AD/BELL 206/170 - Horizontal Stabiliser Skin at the Tailboom Attachment Inserts

The AD employs three core regulatory concepts: applicability by airframe model, identification of affected components by part number and serial numbers, and required rectification steps tied to an industry service bulletin.

Applicability is limited to Model 206L series helicopters (Applicability). This constrains the universe of holders subject to the instrument to those operating that model.

The AD defines the affected component both by part number and by discrete serial numbers. The part number given is 206-023-119-167 (Background). The AD then requires verification of the horizontal stabiliser serial number in accordance with Part I of BHTC ASB 206L-06-141 (Requirement 1). A discrete list of affected horizontal stabiliser serial numbers follows; those serial numbers trigger the subsequent inspection and replacement obligations (Requirement 1, Requirement 2, Requirement 3). Using serial numbers creates a targeted scope: only aircraft with stabilisers carrying one of the listed serial numbers are subjected to the inspections and mandatory replacement.

The AD makes operative the BHTC Alert Service Bulletin 206L-06-141, original issue or later Transport Canada approved revision, as the normative procedure document. The AD divides the ASB into parts and maps them to duties: Part I for serial-number verification, Part II for inspection procedures, and Part III for replacement procedures (Requirement). The AD does not reproduce ASB technical steps in full; it mandates compliance by reference to those ASB parts.

Timing and recurrence are principal enforcement levers. The AD sets an initial compliance window of within 100 hours time in service after 8 May 2007 but no later than 8 June 2007 for the serial-number verification and initial inspection if applicable (Compliance 1). If an affected stabiliser is installed and is not damaged, the AD imposes ongoing inspections at intervals not to exceed 600 flight hours or the annual inspection, whichever occurs first, until replacement is accomplished (Compliance 2). The AD fixes an absolute deadline for replacement of affected stabilisers no later than 30 September 2008 (Compliance 3). These temporal parameters convert the ASB’s technical directions into legally enforceable obligations.

Safety rationale is expressed as a factual hazard statement: manufacturing flaws on the inside surface of the upper and/or lower skin at the tailboom attachment inserts of the specified part may result in cracking of the skin and failure of the horizontal stabiliser (Background). The AD also includes a cross-reference to Transport Canada AD CF-2007-03 (Requirement note), indicating an international safety linkage or commonality in the identified hazard.

Finally, the AD records administrative provenance and effectuation: it becomes effective on 8 May 2007 and bears the sign-off of a CASA delegate, David Villiers (signature block). The AD’s mechanisms therefore rest on: model-based applicability, part-number and serial-number identification, mandatory compliance with specific ASB parts, and explicit timing and recurrence constraints.

The primary legal addressees are operators, owners and maintenance organisations responsible for Model 206L series helicopters that have horizontal stabilisers part number 206-023-119-167. The AD’s applicability line is explicit: "Model 206L series helicopters" (Applicability). The AD’s Requirement 1 then compels whomever is responsible for maintenance to verify the horizontal stabiliser serial number in accordance with Part I of the BHTC ASB. In airworthiness terms that duty commonly falls on the operator or the certificated maintenance organisation performing the work. The AD does not name a specific actor; it uses mandatory wording that translates in practical terms to the aircraft operator and the maintenance provider being the parties obliged to act.

Where an aircraft carries one of the listed serial numbers (BP1516, -1519, -1521, -1530, -1533, -1536, -1539, -1542, -1560, -1566, -1569, -1572, -1584, -1587, -1607, -1608, -1610, -1612, -1615, -1622, -1629, -1630, -1631, -1634, -1643, -1646, -1659), the operator/maintenance organisation must perform the inspections described in Part II of the ASB and, where damaged parts are detected, replace the parts before further flight (Requirement 1-2). Where parts are not damaged, the operator/maintenance organisation must repeat the inspection at the specified recurring interval (Requirement 2). Ultimately, the operator/owner of any helicopter fitted with an affected stabiliser serial number must ensure replacement of that stabiliser in accordance with Part III of the ASB, and no later than the replacement deadline 30 September 2008 (Requirement 3; Compliance 3).

Other affected parties include record-keeping and regulatory oversight entities. The AD’s reliance on the ASB original issue or later Transport Canada approved revision introduces an interaction where the operator/maintenance organisation must obtain and follow that ASB, and must also be alert to any Transport Canada approvals of later revisions of the ASB referenced in the AD (Requirement).

