AD/ATR 42/23 - Rear Pressure Bulkhead Area - Electrical Wire Chafing

The Directive is built around these foundational concepts: targeted inspection, mandatory reporting, conditional repair, mandatory modification, and the acceptability of EASA-approved revisions of the referenced service bulletins. Each concept is expressed in operational terms.

Targeted inspection: The Directive narrows the inspection to "the electrical routing in the rear baggage zone" and references SB ATR42-92-0015 for the precise accomplishment instructions. The aim is to detect "chafing and/or contact between bundles of cables and the airframe structure" as found in the investigation. The inspection is one-time only (Requirement 1), not recurring.

Mandatory reporting: The operator has to report findings. If damage is found, the operator must "contact and report the finding(s) to ATR (by means of the accomplishment form enclosed in SB ATR42-92-0015)" to obtain an "approved repair solution" (Requirement 2.a). If no damage is found, the operator must still report the inspection result using the same enclosed form (Requirement 3.a). Reporting deadlines are explicit: within 15 days for Requirement 3.a; for damage found, reporting and repair are conditions precedent to further flight (Requirement 2.a requires reporting and obtaining an approved repair solution "before further flight" after inspection).

Conditional repair and modification: The Directive distinguishes immediate repair obligations (if damage is present) from subsequent routing modifications. If damage is found, repair must be effected in accordance with ATR instructions (Requirement 2.a) and the routing and protection must be modified per SB ATR42-92-0018 before further flight after repairs (Requirement 2.b). If no damage is found, the structural routing and protection modification is still required but with a different compliance window: within 5 000 hours TIS after the effective date (Requirement 3.b).

Use of approved service information: The Directive requires compliance with two specific SBs (ATR42-92-0015 and ATR42-92-0018), both dated 11 February 2008, and explicitly allows later revisions of those SBs "approved by the European Aviation Safety Agency (EASA)" for compliance. The AD also "refers" to EASA AD 2008-0062, showing direct regulatory cross-reference and reliance on EASA’s determinations.

Safety rationale embedded in the Directive: The background explains the operational safety concern discovered by EASA , spurious warnings and cautions that prevented autopilot use , and traces the root cause to chafed wiring in the rear baggage zone that affected "rudder trim, pitch trim and stick pusher control wires", which "might lead to the loss of fail safe criteria for those critical functions." The Directive operationalises this safety concern into inspections, mandated reporting, repairs, and routing/protection modifications.

Exemptions and applicability corner cases are provided in the Applicability and Notes: certain models and serial-number ranges are excluded where ATR modification Mod 00639 or Mod 05780 have been embodied, or where SB ATR42-92-0018 was previously embodied while in service. These Notes identify which production aircraft had the modification factory-incorporated and the MSN numbers where that occurred.

The Directive directly affects operators of ATR 42 series aeroplanes meeting the specified applicability criteria. The applicability table sets out the models and the conditions:

• ATR 42-200, 42-300 and 42-320 that have embodied ATR modification (Mod) 00639, except aircraft which have received ATR Service Bulletin ATR42-92-0018 whilst in service.
• ATR 42-400 and 42-500, except aeroplanes that have embodied ATR Mod 05780 during production or ATR SB ATR42-92-0018 whilst in service.

The Notes in the Applicability section identify production incorporation points: Mod 00639 was embodied on Manufacturer Serial Number (MSN) 109 and MSN 113 and factory-incorporated from MSN 116; Mod 05780 is factory-incorporated on ATR 42-500 from MSN 667. Operators must therefore determine their aircraft’s MSN and mod/SB history to establish whether their aeroplane falls within the Directive’s scope. An operator that has already implemented SB ATR42-92-0018 while in service appears to be excluded from the mandatory work.

Maintenance providers and certificated repair organisations are secondarily affected because the required actions reference specific accomplishment instructions in SB ATR42-92-0015 (inspection) and SB ATR42-92-0018 (modification). The Directive requires the use of those SBs (and later EASA-approved revisions), which sets the technical standard that maintenance providers must follow.

ATR (the manufacturer) is a party that must receive reports and provide approved repair solutions when damage is found. The Directive requires operators to "contact and report the finding(s) to ATR (by means of the accomplishment form enclosed in SB ATR42-92-0015) to obtain an approved repair solution" (Requirement 2.a) and to report inspection results even when no damage is found (Requirement 3.a). That creates an ongoing information flow from operators to the OEM.

