AD/EMB-120/45 Amdt 1 - Stall Warning Computer

The AD rests on a small set of connected technical and regulatory concepts as expressed in the text. The first concept is a part-specific corrective action. The directive identifies the aircraft system at issue, the stall warning computer, and prescribes replacement with a defined improved unit, citing Embraer SB 120-27-0092 Revision 01 (29 December 2006) or a later ANAC-approved revision. The AD also makes a preparatory action a prerequisite, by requiring accomplishment of Embraer SB 120-27-0091 Revision 02 (29 September 2003) or later ANAC-approved revisions before installation of the improved units. These two SB references are the procedural anchors for the technical work the AD mandates.

The second concept is a prohibition on continued operation with specific hardware part numbers. Requirement 2 prohibits operation of EMB-120( ) aeroplanes with stall warning computers bearing P/N C-81806-1 Mod. A, C-81806-2 Mod. A or C-81806-3 installed after the stated compliance date. The AD thereby uses both a positive duty (replace pursuant to SB) and a negative duty (do not operate with identified P/N) to achieve the same safety objective.

The third concept is compliance timing and alignment. The AD preserves the original 36-month window for completing the replacement (Requirement 1) measured from 7 June 2007, and aligns the prohibition (Requirement 2) to that same effective window by extending its compliance date by 28 days. The text makes the alignment explicit: "This Amendment ... extends the compliance for Requirement 2 by 28 days to align with the Requirement 1 compliance date." The Amendment itself becomes effective 23 October 2008.

The fourth concept is inter-jurisdictional approval and traceability. The AD links required actions to Embraer service documentation, but conditions reliance on later SB revisions on approval by ANAC. It also cross-references ANAC AD 2007-03-03. The AD is framed as an instrument of CASA, with the signature of the CASA delegate, Charles Lenarcic, recorded on 11 September 2008.

Finally, the background concept ties the technical measures to empirical testing. The AD records icing tunnel tests undertaken under a multi-agency research programme and a subsequent flight-test assessment. The chain of evidence in the text links those tests to a finding that "stick shaker to stick pusher speed margins may drop below the minimum required by the applicable regulations in certain icing conditions," and that this reduction can materially increase crew workload in some flight phases. The AD therefore positions replacement of the stall warning computer as the corrective measure to address that identified degradant in stall-margin margins.

The AD applies expressly and exclusively to "All EMB-120( ) model aeroplanes." The applicability statement in the instrument is unqualified by registration, operator type, or region; by its wording, any operator of an EMB-120 model aeroplane that is subject to CASA's airworthiness directives must comply with the two requirements stated. The AD therefore places obligations on all entities that operate or maintain those aeroplanes in the CASA jurisdiction to carry out the specified maintenance interventions by the applicable dates.

Several decision and approval nodes affect who else is implicated. The AD requires that the Embraer Service Bulletins be followed "in accordance with" the embedded procedures, and it conditions later revisions of those SBs on approval by ANAC. That introduces a role for ANAC in authorising which later SB revisions may be relied on to meet the AD. The AD also references ANAC AD 2007-03-03, which suggests cross-reference with Brazilian regulatory action; the AD does not, however, set out any specific obligations for ANAC beyond that approval role.

From a practical standpoint, parties who will bear direct operational and administrative burdens include the aircraft operators who must schedule and fund the SB procedures, maintenance organisations executing the SBs, and parts suppliers or manufacturers providing the "new improved" stall warning computers. The AD identifies three prohibited part numbers (C-81806-1 Mod. A, C-81806-2 Mod. A, C-81806-3) that, after the compliance date, must not remain installed on affected aeroplanes. That places an onus on maintenance and supply chains to verify part numbers and ensure that inventories and installations conform to the AD by the relevant date.

The AD does not expressly allocate costs, nor does it list exemptions or special flight authorisations. It does not specify any administrative procedures for showing compliance within CASA's records, nor does it provide any alternative means of compliance in the text provided. The only procedural pathway referenced for compliance is completion of the specified Embraer SBs (SB 120-27-0091 Rev 02 and SB 120-27-0092 Rev 01) or later revisions approved by ANAC, and adherence to the stated timing.

