AD/B767/173 Amdt 1 - Thrust Reverser Directional Pilot Valve

Directional Pilot Valve (DPV). The DPV is a component within the thrust reverser actuation system that controls pneumatic pressure to deploy and stow the thrust reverser. The directive specifically targets leakage through the DPV, which can arise from a poppet valve that is slightly jammed open or from a deteriorating o-ring. These are latent failures , they may not be immediately detectable in normal operation but can compromise the system’s fail-safe design.

Fail-safe features. The background notes that the leakage is a “latent failure of the fail-safe features” of the thrust reverser system. A fail-safe feature is a design characteristic that ensures a single component failure does not lead to an unsafe condition. In the thrust reverser context, the fail-safe design prevents inadvertent deployment in flight. The mandated functional test is intended to detect these latent failures before they combine with other conditions (such as an in-flight deployment command) to produce a hazard.

Functional test. The directive requires a “functional test of the DPV of the thrust reversers to detect pneumatic leakage” in accordance with Boeing Alert SB 767-78-0084 dated 21 October 1999. A functional test differs from a visual inspection; it involves applying operational pressures and verifying that the valve responds within specified parameters and does not leak beyond acceptable limits. The test follows a detailed procedure set out in the service bulletin, which is incorporated by reference into the directive.

Production equivalent. For aeroplanes modified during production in accordance with a “production equivalent” of Boeing SB 767-78-0063, the initial functional test required by Requirement 1(b) is not necessary. The directive accepts that the production process already includes a functionally equivalent test. This concept reduces the compliance burden on operators of aircraft that left the factory with the improved DPV configuration. However, the operator must still perform the recurrent tests at 6,000-hour intervals.

Alternate Method of Compliance (AMOC). The amendment adds a provision that later revisions of Boeing SB 767-78-0084, when approved by the FAA as an AMOC to FAA AD 2000-17-06, are considered acceptable for compliance with the equivalent requirements of this directive. An AMOC is an alternative means of meeting the regulatory requirement that the regulator has formally approved. This provision avoids the need for a separate CASA amendment each time the manufacturer updates the service bulletin and the FAA approves it. However, it creates a dependency on the FAA’s approval process , the operator must verify that the specific revision used has been FAA-approved as an AMOC.

Airworthiness Directive (AD) structure. The directive is formatted as a CASA AD with a requirement section (1.5), a compliance section (compliance times and intervals), and a background section. The applicability statement limits its scope to Model 767 series aeroplanes with General Electric CF6-80C2 series engines. Other engine types (such as Pratt & Whitney or Rolls-Royce) are not affected, even if fitted to the same airframe.

The primary class of persons affected is the operators of Boeing 767 series aeroplanes equipped with General Electric CF6-80C2 series engines. This includes commercial airlines, cargo carriers, charter operators, and lessees who fly or maintain such aircraft. Each operator must ensure that the functional tests are carried out at the required intervals and that any repairs are performed before further flight. The directive captures Australian operators directly, but because it references the FAA AD, it also affects aircraft maintained under a bilateral safety agreement where the operator elects to use the FAA-approved SB revisions as an AMOC.

Maintenance organisations are the second major affected group. Those that perform scheduled or unscheduled maintenance on the affected aircraft must be capable of executing the functional test procedure in Boeing Alert SB 767-78-0084 (or any FAA-approved later revision). They must also be authorised to perform any necessary repairs in accordance with the aircraft maintenance manual. The directive does not mandate any specific certification beyond what is already required under the operator’s continuing airworthiness management system, but it imposes a strict timeline (before further flight) for corrective actions that arise from a failed test.

Aircraft owners and lessors are indirectly affected because the directive can affect the residual value and lease returns of the aircraft. An aircraft that is not in compliance with all applicable ADs may be considered non-airworthy, could be grounded, and may trigger lease default provisions. The directive’s recurring nature means that the compliance status must be checked at each lease transition.

Passengers and the general public are the ultimate beneficiaries of the safety objective, but they also bear the costs indirectly through increased maintenance expenses that are passed on in ticket prices or reduced aircraft availability. The directive imposes a compliance burden that may be proportionally greater on smaller operators who maintain a limited number of 767s and may have less flexibility in scheduling the tests around revenue service. The 1,000-flight-hour interval for unmodified aircraft is relatively frequent , roughly every six to eight months for a typical long-haul operator , which means the aircraft must be taken out of service for the test, a downtime cost that is not trivial.