Regulatory authorities are implicated by reference: the Civil Aviation Safety Authority issued the AD (signed by a Delegate), and the Directive accepts EASA-approved later revisions of the SBs, and refers to EASA AD 2008-0062. The Directive therefore sits in a transnational compliance landscape between national (CASA) and European (EASA) regulatory instruments. However, the Directive itself sets the specific mandated actions, deadlines, and reporting channels.

Costs and who pays: The Directive does not provide funding; the operational and maintenance costs,time for inspection (within 550 hours TIS), potential immediate repairs (before further flight if damage is found), and the required routing and protection modification (before further flight after repairs or within 5 000 hours TIS if no damage),fall on the aircraft operator or the entity responsible for maintaining the aircraft under their operating certificate, because those parties are obliged to perform the work and file the forms specified by the SBs.

Duties imposed by the Directive are precise and conditional. The principal duties are:

• Perform a one-time inspection: Requirement 1 orders a one-time inspection "in accordance with the accomplishment instructions of SB ATR42-92-0015, dated 11 February 2008" of the electrical routing in the rear baggage zone, to be done "within the next 550 hours time in service (TIS) after the effective date of this Directive."

• Report findings to ATR: Requirement 2.a and Requirement 3.a require reporting to ATR "by means of the accomplishment form enclosed in SB ATR42-92-0015." If damage is found, the operator must report and "obtain an approved repair solution" and perform that repair per ATR instructions. If no damage is found, the operator must still report the inspection result within 15 days after inspection.

• Repair before further flight when damage is present: If the inspection reveals any damage ("chafing and/or contact between bundles of cables and the airframe structure"), Requirement 2.a requires contacting ATR and performing the approved repair, and sets a compliance condition: these repairs (and their related reporting) must be completed "before further flight after the Requirement 1 inspection."

• Modify electrical routing and wire-bundle protection: Both damage-found and no-damage scenarios require modification "in accordance with the accomplishment instruction of SB ATR42-92-0018, dated 11 February 2008." Where damage is found, this modification must be done "before further flight after any repairs accomplished in accordance with Requirement 2.a." Where no damage exists, the modification deadline is "within 5 000 hours TIS after the effective date of this Directive."

• Use of later EASA-approved SB revisions: The Directive gives operators the right to comply using "later revisions of SB ATR42-92-0015 and SB ATR42-92-0018 approved by the European Aviation Safety Agency (EASA)."

Rights implicit in the text are limited but clear: operators may use EASA-approved later revisions of the SBs; operators may obtain an "approved repair solution" from ATR when damage is found. The Directive prescribes the content and timing of reporting to ATR via the SB's enclosed accomplishment form.

Conditionality and sequencing: The Directive imposes strict sequencing for unsafe findings , reporting and repair must occur prior to further flight (Requirement 2.a and 2.b). For no-damage findings, the only immediate obligation is the reporting within 15 days; the modification can be deferred to the longer 5 000 hours TIS window.

Specificity of technical source materials: The Directive does not specify alternative methods of compliance; it requires the accomplishment instructions of the stated SBs or later revisions approved by EASA. That restricts the technical route operators must follow unless ATR or EASA provide an alternative compliance mechanism.

Operational timing details: Exact compliance time windows are stipulated: Requirement 1 within 550 hours TIS; Requirement 3.a within 15 days after inspection; Requirement 3.b within 5 000 hours TIS after the effective date; repairs required by Requirement 2.a and the modification required by Requirement 2.b both must be completed "before further flight" in the relevant situations. The Directive, therefore, links safety-critical repairs to the "before further flight" standard, raising the operational imperative that any detected damage be rectified prior to a subsequent flight.

The Directive text does not specify penalties, fines, or enforcement mechanisms within its own wording. The document prescribes mandatory actions, compliance windows, and reporting obligations, but it contains no express penalty clauses, civil sanctions, or criminal sanctions in the AD itself. It states the effective date ("This Airworthiness Directive becomes effective on 18 April 2008") and prescribes the technical steps that must be taken, but does not set out enforcement procedures or consequences for non-compliance within the text provided.

Because the Directive was issued by the Civil Aviation Safety Authority (CASA) , indicated by the signature block "James Coyne, Delegate of the Civil Aviation Safety Authority" , the AD is framed as a regulatory instrument with mandatory requirements. The Directive’s enforceability and the legal consequences of non-compliance are not articulated in the Directive’s text; they would typically arise from the regulator’s broader statutory powers, but those statutory enforcement provisions are not contained in this instrument and are therefore outside the scope of the AD's explicit wording.

