AD/DAUPHIN/72 Amdt 1 - Hydraulic Power - Hydraulic Pipes Clamps

The instrument centres on three technical and procedural concepts: the mechanical interface between attachment clamps and hydraulic pipes; the chemical and material compatibility of clamp protections in a hydraulic environment; and the use of service literature and foreign authority airworthiness directives as the implementation standard.

Attachment clamps secure hydraulic pipes along routes within the airframe. The AD identifies a failure mode caused by the protection material on the clamp coming into contact with hydraulic fluid, degrading the protective layer and allowing the clamp hardware to chafe the pipe until wear and perforation occurred (Background). The core technical remedy is removal or replacement of clamps that have silicone protection and substitution with clamps that have protection made from materials that retain mechanical characteristics when exposed to hydraulic fluid, specifically acrylonitrile butadiene or polychloroprene according to the background text. For some helicopters the AD requires replacement of clamps outright in accordance with specific Eurocopter ASB instructions (Requirement para 1; ASB reference), while for others the AD requires a targeted inspection of the left-hand hydraulic power system clamps (Requirement para 3; ASB para 2.B.5).

The AD uses Eurocopter Alert Service Bulletin No. 29.00.08 dated 15 November 2005 as the technical standard for both replacement and inspection procedures, and it limits acceptable compliance to the ASB text or later revisions that have been approved by the French DGAC (Requirement paras 1 and 3). The directive therefore delegates detailed technical steps to the manufacturer’s ASB and to DGAC approval of later revisions. The AD also expressly forbids the installation of clamps with silicone protection on hydraulic pipes across the affected fleet from the effective date (Requirement paras 2 and 4; Compliance paras 2 and 4).

The AD places time pressure on two cohorts of aircraft in different ways, creating short and medium compliance windows: an urgent short window for replacement for certain newer-delivered aircraft (50 flying hours or one month), and a longer window for inspection in older-delivered helicopters (660 flying hours or 26 months). The directive thereby balances immediate mitigation for one cohort against a measured inspection programme for another cohort.

Finally, the AD is cross-referenced to related regulatory instruments: it notes DGAC AD UF-2006-042, approved by EASA, and records that the original domestic AD (ADF‑2004‑115) has been superseded. The background also states that the original issue of this AD became effective on 30 September 2004, and this amendment expands applicability and requires installation per the ASB (Background).

Directly affected parties are operators and maintainers of Eurocopter Model SA 365 N and N1, and AS 365 N2 and N3 helicopters that are not modified per Mod 0729B67, as set out in the Applicability cell. The AD imposes mandatory maintenance actions on those operators: replacement of clamps for a subset of aircraft (AS 365 N2/N3 delivered after 1 January 1998), inspections and possible corrective action for others (AS 365 N2/N3 delivered prior to 1 January 1998 and SA 365 N and N1), and a universal prohibition on installing silicone‑protected clamps on hydraulic pipes from the effective date.

Maintenance organisations, licensed aircraft maintenance engineers and component suppliers are operationally impacted because they must carry out the replacements and inspections to the Eurocopter ASB specifications (ASB No. 29.00.08 dated 15 November 2005 or later DGAC‑approved revisions), and must ensure that any clamps installed are not fitted with silicone protection (Requirement paras 1-4). The source requires the use of ASB procedures (para 2.B.4 for replacement and para 2.B.5 for checking) so the maintenance workforce will need access to that ASB and any DGAC‑approved revisions.

Eurocopter, as the design authority and ASB author, is implicated because the AD requires the ASB’s clamp design and installation instructions be followed and references Eurocopter’s analysis and service literature in the background and requirement. The French DGAC and EASA are implicated as approving authorities for subsequent revisions of the ASB and as issuers of related ADs (the AD refers to DGAC AD UF-2006-042 and EASA approval under reference 2006‑0042‑E).

Aircraft owners or operators who have installed modification 0729B67 are excluded from the AD’s applicability, so they are unaffected by these specific requirements according to the text (Applicability). The AD does not reference other helicopter types beyond the listed Eurocopter models; the triggering incident involved an EC 155 B1, but the AD applies only to the listed Dauphin-series models (Background; Applicability).

