition with other jurisdictions is not set out in the text supplied and would rely on external regulatory arrangements.

The instrument as supplied does not contain an internal amendment trail or a list of prior versions within its text. It is labelled with an identifier "AD/ATR 42/3" and a date identifier "8/2007" which together designate this particular AD edition (top table and repeated headings). The document also includes a "Note" that references a related prior foreign AD: "DGAC AD 2002-070-090(B) R1 dated 15 May 2002 refers" (Note). That indicates that there is at least one related or earlier airworthiness directive from another authority, but the supplied text does not indicate that the current AD is an amendment to any prior Australian AD, nor does it include replacement language or a revision history identifying superseded ADs.

The signature block shows the AD was signed by David Punshon, Delegate of the Civil Aviation Safety Authority, on "21 June 2007" and provides an effective date of "2 August 2007". The label "8/2007" suggests this AD is the eighth AD published in 2007 under some numbering convention, but the AD text does not itself provide a narrative explaining prior amendments or versioning. The repeated heading fragments at the end of the supplied text appear to be typographical or formatting artefacts (multiple lines of "AD/ATR 42/3" and "Propeller Pitch Change System Components" and "8/2007"), but they do not contain substantive amendment information.

In short, the AD as provided has no internal amendment history except for its explicit cross-reference to the DGAC AD 2002-070-090(B) R1. If operators or maintainers require a formal amendment history, or confirmation whether this AD amends, supersedes or is superseded by other Australian ADs, that information is not present in the supplied instrument and would need to be located in the regulator’s external AD database or official amendment records.

The supplied document contains no litigation history. It recounts factual incidents in the Background,"Three cases of propeller pitch lock during final approach have been experienced on ATR aircraft" and related investigative observations regarding the pitch control unit ball screw,but does not reference any judicial or administrative proceedings, decisions, enforcement actions, or challenges related to the AD or to the incidents described (Background). There is no mention in the text of appeals, disputes, or precedent decisions concerning this AD.

Accordingly, within the scope of the text provided there is no recorded litigation, no case citations, and no administrative appeals described. If there have been legal proceedings relating to the AD, investigations, compliance disputes or penalties, those are not included in this instrument and would need to be sought in external sources such as court records, tribunal files, or regulator enforcement records.

Because the AD cites a DGAC AD and notes investigative findings, an interested party seeking litigation history or precedent would need to consult the regulator’s public records or legal databases external to the AD text, but the AD itself contains no litigation narrative.

Several practical compliance and operational risks are embedded in the text and merit careful reading by operators and maintenance planners.

1. Narrow applicability definition: The AD applies specifically to "ATR 42-200, -300 and -320 series aircraft" and to Hamilton Sundstrand 14SF5 propellers (Applicability; Requirement). Aircraft of other ATR 42 series, or ATR 42s fitted with different propellers, are not covered by the text. Misidentifying the propeller model could lead to a false sense of compliance or failure to comply where required.

2. Manufacturer procedure is mandated: The AD requires cleaning "in accordance with Hamilton Sundstrand Component Maintenance Manual 61-21-07" (Requirement). Operators that have different internal procedures or historic practices must use the specified CMM procedure; absence of the CMM or failure to follow that exact manual could raise compliance questions.

3. Multiple compliance triggers: There are three separate compliance triggers: a flight-hour threshold and two immediate-action triggers ("Before further flight" in cases of contamination or production anomalies) (Compliance). The "Before further flight" triggers convert inspection findings into immediate operational restrictions and can result in unexpected grounding until the cleaning action is completed and certified.

4. Flight-hour accounting: The flight-hour compliance threshold is defined "since new or since last critical inspection" (Compliance). Operators must ensure their flight-hour tracking aligns with the AD’s reference points. Differences in how "last critical inspection" is interpreted across maintenance records could affect when the cleaning becomes due.

5. Production acceptance tests: The AD requires cleaning "before further flight" if anomalies are found during production acceptance tests (Compliance). For aircraft delivered from production or undergoing acceptance, encountering anomalies at that stage compels immediate cleaning prior to first flight, which could delay delivery or entry into service.

6. No alternative compliance route in the text: The AD does not provide a stated procedure for approving alternative methods of compliance or for seeking exemptions within the instrument. If an operator believes an alternative procedure provides equivalent safety, the AD text contains no route for that variation; any such route would need to be sought from the regulator outside the wording of the AD.

7. Silence on enforcement and documentation: The AD does not set out what documentation suffices to demonstrate compliance or what enforcement action follows non-compliance (Penalties and enforcement). Operators should not assume informal compliance is sufficient; they should prepare maintenance records that clearly reference the AD, the CMM procedure used, the date and FH at which the cleaning was performed, and any inspection findings that triggered the action.

8. Cross-reference to foreign AD: The AD "refers" to DGAC AD 2002-070-090(B) R1 (Note). That reference may contain additional technical or compliance detail not reproduced here; operators should be cautious relying solely on the Australian AD text if they need information contained in the referenced document.