The Directive makes compliance mandatory by prescribing actions and deadlines (for example, "Within the next 550 hours time in service (TIS) after the effective date of this Directive" for Requirement 1, and "before further flight" for repairs and certain modifications). The AD also mandates the route for technical compliance (specific SBs or later EASA-approved revisions) and requires reporting to the OEM using the accomplishment form. The absence of in-Directive penalty language means the text alone does not describe how or by whom enforcement actions (if any) will be carried out, or what penalties will be applied for failure to comply. Practitioners or operators wanting clarity on sanctioning or enforcement outcomes would need to consult the regulator’s general enforcement framework and applicable aviation safety legislation, which are not reproduced in this Directive.

Finally, the Directive references EASA AD 2008-0062 and notes acceptance of EASA-approved later SB revisions; this cross-reference suggests that EASA's parallel or antecedent action informed the CASA AD, but neither EASA AD nor CASA’s broader enforcement arrangements are included in the text of this Directive.

The AD explicitly interacts with other regulatory instruments and service information, but the text confines itself to a small set of cross-references. The Directive states that "The use of later revisions of SB ATR42-92-0015 and SB ATR42-92-0018 approved by the European Aviation Safety Agency (EASA) is acceptable for compliance with the requirements of this Directive." That creates a direct, limited legal-technical linkage: the operator may rely on EASA-approved revisions of the specified service bulletins to satisfy the Directive.

The AD also contains the line "Note 3: EASA AD 2008-0062 refers." This signals that the CASA AD reflects or mirrors action taken by EASA in AD 2008-0062; the CASA Directive thus situates itself in a regulatory conversation with EASA. The Directive does not reproduce the EASA AD text, nor does it spell out how conflicts between CASA and EASA instruments are to be resolved, but it endorses EASA-approved SB revisions as acceptable means of compliance. Practically, that means operators subject to both regimes can seek technical conformity via EASA-approved service information.

Service bulletins are incorporated by reference: SB ATR42-92-0015 governs the inspection instructions and includes an accomplishment form for reporting; SB ATR42-92-0018 governs the routing and wire-bundle protection modification. The Directive requires compliance with those SBs "dated 11 February 2008" or later EASA-approved revisions. The incorporation of SBs makes the AD depend on specific technical documents produced by the manufacturer; compliance therefore requires access to, and execution in accordance with, those SBs.

The Applicability section references ATR modifications Mod 00639 and Mod 05780 and the prior embodiment of SB ATR42-92-0018 "whilst in service." Those references interact with operators’ maintenance records and modification histories. Whether an aircraft is within the scope of the Directive depends on whether those mods were embodied or the SB had been executed. Thus, record-keeping and conformity with prior service actions are legally significant to determine whether the AD imposes new duties.

No other statutory instruments, enforcement statutes, or regulatory acts are reproduced or referenced in the AD. The document’s silence on enforcement mechanisms or penalties means interaction with general aviation enforcement law and administrative procedures is not explicitly laid out here. The Directive’s reliance on EASA-approved SB revisions, reference to an EASA AD, and incorporation of manufacturer SBs are the only cross-jurisdictional or cross-instrument interactions spelled out within the text.

The Directive itself contains a limited internal history relating to service information dates, modification embodiment, and cross-references. The history and amendment-relevant items within the text are:

• Service Bulletin dates: The required SBs are SB ATR42-92-0015 and SB ATR42-92-0018, both dated 11 February 2008. The Directive authorises later revisions of these SBs for compliance only if they are "approved by the European Aviation Safety Agency (EASA)."

• Prior incorporation notes: The Applicability notes describe when certain ATR modifications were embodied in production aircraft. Note 1 states that "Mod 00639 has been embodied on production aircraft Manufacturer Serial Number (MSN) 109 and MSN 113 and was factory-incorporated from MSN 116." Note 2 states that "Mod 05780 is now factory-incorporated on ATR 42-500 from MSN 667." These Notes are not amendments to the AD, but they record production incorporation points that affect whether particular aircraft are within the AD’s scope.

• Reference to EASA AD: The Directive contains “Note 3: EASA AD 2008-0062 refers.” That indicates an antecedent or parallel EASA action which likely informed this CASA AD. The Directive does not recite the text of the EASA AD or provide further detail on amendments to that EASA AD.

• Issue and effective dates: The document is signed "James Coyne, Delegate of the Civil Aviation Safety Authority" and dated 15 April 2008. The AD states it "becomes effective on 18 April 2008." No subsequent amendments, revocations, or supersessions are listed in the text provided.