Regulatory bodies such as CASA and the FAA are affected in their oversight roles. CASA must monitor compliance, issue any additional amendments if necessary, and process any requests for alternative methods of compliance. The FAA’s role is triggered when an operator wishes to use a later revision of the service bulletin; the FAA must have approved that revision as an AMOC to FAA AD 2000-17-06. If the FAA approves a revision that CASA has not independently reviewed, the operator can rely on the FAA’s approval because the directive implicitly accepts it. This interaction reduces duplication but creates a regulatory reliance that may be uncomfortable for some operators if the FAA’s standards differ from CASA’s.

The directive imposes several specific duties on operators and maintenance providers. The primary duty is to carry out and successfully accomplish a functional test of the DPV in accordance with Boeing Alert SB 767-78-0084 (or an acceptable later revision) at the prescribed initial and recurrent intervals. For unmodified aeroplanes, the interval is not exceeding 1,000 flight hours. For modified aeroplanes, it is not exceeding 6,000 flight hours. These duties are ongoing: the operator must maintain a compliance schedule and cannot stop performing the tests merely because the aircraft has been in service for years.

A second duty is to repair any discrepancy detected during the functional test “in accordance with the Aircraft Maintenance Manual.” The duty arises before further flight. This is an immediate grounding obligation. The directive does not permit a grace period for obtaining parts or scheduling repair; the aircraft cannot legally fly until the repair is complete and the test is successfully reaccomplished. The repair must use the procedures in the airframe manufacturer’s maintenance manual, which may differ from the service bulletin procedures.

A third duty is to repeat the Requirement 1 functional tests (the initial test for the applicable configuration) if any discrepancies have been corrected during compliance with requirements 2 or 3 (the repeating tests) or indeed during any earlier requirement. This means that a repair triggered by a repeat test at 10,000 flight hours requires the operator to effectively restart the entire test sequence from Requirement 1. The text reads: “Repeat Requirement 1 functional tests if any discrepancies have been corrected under Requirement 4 during compliance with requirement 1, 2 or 3.” That is a bit of a maze: Requirement 4 is the repair requirement. So if a discrepancy is found and repaired during any test cycle, the operator must then perform the test that would have been due under Requirement 1 (which, for unmodified aircraft, includes the initial test procedure). For modified aircraft, this would be the lower-interval initial test. Practically, this means a repair triggers a full retest, even if the aircraft was already in the 6,000-hour repeat cycle.

Operators also have certain rights. They may rely on a production equivalent functional test accomplished during manufacture to satisfy the initial test requirement for modified aeroplanes. If the aircraft left the factory with the modification and a functional test was performed as part of production, the operator does not have to perform the Requirement 1(b) test again. This is a one-time exemption for the initial compliance. The recurrent 6,000-hour tests still apply.

The operator has the right to use later revisions of Boeing SB 767-78-0084 that have been approved by the FAA as an AMOC to FAA AD 2000-17-06. The directive states that such revisions are “considered acceptable for compliance with the equivalent requirements of this Directive.” This eliminates the need for a separate CASA approval for each revision. However, the operator must verify that the FAA has indeed approved that specific revision as an AMOC. If the FAA approves a revision only as an AMOC for the FAA’s own AD, but not specifically for this CASA AD, the operator should satisfy themselves that the equivalence is maintained. The directive’s wording is permissive: it says “is considered acceptable.” That suggests that using the FAA-approved revision is a compliance option, not a mandatory substitution for the original SB.

Finally, operators have the right to propose alternative methods of compliance for CASA approval if the referenced service bulletin cannot be used or if a different repair is needed. The directive does not expressly grant this right, but the general Civil Aviation Safety Regulations and CASA policy allow operators to apply for an AMOC. The FAA AMOC approval mentioned in the directive applies only to later revisions of the same SB, not to entirely different maintenance procedures.

