AD/GBK 117/18 Amdt 1 - Tail Rotor System - Control Lever - Inspection/Replacement

Applicability and scope: The AD applies only to MBB-BK 117C-2 helicopters fitted with Tail Rotor Control Lever P/N B642M1009103 (Applicability). That is a narrow equipment-and-model trigger. Helicopters without that specific lever are outside the specified scope in this instrument.

Specified unsafe condition and causal fact pattern: The Background records an in-flight incident in which a dynamic weight separated from the control lever and the threaded bolt of the control lever had broken off. The immediate safety risk identified is separation of dynamic weights leading to considerable vibration and reduced controllability (Background). The AD responds to that specific failure mode by prescribing inspections for damage to the control lever and replacement of the affected components.

Two-stage control strategy: The AD implements a two-stage approach. Stage one is an interim mitigation: a repeated visual inspection regime carried out in accordance with section 3.A of EUROCOPTER DEUTSCHLAND Alert Service Bulletin MBB BK117 C-2-64A-002 Revision 02, with a mandatory short interval not exceeding 8 flight hours (Requirements 1 and 2; Compliance). Stage two is a termination measure: replacing the older control lever P/N B642M1009103 and associated weight P/N B642M1011202 with the improved assembly P/N B642M1009104, in accordance with section 3.B of the Alert Service Bulletin, which removes the requirement for further repetitive inspections on that helicopter (Requirement 4).

Parts and part-number control: The AD identifies both the offending parts and the replacement parts by P/N. It mandates removal of P/N B642M1009103 and weights P/N B642M1011202 and installation of the improved assembly P/N B642M1009104 (Requirement 4). It then prohibits installation of the old lever P/N B642M1009103 on any helicopter from the stated date (Requirement 5). This creates a hard inventory control point: the older part becomes unusable for installation once the prohibition is in force.

Interaction with EUROCOPTER documentation and EASA ADs: The AD instructs operators to follow specific sections of the EUROCOPTER Alert Service Bulletin (section 3.A for inspection, section 3.B for replacement) and allows the use of subsequent EASA-approved revisions of that ASB (Requirement 1). It explicitly references, and supersedes, earlier EASA AD action (Background). The AD therefore positions the manufacturer’s ASB and EASA ADs as operational references for accomplishment instructions.

Timelines and effectivity: The amendment becomes effective 11 September 2007. It provides phase-in timelines: immediate inspection requirements before further flight for helicopters not yet inspected, and defined short flight-hour windows for helicopters already inspected under the original AD (Compliance). The terminating replacement had a calendar deadline: before 25 November 2007 (Compliance). The AD supersedes an earlier EASA AD and references another EASA AD number (Background).

Regulatory instrument type: This is an Airworthiness Directive, an operational regulatory instrument that imposes mandatory maintenance action and part-change requirements on affected aircraft. The AD is signed by the CASA delegate, reflecting the administrative authority enforcing it (signature block).

Operators and owners of MBB-BK 117C-2 helicopters fitted with Tail Rotor Control Lever P/N B642M1009103 are directly affected. The Applicability clause confines the AD to that model-part combination, so those who own or operate that variant must ensure the AD requirements are accomplished. The AD language uses compulsory phrasing such as "before further flight" and "do not install" which applies to the operator and maintenance organisation with responsibility for the helicopter’s airworthiness (Requirement 1, Requirement 5; Compliance).

Maintenance organisations, engineers and certifying staff are affected because the AD mandates specific inspection procedures and part replacements "in accordance with section 3.A" and "section 3.B" of the EUROCOPTER ASB (Requirement 1 and 4). Those instructions are the prescribed method of compliance and therefore determine the technical steps that maintenance providers must take and sign off.

Supply chain actors who hold stock of the listed part numbers are affected. The AD requires replacement of P/N B642M1009103 and associated weights P/N B642M1011202 with P/N B642M1009104 and, from a stated date, prohibits installation of the older P/N B642M1009103 (Requirement 4 and 5; Compliance). That affects spare parts inventories for owners, maintenance providers, and suppliers. If an operator relies on the older P/N for spares, the AD compels them to procure the improved part and remove the legacy item from service inventories for installation.

Regulators and oversight entities are affected administratively. The AD references an earlier EASA Emergency AD and indicates that the original issue of this AD became effective 30 August 2007 and that this amendment became effective on 11 September 2007 (Background; Compliance). The CASA delegate executed the amendment; that indicates the instrument’s provenance and which regulator issued the enforceable direction in this jurisdiction (signature block).