• Accepting later SB revisions: The phrase allowing the use of later revisions of the named SBs provided they are EASA-approved is the only pathway the Directive offers for changing the technical means of compliance without amending the AD itself. It effectively delegates approval of later SB revisions to EASA rather than requiring CASA to reissue or amend the AD to accept updated SBs.

Because the source material provided does not include any later ADs, amendment notices, or revocation statements, no further amendment history can be claimed from this text. The Directive, as reproduced, is a single-action instrument dated April 2008 with embedded references to the SBs and EASA AD.

The Directive contains no litigation history, case names, or references to judicial or administrative proceedings. The text does not cite any court judgments, appeal decisions, or dispute outcomes. It presents an administrative safety action taken by the Civil Aviation Safety Authority, relying on manufacturer's service bulletins and EASA references, but it does not describe any challenges to the AD or any legal proceedings arising from it.

Because the Directive does not include any litigation detail, practitioners seeking to know whether this AD has been the subject of legal challenge, stays, or interpretations must consult external sources such as regulatory adjudications, court archives, or CASA/EASA public records. The AD itself is silent on litigation, and no cases are named in the provided text.

Operators and maintenance planners should note several traps and detail-sensitive elements embedded in the Directive’s text that can create operational or compliance risk if overlooked:

• Applicability hinges on modifications and historical SB embodiment: Whether a particular aeroplane is within scope depends on whether Mod 00639 or Mod 05780 was embodied or whether SB ATR42-92-0018 was already executed "whilst in service." The Notes identify specific MSNs where factory incorporation occurred (Mod 00639 on MSN 109, 113, and from MSN 116; Mod 05780 from MSN 667 on ATR 42-500). Operators must check accurate MSN and maintenance/modification records to avoid incorrectly assuming exemption.

• Single inspection but mandatory modification regardless: Although Requirement 1 is a "one-time inspection," the Directive still mandates the routing and protection modification (SB ATR42-92-0018) even if no damage is found, albeit with a longer compliance window (Requirement 3.b within 5 000 hours TIS). Operators may misread the AD as allowing only an inspection; the AD requires both inspection and subsequent modification whether or not damage is detected.

• Tight timeline for repair if damage is found: The AD requires that if "ANY damage is found" during the inspection, the operator must both report to ATR to obtain an approved repair solution and "perform the repair in accordance with the ATR instructions," and the repair must be done "before further flight after the Requirement 1 inspection." Subsequently the routing modification per SB ATR42-92-0018 must also be completed "before further flight after any repairs." This creates an immediate grounding risk if damage is found and the approved repair cannot be executed promptly.

• Mandatory reporting even when clear: If no damage is found, requirement 3.a requires reporting "to ATR the result of inspection by using the form enclosed in SB ATR42-92-0015" within 15 days after the inspection. Failure to file this report within 15 days would be a non-obvious compliance lapse.

• The AD prescribes specific SBs and accepts only EASA-approved later revisions: The instruction to perform inspections and modifications "in accordance with the accomplishment instructions" of the specified SBs means that operators cannot substitute alternative procedures without EASA approval of the SB revision. This limits flexibility and may require coordination with ATR or EASA to adopt alternative repair or modification schemes.

• Critical systems implicated: The background describes the affected wiring as including "rudder trim, pitch trim and stick pusher control wires," and states that damage "might lead to the loss of fail safe criteria for those critical functions." The operational impact of undetected or unrepaired damage could therefore be immediate and safety critical, accounting for the "before further flight" constraint. Maintenance planners should account for the risk of aircraft grounding if damage is discovered.

• Timing metrics use both hours TIS and calendar-like deadlines: Requirement 1 uses "within the next 550 hours time in service (TIS) after the effective date," while Requirement 3.a uses a 15-day deadline from the inspection date. Requirement 3.b uses 5 000 hours TIS after the effective date. Operators must track both TIS thresholds and calendar days to ensure compliance.

• The AD does not include enforcement language: The Directive does not state what sanctions follow non-compliance; while this does not excuse failure to comply, it means that operators will need to consult CASA’s broader enforcement rules to understand remedial or punitive consequences.

• Reporting pathway to OEM: The reporting requirement is to ATR and is to be done "by means of the accomplishment form enclosed in SB ATR42-92-0015." Operators lacking the SB’s accomplishment form or misfiling the form may inadvertently fail to comply with the reporting obligation. Ensure the SB and its enclosed form are obtained and used.