The directive does not itself specify monetary penalties or criminal sanctions. However, as a CASA airworthiness directive, non-compliance is a breach of the Civil Aviation Safety Regulations 1998 (CASR), specifically those provisions that require an aircraft to be maintained in an airworthy condition and to comply with all applicable ADs. Under the Civil Aviation Act 1988, the maximum penalty for operating an aircraft that does not comply with an AD can be substantial , currently up to 500 penalty units for an individual and 5,000 penalty units for a body corporate (with a penalty unit currently around AUD 222, the corporate maximum is over AUD 1.1 million). These figures are not in the source but are standard under the Act; a legal analyst would note them as context.

Enforcement is carried out by CASA, which can take a range of actions. The most immediate is grounding the aircraft. If an operator fails to perform the recurrent DPV test within the required interval, or if the test reveal’s a leakage that is not repaired before further flight, CASA can issue a direction to ground the aircraft under section 29A of the Civil Aviation Act or under regulation 41 of the Civil Aviation Safety Regulations. In practice, CASA compliance inspectors conducting audits or ramp checks will review the aircraft’s maintenance records for AD compliance. A finding of non-compliance can lead to a notice of proposed suspension or cancellation of the air operator’s certificate (AOC), which would ground the entire fleet until the deficiency is corrected and the regulator is satisfied that the operator’s continuing airworthiness management system is functioning.

For maintenance organisations, performing the test incorrectly or failing to ensure compliance could expose the organisation to liability under civil law (e.g., breach of contract or negligence) as well as regulatory action. The directive itself does not impose a duty on the maintenance organisation separate from the operator, but the operator will typically contractually require the organisation to comply with all applicable ADs. If the organisation certifies a test as completed when it was not, or uses a later revision of the SB that has not been FAA-approved as an AMOC, both the organisation and the operator could be found in non-compliance.

The directive does not provide for any specific defence or excuse for non-compliance. The language is mandatory: “carry out and successfully accomplish” and “prior to further flight.” There is no provision for an extension of the compliance time based on operational necessity. This means that an operator that experiences a recurrent test failure while the aircraft is at a remote station without maintenance capability must either defer the aircraft under the minimum equipment list (if the AD can be deferred, which is unlikely for a failure situation) or ferry the aircraft under a special flight permit issued by CASA. The directive does not address ferry permits, so the operator would need to rely on the general rules for obtaining such permits, which typically require that the aircraft be safe for the specific flight and that all other AD requirements are met.

The directive explicitly references FAA AD 2000-17-06 Amdt 39-11880. The relationship is one of equivalence: CASA’s AD is based on the FAA’s mandatory requirement, and it accepts FAA-approved AMOCs for later SB revisions. This is a common pattern in bilateral airworthiness agreements. Under the Bilateral Aviation Safety Agreement between Australia and the United States, each party may accept the other’s approvals, but the directive takes a conservative approach by accepting only the AMOC for the specific service bulletin. It does not automatically accept all FAA ADs for the same aircraft; each CASA AD is a separate instrument.

The directive interacts with the continuing airworthiness management provisions of CASR Part 42. Part 42 requires operators of large aircraft (which the Boeing 767 is) to have an approved maintenance program that includes all applicable ADs. The DPV functional test from this AD must be incorporated into that program. The operator cannot simply rely on the AD itself; they must ensure that the test is scheduled, performed, and recorded in accordance with the operator’s maintenance control manual. Failure to incorporate the AD into the maintenance program could itself be a non-compliance under Part 42, even if the test is somehow performed ad hoc.

The directive also interacts with the aircraft’s type certificate data sheet and the airframe and engine maintenance manuals. The repair requirement in Requirement 4 specifically says “repair in accordance with the Aircraft Maintenance Manual.” For the Boeing 767, that is the Boeing 767 Maintenance Manual (AMM). If the AMM does not contain a specific repair procedure for the DPV leakage condition, the operator must submit a repair design to CASA or use a data-approved source such as a Boeing service bulletin. The directive does not clarify whether repair per the service bulletin is also acceptable; it specifically says “Aircraft Maintenance Manual.” This could create a conflict if the SB contains a repair procedure that differs from the AMM. In such a case, the operator must follow the AMM, or else obtain CASA approval to use the SB repair as an alternative. This is a subtle trap: the directive’s requirement 1 (test) follows the SB, but requirement 4 (repair) follows the AMM.

