AD/F100/89 - Flight Warning Computer

The AD is founded on a safety-technical finding from a design review performed under the guidelines related to FAA SFAR 88 (Fuel Tank Safety Program) and JAA INT/POL/25/12. That review identified a scenario in which prolonged dry running of the centre wing fuel tank transfer pumps could create an ignition source inside the centre wing fuel tank. The AD records the potential consequence: ignition of flammable vapours, fuel tank explosion and consequent loss of the aircraft. To mitigate that risk, the AD prescribes a software and hardware standardisation for the Flight Warning Computer and an AFM amendment.

Key technical concepts in the AD are these:

• Flight Warning Computer (FWC) modifications: The AD distinguishes three P/Ns: the unmodified legacy units P/N 80-0610-3-45 and P/N 80-0610-3-50, and the modified standard P/N 80-0610-3-55. Replacement or modification to the P/N 80-0610-3-55 standard is mandatory for affected aircraft (Requirements 1 and 3).

• Software update V13.55: The background explains that new software, version V13.55, reduces the delay for the centre wing fuel tank low pressure alert from 15 minutes to 60 seconds. The shorter alert interval is the operational mechanism designed to arrest "prolonged dry running" by triggering crew or automated action sooner.

• Documentation change: An AFM amendment specified by Fokker Services MCNO F100-050 dated 31 January 2008 must be incorporated concurrently with hardware/software change (Requirement 2). This aligns operational procedure and flight crew information with the changed warning behaviour.

• Operational applicability: The AD applies to all F28 Mark 0100 aircraft and to a listed set of F28 Mark 0070 serial numbers that carry a centre wing fuel tank. The presence of the centre wing fuel tank is the conditional locus of the unsafe condition.

• Approved procedures: The AD requires compliance according to Fokker Services SBF100-31-067 dated 31 January 2008, or later EASA-approved revisions; and in the case of modifying older units post-compliance, Honeywell SB 80-0610-31-0003 dated 13 February 2008. The AD references EASA AD 2008-0090 for background alignment.

The AD therefore combines a technical mitigation (software/hardware change), a procedural/documentation update (AFM), and parts control (post-compliance prohibition on reinstalling unmodified FWCs), all constrained by approval of certain manufacturer and EASA documents.

The instrument affects a narrowly identified group of aircraft operators, maintenance organisations and parts suppliers:

• Aircraft operators/owners: The AD applies to "F28 Mark 0100 aircraft, all serial numbers," and to a specific list of F28 Mark 0070 serial numbers that are fitted with a centre wing fuel tank. Operators of those aircraft are the primary parties required to act. The AD lists specific Mk 0070 serial numbers (11521, 11528-11537, 11545, 11547, 11553, 11557, 11561, 11562, 11566, 11567, 11571, 11572, 11576-11579, 11581-11583) and states that the requirement applies where the aircraft are fitted with a centre wing fuel tank. Owners and operators must check their fleet’s serial numbers and configuration to determine applicability.

• Maintenance organisations and approved maintenance personnel: The mandated replacement or modification of FWC units must be carried out in accordance with the Accomplishment Instructions of the specified Fokker Services document or Honeywell SB where applicable. Maintenance organisations will perform the physical work and produce conformity records. They must ensure the procedures used are the EASA-approved versions referenced by the AD.

• Parts suppliers and OEMs: Honeywell and Fokker Services are implicated because the AD references Honeywell SB 80-0610-31-0003 for modification to P/N 80-0610-3-55 standard and Fokker Services SBF100-31-067 for the replacement Accomplishment Instructions. Suppliers of FWCs will face demand for modified units (P/N 80-0610-3-55) and the supply or authorisation of appropriate software V13.55. After compliance, any replacement FWC of the older P/Ns is prohibited unless modified per Honeywell SB, which channels aftermarket activity through Honeywell-authorised procedures.

• Flight crew and operators responsible for operational documentation: Because the AD mandates an AFM amendment concurrent with the FWC replacement, the people who manage AFMs and operational documentation must insert the MCNO F100-050 changes or the AFM pages supplied by Fokker Services into the aircraft documentation and ensure crews are made aware of the amended information.

• Regulatory bodies: The Civil Aviation Safety Authority (CASA) issued the AD, with the delegate named as James Coyne. The AD also references EASA AD 2008-0090; EASA is identified as the approval authority for later revisions of the referenced Fokker Services document. CASA and EASA therefore exercise oversight and approval roles for the documentation and procedure revisions.

Who pays and who decides: The operator/owner pays for unit replacement or modification, maintenance labour and any associated aircraft downtime, and is responsible for deciding when to schedule the work, provided it occurs within the 36-calendar-month compliance window. EASA approval is required for later revisions of the Fokker Accomplishment instructions, and Honeywell supplies the approved modification SB for reconditioning legacy units.

