AD/CESSNA 550/26 - Wing Fuel Boost Pumps

The central legal mechanism is an airworthiness directive (AD), a legislative instrument issued by CASA under its delegated authority from the Civil Aviation Act 1988 (Cth). An AD creates a binding set of requirements that the registered owner, operator, and maintenance organisations of the affected aircraft must comply with; non-compliance renders the aircraft unairworthy and its operation potentially unlawful. This AD is a direct adoption of a US FAA airworthiness directive (FAA AD 2006-05-08) with some adaptation to Australian reference materials.

AFM revision (Requirement 1) refers to the temporary alteration of the aircraft flight manual, the document that sets the certified operating limitations and procedures for the aeroplane. By inserting a temporary change (TC) into the Limitations Section, the AD introduces an operational prohibition on using the wing fuel boost pumps for defueling under certain unspecified conditions. The TC remains in effect only until the terminating action (the modification and removal) is accomplished. The AFM revision is the fastest way to impose an operational restriction without immediate physical modification of the aircraft, although it introduces a permanent administrative burden until the later modification is done.

Placard installation (Requirement 2) is a physical warning close to the fuel quantity gauge. The AD imposes a minimum letter height of 6mm, exceeding whatever the service bulletin might specify. The placard serves as a continuing reminder to pilots and ground crew not to use the wing fuel boost pumps for defueling under the prohibited conditions. The placard must remain until the modification is completed, after which it is removed.

Detailed inspection (Requirement 3a) is defined in Note 1 as an intensive examination using good lighting and possibly mirrors or magnifying lenses, with surface cleaning as required. This is a one-off inspection with a specific objective: to detect chafed wiring that could arc inside the fuel tank. The definition is taken directly from the FAA's standard terminology and is legally relevant because the inspection standard must be met to comply with the AD.

Modification (Requirement 3b) refers to altering the wing fuel boost pumps to eliminate the condition that could cause chafed wiring and arcing. The AD does not specify the exact modification; it directs operators to the accomplishment instructions of one of the three Cessna service bulletins (SB550-28-08, SB550-28-14, or SB550-28-15). This means the substantive engineering solution is left to the aircraft manufacturer's design, not prescribed in the AD itself.

Terminating action (Requirement 5) is the completion of the inspection and modification, followed by removal of the AFM temporary change and the placard. Before that point, the aircraft operates under the dual constraints of a manual limitation and a visual placard. Once the terminating action is done, the aircraft returns to its normal operating limitations. This concept is important for compliance planning: operators who have not yet completed the inspection and modification must keep the AFM limitation and placard in place.

Alternate Method of Compliance (AMOC) is referenced in the AD's note about later revisions of service bulletins. An AMOC is an alternative means of achieving compliance with an AD that is approved by the regulatory authority. The AD provides that later revisions of the Cessna service bulletins, if approved by the FAA as an AMOC to FAA AD 2006-05-08, are automatically considered acceptable for compliance with this Australian AD. This avoids the need for a separate Australian AMOC approval, though operators should verify that any later revision they use has indeed received FAA AMOC approval.

The AD applies directly to any person who owns or operates a Cessna Model S550, 550 or 551 aeroplane within the specified serial number ranges: S550 serial 0001 through 0160 inclusive; 550 and 551 serial 0002 through 0733 inclusive; 550 serial 0801 through 1075 inclusive. These cover the Citation II, Citation S/II, and Citation Bravo variants manufactured in those ranges. The population is not trivial; the cumulative range covers over 1,000 individual aeroplanes, many of which are still in service worldwide, including in Australia.

Registered owners bear the primary legal obligation to ensure the AD is complied with. However, the practical duties fall on operators (including charter, corporate flight departments, and owner-pilots) and certified maintenance organisations (CAMOs or LAMEs). The AD does not distinguish between commercial and private operation; it applies equally to air transport, aerial work, and private category aircraft. Maintenance organisations will be the ones procuring the service bulletins, performing the detailed inspection, carrying out the modification, and documenting compliance.

CASA itself is affected as the regulator required to monitor compliance and enforce the AD. The AD was signed by James Coyne as a delegate of CASA, meaning the agency has formally determined that this directive is necessary for air safety.

Indirectly, Cessna Aircraft Company (now Textron Aviation) is affected because the AD relies on its service bulletins. The bulletins are proprietary technical documents that operators must purchase or access through authorised channels. The AD also gives Cessna some control over the AMOC process for later revisions.

Insurance companies and aircraft financiers may have an interest in the AD because non-compliance can affect airworthiness certificate validity and insurance coverage. An operator who fails to comply with the AD may find an aircraft uninsured if a fuel system incident occurs.

Pilots and flight crews are affected because they must be aware of the AFM limitation and placard during the interim period. They must not use the wing fuel boost pumps for defueling under the conditions specified in the temporary change, even if that slows down ground servicing.

