AD/EMB-120/33 Amdt 1 - Aileron and Elevator Rotary Variable Inductive Transducer Bellcrank Assemblies

The AD rests on a small set of core concepts set out in the source text: (1) a defined applicability envelope based on airframe serial numbers and prior modifications; (2) a discrete hardware remedy (part number replacement) described by old and new part numbers and governed by a specific service bulletin; (3) a defined compliance window measured in hours time in service or triggered by a maintenance event; and (4) an amendment mechanism that broadens applicability and permits future revisions of the service bulletin where those revisions receive CTA approval.

Applicability: The AD is not universal to all EMB‑120s. It applies only to “All EMB‑120( ) models, serial numbers 120004 and 120006 through 120358 inclusive,” and then narrows that group to those aircraft “modified in accordance with any revision of Embraer Service Bulletins (SB) 120‑31‑0039, 120‑31‑0040, 120‑31‑0041 or 120‑31‑0042” (source text: Applicability). That creates a two‑part gate: the airframe serial number must fall in the stated range, and a prior modification history must show compliance with one of those SBs. Aircraft outside that set are not captured by the language of this AD as published.

Technical remedy: The technical fix is the replacement of RVIT bellcrank assemblies fitted with the older part numbers 123‑82549‑007 or 123‑82549‑009 with the newer part numbers 145‑51146‑001 or 145‑51147‑001 respectively, undertaken “in accordance with Embraer Service Bulletin 120‑31‑0046 Revision 1 dated 27 December 2002 or later revision approved by the Brazilian Centro Técnico Aeroespacial (CTA)” (source text: Requirement). The replacement is a one‑time modification to ensure the RVIT bellcrank no longer interferes with the head of the pin that attaches the RVIT support.

Compliance trigger and timeline: Compliance is required “Within the next 4000 hours time in service or at the first maintenance action that requires the disassembly of the aileron/elevator RVITs, whichever occurs first, after the effective date of the original issue of this Directive” (source text: Compliance). The AD therefore creates either a time‑in‑service limit (4,000 hours) or an event‑driven trigger (first disassembly), whichever comes earlier, measured from the original AD effective date (17 April 2003 as stated in Background).

Source of authority and cross‑references: The AD expressly links itself to Brazilian DAC directives (DAC AD 2001‑07‑01R2 and Errata dated 25 October 2005) and to Embraer service information. The amendment language permits compliance using future Embraer SB revisions provided those revisions are approved by the Brazilian CTA (source text: Requirement; Background).

Safety rationale: The Background explains the safety issue that motivated the AD: reports of aileron control range being limited due to interference between the aileron RVIT bellcrank and the head of the pin that attaches the RVIT support, and a determination that similar interference may occur with the elevator RVIT bellcrank limiting elevator control range (source text: Background). The directive is therefore preventative and targeted at eliminating that interference by changing the bellcrank geometry or fit via the specified replacement parts.

Administrative effect of the Amendment: The Amendment increases the applicability range and allows compliance with future revisions of the Embraer SB approved by CTA (source text: Background). The amendment’s effective date is stated as 22 December 2005 (source text: Compliance).

The AD affects a particular set of stakeholders explicitly named or implicitly implicated by the directive text. Those stakeholders include aircraft owners/operators of affected EMB‑120 serial numbers that have been modified by the prior Embraer SBs listed; maintenance organisations and certificated engineers who perform the work; parts suppliers and stockholders of the specific part numbers identified; and the regulator in terms of record keeping and oversight. Each is described below with reference to the source.

Aircraft owners/operators: The primary payers and duty‑holders under the AD are the operators or registrants of “All EMB‑120( ) models, serial numbers 120004 and 120006 through 120358 inclusive” that have been modified per any revision of Embraer SB 120‑31‑0039, 120‑31‑0040, 120‑31‑0041 or 120‑31‑0042 (source text: Applicability). Operators outside the serial number range, or those whose aircraft were not modified by those SBs, are not captured by the AD as written.

