AD/A330/95 Amdt 2 - Air Data Inertial Reference Unit Operational Procedure

Air Data Inertial Reference Unit (ADIRU) is a combined sensor unit that provides both air data (airspeed, altitude, angle of attack) and inertial reference (attitude, heading, position) to aircraft systems. The directive applies only to Northrop-Grumman ADIRU Part Number 465020-0303-03ZZ with suffix numbers 09 through 16. This is a precise hardware version that the regulator considers susceptible to certain failure modes.

Inertial Reference (IR) and Air Data Reference (ADR) are the two functional components within the ADIRU. The IR calculates attitude based on gyros and accelerometers; the ADR measures pitot-static and angle of attack parameters. The ECAM cautions “NAV IR1 FAULT”, “NAV IR1+2 FAULT”, etc., indicate a failure in the IR portion. The directive requires the crew to isolate both the IR and its associated ADR, because the ADR may continue providing erroneous data even when the IR appears faulty. Moreover, the ADR fault can itself be the root cause of the IR warning.

Alternate law is a degraded flight control mode that reduces the normal envelope protections. The directive explicitly notes that flight controls are in alternate law during a dual IR fault, and cross-references the Aircraft Flight Manual (AFM) chapter on alternate law. This means the crew must be familiar with the reduced protection regime.

De-energizing the ADIRU is the crucial action. The earlier procedure used the IR and ADR pushbuttons (which are separate on/off switches). Field reports showed that even when the “OFF” light illuminated, the unit could still output erroneous data. The AMENDED procedure therefore requires setting the IR mode rotary selector to OFF, which physically removes power from the unit. This is a more definitive isolation method.

The AFM Temporary Revision (TR) is the means by which this operational procedure is formally incorporated into the approved flight manual. The directive states that either incorporating the AFM TR (specifically TR 4.02.00/46 Issue 3, which covers OEB N°74/4) or inserting the procedure from the directive directly into the AFM satisfies the requirement. The TR thus becomes a mandatory part of the AFM.

EASA Emergency AD 2009-0012-E is referenced as a note. This European Aviation Safety Agency emergency directive is likely similar in content. The note shows international coordination and implies that operators complying with the EASA AD may also need to ensure they meet the CASA requirements, which could differ in compliance dates or exact wording.

Directly affected operators are those who hold an Air Operator’s Certificate for A330 aircraft registered in Australia and who operate any of the 14 listed models (-201 through -343) equipped with the specified ADIRU part number. The directive does not exempt foreign-registered aircraft operating in Australia; however, CASA’s power typically extends only to Australian-registered aircraft unless the AD is adopted under other regulatory instruments. The instrument itself does not address foreign operators.

Flight crew are the primary actors. The directive imposes a specific, sequenced checklist-style procedure that must be executed correctly under time pressure. Crews must distinguish between single and dual IR faults, know when to use speed brakes, and understand the centre-of-gravity trigger (above 32%) and the associated speed restrictions for forward fuel transfer. Training and checking organisations must update their syllabuses to incorporate the new procedure. Recurrent simulator checks must verify proficiency in this scenario.

Maintenance personnel and engineering departments are indirectly affected. Although the directive is an operational procedure rather than a maintenance modification, engineering staff must ensure the AFM Temporary Revision is physically inserted or that the directive’s text is included in the applicable flight manual. The TR reference (Issue 3) must be correctly identified and cross-checked against the current revision status. Maintenance staff also need to verify the ADIRU part number and suffix range on each aircraft, as not all A330s are subject to the directive.

CASA itself is affected as the issuing authority. The rapid amendment history (three versions in two months) indicates that the regulator’s initial analysis was incomplete and field experience forced iterative corrections. This imposes a burden on CASA to communicate changes quickly to operators and to ensure oversight of compliance within tight deadlines.

Third-party training providers, simulator vendors, and AFM publishers must update their materials to reflect the final procedure. The directive’s note that it is covered by AFM TR 4.02.00/46 Issue 3 means that flight manual publishers must distribute the revised TR to all affected operators.

