AD/B767/207 - APU and Engine Fire Shutoff Switches

The directive revolves around several technical and regulatory concepts. An airworthiness directive is a legally binding instrument issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations, requiring an aircraft owner or operator to take specific actions to maintain the aircraft’s airworthiness. Non‑compliance can render the aircraft unairworthy and subject to enforcement action. A functional test refers to checking the operation of the APU and engine fire shutoff switches to ensure they discharge fire suppressant properly. The test must be performed in accordance with Boeing Alert Service Bulletin 767‑26A0127, which contains detailed procedures. The term serviceable switch means a switch that is airworthy, i.e., meets the specifications and has not failed or exceeded its service life. The directive requires replacement with new or serviceable switches, implying that refurbished or overhauled switches may be used as long as they meet the standard.

The optional terminating action is a key feature. An operator may choose to deactivate the Lucas humidifier (part numbers M01AA0101, M01AB0101, M01AB0102, or M01AB0103) to stop the repetitive testing and replacement cycle. However, deactivation is not simply removing power; it must presumably be done in accordance with approved procedures, and the directive requires that all switches be replaced before further flight after deactivation. Once deactivated, the humidifier cannot be reactivated without triggering new compliance obligations. The directive does not specify the method of deactivation; it relies on the operator’s maintenance organisation to determine an acceptable means. This introduces a potential compliance interpretation risk.

Repetitive intervals are expressed as calendar time, not flight cycles or hours. Functional tests are required every 18 months, and full switch replacements every 36 months, unless the optional termination is adopted. The initial compliance window uses the later of two dates: 18 months from original Certificate of Airworthiness or Export Certificate of Airworthiness, or 90 days from the directive’s effective date. This means older aircraft with an earlier C of A get a longer initial period, while newer aircraft need to comply within 90 days. The intervals are maximums; nothing prevents an operator from performing the tasks earlier. However, early compliance does not extend the subsequent interval. The first interval is measured from the date of the directive’s effectiveness, not from the last performance.

The concept of reactivation is a risk for operators who deactivate and later need the humidifier. The directive imposes a fresh set of requirements upon reactivation: functional tests within 18 months and switch replacement within 36 months. The intervals restart from the reactivation date. This creates a disincentive to reactivate unless the operator is prepared to absorb additional maintenance costs and planning. The directive thus encourages operators to commit to either a dry configuration (no humidifier) or a wet configuration (humidifier with perpetual repetitive work). The binary choice reduces flexibility for operators that might want to use the humidifier only seasonally or on certain routes. The directive does not allow a partial or temporary deactivation: once deactivated, any use of the humidifier constitutes reactivation and triggers the full suite of requirements.

This directive directly affects operators of Boeing 767‑300 series aeroplanes listed in Boeing Alert Service Bulletin 767‑26A0127 dated 17 July 2003. That includes airlines, cargo carriers, charter operators, and any entity that holds a Certificate of Airworthiness or operates such aircraft on the Australian register. The directive also applies to aircraft imported into Australia that were originally certified elsewhere; the reference to “original Export Certificate of Airworthiness” captures foreign‑origin aircraft. Given the compliance times, operators must schedule maintenance events for each affected aircraft in their fleet.

Maintenance organisations that service these aircraft are affected because they must be capable of performing the functional test and switch replacement in accordance with the ASB. This may require training, tooling, and access to the service bulletin. The directive imposes a mandatory action that cannot be deferred, so maintenance providers must have capacity to handle the initial and ongoing workload. Failure to comply by the operator could lead to grounding, which would also affect maintenance revenue.

CASA, as the issuing authority, is responsible for monitoring compliance. The directive is a legally binding instrument; CASA may conduct audits, inspections, and spot checks to ensure operators meet the requirements. The delegate James Coyne signed the directive on 4 February 2005, making it operative from 17 March 2005. The directive’s background note references FAA AD 2005‑01‑13, meaning that aircraft on the US register operating in Australia would also need to comply with the US version, but for Australian‑registered aircraft, this CASA directive is the governing instrument. Operators of dual‑registered aircraft may face overlapping compliance regimes, though the CASA directive likely sets the minimum standard.

