AD/F100/91 Amdt 1 - Fuel System - Crossfeed Valve Actuator

Airworthiness Directive (AD). An AD is a mandatory regulatory instrument issued by CASA under Part 39 of the Civil Aviation Safety Regulations (CASR) or under transitional provisions of the Civil Aviation Regulations (CAR) 1988. It requires corrective action on aircraft, engines, propellers, or components when an unsafe condition exists and is likely to exist or develop on other aircraft of the same type. AD/F100/91 Amdt 1 is such an instrument. It is legally binding on all certificate holders, operators and maintainers of the affected aircraft. Non‑compliance can result in enforcement action, including fines, suspension of approvals, or grounding.

Applicability. The AD applies to Fokker Aircraft B.V. F28 Mark 0070 and Mark 0100 aeroplanes (i.e., the Fokker 100), all serial numbers, but only if an actuator P/N 9409122 or P/N 53‑0013 is installed on one or both fuel crossfeed valves. This is a conditional applicability: if the aircraft has never had such an actuator fitted (e.g., it still has the original P/N 9401037 “chimney type” actuator and has never been modified), the AD does not apply. However, the background notes that aeroplanes serial numbers 11244 through 11441 were originally delivered with P/N 9401037, but many of those have since been retrofitted with the susceptible P/N 9409122 during service. Thus, operators must check actual configuration, not just delivery specification.

Configuration definitions. The AD uses two key terms: “pre‑SBF100‑28‑046 configuration” and “post‑SBF100‑28‑046 configuration”. The former refers to aeroplanes that have not yet accomplished the modification described in Fokker Services Service Bulletin SBF100‑28‑046 (dated 27 March 2008) - i.e., they still have the original P/N 9409122 or possibly P/N 9401037 actuators. The latter refers to aeroplanes that have already complied with that bulletin and have P/N 53‑0013 actuators installed. This distinction matters because the compliance path differs: pre‑config aeroplanes can choose to go directly to P/N 53‑0027 (Requirement 1b), while post‑config aeroplanes must replace the intermediate P/N 53‑0013 with P/N 53‑0027 (Requirement 2).

Service Bulletins. The AD relies on two Fokker Services Service Bulletins (SBFs) as the detailed accomplishment instructions. SBF100‑28‑046 introduced the P/N 53‑0013 actuator and associated modifications (mounting blocks, wiring, etc.). SBF100‑28‑061 introduced the P/N 53‑0027 actuator and supersedes the earlier bulletin. The AD allows the use of later approved revisions of these documents, meaning operators should check if Fokker has issued any updates since the original dates (27 March 2008 and 20 April 2009, respectively). This is a practical point: using an outdated revision could result in a non‑compliant installation.

Compliance timeframes. The AD establishes multiple deadlines. Requirement 1 has a compliance time of “within 12 months from 28 August 2008” (the effective date of the original AD). Because this amendment issues in July 2009, that 12‑month window has nearly expired or already expired for some operators. Requirement 2 gives 18 months after the effective date of this amendment (30 July 2009), so due by 30 January 2011. Requirement 3 is a prohibition effective after 12 December 2010. Operators must carefully track these dates and apply the correct deadline to each aircraft based on its configuration. Note that the amendment does not extend the original compliance time for Requirement 1; it remains unchanged.

Part numbers. The directive revolves around three part numbers for the actuator: P/N 9409122 (original, freeze‑prone), P/N 53‑0013 (first fix, later found defective), and P/N 53‑0027 (second fix, the end state). Understanding the lineage is essential for any engineering or logistics planning. The AD does not allow mixing: after the effective date of the prohibition, only P/N 53‑0027 may be installed. Also, note that Note 1 provides relief from another AD (AD/F100/84) after fitting either P/N 53‑0013 or P/N 53‑0027, but since P/N 53‑0013 is itself now banned from new installations after 12 December 2010, the practical effect is that only P/N 53‑0027 installations will eventually be eligible for that relief.

