AD/PHZL/89 - Propeller Mounting Flanges

The AD sets out a risk‑mitigation regime focused on fretting wear at the interface between propeller and engine mounting flanges, and the resulting loss of mounting bolt preload that can lead to mounting bolt failure and propeller separation. The underlying technical concepts in the AD are fretting wear, bolt preload (which is monitored by torque inspections), flange resurfacing, installation and replacement of fretting disks, and replacement of mounting bolts. The AD links those concepts to specific manufacturer procedures in Hartzell Propeller Inc. Alert SB No. A203A and SB No. HC‑SB‑61‑275, and it prescribes the exact portions of the SBs to be used for inspections and resurfacing work, namely paragraphs 3.A-3.A.(4) and 3.B-3.B.(5).

Key technical thresholds and work items in the AD are explicit. The torque acceptance threshold is 90 ft‑lbs; any measured bolt torque below that triggers removal and further work. The AD directs resurfacing of either the propeller mounting flange or the engine mounting flange, or both, when specified, and where fretting disks are present they must be inspected and replaced as directed by the SB. The directive requires replacement of all mounting bolts with new mounting bolts when resurfacing is performed or when a bolt torque falls below the 90 ft‑lbs threshold.

Procedurally, the AD prescribes differing inspection and action paths depending on prior maintenance history: (a) if flanges have not been resurfaced using the Hartzell SBs, do torque inspections; (b) if flanges have been resurfaced and no fretting disk was installed, do torque inspections and act if torque is low; (c) if flanges have been resurfaced and a fretting disk was installed, remove and inspect the flanges and fretting disk, replace the fretting disk as needed, and thereafter repeat removals and inspections at specified intervals. Where a propeller is removed from the engine, or where a propeller is moved to an aeroplane model not listed in the AD, the AD requires inspection and flange resurfacing if necessary.

The AD is also a cross‑jurisdictional instrument. It references FAA AD 2006‑22‑12 and supersedes FAA AD 2004‑21‑01, and it cancels prior CASA ADs AD/SD3‑30/23 Amdt 2 and AD/SD3‑60/41. It relies on Hartzell SB text for the detailed inspection and resurfacing methodology. The AD therefore combines regulatory timing and mandatory outcomes with manufacturer technical procedures, producing a prescribed compliance path that mixes regulator authority and manufacturer technical method.

The directive directly affects the following categories of parties, as defined by the applicability and requirements in the AD: aircraft operators and owners who have the specified Hartzell propeller models installed on their aircraft, maintenance organisations and certificated maintenance engineers who perform the inspections and resurfacing, Supplemental Type Certificate (STC) holders for installations referenced in the Applicability table, and Hartzell as the manufacturer of the SBs relied upon by the AD.

The Applicability table lists specific aeroplane manufacturers and models that commonly carry the subject propellers: Nord 262(A) Frakes (Mohawk), Short Brothers SD3‑30 (Sherpa), Short Brothers SD3‑60 and SD3‑60‑200 (Sherpa), and PZL Mielec PZL‑M18( ) (Dromader). The table also lists specific propeller model designations for those installations, for example HC‑B5MP‑3(A)/M10282A(B)+6 and HC‑B5MP‑3C/M10876ASK, and identifies applicable supplemental type certificates where relevant (for example SA2369SW for the Nord installation, SA1014GL for the PZL installation). The AD explicitly states that the parentheses in the propeller model number indicate optional letters but that the AD applies regardless of whether those letters are present or absent, extending the AD’s reach to variant model suffixes.

Operators of aeroplanes not listed in the Applicability table may also be affected when they accept a propeller removed from an engine and installed on an aeroplane model not listed in the AD. Requirement 5 requires inspection whenever a propeller is removed from an engine and whenever a propeller is removed from an engine to be installed on an aeroplane model not listed in that AD. That creates obligations for maintenance organisations performing transfers or reinstallations of propellers across aircraft types.

Maintenance providers and AMEs who perform torque inspections, flange resurfacing, fretting disk replacement and bolt replacement are affected by the AD’s mandatory reference to specific SB procedures, and by the AD’s torque and interval requirements (for example the 90 ft‑lbs torque threshold and recurring 120 FH and 1,500 FH intervals in the compliance schedule). STC holders and registrars are affected in keeping records and ensuring STC installations remain compliant with AD requirements, since the AD lists STCs and models by which certain propeller/airframe combinations are subject to the directive.