Signatory attribution is to "Charles Lenarcic, Delegate of the Civil Aviation Safety Authority", with date 11 September 2008. That identifies the issuing authority within CASA but does not further elaborate on appeals, variances, or administrative review mechanisms in the AD text.

The AD imposes two primary duties on operators of EMB-120( ) aeroplanes.

First duty (Requirement 1): Operators must replace existing stall warning computers with the specified "new improved versions" in accordance with Embraer Service Bulletin 120-27-0092 Revision 01 dated 29 December 2006, or a later revision only if approved by ANAC. The AD places the procedural authority in the Embraer SBs, with the legal obligation to carry out those procedures within the prescribed timetable. The AD also contains a preparatory duty contained in Note 1: before installing the improved stall warning computers, operators must have accomplished the detailed instructions and procedures in Embraer SB No. 120-27-0091 Revision 02 dated 29 September 2003, or later revisions approved by ANAC. Thus the duty is sequential: accomplish SB 120-27-0091 Rev 02 (or approved later revision), then install per SB 120-27-0092 Rev 01 (or approved later revision).

Second duty (Requirement 2): Operators may not operate EMB-120( ) aircraft with stall warning computers bearing part numbers C-81806-1 Mod. A, C-81806-2 Mod. A or C-81806-3 installed after the stated compliance date (aligned to 7 June 2010). This is a negative duty, preventing the continued operation of aircraft with the identified hardware once the prohibition date is reached. The AD cross-references ANAC AD 2007-03-03 in Note 2, indicating coordination with ANAC's remedy.

Rights and decision-making nodes are limited within the text. The AD does not list any express rights of appeal, alternative means of compliance, or exemptions. The only mechanism for variation mentioned in the AD text is the approval pathway for later revisions of the specified Embraer service bulletins, which requires ANAC approval before an operator may rely upon them to satisfy the AD. The AD does not specify CASA processes for approving alternative procedures or granting extensions; the Amendment itself demonstrates a timing extension for Requirement 2 by 28 days to align both requirements, but that extension is expressed as part of the Amendment rather than an administrative discretion it confers to operators.

Operationally, the duties require operators to schedule the preparatory and replacement work within the maintenance programme and to ensure that prohibited P/N units are removed from service by the prohibition date. The AD's text does not address payment for parts or labour, nor does it state who supplies replacement units. It also does not specify any post-installation inspection, service-release paperwork, or record-keeping format; compliance is established by carrying out the SB procedures in the manner specified and within the timeframe stated.

The text of this Amendment does not set out any specific criminal or civil penalties, administrative fines, or enforcement procedures. The AD identifies the issuing authority as the Civil Aviation Safety Authority, with the instrument signed by a CASA delegate (Charles Lenarcic) dated 11 September 2008, and it sets effective and compliance dates. The AD therefore records mandatory technical actions and compliance timelines, but it contains no express sanctions, inspection mechanisms, or procedures for enforcement in the text provided.

Because the document is framed as an airworthiness directive issued by CASA, the instrument functions as a mandatory regulatory requirement within the issuing authority's oversight regime, but any specific enforcement consequences for non-compliance (for example, grounding, prohibition on operations, revocation of certificates, administrative penalties or prosecutions) are not described in the AD itself. The AD does not set out a process for CASA to verify compliance, nor does it prescribe the form of evidence that operators must file with CASA to demonstrate completion of the Embraer SBs. The AD also does not state any transitional inspection requirements during the compliance window.

The AD does make a clear operational constraint where it prohibits operation with specified P/Ns after the compliance date. That prohibition is an operationally meaningful constraint; the AD does not, however, in the text provided, specify the mechanism by which CASA would detect or act upon a breach, or the remedies it might pursue. The AD does reference ANAC AD 2007-03-03, which may contain parallel or complementary provisions in ANAC's jurisdiction, but that reference does not, in this instrument, supply any penalties or enforcement process.