Indirectly, passengers and cargo customers are affected because compliance work takes aircraft out of service for maintenance. The directive may reduce schedule reliability, especially during the initial compliance period when multiple aircraft require switch replacements. Operators may need to lease spare aircraft or adjust flight schedules, increasing operational costs. These costs may be passed on through ticket prices or freight rates, albeit the amount per passenger is likely small. The directive also affects lessors and financiers of Boeing 767‑300 series aircraft, because the aircraft’s value and maintenance status must reflect compliance with all applicable airworthiness directives. Non‑compliance could affect lease terms or residual value.

The primary duty is on the operator to ensure that the APU and engine fire shutoff switches on each affected aeroplane are tested and replaced according to the compliance schedule. The operator must acquire Boeing Alert Service Bulletin 767‑26A0127 and follow its procedures strictly. The duty extends to ensuring that any switch found to be faulty is replaced before further flight. This imposes a “no go” condition: a failed switch grounds the aircraft until a serviceable switch is fitted. The operator also has a duty to maintain records of the functional tests and replacements, as evidence of compliance during audits.

The directive grants an important right: the option to terminate the repetitive requirements by deactivating the Lucas humidifier. This is a right, not an obligation. An operator may choose to deactivate any or all of the specified humidifier part numbers. However, the right is conditional on performing a one‑time replacement of all APU and engine fire shutoff switches before further flight after deactivation. This means the operator must pay the cost of a full switch replacement even if the switches are functioning correctly. After deactivation, the operator is relieved of the ongoing 18‑month tests and 36‑month replacements. This right may be valuable for operators who do not need the humidifier, or who find the repetitive compliance cost higher than the one‑time replacement plus the loss of humidifier functionality.

The operator also has the right to reactivate a deactivated humidifier, but only by re‑entering the compliance regime. Upon reactivation, the operator must perform the functional test within 18 months and replace all switches not previously replaced within 36 months. The directive does not specify a timeframe for the first test after reactivation; it says “within 18 months after reactivating the humidifier”. The reactivation right is therefore not a simple return to a clean state; it imposes additional maintenance obligations that may discourage reactivation.

The operator does not have the right to extend the compliance intervals. The directive sets maxima, and CASA does not provide a mechanism for extension or alternative means of compliance. The only flexibility is the optional deactivation. This contrasts with some other airworthiness directives that allow for alternative methods based on operational data. The directive also does not provide for a exemption or waiver process; it is a “do this or else” instrument. The operator’s freedom of contract with maintenance providers is limited because the work is mandatory and must be done to the specified bulletin. The operator cannot choose a different test method or a different switch type unless the ASB explicitly allows it.

Finally, the operator has the duty to ensure that any replacement switch is “new or serviceable”. This implies that used switches must be demonstrably airworthy, but the directive does not define the standard. The operator must rely on their own procedures and the switch manufacturer’s recommendations. There may be a risk if a serviceable switch later fails prematurely; that would put the operator back into a non‑compliance situation if the failure is not caught before the next test.

Although the directive itself does not specify penalties, it is issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations. Section 20AB of the Act makes compliance with airworthiness directives mandatory. Failure to comply can result in the aircraft being considered unairworthy, which leads to grounding. Operating an unairworthy aircraft is an offence under regulation 42 of the Civil Aviation Safety Regulations, carrying maximum penalties of up to 50 penalty units for an individual and 250 penalty units for a body corporate (at current indexing, approximately AUD 11,000 and AUD 55,500 respectively, but these figures change over time). Additionally, the Civil Aviation Act provides for imprisonment for up to two years for reckless operation of an unairworthy aircraft that endangers life. The enforcement history for similar CASA directives typically involves administrative action initially, such as a notice of non‑compliance, followed by civil penalties or licence suspension for serious breaches.