Aircraft operators are the primary addressees. Any person or company that operates a Fokker F28 Mark 0070 or Mark 0100 aircraft in Australia, registered in Australia, or operated under an Australian Air Operator’s Certificate (AOC) and subject to CASA’s regulatory reach, must comply with this AD. This includes airlines, charter operators, and private owners. The AD is type‑specific but condition‑based: only operators whose aircraft have the affected actuator part numbers installed are required to take action. However, because the unsafe conditions are systemic, prudent operators of all Fokker 100 aircraft should verify their configuration. The AD also affects foreign operators who bring Fokker 100 aircraft into Australian airspace; while CASA’s jurisdiction over foreign‑registered aircraft is limited, operators wishing to fly into Australia must demonstrate compliance with Australian airworthiness requirements, which often reference applicable ADs.

Approved maintenance organisations (AMOs) and licensed aircraft maintenance engineers (LAMEs) are the entities that will physically perform the actuator replacement, associated modifications, and documentation. They must be authorised under CAR 30 or Part 145 of CASR to perform the work. They must have access to the correct Fokker Services Service Bulletins, the approved actuator part P/N 53‑0027, and any required mounting blocks, wiring changes, or other parts specified in the bulletins. The work may require specific tooling or training if the Fokker 100’s fuel system configuration is unusual for the particular AMO.

Parts suppliers and manufacturers. Eaton Aerospace is named in the background as the manufacturer of the actuators (P/N 53‑0013 and P/N 53‑0027). The AD effectively mandates Eaton’s product because no alternative part is approved. This creates a potential single‑source dependency. Operators and AMOs must order P/N 53‑0027 from Eaton or its authorised distributors; if supply is constrained, compliance timelines could be affected. Fokker Services (the type certificate holder support) is also affected because it issued the Service Bulletins that the AD references. Any updates to those bulletins will flow through to AD compliance.

Regulators. CASA is the issuer and enforcer of this AD. The European Aviation Safety Agency (EASA) issued the equivalent AD 2009‑0116, which is referenced in Note 2. Operators with aircraft that are also on European registers will need to comply with the EASA version; the requirements are substantively identical. The background shows that the unsafe conditions were first identified internationally, leading to EASA AD 2008‑0126, then the revised AD 2009‑0116. CASA adopted the latter as AD/F100/91 Amdt 1, with an effective date a few weeks after EASA’s. This underscores the international nature of airworthiness regulation.

Passengers and the public are indirectly affected insofar as compliance prevents fuel asymmetry events that could cause engine shutdowns, diversions, or potentially more serious incidents. The economic consequences of non‑compliance (grounding, investigation, fines) ultimately affect ticket prices and service reliability, but these are diffuse costs.

The AD imposes four core duties on the operator (or the person responsible for the aircraft’s continuing airworthiness). First, within the prescribed compliance times, each affected aeroplane must have the P/N 9409122 or P/N 53‑0013 actuator removed and replaced with P/N 53‑0027, unless the aircraft is still in pre‑SBF100‑28‑046 configuration and the operator chooses the alternative of first installing P/N 53‑0013 (which is then itself later replaced under Requirement 2). That duty is absolute: there is no exemption, extension, or alternative means of compliance (AMOC) mentioned in the AD itself. However, CASA may grant AMOCs on application under CASR Part 39, though this is not stated in the source.

Second, there is a duty not to install P/N 53‑0013 on any aeroplane after 12 December 2010. This is a straightforward prohibition. It means that even if an operator has a stock of P/N 53‑0013 actuators (perhaps purchased before the issue was known), they cannot be used after that date. The AD does not address disposal or return of obsolete parts; that is left to operator procedures.

Third, the operator must ensure that the installation is carried out in accordance with the Accomplishment Instructions of the relevant Fokker Services Service Bulletin (SBF100‑28‑046 or SBF100‑28‑061 as applicable). Those bulletins prescribe detailed steps, including part variations, mounting block adaptation, and post‑installation tests. Using a different method or a different part than specified would deviate from the AD and render the aircraft non‑compliant. Notably, the AD does accept “later approved revisions” of those bulletins, giving operators some flexibility if Fokker updates the bulletin to correct errors or improve procedures.

Fourth, the operator must maintain an ongoing record of compliance. Typically, the AD compliance is recorded in the aircraft’s maintenance log or airworthiness records, and the AD must be listed in the aircraft’s compliance status documents.

