AD/S-PUMA/58 Amdt 1 - Swashplate Bearing Attaching Screws

The Directive’s core technical concept is the integrity of swashplate bearing attaching screw heads on the main rotor mast assembly of Eurocopter AS 332 L2 helicopters. The swashplate bearing attaching screws secure components that transmit cyclic and collective control inputs from the control linkages into rotor blade pitch changes. The Directive responds to the discovery of a failed screw head and frames the hazard as progression that "could lead to a helicopter control loss" if screw head losses continue unchecked (Background).

Operationally, the document establishes procedural and temporal concepts:

• Inspection modality: a "visual or tactile check" as specified in paragraph 2.B. of Eurocopter Alert Telex AT 62.00.66 R1, or later DGAC approved revisions. The Directive does not itself reproduce the step‑by‑step inspection technique, rather it incorporates those instructions by reference (Requirement para 1).
• Flight-hour thresholds: the Directive pivots on a 750 flying hours threshold. Assemblies with less than 750 hours are subject to an initial deadline of 770 flying hours and then repeat intervals not exceeding 100 flying hours. Assemblies with 750 hours or more follow differentiated timing based on the date and recency of prior inspection under the original AD (Compliance).
• Conditional timing based on prior checks: where an assembly has been checked under the "AD/S-PUMA/58 original issue" less than 80 flying hours ago, the next check is due at the latest 100 flying hours after the last check with subsequent 100-hour intervals. Where checked more than 80 flying hours ago, the Directive requires a check "no later than within the next 20 flying hours after the effective date of this directive" then at intervals not exceeding 100 flying hours (Compliance).
• Actions on finding missing screw heads: remove installed main rotor mast assembly from service; for spares, "do not install the main rotor mast assembly" (Requirement para 3(a)-(b)).

The Directive also cross-references and incorporates external technical material: Eurocopter Alert Telex AT 62.00.66 R1 and "later DGAC approved revision", and it notes DGAC AD F-2005-129 and EASA approval No. 2005-6095 dated 13 July 2005 as references (Requirement note). The Directive therefore functions as a regulatory overlay that mandates adherence to Eurocopter's detailed inspection instructions as adopted or approved by the relevant foreign civil aviation authority.

Finally, the amendment character of the document is a main concept: it "incorporates the existing requirements of current Directive and introduces a periodic inspection" meaning it modifies the original AD/S-PUMA/58 (Background). The original issue of the Directive became effective on 9 May 2005, and this Amdt 1 became effective on 10 September 2005. Those dates and the amendment structure matter for operators because compliance timing is defined relative to the effective date and prior compliance under the original directive.

The Applicability clause is precise: the Directive applies to "Eurocopter AS 332 L2 helicopters." That is the entire scope of applicability stated in the source. Practically, the following groups and resources are directly affected by the Directive:

• Operators and owners of Eurocopter AS 332 L2 helicopters, including commercial, governmental, and private operators who deploy these airframes. They bear the operational and maintenance burdens imposed by the checks and removal/installation restrictions.
• Maintenance organisations, aircraft engineers and licensed maintenance personnel who are responsible for carrying out the "visual or tactile check in order to make sure that all screw heads are in place" in accordance with Eurocopter AT 62.00.66 R1 or later DGAC approved revision (Requirement para 1). These personnel must be familiar with and able to implement the procedures set out in the referenced Alert Telex.
• Logistics and parts managers responsible for main rotor mast assemblies held as spares. The Directive imposes a specific requirement on spares having "logged more than 750 flying hours since new or overhaul", which must comply with paragraph 2.B of Eurocopter AT 62.00.66 R1 prior to installation (Requirement para 2). This affects inventory decisions about whether a spare can be installed, and may trigger refurbishment or avoidance of certain spare items.
• Flight operations and dispatch officers who must ensure that checks required "before further flight" or "before installation in a helicopter" are completed, especially where the Directive prescribes such pre-flight or pre-installation actions (Compliance para 2 and 3).
• Aircraft certification or compliance staff tracking airworthiness directives and maintaining the aircraft’s compliance records. The Directive’s time-based and flight-hour-based triggers require monitoring of logged flight hours and the history of prior checks under the original AD/S-PUMA/58.
• Regulatory personnel and safety managers who must consider the operational impact, scheduling and potential aircraft downtime created by the inspections and removal requirements, because the Directive’s measures can affect fleet availability.

