AD/PHZL/84 - Propeller Control Unit

The AD rests on several technical and regulatory building blocks that determine scope, action and compliance mechanics. First, applicability is component-specific: it targets the combination of Hartzell propeller model HD-E6C-3B/E13890K with model D-1199-2 PCUs having particular serial numbers listed in Table 1. The AD does not apply generically to all D-1199-2 PCUs, only to those serial numbers enumerated. That enumeration is the primary filter for affected equipment.

Second, the AD delegates detailed inspection and overhaul methodology to a manufacturer's Service Bulletin (Hartzell SB HD-SB-61-025, Revision 1 dated 20 December 2000) and any later FAA-approved revision. The AD repeatedly instructs operators to perform the inspections and Major Periodic Inspection “in accordance with” specific SB paragraphs: paragraph 2A for the flight idle blade angle inspection, and paragraphs 2.B and 2.C for Major Periodic Inspection (overhaul). Thus the SB sets technical standards (dimensional checks, non-destructive evaluation, inspection tolerances and procedures) even though the AD text itself does not reproduce those technical particulars.

Third, the AD uses maintenance-check nomenclature , “2A” and “4A” maintenance checks , as anchors for compliance timing but does not define those checks within the AD text. The compliance schedule is: initial inspection at next “2A” check or within 600 hours time-in-service from the effective date; recurring inspections at each “4A” check but not to exceed 1,200 hours between inspections; overhaul when the SB’s limiting time-since-overhaul/time-since-new is reached. The AD therefore ties recurring inspection frequency to established maintenance intervals rather than to a fixed calendar period; operators must map the AD’s references to their maintenance program and to the SB.

Fourth, the AD creates a terminating option: replacement with a “serviceable PCU” ends the repetitive-inspection obligation. The AD defines “serviceable PCU” narrowly: any PCU not listed in Table 1, or a PCU that is listed but which has undergone a Major Periodic Inspection after 17 November 2000 in accordance with the SB paragraphs referenced. The AD thus provides two routes to end recurring inspections , fit an unlisted unit, or overhaul a listed unit to the SB standard with a post-17-Nov-2000 overhaul date.

Fifth, the AD explicitly references a prior FAA AD (FAA AD 2003-04-22 Amdt 39-13071), signalling cross-jurisdictional alignment. The AD also contains a background statement that attributes the AD to Hartzell’s own review of overhaul procedures which identified omissions in dimensional checks and non-destructive evaluation on certain serial-number PCUs. The stated safety endpoint is prevention of flight idle blade angles below the allowable limit.

Finally, the AD is administrative in form: it contains a discrete applicability clause, numbered mandatory requirements, a table of affected serial numbers, compliance timing, and an effective date. It does not itself include enforcement or penalty provisions, technical details of the SB procedures, or definitions of the maintenance-check labels, all of which are left to the SB, the operator’s maintenance program, and broader regulatory practice.

Directly affected parties are operators and maintainers of aircraft fitted with Hartzell propellers model HD-E6C-3B/E13890K when those propellers are fitted with any model D-1199-2 PCU whose serial number appears in Table 1 of this AD. The AD names the Fairchild Dornier GmbH 328-100 series as an example of installation but clarifies the applicability is not limited to that type, therefore any operator of any aeroplane type carrying the listed propeller-PCU combination is within scope.

Who pays: the economic burden falls on aircraft owners, lessees and operators who must perform the inspections and, where units fail, pay for removal, overhaul (Major Periodic Inspection) or replacement with a serviceable PCU. The AD’s optional terminating action , replacement with a serviceable PCU , transfers cost from an indefinite series of inspections to an up-front capital or overhaul expense for the purchaser. The AD itself does not provide funding or subsidies.