Finally, the AD affects Chief Inspectors, Designated Airworthiness Representatives and CASA enforcement officers who oversee implementation, because it cancels prior ADs (AD/SD3‑30/23 Amdt 2 and AD/SD3‑60/41) and replaces those obligations with the present requirements, changing the compliance baseline for affected fleets. The AD does not itself specify penalties in the text provided, but it imposes pre‑flight and interval obligations that operators must observe.

Key duties are expressed as mandatory actions with specified techniques, thresholds and timing. The primary duties are:

• Perform torque inspections of propeller mounting bolts using paragraphs 3.A through 3.A.(4) of Hartzell SB HC‑SB‑61‑275 when either the propeller mounting flange or engine mounting flange has not been resurfaced per Hartzell Alert SB A203A or HC‑SB‑61‑275, see Requirement 1. This is a prescribed method obligation, not a free form inspection.

• If the torque of any one bolt is found to be less than 90 ft‑lbs, remove and inspect the propeller and resurface the flanges as necessary, following paragraphs 3.B through 3.B.(5) of HC‑SB‑61‑275, and replace all mounting bolts with new mounting bolts, see Requirement 2.

• If flanges have been resurfaced using Hartzell SB A203A or HC‑SB‑61‑275 and a fretting disk was not installed, perform the torque inspection per paragraphs 3.A-3.A.(4) of HC‑SB‑61‑275, and if any bolt torque is less than 90 ft‑lbs remove/inspect/resurface and replace all mounting bolts, see Requirement 3.

• If flanges have been resurfaced and a fretting disk was installed, remove the propeller, inspect the propeller and engine mounting flanges, resurface flanges if necessary and replace the fretting disk. Thereafter remove the propeller and repeat the flange inspections and fretting disk replacement at the intervals specified, using paragraphs 3.B-3.B.(5) of HC‑SB‑61‑275 and replace all mounting bolts with new mounting bolts, see Requirement 4.

• Inspect the propeller and engine mounting flanges and resurface if necessary whenever the propeller is removed from the engine, and whenever a propeller is removed from an engine to be installed on an aeroplane model not listed in the AD, see Requirement 5.

Duties include adherence to explicit timing: for propellers with 3,000 or more FH TSN on the effective date, perform an initial bolt torque inspection before further flight if never done and thereafter at intervals not greater than 120 FH; for propellers last inspected under the cancelled ADs, do the next inspection within 120 FH of the last inspection or the AD effective date, whichever is earlier; for propellers with fewer than 3,000 FH TSN, perform the inspection upon reaching 3,000 FH TSN and thereafter every 120 FH. Where flanges were resurfaced and fretting disks installed, different intervals apply, including initial action within 120 FH after reaching 1,500 FH from the time of the last resurfacing and thereafter at intervals not to exceed 1,500 FH where specified.

Rights and procedural aspects apparent from the AD text:

• The AD prescribes specific Hartzell SB procedures to be used for inspection and resurfacing. Operators and maintenance organisations therefore have the right, and the obligation, to follow Hartzell SB HC‑SB‑61‑275 paragraphs 3.A and 3.B for the technical steps. The AD does not supply alternative methods or allow deviations in the text provided; any departure would require separate approval from the regulator or a different approved data source, though the AD itself does not set out an approval mechanism.

• The AD makes explicit that presence or absence of variant suffix letters in the propeller model designation does not exclude applicability. That is a clarity that removes an argument based on model suffixes.

• The AD references other regulatory action (FAA AD 2006‑22‑12) and cancels certain previous CASA ADs. Where a prior inspection was done under the cancelled ADs, compliance timelines are adjusted: the AD provides an interval for bolts last inspected under the cancelled ADs to have the next inspection within 120 FH from the last inspection or effective date, whichever is earlier.

What the AD does not specify in the text provided are sanctions or civil or criminal penalties. The AD does contain pre‑flight prohibitions implicitly through the language "Before further flight after the effective date of this AD" where applicable, thereby operationally preventing further flight unless the listed actions or inspections are carried out. The AD does not, in the text provided, specify a process for approval of alternative methods of compliance nor does it set out an appeals mechanism; those matters are typically handled under CASA administrative processes, but are not contained within the AD text supplied.