The Directive’s text does not extend applicability beyond the AS 332 L2 type. It does not directly name other variants or other Eurocopter types. The note referring to DGAC AD F-2005-129 and EASA approval suggests co‑ordination with foreign airworthiness authorities, but the express applicability in this instrument is limited to AS 332 L2 helicopters (Applicability; Requirement note).

Who pays and who decides. The immediate economic cost falls on the operators and maintenance organisations who will perform the checks, remove mast assemblies where required, and manage spares compliance. The decision-maker issuing the requirement is the Civil Aviation Safety Authority, represented here by its delegate, who signed the Directive (James Coyne, Delegate of the Civil Aviation Safety Authority, 2 September 2005). The Directive itself delegates the technical inspection procedure to Eurocopter AT 62.00.66 R1 or later DGAC-approved revisions, meaning technical practice is determined by the manufacturer’s Alert Telex as adopted through DGAC approval (Requirement).

The Directive imposes distinct, mandatory duties; it does not enumerate rights in express terms. Key duties for relevant parties flow from the Requirement and Compliance sections and can be summarised as follows:

Inspection duties

• Perform a "visual or tactile check" to ensure "that all screw heads are in place", in accordance with paragraph 2.B. of Eurocopter Alert Telex AT 62.00.66 R1 or a later DGAC approved revision (Requirement para 1). The Directive does not restate the detailed inspection steps, it incorporates them by reference to the Eurocopter AT.
• For main rotor mast assemblies held as spares that have logged more than 750 flying hours since new or overhaul, comply with the instructions in paragraph 2.B of the Eurocopter AT before installation (Requirement para 2).

Timing duties

• For installed main rotor mast assemblies with less than 750 flying hours since new or last overhaul: perform the first check by 770 flying hours, thereafter at intervals not exceeding 100 flying hours (Compliance para 1 first limb).
• For installed assemblies with 750 flying hours or more, the next check timing depends on prior checks under the original AD: if the last check under the original AD was less than 80 flying hours ago, perform the next check by 100 flying hours after that last check and then at 100-hour intervals; if the last check under the original AD was more than 80 flying hours ago, perform a check within the next 20 flying hours after the effective date of this Amendment, then at intervals not exceeding 100 flying hours (Compliance para 1 second limb).

Pre-installation and pre-flight duties

• Conduct the required checks "before installation in a helicopter" and "before further flight" as applicable (Compliance para 2 and 3).

Removal and installation prohibition

• If a check reveals that "one or more than one screw heads are missing", operators must remove the installed main rotor mast assembly from service, and must not install a main rotor mast assembly held as a spare where screw heads are missing (Requirement para 3(a)-(b)).

Delegation of technical method

• The Directive delegates the specific inspection technique and any corrective instructions to "paragraph 2.B. of Eurocopter Alert Telex (AT) 62.00.66 R1 or later DGAC approved revision." Therefore the practical content of duties (how the check is performed, any torque or replacement instructions) is determined by that referenced document.

Rights and lack of express alternatives

• The Directive does not state any alternative compliance pathway within its text such as an alternative method of compliance, nor does it specify a process to seek exemptions or deferment. It does not articulate any appeal or review mechanisms in the text provided. It also does not specify maintenance recordkeeping obligations, although effective execution necessarily requires operators to know flight-hour history and prior inspection dates to apply the timing rules.

Operational discretion

• The Directive prescribes specific actions but leaves certain operational matters to the operator’s discretion within the constraints set by the AD and the referenced Eurocopter AT: for example, how to schedule inspections to fit maintenance cycles, how to manage spares inventory, and which maintenance personnel carry out the tactile/visual checks. The Directive, however, does not furnish a formal discretionary process to alter the prescribed intervals.

Summary of duties: perform Eurocopter AT‑specified visual or tactile checks at the stated hours and intervals; do not operate aircraft with main rotor mast assemblies missing screw heads; do not install spares with missing screw heads; and adhere to the 750/770/100/80/20 flight-hour timing rules as specified in the Compliance provisions.

The Directive text itself does not set out civil, administrative or criminal penalties, nor does it specify an enforcement mechanism or sanctioning process. The instrument is framed as an Airworthiness Directive that prescribes required maintenance and operational steps, and it is signed by a CASA delegate (James Coyne) with an effective date of 10 September 2005 (signature and dates). Beyond setting mandatory actions and timelines, the Directive does not, within the supplied text, describe how compliance will be verified or what penalties may follow for non‑compliance.

