AD/B737/161 Amdt 2 - Main Wheel Well Electrical Connectors

The core legal concept is an Airworthiness Directive (AD). An AD is a mandatory regulatory notice issued by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Act 1988 and associated regulations to address an unsafe condition in an aircraft type. Failure to comply with an AD renders the aircraft unairworthy and illegal to fly. This particular AD is incremental: it amends a previous AD (original issue and Amendment 1) by correcting a title error, but it does not change compliance obligations.

The concept of a detailed visual inspection is defined explicitly within the text. It is not a routine walk-around. The definition requires an intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Lighting must be supplemented with a direct source at an intensity deemed appropriate by the inspector. The inspector may use aids such as mirrors and magnifying lenses. Surface cleaning and elaborate access procedures may be required. This definition is critical because it sets a standard of thoroughness; a perfunctory glance would not meet the legal requirement. The AD does not prescribe who may perform this inspection, but under the regulations, only authorised maintenance personnel (typically licensed aircraft maintenance engineers or organisations holding a Part 145 certificate) can sign off a detailed visual inspection for AD compliance.

The concept of terminating action is important. Requirement 3 (the modification) is designated as terminating action for the repetitive inspections in Requirement 1. This means that once the modification is accomplished on a particular aeroplane, the engine fuel shut-off valve connectors are deemed to be no longer susceptible to the unsafe condition in a way that requires periodic monitoring. The operator can stop the 24-month inspection cycle. This is a classic regulatory design: short-term monitoring through repetitive checks is replaced by a permanent design fix.

Discrepancy is not defined in the AD but is implicitly taken from Boeing Service Letter 737-SL-24-138 and the service bulletin. It includes missing spare contacts, filler rods, improper plugs or filler rods, contamination, and corrosion. The operator must repair any discovered discrepancy before further flight. The repair is not left to discretion; it must be in accordance with the Boeing Service Letter, not any generic or alternative repair scheme unless approved via an alternative means of compliance (AMOC) from CASA.

The concept of a service bulletin is used here as both a source of inspection criteria and modification instructions. A service bulletin is a manufacturer's recommendation, not a legal requirement by itself. But when an AD incorporates it by reference, the bulletin's instructions become legally binding. The AD also includes a grandfathering provision: modifications done to earlier revisions of the bulletin are accepted. This means the operator does not have to re-do the modification using the latest revision if they used an earlier acceptable revision. However, the AD does not say that the earlier bulletin is the only acceptable method; if an operator used a different method (not in any bulletin revision), that would not satisfy the AD unless separately approved.

Another concept is the interplay with US FAA ADs. The directive notes that FAA AD 2001-14-06 and AD 2005-10-11 refer. The Australian AD is not identical to the FAA version; it has its own effective dates and amendment history. For operators who also comply with FAA requirements, the Australian AD may impose different timing. For example, the Australian modification deadline for Amendment 2 references the effective date of Amendment 1 (4 August 2005), not the FAA's dates. Operators must track both regimes where the aircraft is registered or operated under Australian certificates.

This AD directly affects any person or organisation responsible for the continuing airworthiness of a Boeing 737-300, -400, or -500 series aeroplane that is registered in Australia or operated under an Australian air operator certificate, or that is otherwise subject to CASA's jurisdiction. Typically this includes:

• Owners of such aeroplanes: they bear the ultimate legal and financial responsibility for compliance. Even if the owner leases the aircraft to an operator, the owner may be named on the certificate of registration and could face enforcement action for non-compliance.

• Operators (airlines, charter companies, freight operators, corporate flight departments): they are the day-to-day users. They must schedule the inspections and modifications, ensure they are performed on time, and retain the records. They also bear the direct costs: labour for detailed visual inspections (requiring specialised personnel), the cost of the modification kit (purchased from Boeing or approved sources), downtime during modification, and any corrective repairs identified during inspection or modification.

• Maintenance organisations (Part 145 repair stations, approved maintenance organisations): they perform the inspection and modification work. They need to understand the detailed visual inspection standard, have the Boeing Service Letter and Service Bulletin, and have personnel trained on the specific connectors. While the AD does not require special certification beyond normal aircraft maintenance licensing, the detailed inspection definition implies a certain level of access and tooling.