Indirectly affected parties include any supplier or manufacturer that markets clamp assemblies for these airframes: clamps with silicone protection are expressly prohibited for installation on hydraulic pipes from the AD effective date (Requirement paras 2 and 4; Compliance paras 2 and 4). The AD will therefore affect procurement choices and may require suppliers to provide clamps with acrylonitrile butadiene or polychloroprene protection material specified or implied by the background text.

Regulatory authorities are affected in that the AD references and aligns with DGAC and EASA documents; the AD also supersedes the original domestic AD and extends applicability (Background), which requires regulators to track and enforce compliance for the broader set of affected helicopters.

Finally, the AD imposes short and medium-term operational constraints on affected aircraft scheduling because the replacement or inspection windows are measured in flying hours or calendar months from the AD effective date (Compliance paras 1 and 3).

Duties imposed by this AD are explicit and time‑bound. The primary duties are:

• For AS 365 N2 and N3 helicopters delivered after 1 January 1998: Replace attachment clamps in accordance with paragraph 2.B.4 of Eurocopter ASB No. 29.00.08 dated 15 November 2005 or later DGAC‑approved revisions (Requirement para 1). This replacement must be completed within 50 flying hours or one month after the AD’s effective date, unless the replacement has already been carried out previously (Compliance para 1).

• For AS 365 N2 and N3 helicopters delivered after 1 January 1998: Do not install clamps that have silicone protection on hydraulic pipes, effective from the AD effective date (Requirement para 2; Compliance para 2).

• For AS 365 N2 and N3 helicopters delivered prior to 1 January 1998, and SA 365 N and N1 helicopters: Inspect the attachment clamps of the left-hand hydraulic power system and carry out corrective action if required, following paragraph 2.B.5 (Checking the attachment clamps of the LH hydraulic power system) of ASB No. 29.00.08 or later DGAC‑approved revisions (Requirement para 3). This inspection must be performed within 660 flying hours or 26 months after the AD’s effective date, unless the replacement has already been carried out previously (Compliance para 3).

• For the same older-delivered cohort and model group: Do not install clamps with silicone protection on hydraulic pipes from the AD effective date (Requirement para 4; Compliance para 4).

Rights and discretions mentioned or implied in the AD are narrower and are limited by the document’s cross‑referencing practice. The AD delegates the detailed technical method for replacement and inspection to Eurocopter ASB No. 29.00.08 and its later revisions approved by the French DGAC. In practice, this gives operators the right to comply by following the procedures laid out in that ASB or any later revision once that revision is approved by DGAC. The AD does not itself prescribe the exact part number or manufacturer of the replacement clamps; rather it requires compliance with the ASB’s specified compliant clamps, which is a technical standard set by the manufacturer and accepted by the foreign authority.

The AD specifies that installation of silicone-protected clamps is prohibited from the effective date, which leaves no discretion to fit such clamps. The AD also excludes helicopters modified per Mod 0729B67 from applicability; therefore operators of helicopters with that modification have the right to treat this AD as not applying, unless further regulatory text or a separate AD states otherwise.

The AD does not set out enforcement mechanisms or administrative appeal rights within its text. It does, however, refer to a chain of authority by citing the DGAC AD which has been approved by EASA; this indicates that the AD’s requirements and the ASB procedures are harmonised with those foreign authority documents (Requirement note). The AD’s background explains the safety rationale supporting the duties: evidence of hydraulic pipe perforation following silicone-protection degradation and chafing (Background).

In short, duties are mandatory replacements, inspections and a prohibition on silicone-protected clamps, performed within the stated hours or calendar timelines and carried out to the ASB procedures; rights are limited to following the ASB and relying on the AD’s applicability exclusion for helicopters modified per Mod 0729B67.