The AD also makes a procedural link to Transport Canada by noting Transport Canada AD CF-2007-03 (Requirement note). That reference may be materially relevant to operators who fly between jurisdictions or who source parts or maintenance instructions from Transport Canada-issued material, but the AD itself is directed at Australian-regulated aircraft operations by virtue of its CASA issuance and effective date (This Airworthiness Directive becomes effective on 8 May 2007).

In summary, the effect is concentrated: it binds owners/operators and maintenance organisations responsible for Model 206L helicopters carrying the specified part number and the listed stabiliser serial numbers to identification, inspection, recurring inspection (if undamaged), and mandatory replacement within the provided time windows.

The AD imposes a set of affirmative duties; it does not articulate express rights such as compensation or exemptions except to permit the use of "later Transport Canada approved revision" of the ASB. The duties are discrete and sequential.

Duty to verify serial number. Requirement 1 directs the verification of the horizontal stabiliser serial number "in accordance with Part I of BHTC Alert Service Bulletin (ASB) 206L-06-141 original issue, or later Transport Canada approved revision." This duty must be performed within the compliance window specified in Compliance 1: within 100 hours time in service after 8 May 2007, but no later than 8 June 2007, unless already accomplished.

Duty to inspect affected parts. If the installed horizontal stabiliser has a serial number listed in Requirement 1, Requirement 2 mandates inspection "in accordance with Part II of ASB 206L-06-141 original issue, or later Transport Canada approved revision." The AD specifies the operative consequence of inspection findings: "If damaged parts are detected during any inspection, replace the parts before further flight." Where parts are not damaged, the AD requires repetition of the inspection at the intervals stated in Compliance 2.

Duty of repetitive inspection. Compliance 2 sets out the repetitive inspection regime: initially at the time of Requirement 1 compliance, if affected, then repetitively thereafter at intervals not to exceed 600 flight hours or the annual inspection, whichever occurs first, until the stabiliser is replaced in accordance with Requirement 3. This creates an ongoing maintenance obligation until replacement is effected.

Duty to replace. Requirement 3 directs replacement of the affected horizontal stabiliser "in accordance with Part III of ASB 206L-06-141 original issue, or later Transport Canada approved revision." Compliance 3 fixes an absolute deadline: replacement no later than 30 September 2008. The AD also instructs immediate replacement where inspections detect damage, before further flight, thus establishing both a deferred absolute replacement obligation and a near-term compulsory replacement condition upon detection of damage.

Permissible technical authority. The AD grants limited procedural flexibility by allowing the original ASB or a later Transport Canada approved revision to be used. That language constitutes a permission to use later approved ASB revisions rather than a private procedural right to substitute alternative methods. The AD does not supply alternative methods of compliance within its text.

No express mention of waivers, exemptions, or relief. The AD contains no text providing for exemptions, alternative compliance methods, or waivers. It does not set out administrative appeal routes, compensation mechanisms, or deferred compliance provisions. The only cross-reference is to Transport Canada AD CF-2007-03 (Requirement note), and the AD records its effective date and signature.

Who pays and who decides in practical terms. The AD’s obligations,verification, inspection, repetitive inspection, and replacement,are operational tasks for which the operator or maintenance organisation will bear the financial and logistical cost. The AD refers the technical steps to the BHTC ASB and any later Transport Canada approved revision; therefore the decisions about execution method rest with those performing the work, subject to following the ASB procedures and the AD’s timing constraints. The Civil Aviation Safety Authority, through the delegate who signed the AD, is the issuing authority and thus the regulator responsible for enforcement and oversight.

The AD text supplied does not specify penalties, sanctions, or the administrative enforcement mechanisms to be applied for non-compliance. The instrument records its effective date as 8 May 2007 and bears the signature of a CASA delegate, David Villiers (This Airworthiness Directive becomes effective on 8 May 2007; David Villiers, Delegate of the Civil Aviation Safety Authority). It directs mandatory actions and timing but contains no express statutory penalty provisions or penalty schedules within its four short tables and accompanying text.