The AD also confers one notable right: Note 1 states that after installation of P/N 53‑0013 or P/N 53‑0027, the requirements of CASA AD/F100/84 no longer apply to the installed fuel crossfeed valve actuators. That is a regulatory relief: the earlier AD presumably imposed some recurring inspection or operational limitation on the older actuators. By complying with this AD, the operator eliminates that recurring burden. However, this relief only applies to the actuators themselves; other parts of AD/F100/84 may still apply to other components of the fuel crossfeed system.

Operators also have the right to apply to CASA for an alternative means of compliance or an extension of compliance time, though such applications are discretionary and subject to CASA’s safety assessment. The AD does not mention any such right; it is inherent in the regulation system.

Finally, operators have the right to use later approved revisions of the referenced Service Bulletins. This is explicitly stated. It means that if Fokker Services issues revision A of SBF100‑28‑061 with improved instructions or parts, the operator may use that revision without needing a separate amendment to the AD. This reduces the likelihood that the AD becomes outdated due to minor bulletin revisions.

The source text does not specify penalties for non‑compliance with AD/F100/91 Amdt 1. However, as a mandatory airworthiness directive issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations or Civil Aviation Regulations, the enforcement regime is provided by those instruments. Generally, operating an aircraft that does not comply with an applicable AD is a serious offence. Under CAR 1988, regulation 43 (and now under CASR Part 39), it is an offence to operate an aircraft that does not conform to its approved type design or is not in an airworthy condition. Non‑compliance with an AD renders the aircraft unairworthy and non‑conforming.

Enforcement actions available to CASA include issuing a direction to the operator to rectify the defect, suspending or cancelling the aircraft’s certificate of airworthiness, imposing a maintenance demand, or referring the matter for prosecution. Penalties for individuals and corporations can include fines (currently up to 50 penalty units for individuals and 250 for corporations per provision, with each day of continuing contravention a separate offence, though exact amounts vary by regulation). In serious cases, CASA may also take administrative action such as issuing a “show cause” notice why an Air Operator’s Certificate should not be suspended or cancelled.

Practically, the most immediate enforcement risk is that the aircraft will be grounded during a ramp check or maintenance inspection if the AD compliance is overdue. Insurance coverage for the aircraft may also be affected if the aircraft is operated in non‑compliance. The background to the AD notes that one event led to an in‑flight engine shutdown; that type of incident would likely trigger an investigation by the Australian Transport Safety Bureau (ATSB) as well as CASA enforcement if non‑compliance with a prior AD is found.

The AD itself is signed by a Delegate of CASA (James Coyne) on 16 June 2009, and became effective on 30 July 2009. The original issue became effective on 28 August 2008. Operators who failed to comply with the original AD (Requirement 1) within the 12‑month timeframe would have been in breach as of late 2009. The amendment does not forgive past non‑compliance; it adds new requirements.

Given the safety‑critical nature of the defect (potential fuel asymmetry and engine shutdown), CASA is likely to treat non‑compliance as high‑risk. There is no evidence in the source of any leniency or grace period beyond the specified compliance times.

CASA AD/F100/84. The most direct interaction is with an earlier directive, CASA AD/F100/84. Note 1 of Amdt 1 provides that after installation of P/N 53‑0013 or P/N 53‑0027 actuators, “the requirements of CASA AD/F100/84 no longer apply to the fuel crossfeed valve actuators installed on that aeroplane.” This implies that AD/F100/84 imposed some requirement (e.g., periodic inspections, airspeed restrictions, or operational limitations) specifically on actuators P/N 9409122 or earlier types. By upgrading to the new part, the operator steps out of the scope of that earlier AD for those components. However, AD/F100/84 may still apply to other aspects of the fuel crossfeed system. Operators must check the full text of AD/F100/84 to understand exactly which requirements are lifted.

EASA AD 2009‑0116. Note 2 states that EASA AD 2009‑0116 dated 29 May 2009 refers. This indicates that CASA’s directive is harmonised with the European equivalent. For aircraft on both an Australian register and a European register (including temporarily imported aircraft), compliance with the EASA AD satisfies the European requirement. However, the compliance timeframes may differ slightly: EASA’s AD was effective 29 May 2009, while CASA’s amendment effective date is 30 July 2009. Operators must comply with the earlier date for the register they are under. For Australian‑registered aircraft operating in Europe, CASA’s AD is the governing requirement for the Australian certificate of airworthiness, but the aircraft must also comply with EASA AD to operate in European airspace unless a difference is accepted.