• CASA itself: the authority issues the directive and enforces it. The text shows the instrument is signed by a Delegate of CASA, Jayaprakashan Ambali, on 13 October 2005. CASA's role is to monitor compliance, investigate reports of defects, and apply penalties for non-compliance.

• Indirectly, passengers and crew are affected because the directive aims to prevent in-flight loss of thrust or engine shutdown. The probability of the unsafe condition was considered significant enough to mandate inspections and a modification. The directive affects their safety and may also affect flight schedules if aircraft must be grounded for modification, potentially causing cancellations or delays.

• Insurers: they may adjust premiums or require proof of AD compliance as a condition of coverage. A failure to comply could void insurance for an incident that results from the unsafe condition.

• Boeing: the manufacturer provided the service letter and service bulletin. Boeing has a commercial interest in the design fix and likely sells modification kits. The directive effectively mandates adoption of Boeing's recommended corrective action, giving Boeing a market for its service products.

The compliance costs are not trivial. For an operator of a fleet of 737 Classics (300/400/500), the Requirement 1 inspection may take a few man-hours per aircraft every 24 months, but the modification (Requirement 3) likely requires more intensive labour and parts. Given the grandfathering, some operators may have already modified earlier, potentially reducing costs. However, for those who were not yet in compliance with Amendment 1 when Amendment 2 took effect, the compliance deadline had already passed (6 months after 4 August 2005, i.e., 4 February 2006). This creates an urgency that can increase costs as maintenance slots and parts may be in short supply. The directive does not quantify the cost, but for a typical 737 Classic, the modification might run into tens of thousands of dollars per aircraft when factoring in labour, parts, and downtime. The AD also has an opportunity cost: the aircraft is out of revenue service during the modification.

The primary duty is to comply with the requirements of the AD on each affected aeroplane. Each requirement is a duty with specific timing.

Duty 1: Perform a detailed visual inspection of connectors D5162P, D5162J, D5164P, D5164J to detect discrepancies (missing spare contacts, filler rods, improper plugs, contamination, corrosion) as per Boeing SL 737-SL-24-138. The inspection must be done within 12 months after the original effective date (6 September 2001) and then every 24 months until the modification is accomplished. However, for many operators, the original effective date is long past. The AD is not self-starting again; the compliance clock continues from the original. If an operator acquired an aircraft that had never been inspected, they would need to determine when the original deadline would have applied relative to the registration date, which can be complex. The safer approach is to treat the AD as current and schedule the first inspection immediately.

Duty 2: If discrepancies are found during the Requirement 1 inspection, repair them before further flight. This is an absolute duty: no flight without repair. The repair must follow the Boeing Service Letter. The operator has no discretion to use an alternative repair unless formally approved by CASA as an alternative means of compliance (AMOC). That process requires submission of data showing the alternative achieves the same safety level.

Duty 3: Modify the connectors per Boeing Special Attention Service Bulletin 737-28-1196, Revision 3 (or earlier accepted revisions). The compliance time depends on inspection history, as discussed. The modification itself might reveal corrective actions (Duty 4), which must be carried out before further flight.

Duty 4: Perform any necessary corrective action identified during the modification per the service bulletin, before further flight.

Rights: Operators have the right to request an alternative means of compliance from CASA. This is not stated in the AD itself but is a standard feature of the airworthiness directive system under Civil Aviation Safety Regulations Part 39. If an operator can show that an alternative inspection method or a different repair provides an equivalent level of safety, CASA may grant approval. However, this right is not a get-out-of-jail-free card; it requires technical justification and likely involves costs of analysis and CASA processing time.

Another right: operators who already modified using an earlier revision of the service bulletin (original, Rev 1, Rev 2) do not have to re-do the modification. The AD expressly accepts those as compliance. This grandfathering avoids double work. But note: the AD does not accept other modifications not in the bulletin series. If an operator implemented a different fix (e.g., replacing connectors with a different type not in the bulletin), that does not comply unless separately approved.

The right to fly is conditioned on compliance. If the AD is not met, the aircraft cannot be operated lawfully. The operator also has a right to challenge the AD through CASA review or judicial review in the Administrative Appeals Tribunal, but that is a separate process; the AD itself does not provide a mechanism.

Record-keeping duties are implicit: the operator must maintain a record of inspection findings, repairs, and modifications in the aircraft's continuing airworthiness records. This is required by maintenance regulations generally, but not detailed in the AD.