Because the Directive requires particular checks and removal actions in specified circumstances, the practical enforcement implications operators should note from the text are:

• Timing and traceability pressures: the Compliance section ties mandatory inspections to logged flying hours and prior AD check timings. To demonstrate that an aircraft meets the Directive’s duties, an operator must be able to show the aircraft’s flight-hour history and the timing of prior checks. The Directive itself does not state recordkeeping requirements, but the control of timing implies that evidence of hours and prior compliance will be relevant when regulators or auditors examine compliance.
• Immediate operational consequences for non‑compliance with the substantive safety action: the Directive expressly requires removal from service if missing screw heads are discovered, and prohibits installation of spares with missing screw heads. Those are operational enforcement steps embedded in the obligations; an operator who fails to follow those steps would, at minimum, continue operating aircraft with a identified unsafe condition according to the Directive’s own hazard statement that missing screw heads "could lead to a helicopter control loss" (Background).
• Cross-reference to manufacturer and to foreign authority approvals: the Directive incorporates Eurocopter AT 62.00.66 R1 and notes DGAC AD F-2005-129 and EASA approval No. 2005-6095. Those cross-references indicate that the technical instructions are endorsed by the manufacturer and, through the DGAC and EASA reference, have been the subject of foreign oversight. While the Directive text does not itself impose enforcement mechanisms, it situates the required actions within internationally recognised technical material, which may be relied upon by auditors or investigators when assessing compliance.

In short, the Directive specifies mandatory actions but does not enumerate penalties or enforcement procedures in its text. The only enforcement signals in the instrument are the mandated removal/installation prohibitions and the fixed timing obligations that create measurable compliance requirements; the document’s signatory and effective date identify the issuing authority and the point from which compliance is expected.

The Directive interacts explicitly with two types of external instruments by incorporation and reference, and implicitly with prior directives through its amendment nature.

Incorporation by reference to manufacturer material

• The Directive requires inspections "in accordance with paragraph 2.B. of Eurocopter Alert Telex (AT) 62.00.66 R1 or later DGAC approved revision" (Requirement para 1). That language effectively integrates the Eurocopter Alert Telex into the Directive’s operative obligations by reference. The practical effect is that the manufacturer’s technical guidance, as approved by the DGAC (the French civil aviation authority), supplies the specific inspection method and possibly corrective actions that operators must follow when complying with this AD.

Cross‑reference to foreign airworthiness decisions

• The note in the Requirement references "DGAC AD F-2005-129 EASA approval No. 2005-6095 dated 13 July 2005." This signals that the underlying safety concern and technical solution have been considered and acted upon by other airworthiness authorities, notably the DGAC and EASA. The Directive therefore aligns CASA’s requirement with action taken by those bodies, incorporating foreign-approved technical material into domestic regulatory action.

Interaction with the original Directive

• The instrument is labelled an amendment: "AD/S-PUMA/58 Amdt 1" and the Background states that "This amendment incorporates the existing requirements of current Directive and introduces a periodic inspection" and notes that the "original issue of this Directive became effective on 9 May 2005." Consequently, compliance obligations depend in part on previous compliance with the original AD. The Compliance section explicitly conditions timing on whether an assembly "Was checked in compliance with AD/S-PUMA/58 original issue less than 80 flying hours ago" or "Was checked in compliance with AD/S-PUMA/58 original issue more than 80 flying hours ago." That creates an explicit temporal interaction between the earlier directive and this amendment; the amendment does not stand alone but modifies the operators’ schedule based on prior actions taken under the original AD.

No express interaction with other domestic legislation in the text

• The supplied instrument does not mention other domestic legal instruments, such as the statutory aviation safety act, regulations, or enforcement provisions. It does not specify how it is adopted into domestic law, nor does it state whether compliance with the Directive constitutes compliance with any other regulatory obligation. The instrument therefore operates by imposing explicit maintenance and operational requirements while relying on the reader’s understanding of the airworthiness directive mechanism; however the document itself contains no textual linkage to other domestic legal provisions.