Fokker Service Bulletins. The AD references SBF100‑28‑046 and SBF100‑28‑061 and makes them mandatory. In normal maintenance, Service Bulletins are often recommended but not compulsory. This AD converts them into a regulatory requirement. Failure to follow the bulletin’s instructions as specified becomes a breach of the AD. Also, the AD interacts with the aircraft’s type design: the modification (replacing the actuator) must be approved. The Service Bulletins themselves are approved data from the type certificate holder (Fokker Services), so compliance is deemed acceptable for the airworthiness approval.

CAR 1988 and CASR Part 39. The AD is issued under the regulatory framework. Operators must ensure that the person performing the work is appropriately authorised (e.g., under CAR 30 for a LAME or under CASR Part 145 for an AMO). The AD does not state this, but the underlying regulations require that all maintenance be carried out in accordance with the approved maintenance data by authorised persons.

Other ADs. The AD does not supersede any other ADs except as noted for AD/F100/84. Other ADs affecting the same aircraft type (e.g., for engines, structure, or systems) remain in full force. Operators must integrate this AD into their overall continuing airworthiness management program.

Trade practices and contract law. Operators who contracted with a lessor or insurer to maintain the aircraft in an airworthy condition must comply with all applicable ADs. Failure to do so could lead to breach of contract, loss of insurance cover, or lessor repossession.

The original issue of AD/F100/91 became effective on 28 August 2008. That initial directive mandated the replacement of P/N 9409122 actuators with P/N 53‑0013 in accordance with Fokker Services SBF100‑28‑046. The compliance time was 12 months from that effective date, i.e., by 28 August 2009. The background to Amdt 1 explains what happened next: after the introduction of P/N 53‑0013 into service, manufacturer Eaton Aerospace discovered manufacturing and design errors with those actuators, specifically that the top‑cap could become loose, leading to potential actuator failure. Eaton then developed a new actuator, P/N 53‑0027, and Fokker Services published SBF100‑28‑061 on 20 April 2009 to introduce it.

CASA then moved to amend the AD. Amendment 1 was signed on 16 June 2009 and became effective on 30 July 2009. The amendment does two things: it adds a new requirement (Requirement 2) mandating replacement of P/N 53‑0013 with P/N 53‑0027 within 18 months, and it adds a new option for pre‑configuration aircraft to go directly to P/N 53‑0027 without installing P/N 53‑0013 first (Requirement 1b). It also adds the prohibition on future installation of P/N 53‑0013 after 12 December 2010.

Notably, the amendment does not change the compliance time for Requirement 1. That remains within 12 months from 28 August 2008. Thus, an operator who had not yet complied with Requirement 1 by the time the amendment issued (July 2009) still had only until late August 2009 to complete the first step (or choose the direct path). The amendment was published with a background explaining the reason for the change, including the manufacturing defects found on the first replacement part. This is a clear illustration of a regulatory fix that itself required a further fix when the first mandated solution proved defective.

The amendment history is not a typical statutory amendment record. The directive itself, as a regulatory instrument, is likely kept on CASA’s register of ADs. The source provided does not show any further amendments beyond Amdt 1. There is no indication of a supersession or withdrawal of the AD. For practitioners, it is important to check whether CASA has issued any subsequent amendments, proposals, or alternative means of compliance, especially given that this AD is now over a decade old.

The source text does not mention any litigation related to AD/F100/91 or this amendment. In general, airworthiness directives are seldom the subject of court proceedings because they are technical and safety‑critical, and non‑compliance carries immediate operational consequences. Operators rarely challenge an AD in court; they either comply or seek an alternative means of compliance through administrative channels. Any litigation would likely arise in the context of contractual disputes (e.g., a lessor accusing an operator of non‑compliance with maintenance obligations) or insurance claims after an incident. The background mentions one reported event where an engine was shut down in‑flight due to fuel asymmetry problems; that event may have prompted the original AD, but no litigation is recorded here.

Since the AD addresses an actual failure event (engine shutdown and diversion), it is plausible that civil litigation for damages (e.g., by passengers against the airline) or product liability claims against Eaton Aerospace could have occurred, but the source does not confirm this. For the purposes of this analysis, we must state that the source provides no litigation history. If a reader needs to investigate litigation, they would search court databases for “Fokker F100 crossfeed valve” or for product liability claims involving Eaton Aerospace and the actuator.