Passengers are affected only indirectly through flight safety. The directive’s purpose is to prevent a recurrence of a sudden nose-down command, which could cause injury or loss of control.

The primary duty is on the operator to ensure that before 19 January 2009, the operational procedure defined in the directive is incorporated into the Aircraft Flight Manual and that flight crews are trained and competent to execute it. The directive states that incorporation may be achieved either by inserting the specified AFM Temporary Revision (TR 4.02.00/46 Issue 3) or by inserting a copy of the directive itself into the AFM. This gives the operator a limited choice of method.

The crew in flight has the duty to apply the procedure precisely when the ECAM caution “NAV IR1 (2) (3) FAULT” or “NAV IR1+2 (2+3) (1+3) FAULT” appears. The procedure is mandatory; any deviation, including failing to set the IR mode rotary selector to OFF after the pushbuttons, could constitute non-compliance with the AD. The directive leaves no room for crew discretion about whether to isolate the unit; the steps are prescribed.

The operator has a right to seek an alternative means of compliance from CASA, although the directive does not expressly mention this. Under the broader Civil Aviation Regulations, an operator may apply for a variation to an AD, but that right is not spelled out here. The instrument itself presents no opt-out mechanism.

The directive creates no new rights for passengers or third parties. Its legal effect is to impose a condition on the operator’s licence.

The crew also has a duty to avoid using speed brakes when flight controls are in alternate law during a dual IR fault. Additionally, if CG is above 32%, manual forward fuel transfer from the trim tank is required, but only if the aircraft is above 270 knots and not climbing (when the trim tank pump is unavailable). This condition links the AD to operational limitations on the aircraft’s configuration and flight regime.

The operator has a duty to ensure that the AFM content is current. Because the AFM is an approved document, inserting the directive or the TR makes the procedure a legal requirement for the flight crew. Failure to maintain an accurate AFM could result in enforcement against the operator.

The directive itself does not specify a penalty amount or type. However, breaching an Airworthiness Directive is an offence under the Civil Aviation Act 1988 and the Civil Aviation Regulations 1988. The maximum penalty for a breach that endangers safety can be substantial , for an individual, imprisonment for up to two years or a fine of many thousands of penalty units; for a corporation, a fine of many tens of thousands of penalty units. Even a strict liability offence can attract significant fines.

CASA’s enforcement powers include issuing infringement notices (on-the-spot fines), suspension or cancellation of the Air Operator’s Certificate, grounding specific aircraft, and prosecuting in court. Because this directive addresses an “unsafe condition” (the sudden nose-down event), CASA is likely to treat non-compliance seriously. The directive’s rapid amendment history suggests the regulator is tracking field reports closely.

The compliance date was “before 19 January 2009”. The amendment became effective on 18 January 2009. Any operation of an affected aircraft after that date without the procedure in place could be an immediate breach. Even a single flight without the correct AFM insertion would expose the operator to enforcement.

The directive does not impose any record-keeping requirement beyond incorporation into the AFM. However, operators typically keep logs of AD compliance, and failure to produce evidence of compliance during an audit could lead to a finding of non-compliance.

There is no civil liability provision in this directive; passengers suing for injury would rely on common law negligence or consumer protection laws, but compliance with the AD would be evidence of taking reasonable care, while non-compliance could be strong evidence of negligence.

Litigation history: the source text records no litigation. There is no mention of any court challenge to this AD. Given the safety urgency and the narrow technical scope, a challenge would be unlikely.

This AD operates under the Civil Aviation Act 1988 and the Civil Aviation Regulations 1988. It has the force of a legislative instrument. It interacts with the Aircraft Flight Manual approval process: the AFM is itself an approved document under Civil Aviation Order 100.7 or similar instruments. The directive effectively amends the AFM for affected aircraft.

The directive explicitly references EASA Emergency AD 2009-0012-E. For an Australian operator that also holds an EASA Part 145 approval or operates into European airspace, the CASA AD and the EASA AD must both be satisfied. If the EASA AD has different wording or a different compliance date, the operator must comply with the stricter requirement , which in this case is the CASA AD, because its compliance date (before 19 January 2009) is not later than the EASA AD’s date. The note also shows regulatory interdependence: CASA adopted a procedure that EASA had already issued as an emergency AD.