Maintenance organisations and approved persons: The required action is a hardware replacement “in accordance with Embraer Service Bulletin 120‑31‑0046 Revision 1 dated 27 December 2002 or later revision approved by the Brazilian Centro Técnico Aeroespacial (CTA)” (source text: Requirement). That indicates maintenance providers must have access to the Embraer service bulletin and the technical competence and approvals necessary to carry out the bellcrank replacement. The AD’s compliance trigger (“first maintenance action that requires the disassembly of the aileron/elevator RVITs”) specifically ties the obligation to actual maintenance events, making maintainers, scheduled maintenance planners and airworthiness managers central to timing and execution.

Parts manufacturers, distributors and supply chain: The directive identifies both old and new part numbers. Parties that supply or manage spares must be able to identify P/N 123‑82549‑007 and 123‑82549‑009 as those to be replaced, and supply P/N 145‑51146‑001 and 145‑51147‑001 as replacement parts (source text: Requirement). That affects inventory management, procurement timelines and potential stock‑holding costs for operators who elect to perform replacements at the earliest convenient maintenance opportunity.

Regulators: The instrument was issued by the Civil Aviation Safety Authority (signed by James Coyne, Delegate of CASA, 9 November 2005) and cross‑references Brazilian DAC AD material (source text: Note; signature). Regulators are affected insofar as they monitor compliance, record AD compliance in aircraft maintenance logs and accept the Embraer SB revisions approved by the Brazilian CTA as compliant means of meeting the AD.

Less directly affected: Operators of EMB‑120s outside the serial range, or those that have not had the earlier SB modifications, are not required by this AD to perform the replacement, but they must still be aware of related directives such as AD/EMB‑120/30 which the source identifies as related (source text: relation to AD/EMB‑120/30). Ancillary services such as maintenance planners, lease companies, and insurers will be interested in whether particular airframes are within scope because the AD creates work and potentially out‑of‑service time.

Who pays and who decides: The source allocates the action to operators (replace bellcranks on their affected aircraft) and places the method under the control of Embraer SB 120‑31‑0046 Rev 1 (or later CTA‑approved revision). Operators therefore bear the cash cost of parts, labour and any AOG or downtime; maintenance providers decide the scheduling and execution, subject to the constraint that the method must follow Embraer SB instructions or their later CTA‑approved equivalents.

The AD sets out a narrow duty regime and a limited set of operational options. The duty is a one‑time physical modification; the rights are procedural flexibility constrained by the service bulletin and CTA approval.

Primary duty: Operators must replace RVIT bellcranks that have part numbers P/N 123‑82549‑007 or 123‑82549‑009 “as applicable” with P/N 145‑51146‑001 or P/N 145‑51147‑001 respectively. The replacement is to be completed “in accordance with Embraer Service Bulletin 120‑31‑0046 Revision 1 dated 27 December 2002 or later revision approved by the Brazilian Centro Técnico Aeroespacial (CTA)” (source text: Requirement). The duty is explicit and limited to bellcranks with the listed part numbers fitted to aircraft within the stated applicability.

Timing duty: The compliance window is specified: “Within the next 4000 hours time in service or at the first maintenance action that requires the disassembly of the aileron/elevator RVITs, whichever occurs first, after the effective date of the original issue of this Directive” (source text: Compliance). This creates a dual trigger; operators must track hours time in service and scheduled maintenance that would disassemble the RVITs. The AD links the timing to the effective date of the original issue (original issue effective 17 April 2003 as noted in Background), not to the amendment effective date, which affects the computation of the 4,000 hours or the determination of whether a maintenance action is the “first” disassembly after the original issue date.

Method duty and approved means of compliance: The AD prescribes the Embraer service bulletin as the method of compliance. The source permits later service bulletin revisions, but only if those revisions are approved by the Brazilian CTA (source text: Requirement; Background). That creates a right to use a later revision, but constrains it to those revisions that have regulatory approval from the CTA.

Cross‑reference duty: The AD makes the link to DAC AD 2001‑07‑01R2 and its Errata (25 October 2005), which are “referred” in the Note (source text: Note). The reference functions as contextual duty: operators should be aware of the related Brazilian ADs as part of the compliance ecosystem. The AD also notes AD/EMB‑120/30 is related (source text: last table row), which required a one‑time inspection of the RVIT bellcrank assemblies; that previous directive may affect whether an aircraft has already had relevant inspections or modifications.

