This directive requires operators of TAY611-8C engines fitted with Engine Electronic Controller P/N TEEC200004AE to electrically check the two transorbs on at least one engine (using Rolls‑Royce ASB TAY‑73‑A1703 or later EASA‑approved revisions). Damaged EECs must be replaced before the next flight, checks repeated every 500 flight hours, and an additional aircraft‑to‑engine bonding lead may be required. It mainly affects aircraft operators (notably Gulfstream GIV‑X installations), who bear inspection, replacement and modification costs and must follow manufacturer/EASA instructions under CASA’s directive.
This Airworthiness Directive (AD/TAY/16, dated 11/2006 and effective 26 October 2006) requires operators of Rolls-Royce TAY611-8C engines equipped with Engine Electronic Controller (EEC) part number TEEC200004AE to perform electrical checks of the EEC transorbs, replace damaged EECs where required, and repeat inspections at specified intervals, in accordance with Rolls‑Royce Deutschland Alert Service Bulletin (ASB) TAY‑73‑A1703 or a later EASA‑approved revision (Requirement 1-3). The directive’s stated purpose is to establish that at least one engine installed on each aircraft has an EEC with undamaged transorbs (Purpose). The operative compliance steps set out are:
Initial electrical check of the two transorbs of the EEC on at least one engine per aircraft, performed in accordance with ASB TAY‑73‑A1703 (Requirement 1). The AD sets the time limit for this initial check at within 300 flight hours time in service (TIS) after the AD’s effective date (Compliance: For Requirement 1).
If an EEC is found to be damaged as a result of Requirement 1, replace that EEC with an undamaged unit in accordance with ASB instructions (Requirement 2). The AD provides conditional steps if a replacement EEC is not available, including checking the other engine’s EEC; if both are damaged, the AD requires at least one damaged EEC to be replaced (Requirement 2(a)-(b)). The AD requires replacement before the next flight after the Requirement 1 check (Compliance: For Requirement 2).
Repeat the Requirement 2 inspection at intervals not to exceed 500 hours TIS (Requirement 3 and Compliance: For Requirement 3).
The AD incorporates by reference the Rolls‑Royce ASB and permits compliance using later EASA‑approved revisions of that ASB (Requirement 1-3). It also refers to EASA AD 2006‑0268‑E (Note 3) and contains a qualification that aircraft modified by Gulfstream Aircraft Service Change 036 may only require a single repeat inspection to establish that at least one EEC is undamaged, after which periodic inspections may be discontinued as applicable (Note 2). The AD text explains the technical concern: damaged transorbs reduce the EEC’s ability to protect circuits from lightning strikes, and investigation linked damage to inadequate bonding between engine and airframe; to prevent this, an additional bonding lead between aircraft and engine is described in the Background as necessary.
Mechanically, the AD establishes inspection and replacement obligations tied to an OEM service bulletin and sets firm time windows for initial and repeat actions. It does not itself contain penalty provisions or enforcement procedures in the text; it is signed by a CASA delegate and bears an effective date (James Coyne, Delegate of the Civil Aviation Safety Authority; effective 26 October 2006).
Main concepts
The directive rests on a small set of technical and procedural concepts that determine compliance scope and mechanism:
Applicability and configuration gating: The AD applies only to TAY611‑8C engines, all serial numbers, that are fitted with a specific EEC, part number TEEC200004AE (Applicability). The applicability is therefore defined by engine model and a single EEC part number; engines without that EEC are outside the AD’s stated scope.
EEC transorb function and failure mode: The transorb is identified as a diode‑type component in the EEC connect module that protects the EEC from lightning current by conducting it to ground. The AD explains that damaged transorbs may compromise circuit protection during lightning strikes (Background). The AD links observed damage in returned in‑service EECs to inadequate bonding between engine and aircraft.
Inspection and replacement protocol: The AD requires electrical checks of the two transorbs of the EEC on at least one engine per aircraft, with replacement of damaged units in accordance with the ASB (Requirement 1-2). The AD refers the operator to the Rolls‑Royce ASB TAY‑73‑A1703 (dated 11 August 2006) for the detailed inspection procedure and for replacement instructions, and allows later EASA‑approved revisions of that ASB (Requirement 1-3).