Less directly affected parties: insurers and lessors may be affected contractually because the AD imposes mandatory maintenance and replacement obligations that could influence aircraft availability and maintenance records. The AD itself does not reference insurance or leasing, but where the AD is applicable, the operator must accomplish the action prior to further flight in certain cases and within short flight-hour windows in others (Compliance).

No broader fleet is captured by the AD. The Applicability clause narrows the scope to the specific model and part number, so other BK 117 variants or helicopters without that P/N are outside the instrument’s coverage (Applicability).

Mandatory inspection duty: Operators of applicable helicopters must perform a visual inspection of the Tail Rotor Control Lever P/N B642M1009103 in accordance with section 3.A of EUROCOPTER DEUTSCHLAND Alert Service Bulletin MBB BK117 C-2-64A-002 Revision 02, or a subsequent EASA-approved revision (Requirement 1). The inspection must be repeated at intervals not to exceed 8 flight hours until terminating replacement occurs (Requirement 2; Compliance).

Mandatory replacement duty for damaged parts: If any inspection detects "score marks, notching, scratching, cracks or similar damage", the AD requires replacement of the affected control lever with an airworthy part (Requirement 3). That replaces any discretion about temporary repairs; the AD mandates part replacement upon discovery of listed damage types.

Mandatory fleet replacement and terminating action: The AD requires replacement of all P/N B642M1009103 Tail Rotor Control Levers and Weights P/N B642M1011202 with the improved P/N B642M1009104 Tail Rotor Control Levers including weights, in accordance with section 3.B of the ASB (Requirement 4). Once the improved assembly is installed on an individual helicopter the repetitive 8 flight-hour inspections no longer apply to that helicopter. This gives operators a clear compliance pathway: a replacement that eliminates recurring inspection obligations for each retrofitted airframe.

Installation prohibition: From the stated date (specified as "From 25 November 2007"), the AD forbids installing P/N B642M1009103 Tail Rotor Control Levers on any helicopter (Requirement 5; Compliance). That is an affirmative prohibition that restricts ongoing maintenance choices and spare-part usage from that date.

Timing constraints and prioritisation: The Compliance section creates different immediate obligations depending on prior compliance with the original AD. Helicopters not inspected under the original AD must be inspected before further flight after the effective date. Helicopters already inspected must be reinspected within the next 8 flight hours or before accumulating 25 flight hours after the last inspection, whichever occurs first (Compliance). The terminating replacement had to be completed before 25 November 2007 (Compliance). These timelines force prioritisation of maintenance resources and scheduling to meet the mandated windows.

Reference-to-manufacturer instructions as mandated method: Compliance must be done "in accordance with" specified sections of the EUROCOPTER Alert Service Bulletin, including allowance for subsequent EASA-approved revisions (Requirements 1 and 4). This ties the legal duty to the manufacturer's specified procedures, removing ambiguity about acceptable inspection and replacement techniques.

Rights or remedies: The AD text contains no express provision granting discretionary deferral, alternate means of compliance, or exemptions; nor does it state appeal or variance processes. The AD does indicate that subsequent EASA-approved revisions of the ASB are acceptable for accomplishing inspections and replacement (Requirement 1), which offers a limited pathway for updated technical methods once EASA approves them.

Delegated administrative authority: The AD is signed by a CASA delegate, showing that the national regulator executed the directive locally (signature block). The AD also explicitly references EASA ADs and the manufacturer’s ASB as the operational standards to implement the AD’s duties (Background; Requirements 1 and 4).

The AD text itself does not specify monetary penalties, criminal sanctions, or enforcement procedures within its language. It sets out mandatory actions and deadlines, such as inspections "before further flight" in certain circumstances, repetitive inspections at intervals not to exceed 8 flight hours, replacement of damaged parts, fleet replacement by a calendar date, and a prohibition on installing the identified older part number from a stated date (Requirements 1 to 5; Compliance). Those mandates function as enforceable regulatory requirements within the aviation safety regime, but the AD does not include explicit penalty clauses in the instrument as presented.

Enforcement mechanism implied by the AD: The instrument is an Airworthiness Directive signed by the Civil Aviation Safety Authority delegate (signature block). In regulatory practice, ADs are enforceable directions that become conditions on continued airworthiness; compliance is usually recorded in maintenance records and may be checked during regulatory oversight, airworthiness reviews, or inspections. The AD makes clear when actions must be accomplished relative to flight hours and calendar dates, and it cross-references the EUROCOPTER ASB as the required method of accomplishment (Requirements 1 and 4; Compliance). The presence of "before further flight" language is operationally significant, because it makes certain actions prerequisites to legal flight operations under the applicable safety regime.

