AD/DHC-1/33 Amdt 2 - Tailplane Support Struts

The AD is structured around a narrow set of technical and administrative concepts. First, applicability is defined by aircraft origin and by component part number. The AD lists "English production (C1), all models, and Portuguese (T Mk 20) production models" as applicable, and the text emphasises that applicability should ultimately be checked by reference to tailplane support strut part number P/N C1-T-5A. Second, the technical requirement is to perform the actions in British Aerospace Mandatory TNS CT(C1) 186 issue 2. The AD does not reproduce the technical content of that TNS; it mandates action "in accordance with" it. Third, compliance timing has two specific triggers. For outstanding actions the AD gives a compliance window: complete the TNS action within three months after the AD's effective date or before a Certificate of Airworthiness is issued for the aircraft, whichever is earlier, unless the initial-issue inspection was already carried out and a BAe radiographic acceptable assessment exists for that inspection. Fourth, the AD sets a repeat inspection interval not exceeding seven years after either the installation of new struts or after compliance with either the initial or this amendment of the directive. Fifth, the AD expressly includes components held as spares within its scope. Sixth, the AD records its effective date and signatory, and it records the historical evolution: initial issue required external visual inspection, rework and non-destructive inspection; Amendment 1 added repeat inspections and revised technical requirements; this amendment extends applicability to Portuguese-built models and clarifies compliance wording while leaving intervals unchanged. Finally, the AD places responsibility on operators to verify part numbers and, if uncertain, to "contact the manufacturer or TC holder for further information on applicability" as stated in the background text. The document therefore operates by importing a manufacturer technical note into a regulatory obligation, tying compliance to both a calendar window and the operational event of obtaining or renewing a Certificate of Airworthiness, and embedding periodic re-inspection obligations.

The AD explicitly affects owners and operators of De Havilland DHC-1 (Chipmunk) aircraft produced in England under the C1 designation, and Portuguese production models designated T Mk 20, when those aircraft carry the specified tailplane support struts. It also affects any person or organisation that holds the relevant tailplane support struts as spares, because the AD states that it "also applies to any struts held as spares." The AD identifies the relevant part number for applicability as P/N C1-T-5A, and it instructs operators to check the strut part number to determine whether their aircraft or spare parts are within scope. Maintenance organisations, approved inspectors and any facility that performs radiographic or non-destructive inspection (NDI) work will be engaged, since the AD references radiographic assessment and NDI as inspection methods used in the initial issue of the Directive and in the BAe TNS. The manufacturer and the type certificate holder are named as points of contact for resolving applicability doubts. The Civil Aviation Safety Authority is the issuing agency as shown by the signature block "Glen Steemson, Delegate of the Civil Aviation Safety Authority." The AD therefore targets a concentrated group: owners and operators of specific Chipmunk airframes and holders of spares with the stated part number, and the maintenance providers who perform the inspections and rework identified in the BAe TNS. The directive does not expand to other aircraft types, nor does it list alternative parts or broader classes; applicability is component- and model-specific. The background statement that "a case of internal corrosion in a tailplane attachment strut was reported" indicates the immediate safety driver of the AD, but the directive’s operational effect is limited to the aircraft and parts matching the stated descriptions and part numbers.

Duties. The primary duty imposed by the AD is to perform the actions set out in British Aerospace Mandatory TNS CT(C1) 186 issue 2 on any applicable tailplane support strut. The AD gives a time limit for initial compliance: complete the required actions "within three months after the effective date of this AD or prior to CofA issue, whichever occurs first," unless the operator already has completed the initial-issue inspection and holds a BAe radiographic acceptable assessment from that inspection. The AD requires repeat inspections "at periods not exceeding seven years" after either the installation of new struts or the last compliance with the initial issue or this amendment. The AD explicitly includes struts held as spares, so holders of spare parts must ensure those spares have the required inspection or are otherwise managed in line with the TNS. Operators must check tailplane support strut part numbers, specifically P/N C1-T-5A, to determine applicability; the AD directs contact with the manufacturer or the type certificate holder when there is doubt about applicability. The AD imports the BAe technical standard as the operative technical prescription; compliance must be "in accordance with" TNS CT(C1) 186 issue 2, not with a derived or substituted procedure. Rights. The AD provides the procedural right to rely on an earlier inspection outcome where the operator "holds a BAe radiographic acceptable assessment from that inspection" performed under the initial issue. The AD also affords an operational clarifying route: operators uncertain about applicability are instructed to "contact the manufacturer or TC holder for further information" which is an explicit pathway for resolution. The AD does not articulate rights of appeal, relief from compliance, or alternative means of compliance within the text. The background notes that Amendment 2 makes "no change to the requirements and the compliance wording has been clarified, but inspection interval is unchanged." That statement frames the amendment as an applicability and wording clarification rather than a substantive change to the technical or temporal requirements, and therefore the duty profile for operators largely continues from earlier Directive provisions except for the added applicability to Portuguese T Mk 20 models.