Conditional procedures for spare availability: The AD contemplates limited spare availability and sets conditional procedural steps. If a damaged EEC is found and no replacement EEC is available, the operator must electrically check the two transorbs of the EEC on the other engine (Requirement 2(a)). If that EEC is also damaged, the directive requires that at least one damaged EEC be replaced in accordance with the ASB (Requirement 2(b)). The AD sets the timing for replacement “before next flight” after the Requirement 1 check (Compliance: For Requirement 2).
Periodicity: After initial actions, the AD requires repeat inspections (the Requirement 2 inspection) at intervals not to exceed 500 hours TIS (Requirement 3; Compliance: For Requirement 3), unless aircraft modification under Gulfstream Aircraft Service Change 036 applies (Note 2).
Reference to other regulatory materials: The AD expressly incorporates an OEM service bulletin and references an EASA Airworthiness Directive (EASA AD 2006‑0268‑E) (Requirement 1; Note 3). The ASB is invoked as the technical specification for performing the required checks and replacements.
Preventive bonding action: The Background states that to prevent transorb damage attributable to potential differences between aircraft and engine, “an additional bonding lead must be installed between the aircraft and the engine.” That preventive action is described in the Background rather than as an independently numbered Requirement in the body of the AD text; however the AD directs compliance with the ASB, which the Background says describes the electrical check and associated actions (Background).
Who it affects
The AD identifies and thereby imposes obligations on a narrow but commercially significant group:
Aircraft operators and owners who have Rolls‑Royce TAY611‑8C engines fitted with EEC P/N TEEC200004AE (Applicability). That includes, per the AD’s Note 1, engines known to be installed on Gulfstream GIV‑X aircraft, although the applicability line itself covers all aircraft with the specified engine and EEC part number.
Maintenance organisations and engineers tasked with performing electrical checks, replacements and bond installations. The AD directs that inspections and replacements be performed “in accordance with the instructions of Rolls‑Royce Deutschland Alert Service Bulletin (ASB) TAY‑73‑A1703 dated 11 August 2006 or later EASA approved revision” (Requirement 1-3). That allocates technical execution to whoever supplies or performs work under the ASB procedure, typically approved maintenance organisations and licensed engineers.
Parts suppliers and spares managers. The AD creates demand for undamaged EEC units as replacements and may require suppliers to provide compatible EEC P/N TEEC200004AE units or loaner units. The AD anticipates spare availability issues by prescribing conditional checks if replacement EECs are not available (Requirement 2(a)).
Regulatory bodies and certification authorities whose processes intersect with the AD. The AD is issued by the Civil Aviation Safety Authority (signature present) and cross‑refers to EASA AD 2006‑0268‑E and later EASA‑approved revisions of the Rolls‑Royce ASB. Operators will therefore need to coordinate between national AD compliance, acceptance of EASA‑approved ASB revisions and any applicable certified aircraft service modifications (Note 3; Requirement 1-3; Note 2).
Those affected bear the practical actions and costs: operators/owners must schedule checks within the AD’s specified TIS windows (within 300 hours for the initial check, then every 500 hours for repeats), prevent dispatch with non‑compliant configurations, and either source undamaged EECs or perform the checks and any necessary bond installations in accordance with the ASB. The AD does not allocate costs to any third party nor establish reimbursement; the text requires action but does not specify who pays,practically, the operator/owner and their maintenance providers will incur labour, parts and downtime costs.
The AD’s Note 2 creates a narrower mitigation pathway for operators that have completed Gulfstream Aircraft Service Change 036: if that modification is present, only a single repeat inspection may be necessary to demonstrate at least one EEC is undamaged, after which periodic inspections can be discontinued “as applicable” (Note 2). That creates a divergence in obligations between modified and unmodified aircraft.