The AD text does not set out statutory penalties, fines or explicit enforcement mechanisms within the document provided. What the AD does do, operationally, is impose pre‑flight and recurring maintenance obligations by directive language, for example the repeated use of “Before further flight after the effective date of this AD” and interval maxima such as “at intervals not to exceed 120 FH” or “at intervals not to exceed 1,500 FH.” Those phrases function as operational prohibitions until compliance is achieved, in that an aircraft operator must not operate the aircraft past the stated point without performing the required inspections or corrective actions.

The AD is signed by a CASA delegate, Charles Lenarcic, and lists an effective date of 17 September 2007. The presence of a named delegate and effective date shows this is an issued CASA AD. While the AD text does not itself list sanctions, in regulatory practice CASA ADs are binding directions under the national aviation regulatory framework, and non‑compliance can lead to regulatory enforcement action by CASA. The AD cancels prior CASA ADs AD/SD3‑30/23 Amdt 2 and AD/SD3‑60/41, which changes the immediately applicable compliance obligations for operators previously subject to those ADs. The AD also references FAA AD 2006‑22‑12 Amendment 39‑14809 and supersedes FAA AD 2004‑21‑01, which indicates coordination with foreign airworthiness directives and may affect obligations for internationally registered aircraft or maintenance performed under foreign approvals.

From the text, enforceable elements include: mandatory inspections per Hartzell SB paragraphs specified, mandatory removal and resurfacing where torque is less than 90 ft‑lbs, mandatory replacement of all mounting bolts in specified circumstances, and mandatory inspection whenever a propeller is removed or transferred to an aeroplane model not listed in the AD. The AD prescribes timing for those elements (for example before further flight, within 120 FH, upon reaching 3,000 FH TSN, and intervals thereafter). These express operational constraints that CASA would expect to be complied with and verifiable in maintenance records.

The AD does not identify which entity is responsible for record‑keeping or the form of records, although standard maintenance practice requires maintenance organisations and certificated engineers to create and retain records of such inspections and corrective actions. The AD also does not set out a formal process within its text for requesting an Alternative Method of Compliance or for obtaining relief; that omission in the AD text may require affected parties to approach CASA by the usual application channels if alternative approaches are desired.

The AD explicitly interfaces with other airworthiness instruments and manufacturer technical publications. It refers to FAA AD 2006‑22‑12 Amendment 39‑14809, and states that it supersedes FAA AD 2004‑21‑01. It also cancels previously issued CASA ADs AD/SD3‑30/23 Amdt 2 and AD/SD3‑60/41. Those cross‑references mean that operators and maintenance organisations must read the AD in the context of the underlying FAA ADs and prior CASA ADs that it replaces or cancels, to determine the net set of obligations and historical compliance credit.

The AD directs mandatory use of specific portions of Hartzell Propeller Inc. Service Bulletin HC‑SB‑61‑275 (paragraphs 3.A-3.A.(4) and 3.B-3.B.(5)) and Hartzell Alert SB No. A203A, dated 5 January 1995. That creates a de facto regulatory reliance on manufacturer approved data, embedding Hartzell SB content into the regulatory instruction. Consequently, the AD interacts with the general principle that manufacturer SBs provide the approved technical method for implementing an AD, and shifts detailed technical responsibility to the SB procedures while CASA sets the required outcomes and timing.

The AD also interacts with regulatory processes for Supplemental Type Certificates. The Applicability table lists STCs such as SA2369SW and SA1014GL for certain propeller/airframe combinations. Where compliance involves an STC installation, the STC holder and operator must ensure the AD actions are compatible with the STC conditions and that any SB‑directed resurfacing or bolt replacement does not conflict with STC limitations.

Operationally, the AD’s requirement that inspections occur “before further flight” in certain circumstances interacts with air operations and certificate holders’ obligations to maintain continuing airworthiness. If the AD’s requirements are not met, the aircraft may not be considered airworthy by the certificate holder, implicating regulatory responsibilities under the Civil Aviation regulations, although specific sanctions or administrative remedies are not included in the AD text itself.

The AD’s cross‑jurisdictional references mean that foreign operators and maintenance organisations that work to FAA data or operate under bilateral agreements must account for both CASA and FAA directives when they overlap. The AD’s note that it supersedes earlier FAA ADs and refers to FAA AD 2006‑22‑12 suggests harmonisation of safety action across jurisdictions, but also requires affected parties to reconcile any differences in compliance timing or method.