In sum, the AD mandates actions and dates, but it does not enumerate penalties or the mechanics of enforcement inside the text provided. Practitioners should note that obligations created by an AD typically interact with broader regulatory frameworks that set out enforcement powers and compliance verification processes, but any such processes or sanctions are not expressed within the AD document supplied here.

Within the text of the Amendment, interaction is limited to references to service documentation and a foreign regulator's directive. The AD explicitly conditions permissible reliance on later revisions of the Embraer service bulletins on approval by ANAC, Brazil's civil aviation authority. The two specifically cited Embraer SBs are SB 120-27-0091 Revision 02 (29 September 2003) and SB 120-27-0092 Revision 01 (29 December 2006). The AD states that later revisions may be used only if they are "approved by Brazilian Agência Nacional de Aviação Civil (ANAC)". Thus the AD integrates CASA's Directive with ANAC's technical approval function, creating a cross-jurisdictional approval gate for any later SB revisions.

The AD also includes a Note 2 referencing "ANAC AD 2007-03-03", which the instrument does not reproduce but which it cites as relevant. That cross-reference indicates that the CASA directive is being aligned or coordinated with an ANAC airworthiness directive addressing the same technical issue. The AD does not, however, specify how conflicts or divergences between CASA's requirements and ANAC's measures would be resolved; it simply requires ANAC approval for later SB revisions and refers operators to the ANAC AD.

The background of the AD reports testing and research conducted "under a joint Embraer-NASA-FAA-CTA research program". Those agencies and organisations are named for context in the background, but the AD does not create obligations for them. The mention of FAA and NASA establishes a technical evidence base rather than a legal nexus. No other domestic statutes, regulations, or instruments are cited in the text as modified or disapplied by the AD.

Because the AD is an instrument of CASA and prescribes specific maintenance and operational constraints, it necessarily interacts with the general regulatory framework that governs aircraft airworthiness and maintenance in the CASA jurisdiction. The AD text itself does not recite those broader statutory or regulatory instruments, nor does it include procedural pathways for variances, alternative methods of compliance, or appeals; the only process detail it contains regarding alternatives is that any later revisions of the listed Embraer SBs require ANAC approval before they may be relied upon.

Practitioners should therefore read this AD in conjunction with the Embraer service bulletins it mandates and with ANAC's referenced AD, where relevant. The AD as supplied creates an operational prohibition tied to part numbers and a duty to follow specified SBs, and those duties will be operationalised within the operator's compliance framework and any broader regulatory obligations under CASA's aviation safety regime, although those broader instruments are not quoted or summarised in the AD text.

This instrument is labelled "AD/EMB-120/45 Amdt 1" and records an amendment to an original airworthiness directive. The AD states that "The original issue of this Directive became effective on 7 June 2007." The Amendment itself becomes effective on 23 October 2008, and is signed by the CASA delegate, Charles Lenarcic, with the date 11 September 2008.

The Amendment "continues the requirements of the original issue" but modifies the compliance timing for one of the requirements. Specifically, the Amendment "extends the compliance for Requirement 2 by 28 days to align with the Requirement 1 compliance date." The formal compliance statements included in the Amendment read: for Requirement 1, compliance "Remains unchanged as 'Within the next 36 calendar months after the effective date of the original issue of this Directive (7 June 2007)'." For Requirement 2, the compliance statement is "After 7 June 2010." The alignment therefore makes the prohibition on operating with certain P/N stall warning computers effective at essentially the same date when the replacement requirement must be completed.

The AD references a prior or related ANAC action, ANAC AD 2007-03-03. The Amendment does not elaborate on the original AD's procedural text beyond restating the core requirements and noting the timing alignment. There is no text in the Amendment indicating further later modifications beyond this alignment, nor does the Amendment provide a schedule of incremental changes; it simply restates and aligns requirements from the original directive.

The signature and dating sequence in the AD shows that the delegate signed on 11 September 2008 and the Amendment took effect on 23 October 2008. The original issue effective date is 7 June 2007. The text does not include additional amendments, rescissions, or a formal list of superseded paragraphs other than the reference to the original issue. The Amendment also contains duplicated headers and formatting lines in the supplied text, but those are typographical and do not alter the substantive requirements as described above.