Key duties and rights
Duties imposed by the AD are concise and anchored to the ASB instructions. The AD text gives no specific rights language (for example, appeals) within the document; it is an operational requirement. The operative duties and timing are:
Duty to inspect: Operators must “electrically check the two transorbs of the EEC on at least one engine of the aircraft” in accordance with ASB TAY‑73‑A1703 or later EASA‑approved revision (Requirement 1). The AD sets a deadline of within 300 flight hours TIS from the effective date for this initial action (Compliance: For Requirement 1).
Duty to replace damaged EECs: If an EEC is found to be damaged as a result of the Requirement 1 check, that EEC must be replaced with an undamaged unit “in accordance with the instructions of ASB TAY‑73‑A1703 or later EASA approved revision” (Requirement 2). The timing is strict: replacement is required “before next flight after the Requirement 1 check” (Compliance: For Requirement 2).
Duty to follow conditional steps when spares are unavailable: If no replacement EEC is available after a damaged unit is discovered, the operator must electrically check the EEC on the other engine as per ASB instructions (Requirement 2(a)). If that second EEC is also damaged, the AD requires that “at least one damaged EEC must be replaced in accordance with the instructions of ASB TAY‑73‑A1703 or later EASA approved revision” (Requirement 2(b)). This creates a minimal recovery option: if both EECs are damaged, operators must at least restore one undamaged EEC before further flight.
Duty to repeat inspections: The AD requires repetition of the Requirement 2 inspection (i.e. the electrical check and any related replacement action) at intervals not to exceed 500 hours TIS (Requirement 3; Compliance: For Requirement 3).
Duty to comply with ASB content: All required actions are to be performed “in accordance with the instructions of Rolls‑Royce Deutschland Alert Service Bulletin TAY‑73‑A1703 dated 11 August 2006 or later EASA approved revision.” This delegates technical method and any ancillary actions (for example installation steps, detailed test procedures, torque values, permissible parts) to the ASB as incorporated material.
Rights and procedural safeguards are not set out in the AD text. The AD does refer to “later EASA approved revision” of the ASB, which implies that updated, EASA‑approved versions of the ASB are acceptable means of compliance, giving operators a path to use updated technical guidance without seeking an exemption (Requirement 1-3). The AD also provides a modification‑based exception pathway via Gulfstream Aircraft Service Change 036: if that modification is embodied, periodic inspections may be reduced or discontinued following a single repeat inspection establishing that at least one EEC is undamaged (Note 2).
Penalties and enforcement
The AD text contains no express criminal, civil, or administrative penalty provisions and does not describe an enforcement process. It is signed by a delegate of the Civil Aviation Safety Authority (James Coyne) and states an effective date (This Airworthiness Directive becomes effective on 26 October 2006), which establishes the regulatory instrument and timing (signature and effective date). Beyond that, the document does not set out sanctions, inspection regimes, or compliance monitoring mechanisms.
From the AD’s contents the following points about enforcement and penalties can be stated from the text itself:
The AD is an official CASA instrument (signed by a CASA delegate) and therefore constitutes regulatory direction; the document creates operational duties (Requirements 1-3) that are time‑bounded (Compliance: For Requirement 1-3). The AD does not itself set penalties in its text.
The AD cross‑references EASA material (EASA AD 2006‑0268‑E and EASA‑approved revisions of the ASB), which suggests a regulatory framework where national ADs follow or coordinate with EASA ADs, but the AD text does not state how enforcement across jurisdictions is to take place (Note 3; Requirement 1-3).
The AD’s compliance schedule (initial check within 300 flight hours; replacement before next flight; repeats not to exceed 500 hours) creates operational non‑compliance risk. The AD does not state what administrative consequences flow from missing those intervals, nor does it set out required reporting procedures for damaged units or replaced parts within the text.
The AD’s lack of explicit enforcement language means any penalties, continuing airworthiness directives, airworthiness limitations, or sanctions would be set out outside the text of this AD, under broader statutory or regulatory frameworks administered by the Civil Aviation Safety Authority, but such frameworks are not described in this document and therefore cannot be asserted here.
Practitioners or compliance officers should therefore treat the AD as an operative regulatory requirement that creates obligations with rigid time frames and operational consequences if not met, and should seek CASA guidance or applicable regulatory procedure documents outside this AD for information on enforcement, reporting, and penalty mechanisms.