• Cross-border SB revisions: The AD accepts later SB revisions only if EASA-approved. An operator using an SB revision approved only by another authority (but not EASA) would not have that revision explicitly accepted by this AD unless EASA approves it. This is relevant for multinational operators or maintenance providers working under non-EASA approvals.

Compliance steps flow directly from the AD’s Requirements and specified service bulletins. Below is a practical checklist and sequencing consistent with the Directive’s instructions:

1. Scope determination:

   • Confirm whether the aeroplane is covered by the Applicability table. Check model, MSN, and whether Mod 00639 or Mod 05780 was embodied or SB ATR42-92-0018 was previously executed while in service. The Notes provide specific MSNs: Mod 00639 on MSN 109 and 113 and factory-incorporated from MSN 116; Mod 05780 factory-incorporated on ATR 42-500 from MSN 667.

2. Obtain technical materials:

   • Acquire SB ATR42-92-0015 (inspection SB) and SB ATR42-92-0018 (modification SB), both dated 11 February 2008. If relying on later revisions, confirm those revisions are "approved by the European Aviation Safety Agency (EASA)" as the Directive permits EASA-approved later revisions for compliance.

3. Schedule the one-time inspection:

   • Plan and perform the required one-time inspection of the electrical routing in the rear baggage zone "in accordance with the accomplishment instructions of SB ATR42-92-0015" within 550 hours TIS after the AD’s effective date (the AD became effective 18 April 2008).

4. During inspection , if damage is found:

   • If the inspection discovers "ANY damage" (chafing and/or contact between cable bundles and structure), immediately complete the accomplishment form included with SB ATR42-92-0015 and "contact and report the finding(s) to ATR" to obtain an approved repair solution (Requirement 2.a).
   • Obtain ATR’s approved repair instructions and perform the repair "in accordance with the ATR instructions." These repairs must be completed "before further flight after the Requirement 1 inspection."
   • After repairs, modify the electrical routing and wire-bundle protection per SB ATR42-92-0018. The AD mandates this modification "before further flight after any repairs accomplished in accordance with Requirement 2.a."

5. During inspection , if no damage is found:

   • If no damage is found, still complete and submit the accomplishment form in SB ATR42-92-0015 to ATR reporting the inspection result, within 15 days after the inspection (Requirement 3.a).
   • Plan and carry out the routing and wire-bundle protection modification per SB ATR42-92-0018 within 5 000 hours TIS after the effective date of the AD (Requirement 3.b).

6. Documentation and record-keeping:

   • Retain copies of the inspection records, the completed accomplishment form, ATR’s approved repair instructions (if any), and evidence of the SB ATR42-92-0018 modification being carried out. The AD’s compliance is procedure-driven and record-sensitive; the accomplishment form and SBs are the specified paperwork.

7. Technical conformity:

   • Ensure maintenance tasks are performed by personnel and organisations authorised to carry out work in accordance with the SBs and ATA/maintenance approvals as applicable. The AD prescribes specific service instructions as the technical standard.

8. If alternative methods are considered:

   • The AD does not provide an alternative method of compliance except by using later revisions of the named SBs approved by EASA. If an operator contemplates a different repair or modification technique, that would require ATR and likely EASA approval to be considered acceptable for compliance under this Directive.

9. Coordination with ATR:

   • Use the accomplishment form included in SB ATR42-92-0015 to report findings to ATR. If damage is identified, contact ATR to obtain the "approved repair solution" prior to repair work; do not proceed on an ad hoc basis without ATR’s approval in that circumstance.

10. Monitor EASA-approved revisions:

    • Since the AD allows use of later EASA-approved revisions of the SBs, monitor EASA approvals for any updated SB revisions that may provide refined procedures, clarifications, or expanded guidance that are acceptable for compliance.

11. Operational planning for possible grounding:

    • Because the AD requires repairs before further flight if damage is found, incorporate contingency planning for potential aircraft grounding and parts/maintenance lead times into scheduling to avoid unexpected service disruptions.

12. Compliance verification:

    • After performing inspections, repairs (if any), and the modification, ensure that records show compliance with the time windows specified in the AD: 550 hours TIS for the initial inspection, 15 days for reporting if no damage, "before further flight" for repairs/modifications when damage is found, and 5 000 hours TIS for modification if no damage is found.

Following these steps will address the technical and administrative obligations set out in AD/ATR 42/23. The Directive is prescriptive about the SBs to use and the reporting method; adherence to those elements, accurate record-keeping, and timely execution aligned to the Directive’s deadlines are the core compliance tasks.