Finally, the AD’s prescription to replace bolts and to resurface flanges per specific SB paragraphs potentially interacts with parts‑approval and maintenance certification rules, because replacing major hub or flange hardware typically requires appropriate part numbers, traceability and installation by certificated personnel. The AD text itself does not specify which category of maintenance approval is required, so practitioners must apply the applicable maintenance regulations and approved data rules to execute the AD.

The document identifies itself as AD/PHZL/89 and bears the label 11/2007 TX, indicating publication in November 2007 classification or catalogue. The AD becomes effective on 17 September 2007, and the signature block shows the AD was signed by Charles Lenarcic, Delegate of the Civil Aviation Safety Authority, on 10 September 2007. The AD text explicitly states it supersedes FAA AD 2004‑21‑01 which is referred to in AD/SD3‑30/23 Amdt 2, and it notes that AD/SD3‑30/23 Amdt 2 and AD/SD3‑60/41 have been cancelled following the issue of this AD. The AD also includes a cross‑reference to FAA AD 2006‑22‑12 Amdt 39‑14809 in the Note.

The presence of the advisory cross‑references and cancellations indicates that this AD consolidated earlier, model‑specific CASA ADs (AD/SD3‑30/23 Amdt 2 and AD/SD3‑60/41) into a single instrument covering additional installations and harmonised with FAA action. The AD records that it results from continued reports of fretting wear between engine and propeller mounting flanges that had persisted despite earlier actions, which suggests an iterative safety response. The AD includes explicit dates for the Hartzell SBs referenced: Hartzell Propeller Inc. Alert SB No. A203A is dated 5 January 1995, and Hartzell SB No. HC‑SB‑61‑275 is dated 2 June 2005, both of which are incorporated as mandated technical methods in the AD.

The AD’s text indicates that it supersedes and cancels other directives rather than amending them. The AD itself therefore functions as the operative amendment to the earlier CASA and FAA directives listed. No further amendments, revisions or subsequent effective dates are contained in the provided text. The AD also includes the note “FAA AD 2006‑22‑12 Amdt 39‑14809 refers,” which signals a linkage to FAA amendment history, but the AD does not reproduce amendments to the Hartzell SBs beyond citing their revision dates.

For practice, an affected operator should check CASA’s AD register and Hartzell’s SB revision history for any later revisions, superseding ADs, or updated SB paragraphs beyond the versions cited here, because the AD mandates specific SB paragraphs and those paragraphs may themselves be updated by the manufacturer. The provided text does not include later amendments or a history after September 2007.

The AD text does not cite any judicial decisions or administrative appeal outcomes, and it does not assert any legal disputes or litigated interpretations. The document provides no litigation history or references to case law. It is a regulatory directive that explains the safety rationale , that fretting wear continues to occur between engine and propeller mounting flanges causing loss of mounting bolt preload and bolt failures, leading to potential propeller separation , but it does not record any enforcement actions, prosecutions or judicial appeals associated with this AD.

Because the AD cancels two prior CASA ADs (AD/SD3‑30/23 Amdt 2 and AD/SD3‑60/41) and refers to FAA actions, it is possible that compliance credit from earlier directives is relevant to present compliance timelines, and that there may have been administrative engagement when those earlier ADs were in force. However, such procedural or contested histories are not contained in the AD text supplied. The AD also does not record any Notices of Intent, public consultations or responses to submissions in the provided text.

In short, the supplied source contains no litigation record, case citations, or adjudicative material. If a practitioner requires whether any court or tribunal has considered this AD, or whether there have been enforcement proceedings or successful appeals, they must consult external case databases, CASA enforcement records, or court registries. The AD itself provides no material on legal disputes.

Several practical and interpretative pitfalls are visible from the AD text that practitioners should note:

• Parenthetical model letters do not change applicability. The AD explicitly states that the parentheses in the propeller model number indicate varying additional letters but that the AD applies regardless of whether the letters are present or absent. Operators who assume that a suffix letter excludes applicability will be mistaken.

• Torque threshold is absolute and uses imperial units. The acceptance torque is 90 ft‑lbs. Maintenance personnel in Australia must ensure correct torque tools and procedures that read in ft‑lbs, or correctly convert if instruments read Nm, because mis‑conversion risks incorrect torque and consequent non‑compliance. The AD gives no tolerance band for torque readings, which makes precise adherence important.