The AD imposes a series of duties, each with a specific compliance time. The duties are:

1. Duty to revise the AFM (within 25 hours TIS after 20 April 2006): The operator or maintenance organisation must insert the correct temporary change into the Limitations Section of the AFM. There is no choice of which temporary change; the AD lists nine specific ones, and the operator must select the one that corresponds to the aircraft model and AFM configuration. The duty is triggered once and the AFM revision must remain in place until the terminating action is completed.

2. Duty to install a placard (within 25 hours TIS): The placard must be placed close to the fuel quantity gauge, with letters at least 6mm tall. The content of the placard is not specified in the AD; it must be derived from the service bulletin. The placard must be physically attached and legible.

3. Duty to perform a detailed inspection (within 300 hours TIS): This is an intensive examination for chafed wiring of the wing fuel boost pumps. The inspection must be done in accordance with the accomplishment instructions of one of the three service bulletins. The operator must ensure that the maintenance organisation conducting the inspection is qualified and that the work is properly documented.

4. Duty to modify the wing fuel boost pumps (within 300 hours TIS, but the modification is part of the same requirement as the inspection): The AD does not give a separate deadline; the modification must be accomplished within the same 300-hour TIS period as the inspection.

5. Duty to accomplish corrective actions (before further flight): If the inspection reveals discrepancies, the operator must correct them immediately in accordance with the service bulletin before the aircraft is next flown. This is a "no go" item until fixed.

6. Duty to remove the AFM temporary change and placard (before further flight, after the inspection and modification are completed): Once the modification is done, the temporary operational restriction is no longer needed and must be removed. The aircraft can then return to its normal AFM configuration.

The rights conferred by the AD are limited. Operators have a right to use later revisions of the Cessna service bulletins as an alternative means of compliance, provided those revisions are approved by the FAA as an AMOC to FAA AD 2006-05-08. The AD does not specify a process for seeking a separate Australian AMOC; it appears to accept the FAA's approval as sufficient. However, this presumed delegation of authority may create uncertainty if CASA later disagrees with an FAA AMOC on an Australian-registered aircraft. The AD also does not provide a right to request an extension of the compliance deadlines; it prescribes fixed times in TIS that cannot be altered without a formal variation to the AD.

There are no explicit rights to a hearing, appeal, or compensation for the costs of compliance. Like all ADs, this is a regulatory order with no procedural rights built into the instrument itself. Any challenge would have to be made under the general administrative law provisions of the Civil Aviation Act or the Administrative Appeals Tribunal Act.

The source AD does not itself specify penalties; enforcement relies on the parent regulatory framework of the Civil Aviation Act 1988 (Cth) and the Civil Aviation Safety Regulations 1998 (CASR). Under the general scheme, an airworthiness directive is a legislative instrument, and failure to comply constitutes a breach of a condition of the airworthiness certificate. Operating an aircraft that does not comply with an applicable AD would likely contravene regulation 42.140 of CASR (or its equivalent at the time), which requires the registered operator to ensure the aircraft meets continuing airworthiness requirements. The Civil Aviation Act provides for civil penalties of up to 60 penalty units for an individual and 300 penalty units for a body corporate for each contravention (indexed to the penalty unit value, which as of 2025 is $330 per unit, so $19,800 for an individual and $99,000 for a corporation). Additionally, the Act provides for criminal sanctions in cases of reckless or intentional non-compliance that endangers safety, with maximum penalties of imprisonment.

Beyond monetary penalties, CASA may take administrative enforcement actions. These include suspending or cancelling the airworthiness certificate of the affected aircraft, issuing a direction to ground the aircraft, or requiring additional maintenance actions before release to service. Non-compliance also has civil liability implications: if an operator suffers an accident involving fuel tank ignition and is found to have not complied with the AD, that could constitute negligence per se in a civil suit, affecting insurance payouts and exposing the operator to damages claims.

The practical enforcement burden on CASA is significant because the AD applies to a large number of aircraft and the compliance deadlines are measured in TIS, not calendar time. CASA would need to track aircraft usage to know when a particular aircraft exceeds its 25-hour or 300-hour window. This is usually monitored during annual airworthiness reviews or through maintenance release documentation. Maintenance organisations that certify compliance without actually performing the required work face separate enforcement under the maintenance regulations, including potential loss of their authorisation.

The AD is part of a larger regulatory ecosystem. It explicitly references and adopts requirements from FAA AD 2006-05-08 (and references FAA AD 2006-06-03 Amdt 39-14511 in Note 2). This is a standard pattern: CASA often adopts US FAA ADs for US-type certificated aircraft, with minimal modification. The effect is that Australian operators are subject to essentially the same requirements as US operators, but the legal force comes from CASA's direction, not the FAA's.