Rights and discretion: Operators have a limited procedural right to comply using later revisions of the Embraer SB where those later revisions are approved by the Brazilian CTA (source text: Requirement). The AD does not state other alternative methods of compliance (AMOCs) or waivers; it does not describe an application route for alternatives in the source text. The AD does not attach any expiry to the one‑time replacement obligation beyond the compliance triggers described.

Record‑keeping and proof of compliance: While the AD does not set out record‑keeping procedures in the provided text, the mechanics of the AD require operators to be able to demonstrate that the specified replacement has been performed in accordance with the Embraer SB or an approved later revision. The AD’s own text implies that proof will rest on maintenance records (identification of replaced P/Ns, reference to SB 120‑31‑0046 Rev 1 or a CTA‑approved later revision, and date of compliance relative to the 4,000‑hour or maintenance disassembly trigger). The source does not specify an inspector, certification statement, or endorsement format.

Scope limits and interpretive points: The duty only applies to those aircraft fitting the two‑part applicability test (serial number and prior SB modification). It is a one‑time modification rather than an ongoing inspection programme. The duty attaches to specific part numbers and to the aircraft maintenance condition that would require disassembly of the RVITs; operators with aircraft that have already had disassembly and replacement per the service bulletin prior to the AD may already be in compliance.

The AD text provided does not set out criminal, civil or administrative penalties or a detailed enforcement mechanism. The source is silent on fines, sanctions or the process the regulator will use to verify compliance. The instrument itself is an airworthiness directive issued by the Civil Aviation Safety Authority (signed by James Coyne, Delegate of CASA, on 9 November 2005), but it contains no explicit penalty schedule or enforcement steps within the printed directive text.

What the source does provide that is relevant to enforcement is the prescriptive compliance requirement (replacement of specified parts in accordance with Embraer SB 120‑31‑0046 Rev 1 or a later CTA‑approved revision) and the compliance timing (within 4,000 hours TIS or at the first maintenance action requiring RVIT disassembly, whichever first, measured from the original AD effective date) (source text: Requirement; Compliance). Those prescriptive elements create objective criteria that a regulator or inspector could use to assess whether an affected aircraft has complied: serial number and modification history; presence of old versus new P/Ns on RVIT bellcranks; evidence of compliance referencing the Embraer SB revision or CTA‑approved revision; and timing of work relative to the 4,000‑hour or maintenance event trigger.

Because the AD cross‑references the Brazilian DAC ADs (DAC AD 2001‑07‑01R2 and Errata dated 25 October 2005) and permits use of Embraer SB revisions approved by the Brazilian CTA, enforcement will involve consideration of those foreign regulatory approvals where an operator asserts compliance via a later SB revision (source text: Note; Requirement). The AD itself does not describe how CASA will treat CTA approvals or what documentary evidence is sufficient.

Absent penalty text, affected parties should assume the AD is mandatory and that non‑compliance may lead to regulatory action under the regulator’s general aviation safety enforcement framework rather than under any penalty provisions contained in the AD document. The AD does not identify which specific CASA statutory powers will be used nor the remedies the regulator might elect to pursue in the event of non‑compliance.

The AD explicitly cross‑references foreign regulatory material and related Australian ADs, and it ties compliance to manufacturer service information. The document shows three explicit interactions within the source text: (1) alignment with Embraer service bulletins; (2) reference to Brazilian DAC AD material; and (3) a stated relation to AD/EMB‑120/30. The AD does not discuss interaction with other domestic statutes, enforcement regimes, or administrative law processes.

Manufacturer service bulletins and foreign approval: The AD requires compliance “in accordance with Embraer Service Bulletin 120‑31‑0046 Revision 1 dated 27 December 2002 or later revision approved by the Brazilian Centro Técnico Aeroespacial (CTA)” (source text: Requirement). That links the domestic AD to manufacturer instructions and to the Brazilian regulator’s approval process. Where an operator seeks to comply via a later SB revision, the AD conditions acceptance on CTA approval of that revision, thereby embedding an international regulatory recognition step into the domestic AD compliance pathway.

Related airworthiness directives: The source notes that “DAC (Brazil) AD 2001‑07‑01R2 and Errata dated 25 October 2005 refer” (source text: Note). It also identifies AD/EMB‑120/30, which required a one‑time inspection of the RVIT bellcrank assemblies, as related (source text: related AD reference). These cross‑references suggest that compliance history under those ADs may be relevant to determining whether the aircraft already had inspection or modification work undertaken. They also indicate that the safety issue has been considered by multiple authorities, with the Brazilian authority playing a central role.