No further amendment entries, later effective dates, or follow-on AD references are included in the supplied text. There is no schedule for review or expiry of the AD contained in the instrument; the compliance requirements are stated in absolute terms tied to the original issue date and to the stated parts and SBs.

The AD text contains no record of litigation, challenges, appeals, or judicial or administrative proceedings. There are no cases cited, no mention of disputes, and no record of review or objections in the instrument provided. The document records the regulatory action, the technical basis in the background, the required actions, the compliance dates, and the issuing delegate and dates, but contains no narrative or footnote referring to legal proceedings.

Because the supplied instrument is an airworthiness directive that prescribes technical corrective measures, it is common for such instruments to be administrative in nature. The absence of any litigation history in the AD means the text itself does not disclose whether any operator, manufacturer, or other party sought review, stayed the directive, or otherwise litigated the requirements. The AD does cross-reference ANAC AD 2007-03-03, but that is a regulatory cross-reference rather than a litigation reference.

Practitioners seeking to understand any legal challenges or precedents that might bear on the AD will not find them in this text. The AD provides no procedural summary of dispute resolution mechanisms or administrative appeal rights. If a party wished to challenge the AD, they would need to consult the broader statutory and administrative law framework governing CASA's actions, or locate any separate administrative or court records, none of which are captured in the document supplied here.

In short, the instrument, as presented, contains no litigation history and no case references. Any analysis that depends on precedent or prior judicial treatment of this specific AD must therefore seek sources beyond the text provided, because this AD does not record them.

The AD contains several specifics that can trip up operators or maintainers if overlooked.

1. Sequential service bulletin requirement. The AD requires that Embraer SB 120-27-0091 Revision 02 (29 September 2003) be accomplished before installing the improved stall warning computers per SB 120-27-0092 Revision 01 (29 December 2006). The order is mandatory: Note 1 states "Before installing the improved stall warning computers, the detailed instructions and procedures described in the Embraer SB No. 120-27-0091 Revision 02 ... must be accomplished." Overlooking this sequencing could result in non-compliance with the AD even if the replacement hardware is later installed.

2. ANAC approval gate for later SB revisions. The AD permits use of later revisions of the cited SBs only if they are "approved by Brazilian Agência Nacional de Aviação Civil (ANAC)." Operators who assume that any later Embraer SB revision automatically satisfies the AD will be incorrect unless that later revision has ANAC approval. The AD thus imposes a cross-jurisdictional approval requirement that must be verified before relying on a later SB revision.

3. Part-number prohibition tied to date alignment. Requirement 2 prohibits operation with stall warning computers bearing P/Ns C-81806-1 Mod. A, C-81806-2 Mod. A, and C-81806-3 after the compliance date. The Amendment aligns that prohibition with the 36-month window from the original AD effective date (7 June 2007), effectively setting the prohibition after 7 June 2010. Operators planning to operate aircraft up to the last minute must ensure that the banned P/N units are removed by that date. The AD states the alignment was achieved by extending Requirement 2 by 28 days, so operators should not rely on any earlier dates from the original issue.

4. No specified administrative compliance process in the AD text. The AD mandates the technical tasks (SBs) and the dates, but it does not specify the documentation, forms, or certification that CASA will require to evidence compliance. Operators should not assume any particular paperwork is optional, but should prepare maintenance records and a verifiable trail that SB procedures were completed in the sequence and to the revisions approved by ANAC.

5. No penalty language present. The AD does not set out penalties or enforcement mechanisms within its text. That absence does not mean non-compliance has no consequence; it simply means the AD itself does not enumerate enforcement steps. Operators should be cautious not to assume the regulatory effect is merely advisory.

6. Cross-reference to ANAC AD 2007-03-03. The AD refers to ANAC AD 2007-03-03 in Note 2. Operators who have maintenance or compliance programmes that operate across jurisdictions (for example, in Brazil and in the CASA state) need to review that ANAC AD to ensure alignment. Failing to reconcile differences in timing, parts acceptance, or required procedures between the two directives could create compliance risk.