The AD interacts with Cessna Service Bulletins SB550-28-08, SB550-28-14, and SB550-28-15. These are proprietary documents issued by the aircraft manufacturer. While the AD mandates compliance, it does not incorporate the bulletins by reference in the Gazette sense; instead, the AD requires that actions be done "in accordance with" those bulletins. This creates a potential cost because the bulletins must be obtained and properly understood. Later revisions of those bulletins are acceptable if FAA-approved as an AMOC. This interaction with FAA approval means the Cessna bulletins are not static; they can be updated, and the AD automatically accepts those updates if they clear the FAA AMOC process.

The AD also interacts with the Australian Maintenance Regulations in that any maintenance organisation performing the inspection and modification must be appropriately authorised under CASR Part 145 or Part 66. The work must be certified in a maintenance release in the aircraft's technical log.

For aircraft registered outside Australia but operating within Australia (e.g. foreign-registered aircraft on temporary stay), the AD's applicability depends on the registration. The AD applies only to aircraft on the Australian register. However, CASA may issue similar operational directions to foreign aircraft under other provisions of the Act.

The AD does not interact with the Trade Practices Act / Competition and Consumer Act because it imposes mandatory safety requirements that do not affect competition between operators in any legally meaningful way, though the cost of compliance is borne entirely by operators without any right to compensation for the mandatory modification.

The source document is the original AD as issued on 4 April 2006, effective 20 April 2006. It does not contain any amendment history; no earlier versions or subsequent revisions are described. The AD appears to have been issued once and not been amended through a separate instrument. However, given that the AD references later revisions of service bulletins as acceptable compliance alternatives, the substantive requirements of the AD may have been affected indirectly by changes to the supporting technical documents. For example, if Cessna issued SB550-28-08 Revision 2 and the FAA approved it as an AMOC to FAA AD 2006-05-08, that would, per the AD's own terms, become an acceptable means of compliance for the Australian AD without any formal amendment to AD/CESSNA 550/26. This means the AD's flexibility provides a form of de facto amendment without the legislative amendment process.

Practitioners should be aware that CASA's online register of ADs may list superseding or related ADs for the same aircraft type. It is possible that subsequent ADs on the Cessna 550 series have addressed other fuel system issues, which might interact with the requirements of this AD. However, from the source provided, no direct amendment history is available. The user should search for any CASA ADs that reference AD/CESSNA 550/26 in their preamble or that contain "AMOC to AD/CESSNA 550/26" to see if there have been later variations.

The source document contains no reference to any litigation concerning this AD. There are no mentioned court cases, tribunal decisions, or legal challenges to the validity or interpretation of AD/CESSNA 550/26. This is not surprising for a relatively narrow airworthiness directive on a specific aircraft model. Airworthiness directives are generally not litigated in Australia; when they are, it is usually in the context of enforcement proceedings where the operator argues the AD was not applicable, not properly issued, or impossible to comply with. There is no record of such a challenge in the source.

Given that the AD was issued in 2006, if no litigation has occurred in the intervening years, it is safe to assume the requirements were generally accepted as technically reasonable and achievable. The absence of litigation does not mean the AD is immune to future challenge, but it suggests that compliance was straightforward for most operators.

The AD's reliance on service bulletins and FAA AMOCs could, in theory, give rise to a dispute if an operator used a later revision of a service bulletin that purported to be an FAA-approved AMOC but was not in fact approved, or if CASA decided not to accept the FAA's AMOC. No such dispute is recorded in the source.

Several features of this AD could trap unwary operators or maintenance organisations.

The AFM limitation is not fully described in the AD. Requirement 1 says the AFM revision must "prohibit use of the wing fuel boost pumps for defueling under certain conditions". The conditions themselves are not defined in the AD; they are presumably contained in the temporary change pages listed or in the service bulletin. An operator who only reads the AD may not know exactly when it is safe to use the boost pumps for defueling and when it is prohibited. The AD gives no further guidance, so operators must obtain the full service bulletin to understand the limitation. This imposes an information cost and reliance on the manufacturer's document.

The placard letter height is mandatory: at least 6mm. Service bulletins may not specify a minimum letter height; the AD overrides the bulletin on this point. A smaller placard that meets the bulletin but has 4mm letters would not comply. The AD explicitly says "in addition to the specifications in the service bulletin, the letters on the placard must be at least 6mm tall." This is a trap for those who assume the bulletin is complete.

Compliance times are in "time in service", not calendar hours. This is standard for ADs based on hours flown, but it can create uncertainty for aircraft that fly infrequently. An aircraft that flies only 50 hours per year would have the full 300 hours TIS to complete the inspection/modification, which could be six years. Conversely, an aircraft that flies 100 hours per month would be due in three months. The compliance window for Requirements 1 and 2 is only 25 hours TIS, which for a high-utilisation aircraft could be as little as a week. Operators must track TIS accurately.