Because the AD imposes mandatory maintenance and replacement obligations, practical enforcement would fall to the issuing aviation regulator, as evidenced by the CASA signature block. The AD, however, does not itself describe the enforcement steps, inspectors’ powers, or civil or criminal sanction regimes. The absence of enumerated penalties in the AD means that any sanction for non-compliance would derive from the broader regulatory framework under which CASA operates, but those broader enforcement mechanisms are not described or referenced in this document. The AD does include a procedural cross-reference to a Transport Canada AD (Transport Canada AD CF-2007-03 refers), but that is a related safety reference and not an enforcement clause.

For practical legal analysis, two points follow directly from the source text. First, the AD makes actions mandatory by its wording and by fixing effective dates and deadlines; those are obligations which operators and maintenance organisations must perform. Second, the text does not state penalties or enforcement procedures; the AD is silent on sanctions. Any reader seeking to know the specific civil or administrative penalties for failure to comply with this AD therefore must consult the enabling legislation and CASA enforcement instruments outside this AD, because such details are not contained in the instrument provided.

In short, the AD creates time-bound, prescriptive duties without stating penalties in its own text; enforcement, if any, is not set out here and must be sought in external regulatory instruments or statutes not included in the supplied text.

The AD expressly incorporates and depends on technical material outside its text, and it makes one explicit cross-jurisdictional reference. First, the AD mandates actions "in accordance with" Parts I-III of BHTC Alert Service Bulletin 206L-06-141, either the original issue or any later Transport Canada approved revision (Requirement). That incorporation by reference means compliance with the ASB as approved by Transport Canada is central to satisfying the AD’s requirements. Therefore, the AD interacts operationally with the BHTC ASB as the technical standard for inspection and replacement. Legal compliance with the AD requires access to and adherence to that ASB or an approved revision.

Second, the AD contains an explicit cross-reference note: "Note: Transport Canada AD CF-2007-03 refers." This signals that Transport Canada issued a corresponding or related AD and the Australian AD acknowledges that linkage. The AD does not reproduce the content of the Transport Canada AD nor does it state that compliance with that Transport Canada AD satisfies the CASA AD; it only records the reference. The effect of that cross-reference in law is not elaborated in the document itself. Practitioners should treat the note as an information linkage: the hazard has been recognised by another civil aviation authority and a related AD exists, but the AD does not transmute Transport Canada approvals or findings into domestic statutory relief except for the permitted use of "later Transport Canada approved revision" of the ASB.

Third, the AD’s time-bound obligations and mandatory replacement requirements will interact in practice with continuing airworthiness record-keeping, maintenance release processes and certification regimes under the broader civil aviation regulatory framework. The AD does not state how compliance is to be recorded nor whether particular maintenance release endorsements are required; it simply mandates compliance per the ASB parts. As a consequence, operators and maintainers must ensure that whatever recording, release, and approval processes required under the broader airworthiness regulations are completed when the AD tasks are performed. Those procedural interactions are not described in this AD text.

Finally, the AD does not state that compliance with the ASB absolves holders from other legal duties, nor does it provide any waiver of regulatory obligations in other safety or contractual regimes. It does not mention warranties, supplier obligations, or product-liability matters. It likewise does not specify any interaction with aircraft continuing airworthiness directives beyond the single Transport Canada reference. Therefore, the AD’s legal footprint is limited to setting a mandatory maintenance/inspection/replacement duty for the specified airframes and components, while technical execution is tied to the incorporated ASB and Transport Canada-approved revisions.

The supplied instrument includes no amendment history apart from the effective date and an allowance for later approved ASB revisions. The AD becomes effective on 8 May 2007, which is explicitly stated (This Airworthiness Directive becomes effective on 8 May 2007). The AD also permits the use of "BHTC Alert Service Bulletin (ASB) 206L-06-141 original issue, or later Transport Canada approved revision" for Parts I-III (Requirement). That language creates an opening for subsequent approved revisions of the ASB to be used for compliance, but the AD text itself does not record any specific subsequent ASB revisions nor any amendments to the AD.

No text in the supplied document records amendments, revocations, supersessions or subsequent ADs issued by CASA modifying this directive. Similarly, the AD does not list any interim amendments, extensions to compliance dates, or post-issue corrections. Although the AD permits later Transport Canada approved revisions of the ASB to be used, the AD does not itself identify any later-approved revision by date or revision number within the document.