Timing and maintenance interaction: The compliance requirement is triggered by “the first maintenance action that requires the disassembly of the aileron/elevator RVITs” as an alternative to the 4,000‑hour TIS deadline (source text: Compliance). That makes the AD interact with operators’ maintenance planning and with maintenance standards that determine when RVIT disassembly is required. Operators will need to align their routine and unscheduled maintenance practices with the AD to avoid missing the first disassembly trigger or to use that maintenance event as an opportunity to complete the mandated replacement.

International regulatory recognition: By allowing later SB revisions only if approved by the Brazilian CTA, the AD creates a dependency on a foreign regulator’s approval process for domestic compliance pathways. The source does not explain how CASA will treat CTA approvals or whether CASA will independently approve an alternative SB revision; the AD text simply conditions later SB use on CTA approval (source text: Requirement).

Absence of expressed conflict resolution mechanism: The AD does not set out a mechanism for resolving conflicts between Embraer SB revisions, CTA approvals and CASA expectations. It does not provide for CASA approval of alternative methods of compliance in the provided text. Therefore, any operator seeking to rely on an alternate compliance route would need to seek guidance directly from the regulator or rely on established maintenance approval processes outside the AD document itself.

The source includes an amendment to the original AD and provides dates for the original AD and the amendment. The original issue of the Directive became effective on 17 April 2003 (source text: Background). This instrument is labelled “AD/EMB‑120/33 Amdt 1” and the Amendment is effective on 22 December 2005 (source text: Compliance: “This Amendment becomes effective on 22 December 2005.”). The signing date on the document is 9 November 2005 (source text: signature block).

What changed with the Amendment, according to the instrument: the Amendment “increases the applicability range but also allows compliance in accordance with futures revisions of the Embraer SB approved by the Brazilian CTA” (source text: Background). The Amendment preserved the original compliance timing formula (“Within the next 4000 hours time in service or at the first maintenance action that requires the disassembly of the aileron/elevator RVITs, whichever occurs first, after the effective date of the original issue of this Directive”) and did not alter that formula (source text: Compliance: “Remains unchanged as ‘Within the next 4000 hours…’”).

Cross‑references in amendment: The AD as amended continues to refer to Brazilian DAC AD 2001‑07‑01R2 and its Errata dated 25 October 2005 (source text: Note). The Amendment therefore retains the cross‑jurisdictional linkage to Brazilian regulatory actions.

Document history notes: The AD lists Embraer Service Bulletin 120‑31‑0046 Revision 1 dated 27 December 2002 as the prescriptive means of compliance, and permits the use of “later revision approved by the Brazilian Centro Técnico Aeroespacial (CTA)” (source text: Requirement). The Amendment explicitly authorised reliance on those future, CTA‑approved revisions.

Signature and authority: The AD is signed by James Coyne, Delegate of the Civil Aviation Safety Authority, on 9 November 2005 (source text: signature block). The Amendment became effective on 22 December 2005.

Limitations of the record: The source provides no further amendment entries, no schedule of versions beyond the Amendment 1, and no later amendments. The source does not state any subsequent revocation, superseding AD, or extension beyond the Amendment. Any further amendment history after 22 December 2005 is not contained in the provided source.

The provided source contains no litigation history. It does not reference any court proceedings, appeals, reviews, or legal challenges to the AD or to the underlying Embraer service bulletins. The document does not record administrative appeals, enforcement proceedings, or judicial outcomes. Where a reader seeks whether the AD has been subject to litigation, the source does not give that information.

Because there is no litigation narrative in the AD text, the document offers no precedent or case law to construe ambiguities in the AD’s language or to interpret the compliance triggers, nor does it set out contested factual histories or adjudicated disputes about the safety issue described. The AD records factual background (reports of interference between the RVIT bellcrank and the head of the pin, and the DAC determination that a similar interference could affect elevator travel) and regulatory action, but not litigation (source text: Background).

If a user requires a history of legal challenges, judicial interpretations, or administrative appeals relating to this AD, that information is not present in the source and would require independent research beyond the AD text provided here.