Who decides operationally: the AD is issued by the Civil Aviation Safety Authority (CASA) via its delegate (James Coyne signed the document) and sets mandatory obligations. For day-to-day decisions, the operator, the aircraft maintenance organisation, and certificated mechanics/engineers decide how to schedule and perform the Hartzell SB inspections and overhauls. The AD directs adherence to specific paragraphs of Hartzell Service Bulletin HD-SB-61-025 Revision 1 or later FAA-approved revision, so the manufacturer’s SB sets the technical methods. The AD does not itself define competence standards for the individual performing the inspection, but operators must follow existing licensing and maintenance-authority rules in practice.

Operational behaviour changes required: affected operators must (a) identify whether any currently-installed PCU serial numbers appear in Table 1; (b) at the next “2A” maintenance check or within 600 hours TIS, perform the flight idle blade angle inspection per SB para 2A; (c) remove and overhaul or replace any PCU that fails the inspection per SB paras 2.B and 2.C; (d) continue recurring inspections at each “4A” maintenance check, not to exceed 1,200 hours between inspections, until the unit reaches the SB’s limiting time-since-overhaul or time-since-new; and (e) remove units from service for overhaul when the SB’s limiting times are reached. These are concrete changes to maintenance scheduling, record-keeping and parts inventory management.

Indirectly affected parties include maintenance facilities (increased workload for initial and recurring inspections and overhauls), parts suppliers and distributors (demand for serviceable replacement PCUs), and fleet managers (scheduling disruptions and possible dispatch limitations pending inspection/repair). The AD also affects aircraft insurers and lessors who monitor airworthiness compliance, although the AD text does not specify insurance or lease consequences.

Duties , what the AD compels:

• Identification: Operators must determine whether the installed propeller/PCU combination falls within applicability. The AD’s applicability clause specifies Hartzell HD-E6C-3B/E13890K propellers with model D-1199-2 PCUs listed in Table 1. The AD includes a Note stating these propellers are installed on, but not limited to, Fairchild Dornier 328-100 series aeroplanes, which is informational rather than limiting.

• Initial inspection (Requirement 1): At the next “2A” maintenance check, but no later than 600 hours time-in-service from the AD’s effective date, perform an initial flight idle blade angle inspection in accordance with paragraph 2A of Hartzell SB HD-SB-61-025 Revision 1, or a later FAA-approved revision. The AD makes the SB paragraph the procedural standard for that inspection.

• Remedial removal and overhaul/replace (Requirement 2): If the PCU fails the initial inspection, remove the PCU and perform a Major Periodic Inspection (overhaul) in accord with SB paragraphs 2.B and 2.C, or replace with a serviceable PCU.

• Recurring inspections (Requirement 3): Continue performing the flight idle blade angle inspection at each successive “4A” maintenance check, with an interval not to exceed 1,200 hours time-in-service, until the SB-specified limiting time-since-overhaul or time-since-new is reached.

• Remedial removal and overhaul/replace for recurring failures (Requirement 4): Remove and overhaul/replace PCUs that fail the recurring inspections per the same SB paragraphs.

• Overhaul at limiting time (Requirement 5): Remove the PCU from service and perform Major Periodic Inspection (overhaul) when the limiting time-since-overhaul or time-since-new specified in Hartzell SB HD-SB-61-025 Revision 1 (or later FAA-approved revision) is reached.

Rights and optional actions:

• Optional terminating action: The AD explicitly permits an option to terminate the repetitive inspection requirement by replacing a listed PCU with a “serviceable PCU.” The AD defines a “serviceable PCU” for this purpose as either (a) a PCU not listed in Table 1, or (b) a PCU listed in Table 1 that has undergone a Major Periodic Inspection (overhaul) after 17 November 2000 in accordance with SB paragraphs 2.B and 2.C. Exercise of this option is at the operator’s discretion, subject to availability of serviceable units and operational considerations.

• Reliance on later FAA-approved revisions: The AD allows the use of Hartzell SB HD-SB-61-025 Revision 1 or later FAA-approved revisions. That confers flexibility to use improved or updated procedural guidance but requires that any revision be FAA-approved. The AD does not authorise the use of non-approved revisions.