No non-compliance penalties specified in document: The AD does not set out fines, licence suspensions, or criminal sanctions. It also does not describe the process for granting exemptions, extensions, or alternate means of compliance. The AD does, however, supersede earlier EASA ADs and references EASA Emergency ADs, situating itself in the chain of mandatory airworthiness directives (Background). Any enforcement consequences for failing to comply would therefore arise under the broader aviation regulatory framework rather than from penalty provisions embedded within this AD text.

Operational enforcement points of friction: The AD requires maintenance organisations to follow specific ASB sections for inspection and replacement (Requirements 1 and 4). Inspectors or auditors verifying compliance will look for documentation that these steps were carried out in accordance with the ASB and within the AD’s flight-hour and calendar limits. The text therefore creates recordkeeping and proof obligations for operators and maintainers: showing that inspections were performed at the required frequency, that damaged parts were replaced, and that the terminating replacement was accomplished by the specified deadline.

References to EASA ADs and the EUROCOPTER ASB: The AD explicitly references and interacts with EASA documentation. It cites EUROCOPTER DEUTSCHLAND Alert Service Bulletin MBB BK117 C-2-64A-002 Revision 02 as the prescribed accomplishment instructions for inspections and replacement, and allows subsequent EASA-approved revisions to be used (Requirement 1). The Background notes that EASA previously issued an Emergency AD (EASA AD 2006-0379-E) and refers to EASA AD 2007-0237 dated 31 August 2007, and states that the AD supersedes EASA AD 2007-0189 E (Background). Thus the instrument places itself in the chain of EASA safety directives and manufacturer service instructions.

Supersession and precedence: The AD expressly supersedes an earlier EASA AD (Background). In jurisdictions where both EASA and the national authority issue directives, this AD indicates that the national amendment supersedes the referenced EASA AD for the fleet it applies to. The AD therefore functions as the operative instrument in this national context, while still tying technical compliance to the manufacturer’s ASB and EASA approvals.

No other statutes or civil aviation regulations referenced: The AD text does not cite specific civil aviation statute sections, criminal law, or administrative penalty provisions. It does not note interaction with contracts, leasing laws, insurance law, or commercial obligations. Any such interactions would arise indirectly because an AD imposes an airworthiness requirement; however those cross-cutting legal effects are not described in this AD text.

No statutory exemption or appeals process set out here: The AD does not specify how to seek an exemption, extension, or alternative means of compliance within the document. The only path for adjusting technical accomplishment appears to be via using subsequent EASA-approved revisions of the manufacturer’s ASB (Requirement 1). Any broader procedural interactions with administrative law, judicial review, or variance processes would derive from the applicable aviation safety legislation and national regulatory framework rather than from the AD itself; the AD does not document those processes.

Technical standard alignment: The AD aligns the legal obligation to comply with the manufacturer’s ASB. It makes the ASB sections the required method of accomplishment and references EASA approval for any subsequent revisions. This channels the technical standard-setting function to the manufacturer and EASA while the national regulator makes the compliance mandatory through the AD.

This AD is an amendment to AD/GBK 117/18. The text records a sequence of related directives and dates. The Background notes that EASA had issued an Emergency AD (EASA EAD 2006-0379-E) in response to an in-flight incident, and later issued EASA AD 2007-0237 dated 31 August 2007; the AD text also states that it supersedes EASA AD 2007-0189 E (Background). The original issue of this AD became effective on 30 August 2007 (Background). This amendment, AD/GBK 117/18 Amendment 1, became effective on 11 September 2007, as stated in the Compliance block (Compliance; effective date line).

Service bulletin revisions and approvals: The AD mandates use of EUROCOPTER DEUTSCHLAND Alert Service Bulletin MBB BK117 C-2-64A-002 Revision 02 dated 6 August 2007, or a subsequent EASA-approved revision, for the inspection and replacement procedures (Requirement 1). This ties amendment compliance to the current or future EASA-approved versions of the ASB, and allows the technical content of compliance to evolve if EASA approves a later ASB revision.

Directive content changes in the amendment: The amendment introduces or confirms a fleet replacement requirement and a terminating action: replace all P/N B642M1009103 levers and P/N B642M1011202 weights with improved P/N B642M1009104 assemblies by a specified date (Requirement 4; Compliance). It also clarifies and prescribes inspection intervals of not more than 8 flight hours until replacement is accomplished (Requirement 2; Compliance). The amendment formalises the prohibition on installing the older P/N after 25 November 2007 (Requirement 5; Compliance).