Net effect

• Within the bounds of the source, the Directive functions as a targeted operative instrument that imports manufacturer instructions and foreign authority approvals, and that modifies an earlier domestic directive. For operators and maintenance organisations, this means compliance is not only an internal maintenance matter, it is compliance with an instrument that cross-references and depends on both the Eurocopter Alert Telex and prior AD history, requiring coordination across technical documentation and historical compliance records.

The supplied text documents a narrow amendment history tied to a specific sequence of directives. The key facts in the instrument are:

• Original Directive: The Background states "The original issue of this Directive became effective on 9 May 2005." That original AD is the predecessor instrument referenced throughout the amendment and is explicitly called "AD/S-PUMA/58 original issue" in the Compliance section.
• Amendment designation: The instrument is presented as "AD/S-PUMA/58 Amdt 1", indicating it is the first amendment to the original AD/S-PUMA/58 (header and repeated labels).
• Amendment effective date: The amendment text states "This Amendment becomes effective on 10 September 2005." The directive is signed by a delegate of CASA (James Coyne) on "2 September 2005," which is the signature date preceding the effective date (signature and effective date).
• Substance of the amendment: The Background explains the amendment "incorporates the existing requirements of current Directive and introduces a periodic inspection of the swashplate bearing attaching screw heads integrity." Therefore the amendment adds a periodic inspection regime that was not part of the original issue, in addition to retaining the original directive’s requirements.
• Referential approvals: The requirement section includes a note: "DGAC AD F-2005-129 EASA approval No. 2005-6095 dated 13 July 2005 refers." This indicates the amendment’s technical basis or concurrence aligns with earlier foreign authority decisions dated 13 July 2005, which predate both the original AD effective date and the amendment. The amendment therefore situates the domestic action in a contemporary international airworthiness context.

Operational consequence of the amendment history

• The Compliance timings explicitly use the amendment and original issue dates as anchors to create different obligations depending on prior compliance under the original AD. For example, if an assembly "Was checked in compliance with AD/S-PUMA/58 original issue less than 80 flying hours ago", the subsequent inspection schedule under the amendment differs from assemblies checked more than 80 flying hours ago. This conditional scheduling logic makes the amendment directly dependent on the operational history of compliance with the original AD.

No further revisions recorded in the supplied text

• The supplied material contains no subsequent amendments, cancellations, or superseding directives beyond Amdt 1. It therefore presents a snapshot showing the original AD effective 9 May 2005 and the first amendment effective 10 September 2005, with cross-reference to DGAC/EASA approval actions taken on 13 July 2005.

For legal or compliance tracking purposes, the supplied lines make clear that operators must account for both the original AD and Amdt 1 when determining inspection deadlines and intervals.

The supplied instrument contains no litigation history. The text does not reference any legal proceedings, disputes, judicial review, or contested enforcement actions relating to AD/S-PUMA/58 or its Amendment 1. There are no cases named in the Directive, and no citations to litigation decisions or appellate rulings.

Consequently, within the bounds of the provided source, there is no recorded or cited judicial engagement, challenge, or interpretation of the Directive’s legal status, its technical prescriptions, or its compliance requirements. The instrument records administrative facts: an original AD effective on 9 May 2005, the amendment effective on 10 September 2005, the technical references to Eurocopter AT 62.00.66 R1 and DGAC/EASA approvals, and the signature of a CASA delegate (James Coyne) dated 2 September 2005.

Implications for practitioners

• Because the source does not list litigation history, practitioners relying on this document therefore cannot draw on judicial interpretation or precedent from the text itself. Any questions about enforceability, appealability, or the scope of the directive vis-à-vis other regulatory instruments would require external legal research beyond the supplied material. The Directive as provided is a primary administrative instrument with no accompanying case law or judicial commentary in the source.

If the reader requires legal precedents or contested history to guide interpretation or to understand enforcement experience, they must consult external sources not contained in the supplied text. Within the document, the only historical legal/administrative items are the dates of original issue and of amendment, and the cross-references to foreign authority approvals, none of which are described as having been litigated.

The Directive contains a number of implementation subtleties that can be operational pitfalls if misread. These are explicit in the text and derive from the way obligations are phrased and timed.

1. Reliance on a referenced technical document for the inspection method

• The Directive requires checks "in accordance with paragraph 2.B. of Eurocopter Alert Telex (AT) 62.00.66 R1 or later DGAC approved revision" but does not reproduce paragraph 2.B in full. Operators must obtain and apply that Eurocopter AT precisely. A gotcha is assuming the Directive’s language alone is sufficient; the detailed tactile/visual technique and any corrective steps are in the Eurocopter AT, not in the AD text (Requirement para 1).