Record-keeping and proof: Although the AD does not set out specific documentary requirements, compliance necessarily depends on maintenance records confirming inspections, failure findings, removal, overhaul dates, overhaul compliance with SB paras 2.B/2.C, and any replacement with a serviceable PCU, particularly to establish termination eligibility (overhaul after 17 November 2000). The AD places the substantive obligation on the operator to perform actions named, and to rely on the SB for technical compliance.

Delegation of technical content: The AD delegates technical definitions, measurement criteria and NDE methods to the Hartzell SB (para 2A for inspection, paras 2.B and 2.C for overhaul). The AD is therefore a regulatory overlay mandating the SB procedures rather than restating them.

The AD document itself sets mandatory maintenance and remedial actions and an effective date (19 January 2006). It is signed by the CASA delegate James Coyne. The text does not, however, specify penalties, fines, or enforcement mechanisms within the body of the AD. The AD also does not include a penalty schedule, breach enforcement procedures, or a statement of sanctions for non-compliance in its text.

Because the AD binds operators to specified maintenance actions, operational compliance implies scheduling, performance and record-keeping consistent with the requirements (inspection at next “2A” or within 600 hours, recurring at each “4A” not to exceed 1,200 hours, overhaul at the SB’s limiting times, and remedial overhaul/replace for failed inspections). The AD references Hartzell SB and FAA AD 2003-04-22, but contains no procedural enforcement steps.

Practically, enforcement of an AD occurs in the context of national aviation regulatory frameworks. The AD’s status as an instrument of the Civil Aviation Safety Authority (CASA) indicates it is a regulatory requirement. The AD does not itself describe CASA’s enforcement levers (such as administrative notices, grounding orders, certificate action, or monetary penalties) and does not instruct how CASA will discover non-compliance. The document likewise does not state how compliance will be audited or what records must be produced on inspection. The AD’s compliance provisions are concrete and time-limited but silent on enforcement consequences.

Operators should therefore treat the AD requirements as mandatory obligations set by CASA, and expect that failure to comply could have regulatory implications under the broader aviation safety framework. The AD’s text, however, provides no internal authority, process, or penalty clauses; those enforcement mechanisms, if any, are found in the broader regulatory law and CASA’s enforcement policies, not in the AD text itself.

The AD cross-references and operates in concert with other aviation safety instruments and with manufacturer documents. The AD cites and relies on Hartzell Service Bulletin HD-SB-61-025 Revision 1 (20 December 2000) and permits later FAA-approved revisions of that SB to be used. Procedurally, the AD delegates technical inspection and overhaul detail to the SB; therefore the SB functions as the technical standard for compliance. The AD also notes FAA AD 2003-04-22 Amdt 39-13071 as a referenced instrument, indicating alignment between CASA’s AD and an earlier FAA AD.

The AD’s Background paragraph states the AD was prompted by Hartzell’s review of the D-1199-2 PCU overhaul procedures, finding that several dimensional checks and a non-destructive evaluation were not performed on certain serial-number PCUs during a Major Periodic Inspection (overhaul). The AD further says that the overhaul procedures are required to comply with the Airworthiness Limitation PCU Major Periodic Inspection (overhaul) directive. That sentence anchors the AD against the Airworthiness Limitation provisions , the AD enforces adherence to those airworthiness limitations through the inspection and overhaul route specified in the SB.

The AD does not define or reproduce the Airworthiness Limitation directive; it simply indicates the overhaul procedures must comply. Consequently, operators must ensure that their maintenance program addresses Airworthiness Limitation obligations in addition to the AD. The AD does not describe any relationship with civil liability law, contractual regimes, insurance, or international treaties; nor does it assert application beyond CASA’s jurisdiction. However, by referencing an FAA AD, the document signals cross-jurisdictional technical consistency that can affect operators who operate transnationally or whose maintenance practices are influenced by FAA directives.

The AD’s reference to FAA-approved revisions creates a procedural interaction: later changes to Hartzell SB must be approved by the FAA to be explicitly authorised for compliance with this AD. The AD does not indicate whether CASA approval of a later SB revision would also be sufficient; it expressly permits only "later FAA approved revision" in each instruction. Therefore, operators ought to check whether Hartzell SB revisions are FAA-approved and how those revisions are treated within CASA’s administrative processes.