The directive implicitly interacts with the Minimum Equipment List (MEL) process. If the DPV test cannot be performed due to a component inoperative condition, the operator might consider whether the MEL allows dispatch with the thrust reverser system inoperative. However, most MELs for thrust reversers require them to be operational for dispatch, or at least for takeoff. Even if the MEL permits dispatch with the thrust reverser locked out, the AD likely overrides that because the AD requires a successful functional test. An operator cannot use the MEL to defer an AD requirement unless the MEL itself is approved by CASA as an alternative compliance method. Typically, ADs take precedence over MELs unless the AD specifically allows deferral. This AD does not contain any deferral language, so the test must be performed on time regardless of MEL status.

The directive does not reference any other Australian airworthiness standards such as Civil Aviation Orders (CAOs) Part 100 series. It stands alone as a mandatory requirement. However, the general law of contract and insurance will apply: a lessor or insurer may require evidence of AD compliance, and failure to maintain such evidence could be a breach of lease covenants or policy conditions. The directive’s effect on the aircraft’s residual value arises from the cumulative cost of compliance and the risk of grounding if records are deficient.

The directive is issued as Amdt 1 to AD/B767/173. The original issue became effective on 5 June 2002. This amendment, dated 16 January 2008 and effective 23 January 2008, makes one substantive change: it adds a statement that later revisions of Boeing Alert SB 767-78-0084, when approved by the FAA as an AMOC to FAA AD 2000-17-06, are considered acceptable for compliance with equivalent requirements of this directive. The text expressly says “there is no change to the requirements or compliance periods.” This suggests that the original AD’s mandatory action and intervals remain identical; only the means of compliance are expanded to include later FAA-approved SB revisions.

Why was this amendment needed? The background section states that the amendment includes “a statement approving the use of later FAA approved service bulletins.” The original 2002 AD referenced only the October 1999 revision of the SB. By 2008, Boeing had likely issued one or more revisions to that SB , perhaps incorporating improved test procedures, clarifying leak limits, or addressing additional part numbers. Without the amendment, any operator who used a later revision of the SB would technically be non-compliant with the CASA AD because the AD specified the 21 October 1999 revision. They would need to apply for an AMOC from CASA, a process that takes time and resources. The amendment effectively streamlines the process by pre-approving any FAA-approved later revision.

There is a condition: the later revision must be approved by the FAA as an AMOC to the referenced FAA AD. The FAA AD referenced is 2000-17-06. So if the FAA approves a revision to the SB for any reason other than as an AMOC to that AD (for example, if the FAA incorporates the revision into a new AD), the provision may not apply. The operator must verify that the FAA approval specifically states it is an AMOC to FAA AD 2000-17-06.

The amendment history is short, but it hints at the increasing acceptance of foreign regulatory approvals in Australian airworthiness regulation. The original AD in 2002 was likely based directly on the FAA AD, but it did not accept future FAA AMOCs. The 2008 amendment corrected that, reducing the lag between US and Australian AD compliance flexibility.

There is no indication of further amendments to this specific AD after January 2008. Typical CASA ADs may be reissued as amendments if new risks are identified, but this particular subject , DPV leakage , appears to have been considered adequately addressed by the 2008 amendment. Operators should still check the current CASA AD database for any subsequent amendments or supersedures.

The source text does not reference any litigation concerning this directive or its predecessor. This is typical for airworthiness directives: they are rarely challenged in court directly. Operators may challenge CASA’s decisions in the Administrative Appeals Tribunal (AAT) if CASA takes enforcement action, but the directive itself is a legislative instrument that is generally immune from direct challenge on merits. Judicial review under the Administrative Decisions (Judicial Review) Act 1977 is possible if an operator alleges that CASA exceeded its power or failed to follow procedure, but such cases are uncommon in the airworthiness context.

There is no public record of a dispute specifically over AD/B767/173 Amdt 1 in Australian courts. The directive’s subject matter , a functional test on thrust reverser valves , is technical and unlikely to generate legal debate about interpretation. However, if an operator had a disagreement about whether a particular later revision of the SB was “approved by the FAA as an AMOC,” that could become a factual dispute in an enforcement proceeding. The operator would need to provide evidence from the FAA that the revision was approved as an AMOC to FAA AD 2000-17-06, not just as an FAA-approved change to the SB generally.