The source text contains several details and phrasing that may create traps or source‑interpretation issues for operators, maintenance providers and compliance officers. The following items are drawn directly from the AD text and its practical implications.

1. Applicability is twofold and explicit: serial number plus prior SB modification. The AD applies only to aircraft within the serial number range “120004 and 120006 through 120358 inclusive” and only those aircraft “modified in accordance with any revision of Embraer Service Bulletins (SB) 120‑31‑0039, 120‑31‑0040, 120‑31‑0041 or 120‑31‑0042” (source text: Applicability). An affected operator must check both the airframe serial number and the aircraft’s modification history to determine whether the AD applies. Misreading the AD as applying to all EMB‑120s would be an error.

2. Part number specificity matters. The AD mandates replacement only where the bellcranks have P/N 123‑82549‑007 or 123‑82549‑009; replacements are specified as P/N 145‑51146‑001 or 145‑51147‑001 respectively (source text: Requirement). If an aircraft already has different bellcrank P/Ns installed, the AD’s replacement requirement may not be triggered. Maintenance records and physical inspection must be used to confirm fitted P/Ns before performing work.

3. The compliance trigger is measured from the original AD effective date, not from the Amendment effective date. The AD’s compliance phrase refers to completion “after the effective date of the original issue of this Directive,” and the Background records that the original issue became effective on 17 April 2003 (source text: Compliance; Background). The Amendment effective date (22 December 2005) does not reset the 4,000‑hour clock. Operators must therefore calculate whether the 4,000 hours or the first disassembly occurred after the original issue effective date.

4. The “first maintenance action that requires the disassembly of the aileron/elevator RVITs” is an event trigger that may be easier to miss than a simple clock. An operator whose aircraft undergo RVIT disassembly for some unrelated maintenance task must treat that event as the compliance trigger unless the replacement is performed at that time. Failure to do so may result in an inadvertent breach of the compliance requirement; the AD does not provide for a grace period beyond the 4,000 hours or the first disassembly.

5. Use of later Embraer SB revisions is conditional on CTA approval. The AD allows compliance with “later revision approved by the Brazilian Centro Técnico Aeroespacial (CTA)” (source text: Requirement). Operators cannot unilaterally rely on later Embraer SB revisions unless those revisions bear CTA approval. That means an operator contemplating use of a later SB revision must verify CTA approval before assuming compliance under the AD.

6. Cross‑jurisdictional references may cause documentation gaps. The AD refers to DAC AD 2001‑07‑01R2 and Errata dated 25 October 2005 (source text: Note). Relying on foreign AD cross‑references to determine compliance status or equivalence requires careful documentation; the AD does not explain how CASA will accept documentation of DAC actions or CTA approvals.

7. Relationship to AD/EMB‑120/30: The AD notes the related AD/EMB‑120/30 required a one‑time inspection of the RVIT bellcrank assemblies (source text: related AD reference). If an operator performed work under AD/EMB‑120/30, that may or may not have already accomplished the required replacement , the AD does not state that AD/EMB‑120/30 satisfies this AD. Operators need to verify whether prior inspection work included the specific P/N replacement prescribed here and whether it was performed in accordance with Embraer SB 120‑31‑0046 Rev 1 or a CTA‑approved revision.

8. “As applicable” phrasing: The requirement to replace P/N 123‑82549‑007 or P/N 123‑82549‑009 is qualified by “as applicable,” which requires judgment about which bellcrank part number is fitted to which control surface. Operators must confirm the correct matching of old and new P/Ns to aileron and elevator assemblies.

9. The AD does not state an alternative method of compliance (AMOC) process in its text. If an operator has a different engineering solution or a different P/N that they believe resolves the interference issue, the AD text does not set out a route for approval of that alternative. Any such request would require engagement with the regulator beyond what the AD text provides.

10. Documentation and proof burden: Because the AD requires conformity with a specific service bulletin or a CTA‑approved later revision, operators must keep maintenance records that identify the SB revision used and the P/Ns removed and installed. The AD text itself does not specify the form of evidence required, but the requirement’s specificity means that deficient documentation could be problematic if an inspector later reviews compliance.

The AD provides a narrow set of steps and conditions for compliance; the following operational checklist translates the AD wording into practical actions grounded in the directive text. All references below are to the AD text provided.