Because the AD requires specific inspections and overhauls, it will interact with operators’ continuing airworthiness records and with any regulatory requirements for maintenance record-keeping, release-to-service certifications, and approved maintenance organisations. The AD itself does not set record-keeping detail; practitioners must reconcile the AD with the wider regulatory framework governing maintenance personnel qualifications, maintenance organisation approvals, and airworthiness certification.

The AD contains internal versioning and reference points. The heading identifies it as AD/PHZL/84 and records the notation "1/2006". The document is signed and dated 30 November 2005 by James Coyne, Delegate of the Civil Aviation Safety Authority, and becomes effective on 19 January 2006. The AD text refers to Hartzell Service Bulletin HD-SB-61-025, Revision 1, dated 20 December 2000, as the baseline technical document. It also allows use of later FAA-approved revisions of that SB.

The AD includes a Note 2 stating "FAA AD 2003-04-22 Amdt 39-13071 refers." That is an explicit cross-reference to a prior FAA AD addressing similar or the same PCU issues; the AD does not state that it supersedes or amends that FAA AD , it records a reference. The AD does not itself contain an amendment chronology beyond identifying the SB revision and the effective date; there are no subsequent in-text amendments recorded in the document.

The AD also records a background origin: a Hartzell review that discovered omissions in the Major Periodic Inspection (overhaul) procedures , specifically that several dimensional checks and a non-destructive evaluation were not performed on certain serial-number PCUs. The AD uses this finding to justify the inspection and overhaul directives.

This document, as presented, does not record later CASA amendments, revocations, or replacements. It permits the technical standard to be a later FAA-approved revision of the Hartzell SB, which creates a pathway for the AD’s technical requirements to evolve (subject to FAA approval of SB updates). Any formal amendment to the AD itself (for example, increased scope or changed compliance times) would ordinarily be published as a subsequent AD or revision; no such amendments are recorded in the provided text.

Practitioners should note two dates for compliance planning and historical tracing: (1) the SB baseline (Revision 1) dated 20 December 2000 and (2) the AD effective date 19 January 2006, issued 30 November 2005. The “serviceable PCU” definition for terminating action hinges on having undergone overhaul after 17 November 2000, which is an important temporal threshold within the AD’s mechanics and therefore part of its amendment-relevant operational detail.

The AD document itself does not record or reference any litigation, legal proceedings, injunctions, or judicial determinations relating to the AD, the Hartzell SB, or the affected PCUs. There are no cases cited in the AD text, nor any indication of legal challenge. The only external instrument the AD references is FAA AD 2003-04-22 Amdt 39-13071 and Hartzell SB HD-SB-61-025 Revision 1; neither reference in the AD text includes litigation history.

Given the absence of litigation detail in the AD, there is no record here of disputes over interpretation, enforcement, or adequacy of the AD’s measures. The AD’s silence on litigation does not preclude the possibility that disputes arose subsequently in courts or administrative forums, but no such outcomes are included or referenced in the provided document.

For practitioners advising clients who may be concerned about legal exposure (for example, leaseholders, lessors, insurers or maintenance organisations), the AD text supplies mandatory obligations and compliance timelines but does not provide the enforcement pathway the regulator might use nor any extant caselaw addressing them. Where litigation risk is a concern, parties will need to consult subsequent regulatory guidance, CASA enforcement materials, and public court records outside the AD document to determine whether enforcement action has been taken in relation to this AD.

The AD contains several practical features that can trip up operators if not carefully navigated.

1. Narrow applicability by serial number: The AD applies only to model D-1199-2 PCUs listed in Table 1. A PCU identical in model but not listed is outside this AD’s scope. Operators must therefore inspect serial numbers precisely. The Table 1 list is long and includes many PCU-A- and PCU-A-EFS-prefixed serials; failure to verify serial numbers against the Table is a common oversight risk.