The only external reference that might imply parallel regulatory action is the note linking to Transport Canada AD CF-2007-03 (Requirement note). That reference suggests that a corresponding or related action was taken by Transport Canada, but the AD does not indicate that CASA has amended this AD in response to Transport Canada action or that the Transport Canada AD amends the CASA AD.

Practically, the AD’s absence of an in-text amendment history means that to determine whether the AD has been amended, superseded or withdrawn since 8 May 2007, one must consult CASA’s official AD registry or follow-up regulatory notices. The supplied document provides no evidence of subsequent legislative or administrative change to the AD itself.

The supplied document contains no litigation history. It is a standalone Airworthiness Directive issued by a CASA delegate dated 2 May 2007 and effective 8 May 2007 (David Villiers, Delegate of the Civil Aviation Safety Authority; 2 May 2007; This Airworthiness Directive becomes effective on 8 May 2007). There are no references in the AD to judicial proceedings, administrative appeals, challenges, determinations, or case law. The AD does not cite or summarise any disputes arising from its issuance.

Because the instrument does not describe litigation outcomes or references to judicial determinations, the AD provides no source-grounded material on enforcement litigation, injunctive relief, or disputes about interpretation or compliance. Any practitioner wishing to know whether this AD was the subject of litigation must consult external legal databases, CASA records, or court files. Those sources are not present in the supplied text.

The only cross-reference in the AD is to Transport Canada AD CF-2007-03 (Requirement note), but that notes only that the Transport Canada AD "refers." The AD does not state that the Transport Canada AD generated litigation either. In sum, the document contains no litigation history and remains silent on any legal challenges to its content, enforcement or scope.

This AD contains several practical pitfalls and discrete implementation risks that flow directly from its phrasing and timing.

Narrow serial-number targeting. The AD does not direct inspection of all 206L series stabilisers, only those with part number 206-023-119-167 and specific serial numbers listed in Requirement 1. Missing or inaccurate serial-number records may result in failure to identify an affected stabiliser. The AD therefore imposes a strict verification duty "in accordance with Part I of BHTC ASB 206L-06-141" (Requirement 1). Operators whose records are incomplete must ensure physical verification of the stabiliser serial number per the ASB to avoid overlooking an affected item.

Reliance on ASB not included in AD text. The AD mandates actions "in accordance with" parts of ASB 206L-06-141 but does not reproduce the ASB processes. Practitioners must obtain and follow Part I, Part II and Part III of the ASB or a later Transport Canada approved revision. If the operator performs a different inspection technique or uses internal procedures that diverge from the ASB, the AD contains no textual allowance for that deviation. The AD allows only the original ASB or "later Transport Canada approved revision." Absent explicit CASA permission in this text, alternative methods risk non-compliance.

Tight initial compliance window. The serial-number verification and, if applicable, initial inspection are required "within 100 hours time in service after 8 May 2007, but no later than 8 June 2007" (Compliance 1). That window creates a dual constraint by hours and calendar date. Operators close to the 8 June 2007 date or with aircraft near 100 flight hours may face scheduling pressures to ground the aircraft and perform the verification or inspection in time.

Repetitive inspections until replacement. Where an affected stabiliser is not damaged, the AD requires repetitive inspections at intervals not exceeding 600 flight hours or the annual inspection, whichever occurs first, "until accomplishment of Requirement 3" (Compliance 2). This creates a continuing maintenance burden and the requirement to track both flight hours and the timing of the annual inspection. Failure to track either metric could result in missed inspections.

Absolute replacement deadline. Requirement 3 together with Compliance 3 fixes replacement "no later than 30 September 2008." This is an absolute calendar deadline, irrespective of flight hours. Operators must plan for procurement and fitment of replacement stabilisers within that timeframe. The AD provides no transitional relief or staged deadline.

Immediate grounding trigger on damage detection. The AD requires that "If damaged parts are detected during any inspection, replace the parts before further flight" (Requirement 2). That wording imposes an immediate grounding consequence for the affected component unless immediate replacement is feasible; operators must be prepared for out-of-service time and replacement logistics for any detection of damage.

Cross-reference to Transport Canada. The AD's note that "Transport Canada AD CF-2007-03 refers" and the allowance to use "later Transport Canada approved revision" of the ASB create potential for confusion over which jurisdiction’s approvals are required. The AD accepts later Transport Canada approved revisions of the ASB for compliance, but the AD itself is CASA-issued. Operators should avoid assuming that any non-Transport-Canada ASB revision or other manufacturer bulletin suffices.