The Australian Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998 make compliance with an airworthiness directive mandatory. Failure to comply is an offence. The AD itself does not list specific penalty amounts, but the underlying legislation does.

Under the Civil Aviation Act, a breach of an airworthiness requirement (including an AD) can attract civil penalties of up to $10,500 for an individual and $52,500 for a body corporate per contravention (as at 2005, amounts have increased with inflation). Additionally, the operator or owner may be issued a direction to ground the aircraft until compliance is achieved. Operating an aircraft known to be non-compliant could also be prosecuted as a criminal offence under section 20A of the Act (reckless operation), which carries higher penalties, though that would typically require a higher standard of proof.

CASA has a range of enforcement tools: infringement notices (on-the-spot fines), enforceable undertakings, suspension or revocation of air operator certificates or maintenance approvals, and prosecution. Since the AD is safety-critical, CASA is likely to take a strong approach. The directive notes the risk of in-flight engine shutdown; any incident attributable to non-compliance could lead to serious penalties and civil liability.

The reference to FAA ADs suggests that CASA may also cooperate with the US FAA. For Australian operators flying aircraft registered in the US but operated under an Australian AOC, dual compliance is necessary. Enforcement could come from either jurisdiction.

In practice, for a directive this long-standing (original 2001, amendments 2005), CASA would expect operators to have documented compliance. During routine audits (e.g., annual airworthiness review), CASA inspectors or authorised persons will check that all applicable ADs are recorded in the aircraft's AD status report. Missing or overdue AD items are grounds for grounding the aircraft immediately.

The AD also imposes a burden on maintenance organisations: they could face enforcement if they sign off work as compliant when it is not. For example, if an inspector performs a detailed visual inspection without adequate lighting or access, and later a problem occurs, the maintenance organisation could be liable for negligence and breach of maintenance regulations.

One should also note that the AD is not self-enforcing; it requires someone to report non-compliance. CASA relies on audits, reports from the operator's own quality systems, and mandatory occurrence reporting. If an operator deliberately suppresses a known AD non-compliance to keep the aircraft flying, that could attract criminal penalties for fraud.

Given that this AD concerns a modification that is terminating action, the enforcement focus is likely on ensuring the modification is done within the compliance window. Operators who miss the deadline and do not have an AMOC are flying illegally.

This AD sits within a hierarchy of regulatory instruments. The primary source of authority is the Civil Aviation Act 1988, under which CASA issues airworthiness directives as a form of delegated legislation or administrative instrument. The specific mechanism is usually the Civil Aviation Safety Regulations Part 39, which governs airworthiness directives. The AD has the force of law equivalent to a regulation.

It interacts with the Civil Aviation Standards (e.g., Civil Aviation Orders, Manual of Standards) which set out maintenance requirements. For example, maintenance regulations require that all applicable ADs be complied with before an aircraft can be released to service. The AD does not override these general standards; it adds a specific, mandatory task.

It also interacts with the Airworthiness Review Certificates system. For an aircraft to remain on the Australian register, it must have a valid airworthiness review certificate (ARC). The ARC process checks AD compliance as one condition. A missing or expired AD item will prevent issuance of the ARC.

The AD interacts with international obligations. Under Article 33 of the Chicago Convention, Australia must accept airworthiness certifications from other contracting states. However, this AD is specific to Australian-registered aircraft. If a foreign-registered aircraft operates in Australia under a permit or foreign air carrier certificate, the AD does not apply to that aircraft unless CASA makes it applicable through a specific regulation. The note referencing FAA ADs is informational; it does not mean the FAA AD is enforceable in Australia. Instead, it indicates that the US FAA had already required similar actions.

For dual-registered aircraft or aircraft leased to Australian operators, careful attention is needed. If an aircraft is registered in the US but operated on an Australian AOC, both the FAA AD and the CASA AD may apply. The operator must satisfy the stricter of the two. Typically, CASA will accept compliance with the FAA AD as satisfying the CASA AD if the FAA AD is equivalent, but not always. In this case, the Australian AD refers to specific Boeing documentation (SL and SB) and has its own compliance times. The FAA ADs referenced (2001-14-06 and 2005-10-11) might have different dates. The note suggests that CASA is aware of the FAA actions but is not adopting them verbatim. Operators should not assume FAA compliance equals CASA compliance.