2. Reliance on Hartzell SB but no definition of “2A”/“4A” in the AD: The AD ties compliance to “2A” and “4A” maintenance checks but does not define those check levels in the AD text. Operators must cross-reference their maintenance programme and the Hartzell SB to map the AD’s “2A” and “4A” to specific inspection intervals. Assuming a calendar-based interval without checking maintenance definitions risks non-compliance.

3. The SB contains the technical detail: The AD specifies procedures “in accordance with” particular SB paragraphs (2A, 2.B, 2.C) but does not reproduce tolerances, dimensional checks, or NDE specifics. If maintenance staff do not or cannot obtain the precise SB paragraphs (or a later FAA-approved revision), they cannot lawfully perform the AD-mandated inspections. The AD permits later FAA-approved SB revisions, but not other revisions per se.

4. Termination depends on overhaul date: The optional terminating action is to fit a “serviceable PCU,” defined to include units overhauled after 17 November 2000 in accordance with SB paras 2.B and 2.C. Overhaul records must clearly show the overhaul date and that it complied with the specified SB paragraphs. Vague or incomplete overhaul documentation will not demonstrate termination eligibility.

5. Effective date vs. action timing: The AD became effective on 19 January 2006, but initial inspections were required by the next “2A” check or no later than 600 hours time-in-service from that effective date. Operators that did not act promptly and who relied solely on the presence of a “next scheduled check” risk missing the 600-hour outer bound. The dual phrasing , tie to a scheduled check but with a hard outer TIS limit , creates a compliance deadline that cannot be postponed by scheduling choices.

6. Recurrence tied to maintenance checks and a 1,200 hour cap: Repetitive inspections are mandated at each “4A” check but not to exceed 1,200 hours time-in-service. Operators must ensure their maintenance intervals do not permit a longer gap than 1,200 hours between inspections. Again, the AD does not define what a “4A” check is; mapping to operator maintenance intervals is required.

7. No enforcement specifics in-text: The AD does not include enforcement or penalty information. Operators should not treat that silence as meaning non-compliance is tolerable. CASA regulatory context will determine enforcement consequences.

8. Aircraft type note is non-limiting: The AD includes a note that the propellers are installed on, but not limited to, the Fairchild Dornier 328-100. Do not construe that note as a limitation; it is illustrative. Operators of other aeroplanes must still check serial numbers.

9. FAA-approved revisions only: The AD allows use of later FAA-approved revisions of the Hartzell SB. If Hartzell issues an SB revision that has not been FAA-approved but perhaps has been revised in other jurisdictions, the AD does not permit automatic use of that revision for compliance. Operators must confirm FAA approval status.

10. Record-keeping gap: The AD does not state in-form what records are required to demonstrate compliance. Operators should assume they will need contemporaneous records that show serial numbers checked, inspection results, overhaul work carried out in accordance with the SB paragraphs and dates of overhauls, especially where termination of the inspection program is claimed.

These procedural and documentary gaps are actionable risks. Address them by: (a) maintaining an accurate register of installed PCU serial numbers cross-checked against Table 1; (b) obtaining Hartzell SB HD-SB-61-025 and ensuring maintenance teams understand its relevant paragraphs; (c) ensuring overhaul records document compliance with SB paragraphs 2.B and 2.C and record overhaul dates; and (d) mapping “2A” and “4A” checks to your maintenance schedule to respect the 600-hour and 1,200-hour limits.

Step-by-step practical checklist, grounded in the AD text and the Hartzell SB references:

1. Identify affected assets:

   • Extract Table 1 from the AD and produce an inventory of all installed model D-1199-2 PCUs on your fleet.
   • Verify serial numbers of installed PCUs against Table 1 precisely; the AD’s applicability is limited to those serials.

2. Obtain the referenced technical standard:

   • Acquire Hartzell Service Bulletin HD-SB-61-025, Revision 1 dated 20 December 2000, and check for any later FAA-approved revisions. The AD requires performing inspections and overhauls “in accordance with” SB paragraph 2A (inspection) and paragraphs 2.B and 2.C (Major Periodic Inspection/overhaul).
   • Confirm whether a later SB revision is FAA-approved before relying on it for AD compliance.