The text of AD/DHC-1/33 Amdt 2 does not set out specific penalties or enforcement procedures within the directive itself. The AD declares an effective date, "This Amendment becomes effective on 22 June 2011," and is issued by a named delegate of the Civil Aviation Safety Authority. The AD links compliance timing expressly to Certificate of Airworthiness issuance by stating the requirement must be met "within three months after the effective date of this AD or prior to CofA issue, whichever occurs first." That linkage creates an operational enforcement lever: compliance, or documentation of compliance such as a BAe radiographic acceptable assessment, is a precondition that the AD makes relevant to the CofA process for an aircraft. The AD also requires retention of inspection evidence where it makes an explicit allowance for compliance if the operator "holds a BAe radiographic acceptable assessment from that inspection." The directive does not itself describe administrative sanctions, criminal penalties, or the process for compliance audits. The document records the issuing authority by signature, which establishes the directive as a formal regulatory instrument, but any enforcement mechanisms beyond the CofA connection are not contained in this text. The AD does not identify specific regulatory remedies for non-compliance, nor does it specify how compliance will be verified in operation. Where the AD instructs contact with the manufacturer or the type certificate holder for applicability queries, it creates a practical route for resolution of uncertainty but not an enforcement mechanism. Any question about statutory or administrative penalties, or the detailed enforcement processes used by the Civil Aviation Safety Authority in the event of non-compliance, is not answered by the AD text provided.

The AD imports and relies on technical material produced by the manufacturer by requiring action "in accordance with British Aerospace Mandatory TNS CT(C1) 186 issue 2." By doing so the directive creates a regulatory obligation that references an external technical standard. The AD also ties compliance to the Certificate of Airworthiness process by stipulating that required actions must be completed "within three months after the effective date of this AD or prior to CofA issue, whichever occurs first." The AD refers to the type certificate holder as a point of contact for applicability queries. The AD does not itself reference other legislative instruments, regulations, or statutory provisions in the provided text. It does, however, reflect an administrative procedure in which a delegated official of the Civil Aviation Safety Authority issues the directive; the signature block identifes the issuer as "Glen Steemson, Delegate of the Civil Aviation Safety Authority." The directive therefore sits in the regulatory matrix as a technical airworthiness requirement issued by the aviation regulator and implemented by reference to a manufacturer's technical note. The AD also interacts with operator and maintenance record-keeping practices because it recognises the existence of prior inspections and accepts a "BAe radiographic acceptable assessment" from an earlier inspection as satisfying the immediate initial compliance requirement. The AD’s instruction to check strut part numbers for applicability creates an interface with an operator’s spares inventory and traceability systems. Beyond the explicit references to the BAe TNS, Certificate of Airworthiness and the type certificate holder, the AD text contains no further cross-references to other statutes or regulations, and it does not identify the legal mechanism by which the Civil Aviation Safety Authority enforces or promulgates airworthiness directives.

The document itself contains a concise internal amendment history. The AD is labelled "AD/DHC-1/33 Amdt 2" indicating this is the second amendment to the original AD/DHC-1/33. The background narrative records the sequence of technical changes: the initial issue of the Directive required an external visual inspection, rework and non-destructive inspection (NDI). Amendment 1 introduced a repeat inspection requirement and revised and clarified the technical requirements via the TNS. The current Amendment 2 adds Portuguese manufactured T Mk 20 models to the applicability of the Directive. The AD notes that a review of documentation indicates the inspection is applicable to any aircraft with tailplane support struts P/N C1-T-5A, which may be fitted to both English and Portuguese produced models. The AD states the compliance date for the initial issue of the Directive was 20 November 1992, indicating the original requirement was issued and had an initial compliance timeline in 1992. The Amendment 2 text asserts there is "no change to the requirements and the compliance wording has been clarified, but inspection interval is unchanged." The AD gives an explicit effective date for Amendment 2 as 22 June 2011, and the document is signed by a CASA delegate on 16 June 2011. The document does not set out full texts of the initial AD or of Amendment 1, nor does it reproduce the BAe Mandatory TNS content; rather it summarises the prior changes and records the current amendment's limited scope: to extend applicability and to clarify wording without altering inspection intervals or technical requirements. The presence of an initial compliance date in 1992 and the later amendment dates indicates a long-running, periodic surveillance approach applied through successive AD issuances and amendments.

The text of AD/DHC-1/33 Amdt 2 contains no references to litigation, court decisions or administrative appeals. There are no cases named in the document and no description of prior disputes or enforcement actions. The AD is an administrative directive that summarises technical findings and changes to applicability and compliance wording, but it does not recount any judicial challenges or litigation outcomes. If one needs to know whether the AD has been subject to dispute or challenge, or whether earlier iterations were litigated, that information is not contained in the document provided. The AD does record the factual background of a reported case of internal corrosion in a tailplane attachment strut, but it does not describe any adversarial proceedings arising from that event. The absence of litigation references in the AD text means the document itself will not serve as a source for case law; external searches in judicial and administrative records would be necessary to establish any litigation history relating to this AD or to the aircraft or parts it covers. The AD does reference the manufacturer and the type certificate holder as parties to consult for applicability questions, but it does not provide any process for dispute resolution or describe rights of review or appeal within this text.