• The AD mandates specific SB paragraphs. The inspection and resurfacing methods are not optional, they must use paragraphs 3.A-3.A.(4) and 3.B-3.B.(5) of Hartzell SB HC‑SB‑61‑275. Substituting a different approved method or an in‑house technique is not authorised by the AD text. If operators wish to use an alternate method, they will need to seek an alternative method of compliance through CASA, but that route is not described in the AD itself.

• Fretting disk presence changes the regime markedly. If flanges have been resurfaced and a fretting disk was installed, the AD requires removal of the propeller, inspection, resurfacing if necessary, replacement of the fretting disk, and thereafter repeated removal and flange inspections with fretting disk replacement at the intervals stated. Conversely, if resurfacing occurred without installing a fretting disk, the required regime is torque inspections and corrective action if torque is low. Failure to identify correctly whether a fretting disk was installed will lead to incorrect compliance steps.

• Interval logic is conditional and tiered. The compliance table contains multiple conditional timelines: (a) for TSN ≥ 3,000 FH on the effective date there is an immediate inspection if never done and then every 120 FH; (b) for bolts last inspected under the cancelled ADs there is an inspection within 120 FH of the last inspection or effective date, whichever is earlier; (c) for TSN < 3,000 FH the inspection is due upon reaching 3,000 FH TSN and then every 120 FH; (d) for resurfaced flanges without fretting disks there are timelines linked to 1,500 FH since last resurfacing with 120 FH inspection windows; and (e) for resurfaced flanges with fretting disks there is an initial 120 FH window after reaching 1,500 FH and repetitive intervals not to exceed 1,500 FH for repeated removals and inspections. Readers must map each condition to the corresponding Requirement number to avoid missing a due date.

• Replacement of all mounting bolts is mandatory in several outcomes. The AD requires that “Replace all mounting bolts with new mounting bolts” whenever removal and resurfacing occurs under the specified SB paragraphs. That is an all‑or‑nothing replacement obligation, not a partial replacement of suspect bolts only. Budgeting and parts provisioning must reflect full bolt set replacement.

• Whenever the propeller is removed, an inspection is required. Requirement 5 mandates inspection and resurfacing if necessary whenever a propeller is removed from the engine, and whenever a propeller is removed from an engine for installation on an aeroplane not listed in the AD. That broad sweep can capture many routine maintenance activities and transfers; operators who routinely swap propellers should ensure procedural checks are in place so inspections are not overlooked.

• The AD cancels prior ADs but provides credit timing. Operators that complied with previously cancelled ADs must still verify the timing in the present AD, because it requires an inspection within 120 FH from the last inspection or effective date, whichever is earlier, if the last inspection was under the cancelled ADs. That can lead to an inspection being due even if recent work was carried out under the earlier AD frameworks.

• The AD text does not specify alternative compliance or approval pathways. If an operator considers a different resurfacing method or a proprietary fretting disk, the AD provides no immediate mechanism to accept it; engagement with CASA will be required.

• Lack of explicit recordkeeping and approval statements. The AD does not detail record‑keeping requirements or explicitly state which certifying personnel are authorised to sign off that the AD has been complied with. Practitioners must therefore apply the broader maintenance regulations when documenting compliance.

These “gotchas” are matters of operational detail and interpretation that can generate non‑compliance if not handled deliberately. The AD’s precise cross‑references to SB paragraph numbers and its absolute torque and replacement requirements make precise procedural compliance necessary.

Actionable steps to achieve compliance, mapped to the AD’s requirements and compliance schedule:

1. Confirm applicability. Check whether the propeller model installed is one of the Hartzell models listed, remembering that the presence or absence of letters in parentheses does not affect applicability. Confirm the aircraft make and model in the AD’s Applicability table and cross‑check STC numbers where present (for example SA2369SW, SA1014GL).

2. Assemble the technical data. Obtain and have on hand Hartzell Propeller Inc. Alert SB No. A203A (5 January 1995) and Hartzell SB No. HC‑SB‑61‑275 (2 June 2005). The AD requires use of paragraphs 3.A-3.A.(4) for torque inspections and 3.B-3.B.(5) for inspection and resurfacing procedures. Ensure maintenance staff have the correct SB revision versions referenced by the AD.