The AD text supplied does not include a schedule of penalties, fines, or an enforcement regime within its own wording. It states mandatory actions, compliance timeframes and the AD effective date (Compliance paras 1-4; Effective date). The document was issued by a CASA delegate (Jayaprakashan Ambali) and carries an effective date for the amendment of 13 April 2006 (Effective date; signature block).

Because the AD does not itself set out penalties, the source does not specify what civil, administrative or criminal sanctions (if any) apply for noncompliance. The AD likewise does not describe the process by which CASA will enforce the AD, inspect compliance, or take action for contraventions. The directive’s references to DGAC and EASA approvals (Requirement note referencing DGAC AD UF‑2006‑042 and EASA reference 2006‑0042‑E) show alignment with foreign authority serviceability and airworthiness determinations, but the instrument as supplied does not identify an enforcement mechanism or penalties.

Any enforcement activity, and any administrative or legal penalties for breach, would therefore have to be determined from the enabling aviation safety legislation, regulatory framework and enforcement policies that sit outside the four corners of this AD. The AD itself functions as a prescriptive safety mandate with precise technical and temporal obligations, but the source text does not specify how CASA will monitor or enforce compliance, nor what sanctions will follow noncompliance. Similarly, the instrument does not prescribe an appeal or exemption process in its text; it instead cross‑references ASB and DGAC approvals for procedural detail (Requirement paras 1 and 3; Requirement note).

Given the absence of penalty or enforcement specifics in the AD text, operators and maintainers must treat the AD’s actions as mandatory and should consult CASA, the applicable regulatory framework, or formal regulatory guidance documents for information about enforcement, acceptable means of compliance, recordkeeping expectations and potential consequences for failing to comply.

The AD explicitly cross-references foreign airworthiness directives and manufacturer service literature rather than setting out comprehensive legal interactions. The AD refers to French DGAC AD UF‑2006‑042, which it notes has been approved by EASA under reference number 2006‑0042‑E dated 10 February 2006, and further notes that UF‑2006‑042 supersedes DGAC ADF‑2004‑115 (Requirement note). The AD requires that the replacement and inspection actions be completed in accordance with Eurocopter ASB No. 29.00.08 dated 15 November 2005 or later revisions approved by the French DGAC (Requirement paras 1 and 3). Consequently, the AD operates by adopting the ASB as the technical standard and by aligning domestic requirements with DGAC/EASA ADs.

The AD extends the original domestic AD’s applicability and replaces the prior domestic instrument; the background clarifies that the original domestic AD became effective on 30 September 2004 and that the current amendment requires installation per ASB No. 29.00.08 and extends applicability to additional SA 365 models (Background). This shows that the AD is part of an iterative safety regulation process that interacts with, and may supersede, prior domestic ADs.

The instrument does not reference domestic aviation acts, regulations, or enforcement provisions in its text. It therefore does not, within its own wording, identify specific statutory provisions that grant CASA power to issue the AD, nor does it specify how the AD affects other domestic legal obligations, such as maintenance recordkeeping, continuing airworthiness obligations or operator obligations under air transport or general aviation regulation. Those interactions would be determined by the wider regulatory framework and enabling aviation safety legislation, which the AD does not reproduce.

The AD’s requirement that work be done in accordance with a Eurocopter ASB subject to French DGAC approval makes the AD operationally interdependent with foreign authority approvals and manufacturer documentation. That is, the technical content of compliance is supplied by service literature and DGAC approval, which the AD incorporates as the standard for acceptable compliance. Operators therefore must coordinate both with the ASB content and with the DGAC/EASA documents referenced to ensure the correct revision and approved procedures are used.

Finally, the AD’s applicability exclusion for helicopters modified per Mod 0729B67 creates a point of interaction with aircraft modification records and airworthiness status. Operators must determine whether Mod 0729B67 has been embodied on a particular helicopter to know whether the AD applies. That determination will involve referencing maintenance/ modification records and any relevant approval documents, matters governed by broader maintenance regulations and airworthiness record requirements not detailed in the AD text.