Administrative sign-off and promulgation: The AD is signed by the CASA delegate Charles Lenarcic and dated 6 September 2007 (signature block). The text states the Amendment becomes effective 11 September 2007 (Compliance). The presence of the delegate’s signature and the effective date demonstrate the administrative steps and timing for promulgation.

No subsequent amendments recorded in the document: This AD text records the immediate amendment history up to Amendment 1 and references earlier EASA ADs. The document does not list any further amendments, revisions, or revocations beyond the scope described in the text.

The AD text does not contain, cite, or summarise any litigation history. It references manufacturer action and EASA emergency and follow-on ADs, and it states that the original issue of this AD became effective on 30 August 2007 and that this Amendment becomes effective 11 September 2007 (Background; Compliance). No court decisions, appeals, administrative law determinations or legal challenges are mentioned in the document.

Because the instrument itself contains no litigation record or case citations, there is no litigation history to report from this source. Any judicial or administrative proceedings relating to the AD, its enforcement, or disputes about compliance would not be visible in this AD text and therefore are not recounted here.

Applicability narrowness can be misread: The AD applies only to MBB-BK 117C-2 helicopters fitted with Tail Rotor Control Lever P/N B642M1009103 (Applicability). Operators or maintainers who assume the AD covers all BK 117 variants or different part numbers risk unnecessary work or, conversely, missing the obligation for the aircraft that actually carry the specified P/N. Confirm the exact P/N on the aircraft before assuming applicability.

Short inspection interval until termination: The required repetitive inspection interval is not typical calendar-based maintenance spacing. The AD requires inspections at intervals not to exceed 8 flight hours (Requirement 2). That is a very short flight-hour interval that may require multiple inspections in a day for some operational profiles. Operators must account for the operational impact and ensure inspections are logged and scheduled precisely. Misinterpreting the "not to exceed 8 FH" interval, or failing to track flight hours accurately, will leave gaps in compliance.

Differing immediate obligations depending on prior compliance: The Compliance clause creates distinct immediate requirements depending on whether the helicopter had been inspected under the original AD. Helicopters not inspected under the original issue must be inspected "before further flight after the effective date" (Compliance). Helicopters already inspected must be reinspected within the next 8 flight hours or before accumulating 25 flight hours after the last inspection, whichever occurs first (Compliance). Misapplication of these clauses can lead to missed deadlines if the history of inspections under the original AD is not tracked.

Terminating replacement deadline: The AD sets a calendar cutoff for completing the full parts replacement "before 25 November 2007" (Compliance). If recordkeeping fails to demonstrate replacement by that date for a given helicopter, the operator may still be subject to the repetitive inspection requirement and to the installation prohibition that takes effect from 25 November 2007. The calendar deadline and the flight-hour inspection intervals create two separate compliance dimensions to track.

Prohibition on installation after a date: From 25 November 2007 the AD prohibits installation of P/N B642M1009103 on any helicopter (Requirement 5; Compliance). Operators or maintenance organisations holding legacy spares need processes to quarantine and prevent inadvertent reinstallation of obsolete P/N parts. Failure to enforce that in-house inventory control could lead to accidental non-compliance.

Dependency on the manufacturer’s ASB and EASA approval: The AD requires inspections and replacement "in accordance with section 3.A" and "section 3.B" of EUROCOPTER DEUTSCHLAND Alert Service Bulletin MBB BK117 C-2-64A-002 Revision 02 or subsequent EASA-approved revisions (Requirements 1 and 4). If an operator does not have access to the specified ASB or to an EASA-approved later revision, there may be practical uncertainty about exactly what inspection steps or replacement procedures satisfy the AD. This is not a legal gap in the AD, but it is an operational gotcha if the ASB is not properly obtained and the approved revision status is not checked.

Replacement parts availability and fit: The AD mandates replacement with P/N B642M1009104 assemblies including weights (Requirement 4). Operators need to confirm procurement lead times and that the improved assembly is the correct fit for their airframes. The AD does not discuss alternative parts or modification approvals; it ties compliance to the specified P/N and ASB method.

Inspection finding leads to immediate replacement: The AD requires replacement of any affected control lever if inspection finds "score marks, notching, scratching, cracks or similar damage" (Requirement 3). That leaves little room for temporary repair strategies or judgment calls about superficial blemishes. Technical staff should be clear about the ASB’s definitions of acceptable versus unacceptable conditions and ensure replacement parts are available.