How it interacts with other laws
The AD expressly cross‑references non‑domestic and OEM materials and contains a note about an aircraft manufacturer modification; those cross‑references shape interaction with other mandated instruments and technical documents:
EASA AD interaction: The AD states “EASA AD 2006‑0268‑E refers” (Note 3). That indicates a related EASA Airworthiness Directive exists and is relevant. The AD accepts later EASA‑approved revisions of the Rolls‑Royce ASB as compliant technical means. Practically, compliance with the EASA AD and with the Rolls‑Royce ASB as EASA‑approved would be co‑operative or mutually reinforcing. The AD text does not set out which AD takes precedence where there might be divergence; it simply refers to EASA AD 2006‑0268‑E and allows EASA‑approved ASB revisions.
OEM service bulletin incorporation: The AD makes detailed actions conditional on and in conformity with Rolls‑Royce Deutschland ASB TAY‑73‑A1703 dated 11 August 2006 or later EASA‑approved revisions (Requirement 1-3). That means the technical content of the ASB (which the AD says “describes the electrical check of two transorbs of the EEC on one engine of the aircraft”) is incorporated by reference as the method of compliance. The AD therefore interacts functionally with OEM documentation, making ASB compliance the technical implementation mechanism.
Manufacturer service change conditionality: The AD includes a specific interaction with Gulfstream Aircraft Service Change 036 (Note 2). If that modification has been embodied on an aircraft, the directive allows only one single (repeat) inspection to establish that at least one EEC is undamaged, and states that periodic inspections may then not be required or may be discontinued “as applicable.” That creates an interaction where an aircraft modification (a service change issued by the aircraft manufacturer) affects the ongoing inspection obligations imposed by this AD.
National regulatory framework: The AD is issued by the Civil Aviation Safety Authority with an effective date and is an enforceable instrument within the national airworthiness regulatory framework, but the AD text does not itself describe how it integrates with local Civil Aviation Regulations, maintenance organisation approvals, air operator certificates, or continuing airworthiness record‑keeping requirements. Those interactions will be found in the broader regulatory corpus but are not specified here.
Parts availability and contractual obligations: Because the AD requires replacement with “an undamaged unit” in accordance with ASB instructions, it will interact with contracts between operators and parts suppliers, maintenance contractors, and possibly warranties or maintenance agreements. The AD does not include supplier obligations or recall mechanisms; those remain contractual and external to the AD text.
Amendment history
The directive contains a limited set of temporal references and cross‑references that form its amendment and provenance history within the four corners of the document:
AD identification and dating: The top of the document lists the AD as “AD/TAY/16” and the header contains “11/2006” indicating issuance in November 2006. The signature block is dated 15 September 2006 (James Coyne, Delegate of the Civil Aviation Safety Authority), and the AD states an effective date of 26 October 2006 (“This Airworthiness Directive becomes effective on 26 October 2006”).
ASB reference date: The AD specifies Rolls‑Royce Deutschland Alert Service Bulletin TAY‑73‑A1703 dated 11 August 2006 as the technical document to be followed for inspections and replacements (Requirement 1-3). The AD accepts “later EASA approved revision” of that ASB as valid for compliance, which creates a mechanism for later ASB revisions to be incorporated without formal amendment to this AD text (Requirement 1-3).
Cross‑reference to EASA AD: The AD notes that EASA AD 2006‑0268‑E is relevant (“Note 3: EASA AD 2006‑0268‑E refers”). The AD does not describe whether that EASA AD predates or postdates this AD; however the presence of the EASA AD reference indicates the AD aligns with or follows from EASA regulatory action.
Aircraft service change reference: The AD refers to Gulfstream Aircraft Service Change 036 in Note 2 as a modification that, if embodied, alters the periodic inspection burden (Note 2). That creates an interaction where a manufacturer service change transaction enacted at aircraft level affects the AD’s periodicity requirement.
No textual amendments within this AD: The document as supplied does not record any amendments, revocations, supersessions or later AD numbers. There is no “amendment” section in the AD text itself; compliance with later EASA‑approved ASB revisions is the only built‑in mechanism for technical evolution.