7. Effective and compliance date distinctions. The Amendment is effective 23 October 2008, but the compliance deadlines are tethered to the original issue date (7 June 2007). Misreading which date controls could cause operators to miss the actual compliance windows. Requirement 1 must be completed within 36 calendar months of 7 June 2007; Requirement 2 becomes effective after 7 June 2010.

8. Scope limitation to EMB-120( ) model aeroplanes. The applicability line is unqualified but limited to the EMB-120 model. Maintenance organisations servicing multiple types must ensure this AD is applied only to the covered model and not erroneously imposed on other types.

The AD prescribes a concise sequence of actions and dates. The steps below reflect the required actions as stated in the instrument.

1. Confirm applicability. Determine whether the aircraft in question is an EMB-120( ) model aeroplane. The AD applies to "All EMB-120( ) model aeroplanes."

2. Accomplish SB 120-27-0091 Revision 02 before installation. Note 1 requires operators to accomplish the detailed instructions and procedures in Embraer SB No. 120-27-0091 Revision 02 dated 29 September 2003, or a later revision only if that later revision is approved by ANAC, before installing the improved stall warning computers. That preparatory step must be completed first.

3. Replace stall warning computers per SB 120-27-0092 Revision 01. Requirement 1 requires replacement of the current stall warning computers with the "new improved versions" in accordance with Embraer SB 120-27-0092 Revision 01 dated 29 December 2006, or a later revision approved by ANAC. Operators should ensure they use the SB revision that is either the specified revision or a later ANAC-approved revision, and that all procedural steps in the SB are followed.

4. Schedule within the compliance window. Requirement 1's compliance timeline is "within the next 36 calendar months after the effective date of the original issue of this Directive (7 June 2007)". That means the replacement work should be completed on or before about 7 June 2010. Organise maintenance planning to ensure the SB tasks are completed within that window.

5. Remove prohibited part numbers by the prohibition date. Requirement 2 forbids operation with stall warning computers bearing P/N C-81806-1 Mod. A, C-81806-2 Mod. A or C-81806-3 installed after the compliance date aligned to after 7 June 2010. Operators must ensure any aircraft still carrying those P/Ns are grounded for maintenance and the parts replaced before operating beyond that date.

6. Verify ANAC approvals for later SB revisions. If relying on any Embraer SB revision later than the specific ones quoted, confirm that ANAC has approved that later revision. The AD conditions later revisions on ANAC approval; without such approval, an operator cannot rely on that later revision to satisfy the AD.

7. Inventory and parts control. Check inventories and supplier documentation to ensure replacement stall warning computers are the "new improved versions" specified in SB 120-27-0092 Rev 01, and that no banned P/Ns remain installed after the prohibition date. Maintenance organisations should tag or segregate prohibited stock to avoid accidental installation.

8. Documentation and record-keeping. Although the AD text does not specify the format of compliance evidence, operators should prepare to document completion of SB 120-27-0091 Rev 02 and SB 120-27-0092 Rev 01 (or ANAC-approved later revisions), record part numbers fitted and removed, and maintain maintenance-release records consistent with their maintenance management system. Such records will be the primary evidence of compliance if queried by the authority.

9. Coordinate with ANAC and reference ANAC AD 2007-03-03. Review ANAC AD 2007-03-03 as referenced in Note 2, and consult ANAC for any approvals or guidance relating to later SB revisions. Ensure any cross-jurisdictional matters are clarified before relying on non-specified revisions.

10. Monitor for further ADs or amendments. This instrument is Amendment 1 to the original AD. Operators should monitor CASA communications for any subsequent amendments, rescissions, or new directives that might change the technical or timing requirements.

These steps derive from the AD's requirements, the service bulletin references, and the compliance timing specified. The AD does not supply forms, approval templates, or alternative means of compliance within the text provided; any administrative variations or formal approvals should be sought from CASA or ANAC using the respective agencies' processes, and operators should retain complete records of the SB work performed to demonstrate compliance with the AD's requirements.