2. Distinct rules for spares versus installed assemblies

• The Directive treats installed main rotor mast assemblies and spares differently. A spare "that have logged more than 750 flying hours since new or overhaul" must comply with the instructions in paragraph 2.B prior to installation (Requirement para 2). A mistaken assumption that spares are exempt would be incorrect where flight hours exceed 750.

3. Complex timing rules tied to prior compliance under the original AD

• The Compliance section creates timing paths based on whether an assembly "Was checked in compliance with AD/S-PUMA/58 original issue less than 80 flying hours ago" or "more than 80 flying hours ago." If the last check under the original AD was more than 80 hours before the amendment, the Directive requires the check "no later than within the next 20 flying hours after the effective date of this directive." Operators must therefore know both flight hours and the timing of any original-AD checks to apply the correct schedule. Failure to reconcile prior check history with the amendment’s deadlines may lead to missed deadlines.

4. Tight short-term deadlines for certain assemblies

• Where the assembly was checked under the original AD more than 80 flying hours ago, the operator has at most 20 flying hours from the amendment’s effective date to perform the check. That is a narrow compliance window that can have operational impact if not anticipated (Compliance).

5. Multiple overlapping thresholds: 750, 770, 80, 100, 20

• The Directive uses multiple numerics: 750 flying hours is the pivot; an initial deadline is set at 770 flying hours for those under 750; inspections then occur "at intervals not exceeding 100 flying hours"; the 80-hour threshold determines which timing path applies for assemblies already checked; and a 20 flying-hours grace window applies in a specified case. Misapplication of any one of these numbers, or confusion between "since new or last overhaul" and "since last check," could produce incorrect scheduling.

6. Immediate pre‑flight or pre‑installation checks

• The Compliance section includes "Before installation in a helicopter" and "Before further flight" as required moments for checks (Compliance paras 2 and 3). Those are stand-alone obligations and may catch operators who assume only periodic scheduled maintenance must include the check. A gotcha is relying solely on scheduled maintenance windows without accounting for pre-installation or pre-flight triggers.

7. Action on missing screw heads is absolute

• The Directive gives no remedial option for installed assemblies found to be missing screw heads other than removal from service. For spares with missing screw heads, the rule is "do not install." There is no text in the AD allowing temporary operation or an alternate fix; the operator must remove or withhold installation.

8. Cross-references to foreign approvals do not replace local compliance

• The Directive notes DGAC and EASA references, but domestic compliance obligations are set by this AD. Treating the DGAC/EASA references as a substitute for domestic action would be a mistake; the domestic AD prescribes what domestic operators must do.

9. No procedural text on recordkeeping, exemptions, or alternative methods

• The AD contains no process for seeking alternatives, nor any recordkeeping prescription. Operators may need to decide on internal documentation practices to evidence compliance, but the AD does not define acceptable formats or retention periods. That leaves a gap in procedural clarity that operators must bridge administratively.

10. Applicability is narrow

• The instrument only names "Eurocopter AS 332 L2 helicopters." Assuming it applies to other Super Puma variants, or to rotor mast assemblies of other types, would be incorrect on the face of the AD.

Practitioners should therefore ensure they have the Eurocopter AT referenced, verify flight-hour histories and prior check dates against the original AD, differentiate installed units from spares, and apply the tight deadlines, particularly the 20-hour window where triggered.

Compliance with AD/S-PUMA/58 Amdt 1 requires translating the directive’s text into operational procedures. The following steps map directly to the instrument’s mandatory content and reflect practicable implementation measures, while remaining within the scope of the Directive’s language.

1. Obtain the referenced technical material

• Secure a copy of "Eurocopter Alert Telex (AT) 62.00.66 R1 or later DGAC approved revision" and identify paragraph 2.B. The Directive mandates that the inspection be "in accordance with paragraph 2.B", therefore the Eurocopter AT contains the operative inspection technique, acceptance criteria, and any corrective actions. Do not attempt to perform the check without consulting the Alert Telex.