The directive interacts with the Air Navigation (Aircraft Noise) Regulations 1998 and other airworthiness standards only indirectly: any modification to the aircraft’s systems (such as replacing the ADIRU) would also need to comply with those standards, but the directive itself is an operational procedure, not a design change.

Because the directive imposes a mandatory cockpit procedure, it interacts with crew training and licensing regulations under the Civil Aviation Safety Regulations (Part 61 and Part 121/135). The procedure must be taught in type rating training and checked in proficiency checks. The operator’s approved training syllabus must reflect the AFM change.

The directive does not interact with competition law, consumer law, or privacy law. It is a pure safety regulation.

Importantly, the directive overrides any conflicting company standard operating procedures that might have instructed a different action (e.g., leaving the IR on or using only the pushbuttons). The AD is the supreme operational instruction for the affected equipment.

The source text provides a clear timeline. The original directive became effective on 20 November 2008. Amendment 1 became effective on 22 December 2008. Amendment 2 (this version) became effective on 18 January 2009, with compliance required before 19 January 2009. That is three versions in exactly 59 days.

The original version required isolation of both the IR and ADR when a faulty IR was detected, using the pushbuttons. After field reports revealed that the “OFF” light sometimes did not illuminate, Amendment 1 added a step: if the light failed, the crew was to de-energize the ADIRU. But then “a new in service event” showed that even when the “OFF” light did illuminate, the IR could still provide erroneous data. Amendment 2 therefore mandates setting the IR mode rotary selector to OFF, which fully de-energizes the unit, regardless of the light.

This rapid evolution indicates that the regulator’s initial understanding of the failure mechanism was incomplete. Each amendment was reactive to service reports. The cost of this iterative approach is borne by operators, who must update their AFMs, retrain crews, and absorb the administrative burden of tracking multiple directives. The short compliance window (one day for Amendment 2) is exceptionally tight; it suggests CASA considered the risk urgent enough to override normal notice periods.

The directive’s background section attributes the amendments to “investigations” and “analysis of available data” that pointed to ADIRU 1 abnormal behaviour. The regulator does not disclose the identity of the operator or the flight involved, but the reference to a “sudden nose down order” makes the safety case compelling.

The amendment history also shows that the AFM Temporary Revision itself was revised: the directive refers to “TR 4.02.00/46 Issue 3”, implying that Issues 1 and 2 corresponded to the original directive and Amendment 1. Operators needed to ensure they had the correct issue.

The source text records no litigation. There is no mention of any court proceeding, tribunal appeal, or legal challenge to this directive. Given the instrument’s narrow scope and the safety imperative, litigation was unlikely. An operator might theoretically seek judicial review of the decision to issue the AD, arguing that the regulator failed to follow procedural fairness or that the scientific basis was flawed. However, the aircraft industry rarely challenges ADs in court, partly because the industry is heavily regulated and partly because the costs of delay (grounded aircraft) outweigh the benefits of a legal fight. Moreover, the directive is an emergency measure; the Civil Aviation Act allows CASA to issue urgent ADs with limited consultation.

The absence of litigation does not mean the directive was uncontroversial. Operators may have objected privately to the rapid changes and the one-day compliance window, but no public record of a formal challenge exists in the source.

Time compression. The compliance date for Amendment 2 was before 19 January 2009, yet the amendment was effective on 18 January. That leaves at most one day between publication and compliance. For an operator with a fleet of A330s scattered across the globe, updating the AFM and ensuring all crews are briefed within 24 hours is practically impossible unless they already had notice from the earlier versions or from the EASA AD. The directive gives no transition period.