1. Confirm applicability:

   • Verify the aircraft serial number is within the stated range: 120004 and 120006 through 120358 inclusive (source text: Applicability).
   • Verify that the aircraft has been modified in accordance with any revision of Embraer SB 120‑31‑0039, 120‑31‑0040, 120‑31‑0041 or 120‑31‑0042 (source text: Applicability). If both conditions are satisfied, the AD applies.

2. Determine whether the bellcranks requiring replacement are fitted:

   • Inspect maintenance records and, if necessary, perform a physical inspection to identify whether the aileron and/or elevator RVIT bellcranks currently fitted have P/N 123‑82549‑007 or P/N 123‑82549‑009 (source text: Requirement). The replacement is only required where those specific old P/Ns are fitted.

3. Schedule the replacement:

   • If the aircraft is within the AD’s applicability and has the old P/Ns fitted, plan replacement “within the next 4000 hours time in service” from the original AD effective date, or at the “first maintenance action that requires the disassembly of the aileron/elevator RVITs,” whichever occurs first, measured from the original AD effective date (source text: Compliance). Note the original issue effective date is 17 April 2003 (source text: Background), and the Amendment became effective 22 December 2005 (source text: Compliance). Use the original issue date to compute the 4,000 hours deadline.

4. Use the correct service bulletin and approvals:

   • Perform the replacement in accordance with Embraer Service Bulletin 120‑31‑0046 Revision 1 dated 27 December 2002, or use a later revision only if that later revision is approved by the Brazilian CTA (source text: Requirement). Obtain and retain the applicable SB revision and any CTA approval documentation used to support compliance.

5. Procure the correct parts:

   • Acquire the replacement bellcranks P/N 145‑51146‑001 and P/N 145‑51147‑001 as required to replace P/N 123‑82549‑007 and P/N 123‑82549‑009 respectively (source text: Requirement). Verify part numbers on delivery and on installation.

6. Perform work with appropriate approvals and records:

   • Ensure the work is performed by a suitably certificated maintenance organisation or approved person under the operator’s regulatory framework. Record the following at minimum: airframe serial number, old P/Ns removed, new P/Ns installed, reference to Embraer SB 120‑31‑0046 Rev 1 (or CTA‑approved later revision), date and Hobbs/TSN/TIS at installation, and maintenance release/endorsement. The AD requires compliance “in accordance with” the SB; therefore maintain the SB work package and completion sign‑offs.

7. Cross‑check related ADs and past maintenance:

   • Check whether work done under prior directives such as AD/EMB‑120/30 (one‑time inspection) and DAC AD 2001‑07‑01R2 (and its errata) affects compliance status. If prior work already installed the replacement P/Ns in accordance with the specified SB, record the evidence; if not, proceed with replacement as required.

8. Demonstrate compliance to the regulator:

   • While the AD does not state the exact certification submission format, be prepared to present maintenance records showing that the replacement was completed in accordance with the Embraer SB revision or CTA‑approved revision and within the AD’s compliance window. Retain SB pages, parts certificates if available, and the maintenance release.

9. Coordinate with lessors, insurers and operations:

   • If the aircraft is leased, advise the lessor and coordinate repair timing. If the replacement will cause revenue‑bearing downtime, schedule it to minimise disruption within the 4,000‑hour or first‑disassembly constraints.

10. If considering an alternative solution:

• The AD text does not specify an AMOC process or CASA acceptance of alternatives in the printed directive. Operators seeking to use a different part, engineering fix or equivalent methodology should engage CASA directly and document any approval before relying on that alternative. Similarly, if relying on a later Embraer SB revision, confirm CTA approval and retain that approval documentation as part of the compliance evidence.

11. Monitor any further advisory material:

• The AD permits reliance on later SB revisions approved by the Brazilian CTA (source text: Requirement). Operators should monitor Embraer SB releases and CTA approvals and, where relevant, obtain and attach the approved revision to maintenance records demonstrating compliance.

Following these steps will align on‑aircraft work with the AD’s textual requirements: confirming applicability, replacing the specified P/Ns using Embraer SB 120‑31‑0046 Rev 1 or CTA‑approved later revision, and completing the work within the prescribed 4,000‑hour or maintenance‑disassembly trigger window. The AD’s text is prescriptive on parts, method and timing, and those are the operative criteria for compliance as given in the source.