CASA’s enforcement powers include issuing directions to ground the aircraft, suspending or cancelling the Certificate of Airworthiness, and taking legal action for breaches. The cost of non‑compliance extends beyond fines: an aircraft grounded for non‑compliance loses revenue, and the operator may face compensation claims from passengers or lessors. Reputational damage also deters investors and customers. For maintenance organisations, failing to properly execute the directive could expose them to liability under contract or tort if a fire incident occurs.

The directive’s compliance schedule uses dates like “within 18 months after the effective date”. An operator who misses that deadline is immediately in breach, even if the switches are functional. There is no grace period. The enforcement risk is especially high for the initial compliance actions due to the 90‑day/18‑month calculation. An operator must proactively plan to meet the earlier of the two triggers. The optional deactivation does not eliminate the one‑time replacement requirement; failure to replace switches before further flight after deactivation also constitutes a breach.

The directive references FAA AD 2005‑01‑13, which may result in dual enforcement by CASA and the FAA for aircraft under both jurisdictions. In practice, the two authorities often coordinate, but an operator cannot rely on compliance with one to satisfy the other. Each agency will enforce its own directive. The penalty for FAA non‑compliance could include additional civil penalties and restrictions on operations into the United States.

A practical enforcement risk arises from the record‑keeping duty. An operator must demonstrate compliance during routine surveillance audits. Inadequate records may be treated as evidence of non‑compliance, even if the work was done. The cost of defending an enforcement action could far exceed the cost of compliance, incentivising operators to follow the directive to the letter.

This airworthiness directive operates within the broader framework of the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations (CASR). Specifically, CASR Part 39 governs the issuance and management of airworthiness directives. The directive itself is a legislative instrument, not a simple advisory notice. It has the force of law. Compliance with the directive is a condition of the aircraft’s Certificate of Airworthiness under CASR 21. Operators must incorporate the directive into their maintenance schedule and ensure that any maintenance release or certificate of release to service references the work performed.

The directive may interact with the aircraft’s approved maintenance program. Operators typically have a CASA‑approved maintenance schedule that includes tasks derived from manufacturer recommendations. Repetitive airworthiness directive tasks must be included in that program if they are more frequent than the existing tasks. If the directive’s intervals differ from the manufacturer’s baseline, the operator must adjust the maintenance program accordingly, which may require CASA approval. This introduces administrative cost and delay.

There may be interaction with occupational health and safety laws at the Commonwealth and state levels. The deactivation of a humidifier could affect cabin air quality or temperature, potentially leading to complaints or issues under workplace safety regulations, particularly for crews. However, those laws do not override the airworthiness directive; an operator would need to balance both requirements. The directive itself does not mandate any specific safety assessment of the deactivation.

International aviation agreements, particularly those between Australia and the United States, are relevant because the directive mirrors FAA AD 2005‑01‑13. Operators of aircraft on the Australian register that also fly to the US must comply with both directives. The FAA may recognise CASA’s directive as an acceptable alternative means of compliance if there are minor differences, but the directive does not state this. The interplay could cause administrative confusion if the FAA’s compliance intervals differ even slightly; in this case, they appear aligned.

For imported aircraft that hold an Export Certificate of Airworthiness from the manufacturing state, the operator must first comply with that state’s airworthiness directives. Upon import into Australia, CASA requires compliance with all Australian airworthiness directives as well. The directive accounts for this by referencing the original Export Certificate of Airworthiness date. If the FAA directive had been complied with before import, the operator must still check that the Australian requirements are met. They may need to repeat test cycles.

The directive also interacts with lease agreements. Lessees are typically contractually obligated to comply with all applicable airworthiness directives. If the lessee fails to comply, the lessor may have remedies for breach of contract. The lessor may also require evidence of compliance upon return of the aircraft. The one‑time replacement of switches upon deactivation could be a cost dispute if the lessor prefers to keep the humidifier for future use.

The source text of the directive does not include any amendment history. The document is labelled AD/B767/207 and cites an FAA AD (2005‑01‑13) as a reference, but no prior versions or amendments are mentioned. The directive is dated 4 February 2005 and became effective on 17 March 2005. There is no indication that this directive amended or replaced an earlier directive on the same topic. The numbering “AD/B767/207” suggests it is the 207th directive issued for the Boeing 767 series under CASA’s system. Without additional sources, we cannot confirm whether subsequent amendments have been issued after the cut‑off of the provided text. The analysis must rest solely on the document as provided.