The AD also interacts with aircraft type certificate data sheets and continuing airworthiness instructions issued by the manufacturer. The service bulletin and service letter are Boeing technical documents, but when incorporated by reference, they become regulatory. If Boeing revises the service bulletin after the AD is issued, the operator is still bound to the revision specified (Rev 3, or earlier accepted). The AD does not automatically update when Boeing issues a new revision. The operator would need an amendment to the AD to use a later revision.

There is an interaction with insurance contracts. Most aviation insurance policies require compliance with all applicable regulations and ADs. Non-compliance could be a basis for the insurer to deny coverage for an incident, potentially leaving the operator liable for hull damage or third-party claims.

Additionally, the AD has implications for aircraft sales and lease returns. A seller or lessee must demonstrate that all ADs are complied with. The AD's history of amendments means that due diligence must check not only the current amendment but also that earlier compliance (e.g., modifications using Rev 1 or 2) was properly documented and accepted. A buyer or lessee may require proof that any inspections or modifications were performed by authorised personnel and recorded.

The original issue of this Airworthiness Directive became effective on 6 September 2001. It required repetitive detailed visual inspections of the specified electrical connectors every 24 months and corrective actions. At that time, there was no terminating modification; the inspections continued in perpetuity.

Amendment 1 became effective on 4 August 2005. This was the substantive change: it added the modification requirement (Requirement 3) as terminating action for the repetitive inspections. It also adjusted the compliance times for the modification relative to the inspection history. Amendment 1 removed the need for ongoing inspections for aircraft that received the modification. So for operators, this was a step change: from indefinite inspections to a one-time fix.

Amendment 2, the subject instrument, became effective on 24 November 2005. It corrected a typographic error in the title of the Directive. The only change was to the instrument's title; the compliance requirements remain exactly as set out in Amendment 1. The signatory (Delegate of CASA) and date (13 October 2005) indicate it was promulgated shortly after Amendment 1.

The background section explains the rationale for the original issue and Amendment 1. The original issue was prompted by Boeing reports of engine shutdown during flight due to uncommanded movement of the engine shut-off valve. Repetitive inspections were the initial response. Amendment 1 then made available the modification as a more permanent fix. Amendment 2's title correction is minor but necessary for clarity: if the title was wrong, it could cause confusion in records and cross-references.

The amendment history reveals a regulatory process that evolved over four years: from 2001 (inspections only) to 2005 (modification available, then implemented via amendment). The timing of Amendment 1 (August 2005) and Amendment 2 (November 2005) suggests that the typo was noticed quickly and corrected in a second amendment. The AD format includes a footer "12/2005", likely a CASA reference number.

For compliance purposes, operators must be aware of all three versions. If an operator complied with the original issue by performing inspections but never did the modification, they are now out of compliance since Amendment 1 became effective. Amendment 2 does not change that. If an operator modified after Amendment 1 but before the effective date of Amendment 2, they are fine. The grandfathering of earlier service bulletin revisions means that even if a modification was done in 2002 under the original bulletin, it satisfies Requirement 3.

Operators must also be careful about record-keeping: the AD status log should note the amendment number and effective date used for each compliance event. CASA may check whether the compliance was to Amendment 2 or an earlier version. However, since the requirements are identical between Amendment 1 and Amendment 2, the only risk is if the operator relied on a different title to avoid compliance, which would be untenable.

The text of this AD does not reference any case law, litigation, or tribunal decisions. There is no incorporated material that mentions lawsuits. The AD is a technical regulatory instrument, and it is uncommon for airworthiness directives to directly name cases.

However, in the broader context of Australian administrative law, airworthiness directives have been challenged. For example, operators have sometimes sought review of CASA decisions in the Administrative Appeals Tribunal (AAT) on grounds that the directive was disproportionate or that alternative means of compliance were unreasonably denied. But specific to AD/B737/161 Amdt 2, there is no information in the source about any litigation.

The absence of litigation in the source does not mean none exists. Perhaps litigation occurred but is not recorded in the AD text. The deep dive cannot invent. Instead, it can note that the AD gives no hint of challenge. Given the safety-critical nature of the issue (engine shutdown), it is likely that operators accepted the AD without formal legal challenge. Moreover, the cost of litigation relative to the cost of compliance likely reduces the incentive to sue.