It is also possible that the AD itself was referenced in proceedings before the Administrative Appeals Tribunal if an operator sought review of a CASA decision (e.g., denial of an alternative means of compliance). However, no such matter is evident from the source.

Thus, the litigation history of this specific AD is nil according to the provided material. The absence of litigation could suggest that operators complied without resistance, or that the costs of litigation outweighed the costs of compliance. Given the safety implications, compliance was likely straightforward.

Several aspects of AD/F100/91 Amdt 1 can trap the unwary operator, maintainer, or compliance manager.

Dual compliance paths and the risk of doing the job twice. For aeroplanes in pre‑SBF100‑28‑046 configuration, the AD offers two choices: Requirement 1a (install P/N 53‑0013 per the older bulletin) or Requirement 1b (install P/N 53‑0027 per the newer bulletin). An operator who chooses 1a will then later have to accomplish Requirement 2 (replace P/N 53‑0013 with P/N 53‑0027) within 18 months of 30 July 2009. That means performing the same job twice on the same valve, incurring double labour, parts, and downtime. Requirement 1b is clearly the better economic choice, as it goes directly to the final approved part. However, an operator who already complied with Requirement 1a (perhaps before the amendment issued) is forced to do the second replacement. There is no credit for early compliance; the amendment is retroactive in effect for those who followed the earlier mandate.

Compliance date snarls for Requirement 1. The compliance time for Requirement 1 is “within 12 months from 28 August 2008”. The amendment effective date is 30 July 2009, which is only about a month before the 12‑month deadline. An operator who had not yet complied by the amendment date would have had only four weeks to source the parts and accomplish either 1a or 1b. Since 1b requires the newer actuator P/N 53‑0027, which may not have been as readily available in early‑mid 2009, the operator might have been forced into 1a (the temporary fix) and then later 2. Operators must be aware that the original deadline was not extended.

The prohibition after 12 December 2010 applies to installation only. Requirement 3 says “Do not install a P/N 53‑0013 fuel crossfeed valve actuator on any aeroplane” after that date. It does not say that existing installations of P/N 53‑0013 are immediately banned. Rather, those existing installations must be removed and replaced with P/N 53‑0027 within the 18 months for Requirement 2. If an operator replaces an actuator after 12 December 2010, it cannot use P/N 53‑0013. But even before that date, using P/N 53‑0013 in a new installation is only permitted if the aeroplane is pre‑configuration and the operator chooses path 1a. However, doing so would then trigger Requirement 2 anyway. So, practically, after the amendment, there is little reason to ever install P/N 53‑0013.

Note 1 relief is conditional. Note 1 provides that after installing P/N 53‑0013 or P/N 53‑0027, the requirements of AD/F100/84 no longer apply “to the fuel crossfeed valve actuators installed on that aeroplane.” This suggests that AD/F100/84 may also impose requirements on other parts of the fuel crossfeed system (e.g., pipes, mounting blocks, or the valve body itself). An operator cannot assume the entire AD is discharged; only the actuator portion is relieved. The exact wording of AD/F100/84 must be checked.

Permissive use of later approved revisions. The AD states that “the use of later approved revisions of these documents is acceptable for compliance.” This means an operator should check whether Fokker Services has issued Revision A, B, etc., of SBF100‑28‑046 or SBF100‑28‑061. Using the original issue of the bulletin may be acceptable, but if a revision corrects an error or adds a caution, the operator may be better off using the latest version. However, the operator must ensure that the revision is approved (typically by Fokker and accepted by CASA). If the bulletin is revised to require a different part number, the operator would need to ensure that still satisfies the AD.

Interaction with AD/F100/84. As noted, the relief from AD/F100/84 only applies after installation of the new actuators. For aeroplanes still in pre‑SBF100‑28‑046 configuration with P/N 9409122, all requirements of AD/F100/84 remain in full force. Operators must not assume that complying with this AD automatically lifts all preventive requirements; the relief is specific.

No explicit alternative means of compliance (AMOC). The AD does not mention AMOCs. While CASR Part 39 generally allows CASA to approve an AMOC, the source does not provide that right explicitly. Operators seeking to use a different method or part must apply to CASA separately. Relying on an AMOC without prior approval could be found non‑compliant.