Lack of penalty text. The AD is silent as to sanctions for non-compliance. That absence does not remove enforcement risk; it merely places the enforcement regime outside the AD. Parties should not infer the absence of consequences from the AD’s silence.

Record-keeping and proof of compliance. The AD does not specify record-keeping formats or certification endorsements. Operators must ensure that the performance of verification, inspection, repetitive inspections, and replacement is properly recorded under prevailing maintenance record rules, because the AD itself will not contain evidence of compliance and the AD’s text offers no procedural template.

In sum, the gotchas are administrative and logistical: identifying serial numbers accurately, obtaining and following the specified ASB parts, meeting narrow deadlines, preparing for immediate replacement where damage is detected, and planning procurement and maintenance resources to meet the replacement deadline.

The AD sets out a clear, three-step compliance protocol tied to specific dates and inspections. Follow these steps, using the ASB parts specified.

1. Obtain the ASB. Acquire BHTC Alert Service Bulletin 206L-06-141 original issue and determine whether any later Transport Canada approved revisions exist. The AD explicitly permits using the ASB original issue or a later Transport Canada approved revision for Parts I-III (Requirement). Ensure you are using the ASB part content that has the Transport Canada approval if it is a later revision.

2. Verify serial number within the initial window. Under Requirement 1 and Compliance 1, verify the serial number of the horizontal stabiliser "in accordance with Part I of BHTC ASB 206L-06-141" within 100 flight hours time in service after 8 May 2007 but no later than 8 June 2007, unless already accomplished. The verification must identify whether the installed horizontal stabiliser carries any of the serial numbers listed in Requirement 1 (BP1516, -1519, -1521, -1530, -1533, -1536, -1539, -1542, -1560, -1566, -1569, -1572, -1584, -1587, -1607, -1608, -1610, -1612, -1615, -1622, -1629, -1630, -1631, -1634, -1643, -1646, -1659).

3. If the serial number is listed, perform the inspection immediately. Requirement 2 instructs operators to inspect the affected parts "in accordance with Part II of ASB 206L-06-141 original issue, or later Transport Canada approved revision." Perform the inspection as directed in the ASB. If the inspection detects damaged parts, the AD mandates replacement "before further flight." If no damage is detected, you must schedule and perform repetitive inspections at intervals not to exceed 600 flight hours or at each annual inspection, whichever occurs first, until replacement is accomplished (Compliance 2).

4. Replace the affected stabiliser per the ASB by the deadline. Requirement 3 and Compliance 3 set the mandatory replacement requirement: replace the affected horizontal stabiliser "in accordance with Part III of ASB 206L-06-141 original issue, or later Transport Canada approved revision" and do so no later than 30 September 2008. Prepare procurement and maintenance scheduling to ensure replacement by that deadline.

5. Record actions. Although the AD does not specify record-keeping procedures, maintain clear records of the serial-number verification, inspection results, dates, flight hours at inspection, any damage findings, replacement parts used, and by whom the work was performed. Given that the AD requires replacement "before further flight" where damage is found, contemporaneous recording of the grounding and replacement steps will be necessary to demonstrate compliance.

6. Coordinate with the ASB and Transport Canada references. When relying on a later Transport Canada approved revision of the ASB, document the revision used and any Transport Canada approval reference. The AD’s wording allows those later approved revisions; ensure that the ASB revision actually carries the Transport Canada approval before relying on it for compliance.

7. Prepare for contingency costs and downtime. The AD’s immediate replacement-on-damage requirement and the absolute replacement deadline create potential for unexpected grounding and logistic burdens. Budget for replacement parts and arrange certified maintenance capacity to execute the replacement in accordance with Part III of the ASB.

8. Safety-first compliance. The AD’s Background notes the hazard: manufacturing flaws inside the skin at the tailboom attachment inserts "may result in cracking of the skin and failure of the horizontal stabiliser." Follow the inspection and replacement steps precisely as they are mapped to the ASB parts to address that hazard.

These steps follow directly from the AD’s Requirements and Compliance sections. The AD does not provide exemptions or alternative methods; compliance means following the ASB parts named, meeting the timing windows, and replacing any stabiliser found damaged prior to returning the aircraft to service.