Recordkeeping and proof obligations: The AD does not specify the format for proof of compliance but uses "before further flight" language and short inspection intervals. Operators must ensure their maintenance logs and certificates of release to service clearly show compliance timing, inspection findings, and any parts replaced, to demonstrate adherence to the AD if audited.

No penalty text but regulatory significance: The AD does not list specific penalties. Nevertheless the operational language makes certain actions prerequisites to flight in some circumstances (Compliance). The lack of explicit penalty descriptions may be misread as optionality. It is not optional: the AD prescribes mandatory aircraft airworthiness actions which are enforceable under the aviation safety framework.

Step 1, confirm applicability: Verify each BK 117C-2 in fleet to determine whether it is fitted with Tail Rotor Control Lever P/N B642M1009103. The AD’s Applicability clause confines obligations to aircraft with that specific P/N (Applicability). Do not assume applicability based on model alone.

Step 2, obtain and follow the ASB: Acquire EUROCOPTER DEUTSCHLAND Alert Service Bulletin MBB BK117 C-2-64A-002 Revision 02 dated 6 August 2007, and any subsequent EASA-approved revisions. The AD requires inspections and replacement to be performed "in accordance with section 3.A" and "section 3.B" of that ASB (Requirement 1 and 4). Use only the ASB provisions that are current and EASA-approved as the method of accomplishment.

Step 3, schedule and execute the initial inspection according to prior compliance status: If the helicopter has not been inspected under the original issue of the AD, perform the visual inspection before further flight after the amendment’s effective date (Compliance). If the helicopter was inspected under the original AD, perform the next inspection within 8 flight hours or before accumulating 25 flight hours after the last inspection, whichever occurs first (Compliance). Ensure the mechanic or certifying staff records the inspection in the aircraft’s maintenance log.

Step 4, perform repetitive inspections until terminating action: After the initial inspection, repeat the inspection at intervals not to exceed 8 flight hours until the full replacement is completed on that helicopter (Requirement 2; Compliance). Set up flight-hour tracking and inspection scheduling to ensure no interval exceeds 8 flight hours.

Step 5, replace damaged parts immediately: If any inspection identifies "score marks, notching, scratching, cracks or similar damage", remove the affected control lever and replace it with an airworthy part before further flight in accordance with the ASB (Requirement 3). Document the defect and the replacement action in the maintenance records.

Step 6, accomplish fleet replacement to obtain terminating action: Replace all P/N B642M1009103 Tail Rotor Control Levers and weights P/N B642M1011202 with the improved P/N B642M1009104 Tail Rotor Control Levers including weights in accordance with section 3.B of the ASB (Requirement 4). After installing the improved assembly on any helicopter, the repetitive 8 flight-hour inspections are no longer required for that helicopter. Ensure the replacement is documented and show how the ASB procedures were followed.

Step 7, enforce the installation prohibition: From 25 November 2007, do not install P/N B642M1009103 on any helicopter (Requirement 5; Compliance). Implement inventory controls to segregate and if necessary destroy or render unusable any legacy P/N B642M1009103 spares that remain in stock to prevent inadvertent installation. Update parts lists and maintenance policies to reflect the prohibition.

Step 8, maintain clear records: Log each inspection with date, flight hours at inspection, findings, corrective action taken, parts installed including P/Ns, and reference to the ASB section used. Because the AD uses "before further flight" and short inspection intervals, accurate maintenance log entries are essential to demonstrate compliance.

Step 9, coordinate procurement and maintenance planning: Given the short inspection intervals and the fleet replacement requirement, plan procurement of P/N B642M1009104 assemblies in advance to meet the AD’s terminating action. Coordinate with approved maintenance organisations to ensure replacement work is executed in accordance with section 3.B of the ASB.

Step 10, follow updated EASA-approved ASB revisions if they become available: The AD permits using subsequent EASA-approved revisions of the ASB for inspection and replacement (Requirement 1). If a new EASA-approved revision of the ASB is published, confirm whether it changes inspection techniques, acceptance criteria, or replacement steps, and update maintenance procedures accordingly.

Step 11, confirm regulatory status and sign-off: Ensure that the maintenance release or certificate of release to service references the AD and the ASB sections used for compliance. The AD is an Airworthiness Directive issued by CASA and signed by the delegate; demonstrate regulatory compliance in the aircraft’s records and through any required notifications to the authority, consistent with national maintenance and airworthiness practices (signature block; Compliance).

The AD text prescribes the required actions and references the ASB methods. Follow the precise P/N and ASB references in the AD to ensure compliance, and do not substitute alternative methods unless an EASA-approved revision or regulator-authorised alternate means of compliance is documented.