3. Determine flange history and fretting disk status. Establish, from maintenance records or physical inspection, whether the propeller and engine mounting flanges have been resurfaced under the Hartzell SBs and whether a fretting disk was installed during that resurfacing. The subsequent inspection regime depends on these facts (see Requirements 1-4).

4. Schedule inspections in accordance with TSN and prior inspections. For propellers with 3,000 or more FH TSN on the AD effective date, perform a torque inspection before further flight if a torque inspection has never been done, and thereafter every 120 FH. For propellers that were last inspected under the cancelled ADs, schedule the next torque inspection within 120 FH from the last inspection or from the AD effective date, whichever is earlier. For propellers below 3,000 FH TSN at the effective date, schedule the inspection when TSN reaches 3,000 FH and then every 120 FH thereafter. For resurfaced flanges consult the AD’s special intervals: within 120 FH after reaching 1,500 FH since last resurfacing for certain scenarios, and repeat at intervals not to exceed 1,500 FH where specified.

5. Conduct torque inspections per SB paragraphs 3.A-3.A.(4). Use calibrated torque wrenches capable of ft‑lb measurement, apply the SB’s sequence and methodology, and record measured torques for each mounting bolt. The AD sets 90 ft‑lbs as the minimum acceptable torque for any single bolt.

6. If any bolt torque < 90 ft‑lbs, remove the propeller and perform inspection and flange resurfacing per SB paragraphs 3.B-3.B.(5). When removal and resurfacing occur, replace all mounting bolts with new mounting bolts as the AD mandates. Ensure replacement bolts meet the manufacturer’s part numbers and traceability requirements. Document the resurfacing work and bolt replacement in the aircraft maintenance records.

7. If flanges were previously resurfaced and a fretting disk was not installed, perform torque inspections per SB paragraphs 3.A-3.A.(4). If torque readings are acceptable, continue to monitor per the 120 FH interval. If any torque is below 90 ft‑lbs, remove and resurface per the 3.B sequence and replace bolts.

8. If flanges were previously resurfaced and a fretting disk was installed, remove the propeller, inspect propeller and engine mounting flanges and the fretting disk, resurface flanges if necessary, and replace the fretting disk as required. Thereafter, the AD requires removal and repeated flange inspections and fretting disk replacement at the intervals stated; follow the AD’s timing provisions, in particular the 120 FH window after reaching 1,500 FH and the 1,500 FH repetitive interval where that applies.

9. Whenever a propeller is removed from an engine, or when a propeller is removed for transfer to an aeroplane model not listed in the AD, inspect the propeller and engine mounting flanges and resurface if necessary, following SB paragraphs 3.B-3.B.(5) and replace all mounting bolts with new mounting bolts.

10. Record keeping and certification. Although the AD does not specify the exact form of records, standard maintenance regulations require written entries detailing the work performed, parts replaced (including new bolt batch/part numbers), torque readings, SB paragraph references used, the identity of the AME or maintenance organisation performing the work, and dates. Ensure the maintenance release or certification entry references AD/PHZL/89 compliance and includes relevant SB paragraph citations.

11. Plan parts and tooling. Because full bolt set replacement is mandated in multiple scenarios, stock the correct quantity and part numbers for mounting bolts before performing resurfacing. Ensure resurfacing tooling and measurement equipment meet SB specifications. Calibrate torque tools to ensure accurate ft‑lbs readings.

12. Where an operator seeks an alternative method of compliance, engage CASA early. The AD does not describe an alternate compliance approval route within its text, so apply the usual CASA channels to seek an Alternative Method of Compliance (AMOC) or equivalent approval prior to performing non‑SB methods.

13. Monitor AD cancellations and amendments. The AD cancels older CASA ADs and references FAA ADs. Check CASA’s AD register and Hartzell SB updates to ensure no further amendments or superseding ADs have been issued after the effective date.

14. Safety signalling. Given the AD’s preventive aim to prevent bolt failure and propeller separation, ensure operational checks and dispatch procedures reflect that no further flight is authorised where the AD demands action “Before further flight after the effective date.” If torque inspections were not previously done and the AD requires immediate action, ground the aircraft until inspection is completed.

Following these steps, and using the specific SB paragraphs mandated by the AD, will satisfy the technical and timing obligations the AD establishes. Practitioners should document each step carefully, because the AD ties compliance to the technical procedures in the Hartzell SB and to explicit timing windows that are verifiable in maintenance logs.