The AD therefore relies on two vehicles for evolution without formally amending the AD document itself: later EASA‑approved revisions of the referenced Rolls‑Royce ASB, and aircraft modification embodied by Gulfstream Service Change 036. Any formal amendment or supersession of this AD itself would need to be recorded in subsequent ADs or regulatory notices, but there is no such amendment history recorded within this AD text.
Litigation history
The AD text does not record any litigation history. It contains no references to court cases, judicial review, or dispute decisions. The document includes only technical findings, requirements, cross‑references to an EASA AD, and administrative signature and dates. Consequently, the AD as provided contains no litigation record, appeals, or contested enforcement proceedings within its text.
Practically, if litigation or dispute were to occur (for example over enforcement, interpretation of ASB instructions, or availability of spares), that would be outside the scope of this directive text and would need to be sourced from administrative records, judicial databases, or CASA enforcement files that are not reproduced here. The AD itself provides no procedural or administrative appeal mechanism within its four corners.
Gotchas
This AD contains a number of specific features and potential operational pitfalls that practitioners should note precisely as stated:
Narrow applicability tied to an EEC part number: The AD applies only to TAY611‑8C engines that are equipped with EEC P/N TEEC200004AE (Applicability). Engines lacking that exact EEC part number fall outside the stated scope. Operators must therefore confirm the EEC part number on each installed engine to determine applicability.
ASB as the operative instructions: The AD requires actions “in accordance with the instructions of Rolls‑Royce Deutschland Alert Service Bulletin (ASB) TAY‑73‑A1703 dated 11 August 2006 or later EASA approved revision” (Requirement 1-3). The AD does not itself set out the detailed inspection procedures, pass/fail criteria, or replacement steps: those are delegated to the ASB. Practitioners must obtain the ASB and any later EASA‑approved revisions to know the exact technical steps and acceptance criteria.
Timing stringency and dispatch consequence: The AD requires the initial check “within 300 flight hours TIS after the effective date” and requires replacement of any damaged EEC “before next flight after the Requirement 1 check” (Compliance: For Requirement 1; Compliance: For Requirement 2). This means discovery of damage during the initial check obliges replacement prior to next flight; if a replacement is not immediately available, the AD prescribes a contingency but ultimately requires replacement before flight if both EECs are damaged.
Spare availability contingency may be practically constraining: The AD’s conditional procedure provides that if a replacement is not available the operator must check the other engine’s EEC (Requirement 2(a)). If both are damaged, the AD requires at least one damaged EEC be replaced (Requirement 2(b)). The AD does not state how long operators may take to procure replacement parts; it does require replacement before next flight, creating an implied risk of grounding if spares are not on hand.
Preventive bonding lead not explicitly placed in the Requirements section: The Background states that “an additional bonding lead must be installed between the aircraft and the engine” to prevent transorb damage due to differential potential between engine and airframe (Background). However, the numbered Requirements in the AD are limited to electrical checking and replacement, with the ASB as the vehicle for instructions. Practitioners should note that the AD’s Background expresses the preventive measure in mandatory language (“must be installed”), but the AD’s formal Requirements rely on ASB instructions; there is therefore potential ambiguity about whether bonding lead installation is a separate AD requirement or part of the ASB‑mandated work. Operators must therefore consult ASB TAY‑73‑A1703 (and any later EASA‑approved revisions) to determine whether the bonding lead installation is specified there and treated as required action for compliance with the AD.
How to comply
Below is a practical, document‑centred compliance checklist distilled from the AD text. All referenced actions must be done “in accordance with the instructions of Rolls‑Royce Deutschland Alert Service Bulletin TAY‑73‑A1703 dated 11 August 2006 or later EASA approved revision” (Requirement 1-3). Operators must therefore obtain that ASB and any later EASA‑approved revisions and follow the ASB’s procedural details.
Confirm applicability
Verify whether each aircraft fitted with a TAY611‑8C engine has EEC P/N TEEC200004AE. The AD applies only to TAY611‑8C engines with that EEC part number (Applicability). Log configuration for each aircraft to demonstrate applicability or non‑applicability.