If a catastrophic incident occurred due to a DPV failure, litigation might arise under tort law (negligence) against the operator or the maintenance organisation. The directive would be used as evidence of the standard of care expected. Compliance with the directive would be a strong defence, while non-compliance could be used as evidence of negligence per se. However, that would be civil litigation, not a direct challenge to the directive itself.

The absence of litigation history suggests the directive is clear and workable, and that operators have generally complied without dispute. That said, the lack of litigation does not prove the directive is optimal; it may simply reflect the high cost and low chance of success in challenging safety regulations.

Several traps await the unwary operator or maintenance planner. The first is the dual interval structure. An unmodified aeroplane requires the DPV functional test every 1,000 flight hours; a modified aeroplane requires it every 6,000 flight hours. The modification is defined as compliance with Boeing SB 767-78-0063 or its production equivalent. If an operator mistakenly thinks their aircraft is modified (perhaps because a later SB was incorporated) but that SB is not the precise 767-78-0063, they may apply the longer 6,000-hour interval erroneously. The directive only accepts SB 767-78-0063 or production equivalent, not any later revision of that SB. So if the operator installed a later revision of the modification SB, they must verify that it is equivalent to 767-78-0063 for purposes of this AD. If not, the aircraft is still in the unmodified category and the 1,000-hour interval applies.

A second trap relates to the production equivalent exemption. It only applies to the initial test under Requirement 1(b). It does not exempt the operator from the recurrent tests under Requirement 3 (every 6,000 hours). An operator of a new-build 767 with the production modification installed should not assume the AD is fully satisfied forever. They still need to schedule the 6,000-hour test. Moreover, the production equivalent must have been a functional test accomplished during production. If the production modification was installed but no functional test was performed at the factory, then the operator must perform the initial test and may not claim the exemption.

The third trap is the requirement to repeat Requirement 1 tests after any repair. The wording is: “Repeat Requirement 1 functional tests if any discrepancies have been corrected under Requirement 4 during compliance with requirement 1, 2 or 3.” This means that if a repair is performed following a failed test at, say, 5,000 hours on a modified aircraft (which falls under Requirement 3), the operator must then perform the Requirement 1 test again. For a modified aircraft, Requirement 1(b) requires the test at a 60-day initial compliance (now irrelevant) and sets the test procedure. The operator must effectively re-do the test that was originally done at the initial compliance, even if the aircraft is deep into the 6,000-hour repeat cycle. This could be interpreted as requiring the test to be done immediately after the repair, potentially shortening the interval to the next scheduled test.

The fourth trap concerns the effective date of this amendment. The amendment was issued on 23 January 2008. Requirements 4 and 5 apply “prior to further flight after the effective date of this Directive.” This means that if an operator had, before 23 January 2008, identified a discrepancy during a functional test and repaired it, but had not repeated the Requirement 1 test as required by the original AD, they would have been non-compliant from 23 January 2008 onward. The amendment does not provide a transition period for this. Similarly, if an operator was using a later revision of the SB that had not been FAA-approved as an AMOC before 23 January 2008, that usage became authorised only on that date. Any tests performed with that revision before 23 January 2008 would not be compliant with the original AD. Operators may need to re-examine their records for the period between the original AD and the amendment to ensure that tests performed with later SB revisions were not relied upon.

The fifth trap is the FAA AMOC condition. The operator must verify that the later revision of the SB has been approved by the FAA as an AMOC to FAA AD 2000-17-06. If the FAA approves a revision only as a new standard (e.g., by superseding the AD), or approves it as an AMOC to a different FAA AD, then the provision does not apply. The operator then has no compliance option other than to use the original October 1999 revision or to obtain a specific AMOC from CASA. Relying on a revision that is not properly approved as an AMOC would be a compliance breach. The directive does not state that the operator must keep a copy of the FAA approval letter, but in practice that would be essential for an audit.