Rotary selector confusion. The procedure says: “Set the affected IR mode rotary selector must be set to OFF.” The grammar (“must be set”) is awkward, but the meaning is clear. However, the earlier version (Amendment 1) used the pushbuttons as the primary method. A crew that has been trained to use pushbuttons may reflexively stop there, believing the “OFF” light is sufficient. The directive does not warn crews that their earlier training may now be incorrect; it simply states the new procedure. Operators must ensure their training materials clearly mark the change.

The double “OFF” light trap. The background explains that even with the “OFF” light illuminated, the ADIRU could keep providing erroneous data. That is counterintuitive: an illuminated “OFF” light normally indicates the unit is de-energized. A crew relying on that indication could leave the unit powered and risk further erroneous inputs.

Speed and CG restrictions are conditional. The note about forward fuel transfer says: “If trim tank pump is not available, do not perform manual forward fuel transfer while speed is at or below 270 kt or while in climb.” This adds complexity: the crew must know whether the trim tank pump is available, assess speed relative to 270 knots, and determine whether the aircraft is climbing. If the pump is available, no speed restriction applies. If it is not, the transfer must be delayed until below 270 knots or during level flight/descent. That is a lot of decisions to make in a busy cockpit during a dual IR failure.

No mention of post-flight actions. The directive does not require any maintenance action after landing. It only mandates the flight procedure. But a de-energized ADIRU will need to be reset or replaced before the next flight. Operators must have supplementary procedures for return to service; this directive is silent on that.

The ADIRU part number range is narrow. Only suffix 09 through 16. Operators must verify the exact part number on each aircraft. A misidentification could cause either unnecessary work or missed compliance.

AFM TR availability. The directive says the procedure is covered by AFM TR 4.02.00/46 Issue 3. If that TR is not distributed in time, operators may need to rely on inserting a copy of the directive itself. But the directive does not specify how to insert it (e.g., print and paste, or electronic). The ambiguity could be exploited in an audit but is not ideal.

Compliance requires two actions by the operator. First, incorporate the operational procedure into the Aircraft Flight Manual. Second, ensure flight crew are trained and capable of performing the procedure before the compliance date.

For incorporation, the operator may use either the AFM Temporary Revision (TR 4.02.00/46 Issue 3) or a direct insertion of the directive’s text. The directive states that either method “is acceptable to comply with the requirements”. In practice, the operator should obtain the official TR from Airbus or the approved AFM holder and insert it into the AFM permanently (or for the duration of the directive’s effect). If the TR is not available in time, the operator should print the text of the directive (including the requirement table, notes, and background) and insert it into the applicable volume of the AFM, preferably with a visible cover page marking it as mandatory. The operator should log the insertion in the AFM revision record.

For crew training, the operator must update the existing A330 type rating syllabus and the company’s standard operating procedures. The key changes from earlier versions are:

• Using the IR mode rotary selector to OFF, not just the pushbuttons.
• The condition that “OFF” light status is irrelevant; always use the rotary selector.
• The dual IR fault alternate law procedures, including the fuel transfer and speed restrictions.

The operator should issue a written bulletin to all affected crews, ideally with a quick-reference card for the cockpit. A simulator session should be scheduled, but if that is impossible before the compliance date, a detailed briefing with a written test may be acceptable, but only if the regulator is satisfied. The one-day compliance window makes simulator training before the date impractical; the operator must rely on briefing and possibly a recurrent training event within a few days after the date, but the procedure must be in the AFM and available to crews from 18 January.

The operator must also verify aircraft eligibility. For each A330 in the fleet, check the ADIRU part number against the list: P/N 465020-0303-03ZZ, where ZZ is 09 to 16. If the part number does not match, the directive does not apply. If it matches but the suffix falls outside the range, the directive also does not apply. This check should be documented.

The operator should also monitor the EASA AD 2009-0012-E. If it is identical, no additional action is needed. If it differs, the operator must resolve any conflict in favour of the most restrictive requirement.

Finally, the operator should retain records of compliance: a copy of the AFM insertion, the crew briefing attendance log, and the aircraft eligibility check. These records should be available for CASA inspection on request. Given the short compliance period, the operator should also be prepared to respond to a CASA audit shortly after 18 January, as the regulator will likely check that the directive was met.