One could also consider that the AD references the FAA, which has its own enforcement and litigation history. FAA AD 2001-14-06 and AD 2005-10-11 might have been subject to petitions for review in US courts, but that is outside the scope of this Australian directive.

In short, no litigation history is disclosed by the source. The deep dive should honestly state that the text does not reference any cases, and that the directive appears to have been implemented without legal challenge, though that may reflect the limited practical recourse for operators.

Several aspects of this AD can trap unwary operators or maintenance organisations.

First, the compliance times in Requirement 3 are contingent on inspection history, but the effective dates are historical. The AD became effective 24 November 2005, but the compliance clock for the modification starts from the effective date of Amendment 1 (4 August 2005). For an operator coming across this AD today, it is critical to understand that the deadlines are long past. The AD does not re-set compliance; it imposes a one-time modification deadline that has already elapsed. Any aircraft that has not been modified is now in a state of continuous non-compliance, and the only way to rectify is to perform the modification immediately and possibly apply for retroactive AMOC or enforcement discretion.

Second, the definition of detailed visual inspection may be more onerous than typical routine inspections. The definition explicitly allows the use of mirrors and magnifying lenses and requires surface cleaning and elaborate access procedures "as may be required." That phrase gives discretion to the inspector but also imposes a legal standard. An inspector who does not use mirrors when necessary could be performing an inadequate inspection, exposing the operator to liability. The operator should ensure that the inspection is documented with sufficient detail to demonstrate compliance with the definition.

Third, the AD says that modifications accomplished before the effective date of Amendment 2 in accordance with earlier revisions of the service bulletin are acceptable. But the operator must have records proving which revision was used. If the records are missing or ambiguous, the operator may need to re-accomplish the modification to be sure. This is a common due diligence problem when purchasing second-hand aircraft.

Fourth, the note that "FAA AD 2001-14-06 Amdt 39-12316 and AD 2005-10-11 Amdt 39-14088 refer" could mislead an operator into thinking FAA compliance is sufficient. It is not. The Australian AD must be complied with separately unless CASA has specifically accepted FAA compliance. Cross-border lessors and operators often assume equivalence, but the different effective dates mean different compliance deadlines.

Fifth, the AD requires repair of discrepancies found during the inspection "in accordance with SL 737-SL-24-138." That service letter is not reproduced in the AD. The operator must obtain it from Boeing. If the operator does not have access (e.g., if they are a small private owner), they must seek it from Boeing or from maintenance providers. Similarly, the service bulletin for the modification must be procured. The cost of obtaining these documents may be additional.

Sixth, Requirement 4 says: "Carry out any necessary corrective action identified during the Requirement 3 modification in accordance with the service bulletin." This implies that the modification itself may reveal further issues (e.g., corrosion behind the connectors). The operator must have resources ready for unscheduled repairs. These repairs must be done before further flight. This can cause unexpected downtime and expense.

Seventh, the compliance status of aircraft that were stored or out of service during the compliance windows is not addressed. If an aircraft was parked from 2001 to 2006 without any inspections, the compliance history is blank. The operator would need to determine whether the AD clock was running; generally, an AD applies irrespective of storage. The aircraft must be brought into compliance before returning to service, even if the original deadlines have passed.

Eighth, the AD's signature by a "Delegate of the Civil Aviation Safety Authority" on 13 October 2005, with effective date 24 November 2005. There is a gap of 42 days. An operator could have commenced modification work after 13 October but before 24 November and should ensure that the modification was to the accepted revisions. The effective date is when the AD becomes legally binding; no obligation before that date. However, if an operator did the modification on 1 November 2005, they would need to verify that it meets the accepted revision (if using Rev 2, fine; if using an unofficial approach, it would not comply as of 24 November unless retroactive).

Ninth, the AD applies to "All Model 737-300, -400 and -500 series aeroplanes." It does not exclude military, private, or cargo operations. Any operator of these models must comply, whether commercial or non-commercial.

Lastly, note that the AD is part of a series (AD/B737/161). There may be other ADs applying to same aircraft that have overlapping compliance actions. Operators must manage the entire AD status, not just this one. A missed AD could ground the aircraft even if this one is fine.

Compliance with AD/B737/161 Amdt 2 requires a structured approach integrated into the aircraft's maintenance program. The steps are based on the AD's text and general regulatory expectations.