Several practical traps and points of potential misunderstanding are visible directly in the AD text. Part-number specificity. Applicability is not solely by aircraft model label. The AD instructs operators to check the tailplane support strut part number, P/N C1-T-5A, because that part can be fitted to more than one production origin. The AD therefore can capture aircraft beyond a simple model list if that part number is present. Spares are in-scope. The AD explicitly applies to struts "held as spares," so the inventory and management of spare parts is within the AD’s reach. Operators who retain spare struts without inspection documentation must treat those spares as requiring action. Prior inspection reliance. The AD allows an exception where the required action is "already accomplished in accordance with the initial issue of this Directive and holding a BAe radiographic acceptable assessment from that inspection." That means operators must be able to produce that BAe radiographic acceptable assessment to rely on it. Timing nuance. The initial compliance window is "within three months after the effective date of this AD or prior to CofA issue, whichever occurs first." Operators awaiting a Certificate of Airworthiness need to be aware that the CofA issuance can pre-empt the three-month calendar window. The AD does not alter inspection interval. The amendment states that the inspection interval remains unchanged. That means existing seven-year repeat timing is preserved. Technical standard versioning. The AD mandates compliance with BAe Mandatory TNS CT(C1) 186 issue 2. Operators must ensure they use the issue 2 version of the TNS; the AD does not authorise use of other versions. Applicability uncertainty. The AD instructs operators to "contact the manufacturer or TC holder for further information on applicability" if there is any doubt. That is the prescribed route for resolving uncertainty but may require time and documentation. Limited text on enforcement and remedies. The AD does not set out enforcement mechanisms, penalties, or processes for alternative compliance within the document. If an operator requires relief, the AD does not state the mechanism for obtaining it. Historical compliance date. The AD records that the initial issue compliance date was 20 November 1992. That legacy date may cause confusion in record reviews unless operators carefully track which iteration of the directive their records address. Record keeping. Because the AD specifically recognises a BAe radiographic acceptable assessment as satisfying immediate compliance in some cases, maintaining and being able to produce that specific document is critical.

Follow these steps based on the AD text. 1) Identify applicability. Confirm whether the aircraft is an English production (C1) model or a Portuguese production T Mk 20 model, and verify whether the installed or spare tailplane support strut bears part number P/N C1-T-5A. The AD instructs operators to check the tailplane support strut part number to determine applicability. 2) Review prior inspections. Determine whether the actions required under the initial issue of the Directive have already been accomplished and whether you "hold a BAe radiographic acceptable assessment from that inspection." If so, that assessment satisfies the immediate initial compliance requirement set out by the AD. 3) Obtain the mandated technical standard. Acquire British Aerospace Mandatory TNS CT(C1) 186 issue 2. The AD requires actions "in accordance with" that TNS; the AD does not reproduce the procedures. 4) Schedule and perform inspections and any rework. If the work has not already been done to the initial-issue specification with an acceptable BAe radiographic assessment, perform the actions required by TNS CT(C1) 186 issue 2 within three months after the AD effective date or prior to issue of the aircraft’s Certificate of Airworthiness, whichever comes first. The initial issue required external visual inspection, rework and non-destructive inspection; Amendment 1 introduced repeat inspections and revised the technical requirements via the TNS. 5) Obtain and retain documentation. Where radiographic assessment or NDI is performed, obtain a "BAe radiographic acceptable assessment" or equivalent documentation as required by the TNS and retain it in aircraft maintenance records, because the AD explicitly recognises that document as satisfying compliance for some operators. 6) Implement the repeat inspection regime. Set a repeat inspection schedule not exceeding seven years after either the installation of new struts or after compliance with this AD or the initial issue. Ensure maintenance programmes and tracking systems reflect this seven-year maximum interval. 7) Include spares in your process. Treat struts held as spares as subject to the AD. Ensure spares inventories are checked and that required inspections or documentation are attached to spare parts records. 8) Resolve applicability doubts. If there is any doubt about applicability, contact the manufacturer or the type certificate holder for clarification as the AD advises. 9) Coordinate with Certifying Authorities. Be aware of the AD’s link with Certificate of Airworthiness issuance: the AD must be complied with prior to CofA issue if the CofA precedes the three-month calendar window. 10) Audit and record retention. Keep clear records of inspections, rework, radiographic assessments and communications with the manufacturer or TC holder. The AD’s allowance for prior acceptable assessments means record availability is central to operational compliance. The AD text does not describe alternative means of compliance or administrative relief; if relief or alternative methods are considered necessary, operators should consult the manufacturer or TC holder as the AD recommends.