Effective date confusion. The original AD had an effective date of 28 August 2008. The amendment effective date is 30 July 2009. The compliance times for Requirement 2 are measured from “the effective date of this AD” - which refers to the amendment effective date (30 July 2009), not the original date. For Requirement 1, it refers to “the effective date of the original issue of this AD” (28 August 2008). Operators must read carefully to avoid applying the wrong base date.

Compliance with AD/F100/91 Amdt 1 requires a systematic approach tailored to the aircraft’s current configuration. The operator should follow these steps:

1. Determine aircraft configuration. For each affected aeroplane, check maintenance records and physical configuration to ascertain whether it has ever accomplished Fokker Services SBF100‑28‑046. If it has not, it is in pre‑SBF100‑28‑046 configuration. If it has, it is post‑SBF100‑28‑046 configuration. Also check the current actuator part numbers installed (P/N 9409122, P/N 53‑0013, or others). This will determine which requirement applies.

2. For aeroplanes in pre‑SBF100‑28‑046 configuration with P/N 9409122 installed: The operator has two options. Option A: remove each P/N 9409122 and replace with P/N 53‑0013 per SBF100‑28‑046; this satisfies Requirement 1a but then Requirement 2 will later apply. Option B (preferred): remove P/N 9409122 and replace with P/N 53‑0027 per Part 1A or 1B of SBF100‑28‑061; this satisfies Requirement 1b and avoids the later replacement. The compliance time is within 12 months from 28 August 2008. Since that date has long passed, operators who have not yet complied are already in breach and should take immediate action. They should choose Option B to minimise future work.

3. For aeroplanes in post‑SBF100‑28‑046 configuration (i.e., already have P/N 53‑0013 installed): Requirement 2 applies. Remove each P/N 53‑0013 and replace with P/N 53‑0027 in accordance with Part 2 of SBF100‑28‑061. Compliance time is within 18 months after 30 July 2009 (i.e., by 30 January 2011). Again, this deadline has long passed, so any aircraft still with P/N 53‑0013 is likely non‑compliant.

4. Ensure no P/N 53‑0013 is installed after 12 December 2010. For all aircraft, if any maintenance or component replacement occurs after that date, only P/N 53‑0027 may be installed.

5. Obtain and use the correct Service Bulletins. Download or request the latest approved revision of SBF100‑28‑061 (for the final fix) and, if using the intermediate path, SBF100‑28‑046. The operator may use later approved revisions of these documents. Carefully follow the Accomplishment Instructions, including any flapper valve modifications, mounting block changes, wiring or harness updates, and post‑installation testing.

6. Source the correct parts. Order P/N 53‑0027 fuel crossfeed valve actuators from Eaton Aerospace or authorised distributors. Ensure the part number matches exactly. If the bulletin requires additional parts (e.g., mounting blocks, new washers, sealant), procure those as per the parts list.

7. Authorised maintenance. Ensure the work is performed by a CAR 30‑licenced or Part 145‑approved maintenance organisation authorised for the aircraft type. The installer must sign off the maintenance release.

8. Document compliance. Record the AD number (AD/F100/91 Amdt 1) in the aircraft maintenance records, the part numbers removed and installed, the Service Bulletin and revision used, date of compliance, and the signature of the certifying staff. Update the aircraft’s AD compliance status list.

9. Review interaction with AD/F100/84. After compliance, note that AD/F100/84 no longer applies to the fuel crossfeed valve actuators. However, ensure that any other requirements of AD/F100/84 (e.g., for other components) are still being met. Remove any recurring inspection tasks specific to the old actuators from the maintenance schedule if appropriate.

10. Monitor for further amendments. Although this AD is established, CASA may issue further amendments if additional defects are found in P/N 53‑0027, or if alternative parts become available. Operators should subscribe to CASA’s AD distribution service and regularly check the Fokker Services website for updated bulletins.

11. If unable to comply within the required times, seek an alternative means of compliance or extension from CASA. This requires a formal application demonstrating safety equivalence and a plan. However, given the age of the AD, this is likely moot.

12. For future purchases or leases of Fokker 100 aircraft, verify that the aircraft’s compliance with AD/F100/91 Amdt 1 is documented, and that the fuel crossfeed valve actuators are P/N 53‑0027. This will avoid subsequent retrofit costs.