Corrective actions must be done "before further flight" if discrepancies are found. This means if the detailed inspection reveals chafed wiring, the aircraft cannot fly until the problem is fixed. The AD does not allow a ferry flight to a maintenance base; the aircraft is effectively grounded at the inspection location. This could cause operational disruption if the inspection is performed at a remote location.

The terminating action requires removal of the AFM temporary change and the placard. This is straightforward, but there is a risk that an operator fails to remove the placard after the modification, leaving an inaccurate warning placard in the cockpit. Alternatively, an operator might remove the AFM temporary change prematurely (thinking the modification is done when it is not) and then continue operating without the limitation.

The acceptance of later FAA AMOCs via later service bulletin revisions is automatic but carries risk. The AD states that later revisions of the service bulletins, approved by the FAA as an AMOC to FAA AD 2006-05-08, are "considered acceptable for compliance with the equivalent Requirements of this Directive." That means an operator who relies on a later revision that the FAA has approved as an AMOC does not need separate CASA approval. However, if CASA later determines that the FAA's AMOC was not equivalent, the operator could be found non-compliant. The AD does not require the operator to obtain written confirmation from CASA; it relies on the operator's judgment that the FAA approval is valid.

Compliance with AD/CESSNA 550/26 is a multi-step process that should be planned well before the effective date of 20 April 2006. The steps are as follows, based entirely on the requirements in the source.

Step 1: Determine applicability. Check the aircraft model and serial number against the table in the AD: S550 serials 0001 through 0160; 550 and 551 serials 0002 through 0733; 550 serials 0801 through 1075. If the aircraft falls within these ranges, the AD applies.

Step 2: Obtain the required service bulletins. The AD references SB550-28-08 (7 May 2004), SB550-28-14 (2 December 2003), and SB550-28-15 (20 January 2004). All three may be needed depending on which requirement applies. The operator or maintenance organisation must purchase or access these bulletins from Cessna/Textron Aviation. For the AFM revision (Requirement 1), SB550-28-14 is explicitly mentioned, but the table within the AD lists nine specific AFM temporary changes that correspond to different AFMs. The operator must identify the correct AFM temporary change for the aircraft and insert it into the Limitations Section of the AFM.

Step 3: Comply with Requirements 1 and 2 within 25 hours TIS after 20 April 2006. This is a short deadline; the actions should be performed at the next available maintenance opportunity. Requirement 1: insert the correct AFM temporary change into the Limitations Section of the applicable AFM. Requirement 2: install a placard close to the fuel quantity gauge, with letters at least 6mm tall, following the accomplishment instructions of the relevant service bulletin. The placard must warn against using the wing fuel boost pumps for defueling under conditions specified in the bulletin.

Step 4: Schedule compliance for Requirement 3 within 300 hours TIS after 20 April 2006. This involves performing a detailed inspection for chafed wiring of the wing fuel boost pumps and modifying the pumps in accordance with the accomplishment instructions of SB550-28-08, SB550-28-14, or SB550-28-15 as applicable. The inspection is defined as an intensive examination with good lighting and possible inspection aids. The modification is the physical change to the pumps to eliminate the chafing hazard. The AD gives flexibility to use any of the three service bulletins; the operator should choose the most appropriate one for the aircraft configuration.

Step 5: Handle discrepancies immediately. During the inspection, if chafed wiring or other conditions are found, the operator must accomplish all applicable corrective and other specified actions in accordance with the service bulletin before further flight. The aircraft cannot be flown until the discrepancies are rectified.

Step 6: Remove the temporary AFM change and placard before further flight after the modification. Once the inspection and modification are completed, the aircraft no longer needs the operational restriction. The AFM temporary change must be physically removed or removed from the manual, and the placard must be removed. This is the terminating action that ends the AD's requirements.

Step 7: Document compliance. The AD does not explicitly require a log entry, but standard practice under CASR requires that compliance with an AD be recorded in the aircraft's technical log or maintenance register. The entry should reference AD/CESSNA 550/26, the service bulletin used, the date of compliance, the TIS reading at the time, and the certifier's details.

Step 8: If using a later revision of a service bulletin, confirm that the revision has been approved by the FAA as an AMOC to FAA AD 2006-05-08. Retain evidence of that approval (e.g. FAA AD Docket reference) in the aircraft records.

Operators who have already completed the actions described in the AD before the effective date should verify that the actions are equivalent. The AD does not provide credit for prior compliance unless the work was done in accordance with the listed service bulletins or an FAA-approved AMOC. If the aircraft already has a placard or AFM revision installed per earlier correspondence, it may need to be updated to meet the specific requirements of this AD (e.g. the 6mm letter height).