Obtain referenced technical documentation
Obtain Rolls‑Royce Deutschland ASB TAY‑73‑A1703 dated 11 August 2006 and check for any later EASA‑approved revisions. The AD specifies that required actions are to be performed in accordance with that ASB or later EASA‑approved revisions (Requirement 1-3). Ensure the copy used is EASA‑approved if relying on a later revision.
Schedule initial inspections within the AD’s window
Plan the initial electrical check of the two EEC transorbs on at least one engine per aircraft within 300 flight hours TIS after the AD’s effective date (Compliance: For Requirement 1). If the aircraft’s clock is near the deadline, prioritise scheduling in maintenance windows.
Perform electrical checks
Carry out the EEC transorb electrical checks in accordance with the ASB’s step‑by‑step procedures (Requirement 1). The AD delegates inspection method and acceptance criteria to the ASB; do not improvise or use alternate procedures unless formally approved by the regulator.
If an EEC is found damaged
Replace the damaged EEC with an undamaged unit using the ASB’s replacement instructions (Requirement 2).
The AD requires this replacement before the next flight after the Requirement 1 check (Compliance: For Requirement 2). Therefore, do not release the aircraft for flight until replacement is carried out as required by the AD.
If replacement EEC is not available
Follow the AD’s contingency: electrically check the two transorbs of the EEC on the other engine in accordance with the ASB (Requirement 2(a)). If that second EEC is also damaged, arrange replacement such that at least one damaged EEC is replaced (Requirement 2(b)).
Current sections
Direct links to the current provisions in AD/TAY/16 - Engine Electronic Controller - Inspection/Replacement.
All TAY611-8C engines, all serial numbers, if equipped with Engine Electronic Controller (EEC), part number (P/N) TEEC200004AE.
Note 1: These engines are known to be installed on Gulfstream GIV-X aircraft.
Requirement:
1. Electrically check the two transorbs of the EEC on at least one engine of the aircraft in accordance with the instructions of Rolls-Royce Deutschland Alert Service Bulletin (ASB) TAY-73-A1703 dated 11 August 2006 or later EASA approved revision.
2. If, as a result of the Requirement 1 check, an EEC is found to be damaged, replace the EEC with an undamaged unit in accordance with the instructions of ASB TAY-73-A1703 or later EASA approved revision taking into account the following conditions:
a. If no replacement EEC is available, electrically check the two transorbs of the EEC installed on the other engine of the aircraft in accordance with the instructions of ASB TAY-73-A1703 or later EASA approved revision.
b. If this EEC is also found to be damaged, at least one damaged EEC must be replaced in accordance with the instructions of ASB TAY-73-A1703 or later EASA approved revision.
3. Repeat the Requirement 2 inspection in accordance with the instructions of ASB TAY-73-A1703 or later EASA approved revision.
Note 2: When the aircraft has been modified in accordance with Gulfstream Aircraft Service Change 036, only one single (repeat) inspection is required to establish that at least one EEC is undamaged. If so, the periodic inspections are not required, or may be discontinued, as applicable.
Note 3: EASA AD 2006-0268-E refers.
Compliance:
For Requirement 1 - Within 300 flight hours time in service (TIS) after the effective date of this Directive.
For Requirement 2 - Before next flight after the Requirement 1 check.
For Requirement 3 - At intervals not to exceed 500 hours TIS.
This Airworthiness Directive becomes effective on 26 October 2006.
Background:
Some EECs, returned from in-service to the manufacturer, had damaged transorbs. A transorb is a diode type device in the EEC connect module that protects the EEC from the effects of lightning strikes by conducting the current to the ground. A damaged transorb may compromise the EECs ability to protect circuits from damage during a lightning strike event. Investigation has shown that the transorbs could be damaged due to an inadequate bonding between the aircraft and the engine.
As the EEC aircraft power supply 0 Volt return line is clamped to the engine through a transorb while it is bonded to the aircraft, a difference in potential between the engine and the aircraft could result in a transorb damage. To prevent this, an additional bonding lead must be installed between the aircraft and the engine. In addition, all EEC units need to be electrically checked to find out if any transorb is damaged.