In practice, airworthiness directives are occasionally revised to extend compliance times, add new part numbers, or correct typographical errors. The absence of amendment history in the source does not imply that no amendments exist. However, for the purposes of this deep dive, we can only note that the provided text is the original directive. Users should check the current CASA database (e.g., the Airworthiness Directives search function) to see if a later amendment has superseded or modified AD/B767/207. The directive references FAA AD 2005‑01‑13, which itself may have been amended by the FAA; CASA often adopts FAA amendments automatically, but not always. An operator relying on this directive should verify the latest version before planning compliance.

The lack of amendment history also means the directive has not been updated to reflect changes in the service bulletin. The ASB is dated 17 July 2003. If Boeing issues a later revision, the operator would need to determine whether CASA accepts the later revision. Usually, CASA directs that the specific edition of the ASB be used unless an alternative is approved. Using a later revision without CASA approval could risk non‑compliance. The directive does not include a revision‑catching clause.

The source text does not contain any litigation history. No court or tribunal cases are referenced in the directive. Airworthiness directives are rarely the subject of litigation in Australia, because compliance is mandatory and the technical nature of challenges is limited. An operator could theoretically seek judicial review of the decision to issue the directive under the Administrative Decisions (Judicial Review) Act 1977, but the grounds would be narrow: unreasonableness, procedural error, or lack of evidence. Given that the directive is based on Boeing’s own safety findings, a challenge would face significant hurdles. There is no publicly known case against AD/B767/207 specifically.

If litigation had occurred, it likely would have been reported in aviation‑law databases. The absence suggests either no challenge was brought, or any disputes were resolved at an administrative level (e.g., through CASA’s enforcement review process). Operators may have sought extensions or alternative means of compliance informally, but that would not generate a published case.

The directive’s reference to an FAA AD could lead to cross‑border enforcement disputes. For example, if CASA grounds an aircraft for non‑compliance and the aircraft is operated by a foreign carrier, that carrier might seek relief in a court. But again, no such case is cited. The litigation history for this directive is blank.

Several aspects of the directive may catch operators off guard. First, the optional terminating action is not as simple as it appears. Deactivating the humidifier does not allow the operator to skip the switch replacement. Requirement 4 states: “For any aeroplane on which Lucas humidifier … is deactivated - Replace all APU and engine fire shutoff switches with new or serviceable switches”. This is required before further flight after deactivation. An operator who merely disables the humidifier without replacing switches is in breach. The cost of replacing all switches may be substantial, especially if the aircraft has many switches (likely at least two engines and the APU). The directive does not specify how many switches are affected, but the ASB should clarify.

Second, if an operator deactivates the humidifier and later needs it (e.g., for a charter flight requiring cabin humidification), reactivation triggers a new set of duties. The operator must then perform functional tests within 18 months and replace all switches not previously replaced within 36 months. The phrase “not previously replaced in accordance with Requirement 2” is ambiguous. If the operator had replaced all switches per Requirement 4 at deactivation, then there may be no switches left to replace upon reactivation. But if some switches were replaced earlier by Requirement 2 (failed test) and others are older, the operator must track which switches were replaced under which requirement. This record‑keeping burden is easy to overlook.

Third, the compliance intervals are based on calendar time from the effective date or from original certification dates. An operator that acquires a used 767‑300 from another operator may not know the exact dates of previous compliance. The directive says initial test is within 18 months from the original Certificate of Airworthiness or the original Export Certificate of Airworthiness, whichever occurs later. If the aircraft has been out of service for years, that date may be in the past, meaning the operator must comply within 90 days of the directive’s effective date (17 March 2005) or immediately upon purchase. The operator must verify the aircraft’s certification history.