9. Potential operational disruption: The "Before further flight" requirement, when triggered, effectively requires operators to stop flying the affected aircraft until cleaning is completed. Operators should plan for the contingency, including availability of the required cleaning capability and potential supply-chain or slot constraints for maintenance facilities qualified to follow CMM 61-21-07.

10. Timing of effectiveness vs signature date: The AD was signed on 21 June 2007 and "becomes effective on 2 August 2007" (signature/effective date). Operators need to ensure compliance schedules take the effective date into account; work performed prior to the effective date may not satisfy the AD unless otherwise authorised, which the text does not address.

The AD prescribes three discrete compliance pathways, and an operator should plan actions that translate those requirements into maintenance tasks, record-keeping, and contingency procedures.

1. Identify affected fleet and components

• Confirm which aircraft in the fleet are ATR 42-200, -300 or -320 series and whether they are fitted with Hamilton Sundstrand 14SF5 propellers (Applicability, Requirement).
• Tag or log the specific PCU assemblies and their serial numbers and flight-hour counters so that compliance tracking is component-specific, particularly because the flight-hour limit is measured "since new or since last critical inspection" (Compliance).

2. Schedule the flight-hour-triggered cleaning

• Implement a tracking mechanism so that each affected PCU is scheduled for ultrasonic cleaning before it reaches 10,500 flight hours since new or since last critical inspection (Compliance). That will require aligning the AD with existing critical inspection intervals and maintenance planning.
• Ensure maintenance slots and necessary equipment for ultrasonic cleaning per Hamilton Sundstrand CMM 61-21-07 are booked in advance to avoid missing the threshold.

3. Establish immediate-action procedures for contamination/anomalies

• For any detection of contamination of the PCU servo ball screw or any anomalies during production acceptance tests, the operator must perform the ultrasonic cleaning "Before further flight" (Compliance). Put an operational procedure in place that requires immediate suspension of flight and rapid initiation of maintenance action upon such findings.
• Define who within the organisation has authority to declare the aircraft unserviceable under this AD and to direct the cleaning action and record the event.

4. Follow the manufacturer's CMM precisely

• Perform ultrasonic cleaning "in accordance with Hamilton Sundstrand Component Maintenance Manual 61-21-07" (Requirement). Obtain and keep an up-to-date copy of that CMM and follow its steps and any requisite verification or functional tests specified therein.
• If the CMM requires specific equipment, consumables or qualified personnel, ensure those are available or contracted.

5. Recordkeeping and maintenance release

• Document the cleaning event in the aircraft/component maintenance records, explicitly citing the AD identifier (AD/ATR 42/3, 8/2007), the CMM reference (61-21-07), the date, the flight hours at the time of cleaning, the work performed, and the name and signature of the certifying maintenance engineer. Although the AD does not specify the exact documentation format, clear records will be necessary to demonstrate compliance in audits.
• Retain records of any contamination findings or anomalies discovered during production acceptance testing and the actions taken, since the AD requires a "Before further flight" action in those circumstances (Compliance).

6. Integrate with production acceptance processes

• For aircraft undergoing production acceptance testing, include inspection criteria and acceptance-test checks for PCU contamination in the acceptance protocol. If anomalies are identified, ensure that the acceptance process includes immediate referral to maintenance and completion of the ultrasonic cleaning before authorising first flight.

7. Contingency planning

• Because the AD's "Before further flight" requirement can create immediate operational impacts, maintain a contingency plan for aircraft availability, including alternative aircraft, customer notifications, and logistic arrangements for maintenance resources capable of performing the CMM-specified ultrasonic cleaning promptly.

8. Liaise with regulator and manufacturer if needed

• The AD references a DGAC AD and mandates use of the Hamilton Sundstrand CMM. If questions arise about the adequacy of the CMM procedure, potential alternative methods, or the applicability to a particular configuration, seek formal guidance from the Civil Aviation Safety Authority or from Hamilton Sundstrand. The AD text does not provide an alternative-method route, so any deviation should be formally approved by the regulator outside the AD text.

9. Verify the effective date and retrospective work

• The AD "becomes effective on 2 August 2007" (effective date). For scheduling and record purposes, treat that date as the point at which the obligation must be in the operator’s compliance planning. Works completed prior to that date should be documented, but the AD does not state whether earlier cleaning satisfies the requirement; if in doubt, seek confirmation from the regulator.

10. Audit readiness

• Expect that the regulator will assess maintenance records and that inspectors will look for explicit references to the AD and to the CMM procedure followed. Prepare records and checklists that make it straightforward to demonstrate compliance with the AD’s three triggers and with the CMM procedure.

By following the prescribed procedure in the Hamilton Sundstrand CMM and by mapping the AD’s timing rules into maintenance planning and production acceptance tests, an operator can create a defensible compliance pathway that meets the AD’s specified requirements. The AD itself does not provide a process for alternative compliance, nor does it supply enforcement detail, so compliance should be documented precisely and any uncertainties should be resolved with the regulator or with the component manufacturer.