The purpose of this Directive is to establish that at least one engine installed on an aircraft has an EEC installed with undamaged transorbs. Rolls-Royce Deutschland Alert Service Bulletin TAY-73-A1703 describes the electrical check of two transorbs of the EEC on one engine of the aircraft.
All TAY611-8C engines, all serial numbers, if equipped with Engine Electronic Controller (EEC), part number (P/N) TEEC200004AE.
Note 1: These engines are known to be installed on Gulfstream GIV-X aircraft.
Requirement:
1. Electrically check the two transorbs of the EEC on at least one engine of the aircraft in accordance with the instructions of Rolls-Royce Deutschland Alert Service Bulletin (ASB) TAY-73-A1703 dated 11 August 2006 or later EASA approved revision.
2. If, as a result of the Requirement 1 check, an EEC is found to be damaged, replace the EEC with an undamaged unit in accordance with the instructions of ASB TAY-73-A1703 or later EASA approved revision taking into account the following conditions:
a. If no replacement EEC is available, electrically check the two transorbs of the EEC installed on the other engine of the aircraft in accordance with the instructions of ASB TAY-73-A1703 or later EASA approved revision.
b. If this EEC is also found to be damaged, at least one damaged EEC must be replaced in accordance with the instructions of ASB TAY-73-A1703 or later EASA approved revision.
3. Repeat the Requirement 2 inspection in accordance with the instructions of ASB TAY-73-A1703 or later EASA approved revision.
Note 2: When the aircraft has been modified in accordance with Gulfstream Aircraft Service Change 036, only one single (repeat) inspection is required to establish that at least one EEC is undamaged. If so, the periodic inspections are not required, or may be discontinued, as applicable.
Note 3: EASA AD 2006-0268-E refers.
Compliance:
For Requirement 1 - Within 300 flight hours time in service (TIS) after the effective date of this Directive.
For Requirement 2 - Before next flight after the Requirement 1 check.
For Requirement 3 - At intervals not to exceed 500 hours TIS.
This Airworthiness Directive becomes effective on 26 October 2006.
Background:
Some EECs, returned from in-service to the manufacturer, had damaged transorbs. A transorb is a diode type device in the EEC connect module that protects the EEC from the effects of lightning strikes by conducting the current to the ground. A damaged transorb may compromise the EECs ability to protect circuits from damage during a lightning strike event. Investigation has shown that the transorbs could be damaged due to an inadequate bonding between the aircraft and the engine.
As the EEC aircraft power supply 0 Volt return line is clamped to the engine through a transorb while it is bonded to the aircraft, a difference in potential between the engine and the aircraft could result in a transorb damage. To prevent this, an additional bonding lead must be installed between the aircraft and the engine. In addition, all EEC units need to be electrically checked to find out if any transorb is damaged.
The purpose of this Directive is to establish that at least one engine installed on an aircraft has an EEC installed with undamaged transorbs. Rolls-Royce Deutschland Alert Service Bulletin TAY-73-A1703 describes the electrical check of two transorbs of the EEC on one engine of the aircraft.
James Coyne
Delegate of the Civil Aviation Safety Authority
These core elements determine who must act, what they must do, the timing of actions and the technical procedures to follow. The AD anchors operational obligations to the ASB (including later EASA‑approved revisions), which is the delegated source of the detailed steps and technical instructions.
The AD does not specify appeals, derogations, or alternate means of compliance within the document. It does not set out record‑keeping or reporting obligations in the AD text itself. The lodged technical content and timelines effectively become mandatory operational duties for affected operators, with the ASB serving as the prescriptive technical standard.
In short, the AD delegates technical specifics to an ASB and references an EASA AD and a Gulfstream service change that can alter obligations. Compliance therefore requires coordination between the AD, the ASB (including any EASA‑approved revisions), any relevant EASA AD, and aircraft manufacturer modifications. The AD does not itself resolve conflicts between these documents, nor does it set out procedural mechanisms for when multiple instruments intersect.