The supplied instrument contains a concise internal amendment history embedded in the background and header material. The original issue of AD/DAUPHIN/72 was effective on 30 September 2004 (Background). This document is an amendment (Amdt 1) numbered AD/DAUPHIN/72 Amdt 1 and dated 4/2006; the amendment became effective on 13 April 2006 (Effective date). The amendment expands the AD’s applicability to include Eurocopter SA 365 N and N1 models and requires installation of clamps in accordance with Eurocopter ASB No. 29.00.08 dated 15 November 2005 (Background; Requirement).

The ASB referenced in this AD is Eurocopter Alert Service Bulletin No. 29.00.08 dated 15 November 2005. The AD requires that replacements and inspections be performed in accordance with paragraph 2.B.4 and paragraph 2.B.5 of that ASB (Requirement paras 1 and 3). The AD permits later revisions of that ASB provided those revisions are approved by the French DGAC (Requirement paras 1 and 3). The AD also notes DGAC AD UF‑2006‑042, approved by EASA under reference number 2006‑0042‑E dated 10 February 2006, and states that UF‑2006‑042 supersedes DGAC ADF‑2004‑115 which now stands cancelled (Requirement note).

The background explains the amendment rationale: after an incident on an EC 155 B1 helicopter where a hydraulic warning light illuminated and a leak was found, Eurocopter’s analysis showed silicone protection on a clamp had been damaged by hydraulic fluid, enabling chafing that perforated the pipe. The original AD imposed mandatory periodic checks pending installation of clamp protections made from materials (acrylonitrile butadiene or polychloroprene) that retain mechanical characteristics in a hydraulic environment. The current amendment requires installation of clamps compliant with ASB No. 29.00.08, extends applicability to other Dauphin models and references the latest DGAC AD and related service literature (Background).

Summary of amendment-related dates and documents contained in the source:

• Original AD effective: 30 September 2004 (Background).
• Eurocopter ASB No. 29.00.08 dated: 15 November 2005 (Requirement).
• DGAC AD UF‑2006‑042 (approved by EASA reference 2006‑0042‑E): dated 10 February 2006 (Requirement note).
• AD amendment (this document) signed: 21 February 2006 (signature block), and amendment becomes effective: 13 April 2006 (Effective date).

No further amendment history or later revocations are contained in the supplied text.

The supplied instrument contains no litigation history, case citations or references to judicial or administrative challenges. The AD records the technical incident that prompted regulatory action and cites manufacturer analysis and foreign authority documents; it does not reference any disputes, appeals, or court decisions.

Specifically, the background describes an operational incident on an EC 155 B1 helicopter that resulted in a hydraulic leak and Eurocopter analysis concluding that silicone protection on a clamp had degraded leading to chafing and pipe perforation (Background). The AD sets out the resulting mandatory maintenance and prohibition measures. No part of the AD text mentions any legal proceedings, enforcement actions taken in court, or contested reviews of this AD or the underlying DGAC ADs or ASB.

Because the AD text does not include litigation history, there is no material in this document that identifies precedents, judicial interpretations, or administrative appeals regarding the AD’s validity or scope. Any search for litigation affecting this AD, conflicts over its application, or appeals would need to consult external legal records and case law, which are not referenced or summarised in the supplied source.

The AD contains several implementation and interpretation points that merit attention because misreading them could lead to noncompliance.

1. Applicability is conditional on a modification status. The AD applies to Eurocopter Model SA 365 N and N1, and AS 365 N2 and N3 helicopters that are not modified per Mod 0729B67 (Applicability). If an operator’s helicopter has Mod 0729B67 embodied, the AD’s actions may not be required under this instrument; operators must verify modification status precisely in aircraft maintenance/modification records. The AD itself does not define Mod 0729B67; the operator must consult its maintenance records to determine applicability.

2. Delivery date distinction changes required action. The AD divides obligations by delivery date relative to 1 January 1998. AS 365 N2 and N3 helicopters delivered after 1 January 1998 must have attachment clamps replaced per ASB para 2.B.4 within 50 flying hours or one month (Requirement para 1; Compliance para 1). AS 365 N2 and N3 helicopters delivered prior to that date, and SA 365 N and N1 helicopters, are required only to inspect the left-hand hydraulic power system clamps per ASB para 2.B.5 within 660 flying hours or 26 months (Requirement para 3; Compliance para 3). That bifurcation means two different cohorts will have different workloads and time pressures; failure to correctly classify a helicopter by delivery date could result in adopting an incorrect compliance action.