The sixth trap is the distinction between “successfully accomplish” and “carry out” the test. The directive requires that the test be “successfully accomplished.” That means the test must be performed and the results must demonstrate no leakage or acceptable leakage. If the test reveals a leak, it is not successfully accomplished; the operator must proceed to Requirement 4 (repair) and then repeat Requirement 1. An operator cannot simply document the test as performed if it fails the acceptance criteria. This places an absolute burden on the operator to ensure the hardware is in acceptable condition.

Compliance with this directive requires a systematic approach. The first step is to identify all aircraft in the operator’s fleet that are Boeing 767 series with General Electric CF6-80C2 engines. The directive does not apply to other engine types, so a fleet containing 767s with Pratt & Whitney engines would not be affected. Check the engine manufacturer and model on each aircraft’s type certificate data sheet.

The second step is to determine the modification status of each aircraft with respect to Boeing SB 767-78-0063 or its production equivalent. This requires reviewing the aircraft’s maintenance records to see if the modification has been embodied. Look for a logbook entry or an engineering order referencing SB 767-78-0063. If the aircraft was delivered new from the factory with the modification, check the delivery documents for a production equivalent functional test record. If the modification is not installed, the aircraft is in the unmodified category and the 1,000-flight-hour interval applies. If the modification is installed but no production test exists, the aircraft is modified but requires the initial test under requirement 1(b) (though the initial compliance date has passed; the operator must still perform the test if not already done, but the directive does not state a grace period for late initial compliance). Practically, if the initial test was missed, the operator should perform it as soon as possible and start the clock on the 6,000-hour repeat interval from that test.

The third step is to incorporate the DPV functional test into the aircraft’s approved maintenance program. The test must be scheduled at intervals not exceeding 1,000 flight hours (unmodified) or 6,000 flight hours (modified). The operator should choose a cycle that minimises disruption to revenue service, but the maximum interval is a hard limit. The test can be done on a calendar basis if flight hours are not accumulated rapidly, but the directive specifies flight hours, so the operator must track hours accurately.

The fourth step is to obtain the correct version of the service bulletin. The original directive references Boeing Alert SB 767-78-0084 dated 21 October 1999. The operator may use a later revision if and only if that later revision has been approved by the FAA as an AMOC to FAA AD 2000-17-06. To confirm this, the operator should check the FAA’s AD docket for FAA AD 2000-17-06, which lists approved AMOCs. The FAA’s AD website or a subscription service like the FAA’s DMS can be used. The operator should print or save the FAA’s approval notification. If using a later revision, note that the compliance period still runs from the original 2002 dates for initial compliance, but for recurrences, the interval is the same regardless of which SB revision is used.

The fifth step is to perform the functional test in accordance with the procedure. This will typically require the aircraft to be on jacks with hydraulic and pneumatic systems pressurised. The test should be documented in a maintenance release, noting the results and the SB revision used. If the test fails (leak detected), the operator must not release the aircraft to service until the leak is repaired in accordance with the Boeing 767 Maintenance Manual. The repair does not need to follow the service bulletin; the AMM is the specified reference. After the repair, the operator must perform the Requirement 1 functional test again. This retest should be documented as a separate action.

The sixth step is to maintain records of each test and any repairs. The records should be retained for at least the life of the aircraft, as CASA auditors may request them. An operator should also keep evidence of the FAA AMOC approval if using a later SB revision. A compliance status log for each aircraft, showing the date and hours of each test and the next due date, is recommended.

The seventh step is to stay alert for further amendments. CASA may issue additional amendments if new failure modes are discovered, or if Boeing issues a superseding SB. The operator should subscribe to CASA’s AD email notifications and check the FAA’s ADs for the 767 periodically. The directive’s acceptance of later FAA-approved revisions means that the operator can adopt new revisions without a CASA amendment, but only if the FAA has approved them as AMOC to the base AD. The operator must still verify that the revision addresses the DPV leak issue and does not introduce any conflicting requirements.

Finally, if the operator has a fleet that includes some aircraft that were previously modified and some not, a simple tracking system differentiating the two categories is essential to avoid applying the wrong interval. A single spreadsheet or airworthiness program module can handle this. The cost of getting it wrong could be a grounding if CASA discovers a test was due but missed, so the overhead of meticulous tracking is justified.