2. Identify affected assets

• Compile an accurate inventory of all Eurocopter AS 332 L2 helicopters in the operator’s control. For each helicopter, identify the installed main rotor mast assembly and any main rotor mast assemblies held as spares. For each assembly, record "flying hours since new or overhaul" as the Directive uses that metric for distinguishing obligations (Applicability; Requirement).

3. Establish flight-hour tracking and prior-check history

• For each main rotor mast assembly, document:
  • Total flying hours since new or last overhaul.
  • Dates and flight hours at which any checks were previously performed under the "AD/S-PUMA/58 original issue." The Compliance obligations turn on these tracked values: whether an assembly has logged more or less than 750 flying hours; whether a previous check under the original AD occurred less than or more than 80 flying hours ago; and whether an assembly with less than 750 hours needs its first check at 770 hours.

4. Schedule and perform the inspections

• For installed main rotor mast assemblies with less than 750 flying hours: schedule the visual or tactile check no later than at 770 flying hours; thereafter schedule inspections at intervals not exceeding 100 flying hours (Compliance para 1).
• For installed assemblies with 750 flying hours or more, apply the conditional timing:
  • If the assembly "Was checked in compliance with AD/S-PUMA/58 original issue less than 80 flying hours ago": schedule the next check "at the latest 100 flying hours following the last check" and thereafter at intervals not exceeding 100 flying hours.
  • If the assembly "Was checked in compliance with AD/S-PUMA/58 original issue more than 80 flying hours ago": schedule a check "no later than within the next 20 flying hours after the effective date of this directive", then at intervals not exceeding 100 flying hours.
• For spares with more than 750 flying hours, perform the Eurocopter AT paragraph 2.B procedures before installation (Requirement para 2).
• Ensure checks required "before installation in a helicopter" or "before further flight" are performed as explicitly required (Compliance paras 2 and 3).

5. Execute the inspection method exactly as per the Eurocopter AT

• Perform the Eurocopter AT’s paragraph 2.B visual or tactile checks. If the AT specifies tools, safety precautions, or positions for tactile verification, follow those instructions. The AD incorporates that method by reference rather than restating it.

6. Actions if missing screw heads are found

• If any check reveals "one or more than one screw heads are missing":
  • For assemblies installed in a helicopter: immediately remove the main rotor mast assembly from service (Requirement para 3(a)).
  • For assemblies held as spares: do not install the main rotor mast assembly (Requirement para 3(b)).
• There is no alternative remedial option in the Directive; removal and non-installation are the specified actions.

7. Manage spares inventory and overhaul decisions

• Identify any spares with more than 750 flying hours and subject them to the paragraph 2.B procedure before considering installation. Consider whether to overhaul, repair, or discard spares that fail inspection to maintain fleet readiness.

8. Integrate AD timing into maintenance planning

• Incorporate the 100-hour periodic inspection interval into the operator’s maintenance schedule, ensuring checks are aligned with other scheduled maintenance where possible to reduce aircraft downtime. Note that the Directive requires checks "at intervals not exceeding 100 flying hours", so scheduling must ensure the interval does not exceed that cap.

9. Documentation and proof of compliance

• Although the Directive does not state specific documentary formats, maintain contemporaneous records of:
  • Which assemblies were inspected, by whom and when.
  • Flight hours at the time of inspection.
  • Findings of the inspections, particularly any missing screw heads.
  • Any removal-from-service decisions and spares withheld from installation.
• Retain copies of the Eurocopter AT used to perform the method, and note the specific revision approved by DGAC if applicable. These documents will be necessary to demonstrate compliance should an auditor or investigator request evidence.

10. Communicate with flight operations

• Before returning an aircraft to service after an inspection, ensure the inspection is completed "before further flight" where that requirement applies. Communicate with operations and dispatch to prevent flight departures with pending checks.

11. Monitor for future amendments and foreign authority actions

• Note the Directive’s cross-reference to DGAC AD F-2005-129 and EASA approval No. 2005-6095 dated 13 July 2005. Monitor for further DGAC, EASA or CASA updates to the Eurocopter AT or to AD/S-PUMA/58 that could change inspection methods or intervals.

These steps, tied directly to the Directive’s operative text, convert the AD into an auditable maintenance process. The principal compliance tasks are to obtain the referenced Eurocopter AT paragraph 2.B, track flight hours and prior AD check history, schedule and conduct tactile/visual inspections at the specified times, and remove or withhold from installation any mast assembly found with missing screw heads.