3. The replacement requirement is not specified to a particular side but the inspection is left-hand only. The AD requires "Replace attachment clamps" for the post-1998 AS 365 N2/N3 cohort (Requirement para 1), without specifying side; however, the inspection requirement for the older cohort is explicitly for the left-hand (LH) hydraulic power system attachment clamps (Requirement para 3). Misreading the AD to inspect only the LH side where replacement of multiple clamps is required could lead to incomplete compliance. Operators should follow the ASB para references to determine the exact scope of components to replace or inspect.

4. The ASB and DGAC approvals determine accepted procedures and revisions. The AD requires performance "in accordance with paragraph 2.B.4" and "paragraph 2.B.5" of Eurocopter ASB No. 29.00.08 dated 15 November 2005 or later DGAC‑approved revisions (Requirement paras 1 and 3). This means the exact procedural steps, part numbers and acceptance criteria are contained in the ASB and later revisions approved by DGAC. Failing to obtain and use the correct ASB revision approved by DGAC could cause nonconformance with the AD.

5. Prohibition on silicone-protected clamps is immediate and universal for the affected fleet. The AD forbids installation of clamps with silicone protection on hydraulic pipes from the AD effective date (Requirement paras 2 and 4; Compliance paras 2 and 4). That is an absolute prohibition in the AD text for the applicable aircraft and leaves no schedule for phasing out existing silicone-protected clamps except where the AD requires replacement or inspection. Operators must ensure procurement and maintenance practices do not introduce silicone-protected clamps after the effective date.

6. Material specification language in the background is descriptive not normative. The background states that replacement clamps use an acrylonitrile butadiene or polychloroprene protection which retains mechanical characteristics in a hydraulic environment (Background). The normative requirement in the AD is to follow ASB para 2.B.4 and the ASB is the controlling document for which specific clamp constructions and part numbers are acceptable. Operators should not treat the background’s material descriptors as a substitute for following the ASB and approved revisions.

7. Compliance windows differ by cohort and are measured in flying hours or months. For some aircraft the replacement time is short (50 flying hours or one month) while inspection windows for others are much longer (660 flying hours or 26 months) (Compliance paras 1 and 3). Operators must track both flying hours and calendar time from the AD effective date to ensure compliance within whichever limit is reached first.

8. The AD references a DGAC AD that superseded a prior DGAC AD. The AD notes that DGAC AD UF‑2006‑042 (approved by EASA) supersedes DGAC ADF‑2004‑115 (Requirement note). Operators should ensure they are following the current DGAC/EASA AD version referenced by the ASB and this AD. Relying on an older cancelled DGAC AD could result in incomplete compliance.

9. The AD does not attach penalty or enforcement detail. The instrument mandates actions but does not specify penalties or an enforcement process in its text (Penalties and enforcement). Operators should not assume the AD contains those elements and should confirm enforcement expectations through CASA or other regulatory guidance.

10. The AD does not provide parts availability or provisioning guidance. The AD requires replacement per the ASB, but the document does not address procurement timelines, lead times for compliant clamps, or availability of approved clamp assemblies. Operators must consider potential supply constraints when scheduling the required work, especially given the short 50 flying hours/one month window for some helicopters.

These points highlight areas where an operator may inadvertently misinterpret scope, timing, or the technical standard and where cross‑checking with ASB para 2.B.4/2.B.5, DGAC documents and modification records is necessary.

The AD prescribes discrete compliance actions and timeframes. To comply with this AD, operators and maintenance organisations should take the following steps, strictly following the actions and time limits stated in the AD and the referenced ASB:

1. Establish applicability for each helicopter in the fleet. Check the aircraft type (SA 365 N or N1, AS 365 N2 or N3) and verify whether Mod 0729B67 has been embodied. The AD applies only to helicopters that are not modified per Mod 0729B67 (Applicability). If Mod 0729B67 is embodied, the AD does not apply under the instrument’s own wording.