Modified aircraft path: Note 2 states that aircraft modified in accordance with Gulfstream Aircraft Service Change 036 may require only a single repeat inspection to establish that at least one EEC is undamaged, and that periodic inspections may then not be required or may be discontinued “as applicable.” Operators must confirm embodiment of that service change to rely on reduced inspection obligations. The AD does not state the administrative record or certification evidence required to demonstrate the modification has been embodied.
Delegation to EASA‑approved ASB revisions: The AD allows compliance using “later EASA approved revision” of the ASB (Requirement 1-3). Operators must therefore ensure that a later ASB revision is EASA‑approved; an unapproved ASB revision would not satisfy the AD’s incorporated method of compliance.
No express reporting or paperwork clause in the AD: The document does not set out reporting obligations (for example to CASA or Rolls‑Royce) for discovered damage or for parts replaced, nor does it contain record‑keeping specifics. Operators should not assume that no reporting is required; oversight and reporting obligations may exist elsewhere in national continuing airworthiness regulations, but they are not stated in the AD.
Reference to EASA AD without hierarchy or detail: The AD notes that EASA AD 2006‑0268‑E “refers” (Note 3) but does not explain interaction, precedence, or divergence between the instruments. Operators operating across jurisdictions should verify whether there are any differences between the CASA AD and the EASA AD that affect compliance methods or timing.
These items are directly traceable to the AD text and represent practical points where misinterpretation or incomplete action could lead to non‑compliance or operational disruption. The primary mitigation is to obtain and follow the Rolls‑Royce ASB TAY‑73‑A1703 (and confirm any EASA approvals), verify parts and modification status, and plan for parts and maintenance windows consistent with the AD’s flight‑time deadlines.
Plan logistics for rapid procurement or cannibalisation where necessary to meet the “before next flight” requirement. The AD does not provide for a dispatch with both engines having damaged EECs.
Repeat inspections
After initial compliance, repeat the Requirement 2 inspection at intervals not to exceed 500 hours TIS (Requirement 3; Compliance: For Requirement 3). Ensure repeated inspection scheduling is integrated into the maintenance programme and tracked.
Check Gulfstream modification status
Determine whether Gulfstream Aircraft Service Change 036 has been embodied on the aircraft. If so, follow Note 2’s provision: a single (repeat) inspection may be sufficient to establish that at least one EEC is undamaged, after which periodic inspections may not be required or may be discontinued “as applicable.” Retain documentation proving embodiment of the service change to justify altered inspection frequency.
Consider bonding lead installation
The AD Background states that “an additional bonding lead must be installed between the aircraft and the engine” to prevent transorb damage due to potential differences (Background). Confirm in the ASB whether bonding lead installation is specified and required as part of the AD’s incorporated procedures. If the ASB requires bonding lead installation, perform it per ASB instructions.
Record keeping and evidence
The AD itself does not specify reporting requirements. Nonetheless, maintain contemporaneous records evidencing compliance: parts replaced (including part numbers and serials), inspection results, ASB revision used, maintenance release signatures, and dates. If relying on Gulfstream Service Change 036 to reduce inspection frequency, retain modification embodiment evidence.
Liaise with authorities and suppliers
Confirm with CASA or delegated authority if any additional reporting, alternate means of compliance, or credits apply. For sourcing replacement EECs, coordinate with Rolls‑Royce or authorised suppliers to ensure replacements meet the AD’s P/N requirement and are undamaged.
Monitor for ASB/EASA updates
Because the AD permits compliance using later EASA‑approved revisions of the ASB, monitor for ASB updates that are EASA‑approved and incorporate them in the compliance process as appropriate (Requirement 1-3). Also monitor the referenced EASA AD 2006‑0268‑E for related requirements (Note 3).
This compliance pathway follows the AD’s exact prescription: perform the initial check within 300 flight hours, replace damaged EECs before next flight, and repeat inspections at intervals not to exceed 500 hours, all carried out under the ASB’s instructions. The main practical risks are spare availability, scheduling to meet the tight “before next flight” replacement requirement, and confirming whether bonding lead installation is treated as part of the ASB requirements.