3. Schedule the initial inspection:

   • For any PCU in Table 1, plan and perform the initial flight idle blade angle inspection specified in SB para 2A at the next scheduled “2A” maintenance check or, if that is further out, ensure the inspection is done no later than 600 hours time-in-service from 19 January 2006 (the AD effective date).
   • If the next “2A” check will occur beyond the 600-hour outer limit, schedule an earlier visit to meet the AD’s timing requirement.

4. Execute the inspection exactly as the SB prescribes:

   • Use the SB’s inspection procedure, measurement techniques, and acceptance criteria. The AD does not provide technical tolerances; comply with SB para 2A or a later FAA-approved revision.
   • Record the inspection results contemporaneously in the aircraft’s maintenance log, including measured flight idle blade angles, operator, date, and any anomalies.

5. React to defects:

   • If the PCU fails the initial inspection, remove it per Requirement 2 and perform a Major Periodic Inspection (overhaul) in accordance with SB paragraphs 2.B and 2.C, or replace with a serviceable PCU.
   • Document overhaul activity to demonstrate compliance with SB paras 2.B and 2.C, and record the overhaul date (important for terminating action eligibility with respect to the 17 November 2000 threshold).

6. Establish recurring inspection programme:

   • Continue inspection at each successive “4A” maintenance check but ensure no interval between inspections exceeds 1,200 hours time-in-service, per Requirement 3.
   • Map the AD’s “4A” language to your maintenance schedule (the AD itself does not define what a “4A” check is); implement safeguards to prevent exceeding 1,200 hours between inspections.

7. Overhaul at limiting times:

   • Remove the PCU for Major Periodic Inspection/overhaul once the limiting time-since-overhaul or time-since-new specified in Hartzell SB HD-SB-61-025 Revision 1 (or later FAA-approved revision) is reached, per Requirement 5.
   • Ensure overhaul work is performed in accordance with SB paras 2.B and 2.C and that overhaul documentation clearly records compliance.

8. Consider terminating action:

   • If recurring inspections are operationally burdensome or if a serviceable PCU is available, replace the listed PCU with a serviceable PCU , defined by the AD as either a PCU not listed in Table 1, or one listed that has undergone Major Periodic Inspection after 17 November 2000 in accordance with SB paras 2.B/2.C.
   • Before claiming termination, verify overhaul dates and SB-paragraph compliance in the serviceable PCU’s records.

9. Maintain documentary evidence:

   • For each affected PCU, keep records of: serial number verification, SB revision used, dates and results of each flight idle blade angle inspection, removal/overhaul/repair actions, overhaul reports confirming SB para 2.B/2.C compliance, and dates of overhauls or replacements.
   • For termination claims, ensure the overhaul date is after 17 November 2000 and recorded.

10. Coordinate with maintenance providers and regulators:

• Ensure maintenance staff are familiar with SB paras 2A, 2.B, and 2.C and with the AD’s timing constraints (600-hour outer bound and 1,200-hour recurrence cap).
• Where necessary, seek clarification from CASA or from Hartzell (or the FAA approval status of SB revisions) regarding technical or procedural questions.

11. Plan logistics and spares:

• Anticipate demand for overhauls or serviceable replacement PCUs. Inventory management and lead times can be material and affect fleet dispatchability.
• Consider the cost-benefit of replacing with a serviceable PCU (terminates recurring inspection burden) versus retaining the unit and complying with recurrent inspections and eventual overhaul.

12. Audit readiness:

• Ensure the maintenance file for each aeroplane demonstrates compliance with the AD’s schedule and with the SB’s overhaul requirements where applicable. Given the AD’s silence on enforcement specifics, clear contemporaneous records are the practical measure of compliance should CASA query or audit.

Following these steps will align operations with the AD’s five numbered requirements and its compliance timings while ensuring documentary proof to establish that the operator met the AD’s obligations.