2. Determine delivery-date cohort for each AS 365 N2/N3 helicopter. Identify whether each AS 365 N2/N3 was delivered before or after 1 January 1998. This determines which set of obligations applies: immediate replacement (post-1998) or inspection of the LH hydraulic clamp (pre-1998) (Requirement paras 1 and 3; Compliance paras 1 and 3).

3. Obtain Eurocopter ASB No. 29.00.08 dated 15 November 2005 and any later revisions approved by the French DGAC. The AD requires compliance in accordance with paragraph 2.B.4 for replacement and paragraph 2.B.5 for the left-hand hydraulic system inspection (Requirement paras 1 and 3). Ensure the ASB revision used has DGAC approval if not the 15 November 2005 edition.

4. For AS 365 N2/N3 helicopters delivered after 1 January 1998: Schedule and carry out replacement of attachment clamps per ASB para 2.B.4 within 50 flying hours or one month after the AD effective date, whichever occurs first, unless the replacement was already completed prior to the AD (Requirement para 1; Compliance para 1). Confirm the ASB’s specified clamp parts and installation procedure are followed exactly.

5. For AS 365 N2/N3 helicopters delivered prior to 1 January 1998, and for SA 365 N and N1 helicopters: Schedule and carry out the inspection of the attachment clamps on the left-hand hydraulic power system per ASB para 2.B.5 within 660 flying hours or 26 months after the AD effective date, whichever occurs first, unless the replacement has already been completed (Requirement para 3; Compliance para 3). Where the inspection identifies clamp damage or unsafe condition, perform the corrective action that the ASB or the AD requires.

6. Do not install any clamps with silicone protection on hydraulic pipes from the AD effective date. This prohibition is immediate and applies irrespective of whether a specific helicopter is otherwise subject to replacement or inspection timelines (Requirement paras 2 and 4; Compliance paras 2 and 4).

7. If the ASB specifies particular part numbers, materials or installation torque/retention criteria, ensure those specifications are strictly adhered to. The AD incorporates the ASB by reference as the technical standard. Use only the ASB procedures or later DGAC‑approved revisions as the procedural basis for replacement or inspection (Requirement paras 1 and 3).

8. Document compliance actions. While the AD text does not prescribe recordkeeping procedures, operators should record the work performed, the ASB revision relied upon, the flying hours at the time of replacement/inspection, and any parts fitted. This is necessary to establish that the AD’s time limits were met, and to demonstrate the prohibition on silicone-protected clamps was followed.

9. Plan parts procurement and logistics to meet the compliance windows. The 50 flying hours or one month timeframe for some helicopters is short. Coordinate with suppliers to secure ASB‑compliant clamps and schedule maintenance slots to meet the statutory period.

10. If there is uncertainty whether an action in the ASB or AD has been correctly interpreted, consult CASA or the supervising regulatory authority for clarification before performing work that could be noncompliant. The AD does not include an exemption mechanism in its text; any deviation from the AD’s mandatory steps should be discussed with the regulator.

11. Monitor DGAC and EASA guidance and any further revisions to the ASB or related DGAC ADs. The AD allows compliance with later revisions of the ASB provided those revisions are approved by the French DGAC (Requirement paras 1 and 3). Ensure that the revision used for compliance is indeed DGAC‑approved.

12. If an operator identifies silicone-protected clamps already fitted that are not replaced under the AD’s replacement schedule, treat them as prohibited from further installation and, where the AD requires replacement or inspection, address them according to the ASB’s corrective criteria.

Taken together, these steps implement the AD’s requirements as stated in the supplied instrument: confirm applicability and modification status, classify by delivery date, follow ASB procedural paragraphs 2.B.4 and 2.B.5 (or later DGAC‑approved revisions), meet the AD’s specified time windows, and adhere to the immediate prohibition on installing silicone-protected clamps.