Step 1: Confirm applicability. The AD applies to Boeing 737-300, -400, and -500 series. Check the aircraft's registration and type certificate. If the aircraft is one of these, proceed. If not, no further action.

Step 2: Gather required documentation: Boeing Service Letter 737-SL-24-138 dated 24 May 1999; Boeing Special Attention Service Bulletin 737-28-1196, Revision 3 dated 1 April 2004, and (if applicable) earlier revisions (original, Rev 1, Rev 2). Also obtain the aircraft's AD compliance history to determine what has already been done.

Step 3: Determine compliance status for each of the four requirements.

• Check if Requirement 3 (modification) has been accomplished. If yes, verify which service bulletin revision was used and that it is one of the accepted revisions. Also confirm that any corrective action from the modification (Requirement 4) was completed. If the modification is done and accepted, no further inspection is needed. Record this in the AD compliance log.

• If Requirement 3 has not been accomplished, the aircraft is non-compliant. The operator must schedule the modification immediately. Prioritise it because the aircraft cannot lawfully be operated until Requirement 3 is accomplished. However, note that Requirement 1 and 2 also apply until the modification is done. So before flying, the aircraft must have a current Requirement 1 inspection (within the past 24 months) and any discrepancies from that inspection must be repaired. Given the historical deadlines, the operator should probably perform a fresh detailed visual inspection as part of the pre-modification work, even if the last inspection was within 24 months, because the inspection must also confirm condition before modification per the service bulletin.

Step 4: If Requirement 3 is not yet done and the aircraft has never had a Requirement 1 inspection, the operator must perform the detailed visual inspection as defined in the AD. This should be done by a qualified licensed aircraft maintenance engineer (LAME) or under a Part 145 organisation. Use the criteria from the Service Letter. Document all findings. If discrepancies are found, repair them per the Service Letter before further flight. The inspection is terminating once the modification is done, so the operator can choose to combine the inspection with the modification work.

Step 5: Accomplish the modification. This requires purchasing the modification kit (if any) and following the Accomplishment Instructions of the Service Bulletin. The work can be done by an approved maintenance organisation. Ensure that the modification is recorded in the aircraft's logbook, referencing the specific service bulletin revision used. If using an earlier revision, confirm the AD acceptance. After modification, carry out any necessary corrective action identified (e.g., torquing, sealant, additional repairs) before further flight.

Step 6: Update the aircraft's continuing airworthiness records. This includes:

• AD compliance schedule: note that Requirement 1 repetitive inspections are no longer needed because terminating action has been accomplished.
• A signed release to service (Certificate of Release to Service) in accordance with Part 43 or Part 145.
• If the modification was done using an earlier revision, note that it is accepted as per the AD.

Step 7: If the aircraft is operated under an air operator's certificate (AOC), the operator's maintenance control manual should include a procedure for tracking AD compliance. The AD should be added to the maintenance program's AD list with a notation that the modification, once accomplished, eliminates the need for further inspections.

Step 8: If the operator cannot comply within the required timeframe (which is already overdue), they should not fly the aircraft. They must apply to CASA for an alternative means of compliance or a time extension. Given that the AD's deadlines were set in 2005, CASA may require evidence of why compliance was not achieved earlier. While CASA has discretion, it is unlikely to grant a blanket extension; they may require immediate grounding until the modification is done.

Step 9: For a fleet of multiple 737 Classics, prioritise aircraft that are currently active. Use the AD's grandfathering provisions to avoid re-doing work. But if an aircraft has no records of prior modification, assume it is non-compliant and treat it as overdue.

Step 10: Finally, review the AD for any cross-references to FAA ADs. If the aircraft is also maintained under FAA rules, coordinate with the FAA AD compliance schedule to avoid duplication but ensure the stricter requirements are met.

Cost considerations: budget for labour, parts, and downtime. The modification likely requires wiring work in the main wheel well. The AD's costs are borne entirely by the operator; no government support. For a small owner of a single 737-300, the cost could be significant relative to the aircraft's value. However, non-compliance carries enforcement risks and safety risks.

In summary, the most direct path to compliance for any affected aircraft that has not yet been modified is: do a detailed inspection, repair any discrepancies, then perform the modification per the service bulletin, and document everything. After that, the AD is satisfied and requires no further action.