Fourth, the directive does not specify what constitutes “deactivation” of the humidifier. Must it be physically removed? Electrically disconnected? Plated over? The operator must determine an acceptable method and obtain approval if necessary. Improper deactivation could cause other problems, such as air leaks or imbalance, leading to further maintenance issues. The risk of a later audit finding the deactivation non‑compliant is real if no approved procedure exists.

Fifth, the directive’s reference to FAA AD 2005‑01‑13 may imply that the FAA version has alternative provisions. For example, the FAA AD might allow extending intervals based on a different humidifier part number. An operator that complies only with the FAA AD may not fully meet CASA’s requirements. The directive says “FAA AD 2005‑01‑13 Amdt 39‑13938 refers”, but that is a note, not a substitute. Operators licensed in both countries must satisfy the stricter of the two.

Sixth, the functional test requirement is for all APU and engine fire shutoff switches. The directive does not require testing of the fire control circuits themselves beyond the switches. An operator who only tests the switches might miss a wiring fault that also prevents fire suppressant discharge. The directive is focused on the switch internal continuity failures, but other components could fail independently. Operators should consider broader maintenance beyond this directive.

Compliance with AD/B767/207 requires a systematic approach. The operator must first identify each aircraft in its fleet that falls under the applicability: Boeing 767‑300 series aeroplanes listed in Boeing Alert Service Bulletin 767‑26A0127. The list likely includes specific line numbers or serial numbers. Obtain the full text of the ASB from Boeing or an approved distributor. Review the procedures for functional testing and switch replacement. Ensure that the maintenance organisation has the necessary tooling, training, and replacement switches (part numbers as defined in the ASB).

Determine the initial compliance dates for each aircraft. For Requirement 1 (functional test), the initial due date is the later of: (a) 18 months after the date of issue of the original Certificate of Airworthiness or original Export Certificate of Airworthiness, or (b) 90 days after 17 March 2005 (i.e., 15 June 2005). For Requirement 3 (full switch replacement), the initial due date is 17 September 2006 (18 months after the effective date). Use a maintenance tracking system to schedule these tasks. If any aircraft is approaching its 18‑month anniversary from its C of A before 15 June 2005, the operator must perform the test by that earlier date. Otherwise, the 90‑day window applies. The operator should calculate each aircraft individually.

Perform the functional test in accordance with the ASB. If any APU or engine fire shutoff switch fails, replace it with a new or serviceable switch before further flight. Document the test results and replacement details. For the initial replacement (Requirement 3), replace all switches that have not already been replaced under Requirement 2, even if they passed the test. After the initial actions, continue repetitive tests every 18 months and replacements every 36 months, unless the operator executes the optional terminating action.

Consider whether to deactivate the Lucas humidifier. If the operator decides to pursue this option, perform a one‑time replacement of all APU and engine fire shutoff switches in accordance with the ASB, before further flight after deactivation. Then deactivate the humidifier using an approved method (check the Aircraft Maintenance Manual or the ASB for guidance). No further tests or replacements are required, provided the humidifier remains deactivated. Maintain a record of the deactivation and the switch replacement. If the operator later decides to reactivate the humidifier, schedule a functional test within 18 months of reactivation, and replace any switches not previously replaced within 36 months. Thereafter, resume the 18‑month test and 36‑month replacement cycles.

Record keeping is critical. For each aircraft, keep copies of the ASB, the signed maintenance release for each test and replacement, and a log of the dates of deactivation or reactivation. These records must be available for CASA audit. Enter the directive tasks into the operator’s approved maintenance schedule as mandatory items. Ensure that the maintenance organisation uses the correct ASB revision. If Boeing issues a later revision of the ASB, the operator should contact CASA to confirm whether the new revision is acceptable or if a new directive is needed.

Finally, check for any additional requirements from other jurisdictions. If the aircraft also operates under FAA oversight, ensure compliance with FAA AD 2005‑01‑13. Coordinate with the lessor or financier to address any contractual implications of deactivating the humidifier, as this may affect the aircraft’s residual value or future lease terms. Monitor CASA’s website for any amendments or superseding directives regarding AD/B767/207.