The AD imposes discrete duties on operators and maintenance organisations and sets constraints on parts installation; it does not, in the text provided, set out procedural penalties or appeal rights. Duties and the required sequencing are explicit.

Duties

• Replace specified FWCs: Operators must remove FWCs with P/N 80-0610-3-45 and P/N 80-0610-3-50 and replace them with units modified to P/N 80-0610-3-55 in accordance with Fokker Services SBF100-31-067 (dated 31 Jan 2008) or an EASA-approved later revision. This is Requirement 1. The AD gives a compliance timeframe: within 36 calendar months after the AD’s effective date (effective 31 July 2008).

• Amend AFM: Operators must amend the AFM as specified in Fokker Services MCNO F100-050 dated 31 Jan 2008, or by using AFM pages supplied by Fokker Services, and must do so concurrently with the FWC replacement. This is Requirement 2.

• Control replacement parts: After accomplishing Requirements 1 and 2, operators may not install an FWC with P/N 80-0610-3-45 or 80-0610-3-50 as a replacement unless that unit has been modified to P/N 80-0610-3-55 standard per Honeywell SB 80-0610-31-0003 dated 13 Feb 2008. This is Requirement 3 and establishes a continuing parts control obligation post-compliance.

• Use approved procedures: The replacement and any modification must be performed in accordance with the specific Accomplishment Instructions or service bulletins referenced in the AD, and any later revisions must be approved by EASA where specified.

Rights and scope-limiting items (as stated in the AD)

• Limited applicability: The AD applies only to the enumerated aircraft types and serial numbers; operators not on the list are not captured by this directive.

• Use of later approved revisions: The AD allows the use of later revisions of the Fokker Services Accomplishment Instructions so long as EASA has approved them, providing some flexibility in method as long as the later revision has regulatory approval.

• Modification alternative to replacement: The AD permits modified legacy units to be returned to service only if they are upgraded to the P/N 80-0610-3-55 standard in accordance with the Honeywell SB. That gives operators a choice: procure pre-modified replacement units or modify existing units under Honeywell SB procedures.

What the AD does not state

• The AD does not specify monetary fines, certificate action procedures, or criminal penalties. It is an airworthiness directive that prescribes mandatory corrective actions and compliance dates; enforcement comes through the aviation regulatory framework (CASA), but the AD text itself does not list enforcement measures or appeal rights.

• The AD does not provide alternative means of compliance (AMOC) procedures within its text. It references specific service documents and EASA approval for later revisions.

Sequencing

• Requirement 2 (AFM amendment) must be done concurrently with Requirement 1 (FWC replacement), while Requirement 3 applies thereafter. The AD’s compliance section sets the sequencing and the 36-month deadline for Requirement 1.

The AD text itself does not enumerate civil or criminal penalties, nor does it set out a step-by-step enforcement scheme or administrative sanctions. It is an instrument from the Civil Aviation Safety Authority (CASA) that prescribes mandatory corrective actions. The document identifies the issuing authority (CASA) and the delegate who signed the AD (James Coyne, 13 June 2008), and provides compliance schedules, but it leaves enforcement mechanisms to the broader regulatory framework rather than specifying penalties within the directive.

What the AD does specify that affects enforceability

• Mandatory actions and deadlines: The AD sets mandatory actions (Requirements 1-3) and a compliance deadline for Requirement 1 of within 36 calendar months after the AD’s effective date. Deadlines and specific mandatory actions are the core substance an operator must demonstrate compliance with to maintain an aircraft’s airworthiness. The AD’s effectiveness date is explicitly stated as 31 July 2008.

• Parts installation prohibition after compliance: The AD prohibits installing unmodified FWCs (P/N 80-0610-3-45 or 80-0610-3-50) as replacements on aircraft that have complied with Requirements 1 and 2, unless the unit has been modified per Honeywell SB. That ongoing restriction can be used by regulators to check whether replacement parts contravene the AD after compliance has been recorded.

Implicit enforcement pathways (not stated in text but typical of ADs)

• Regulatory oversight and certification: While not specified in this AD text, airworthiness directives are enforced through the aviation regulatory regime; typical enforcement would involve CASA oversight of maintenance records, continuing airworthiness management, and certificate holders’ compliance. The AD’s absence of explicit sanction wording does not mean non-compliance has no consequence; rather the AD establishes mandatory technical requirements that feed into the airworthiness record and authority oversight processes. The AD itself does not enumerate those oversight steps.

• Use of approved documents: The AD requires work to be done in accordance with specified manufacturer or OEM instructions and EASA-approved revisions; failure to use approved methods would complicate an operator’s ability to evidence proper compliance.

Limitations in the AD’s text

• No fine schedule or named sanctions: The AD does not state fines, suspensions, or explicit enforcement timelines beyond the compliance period. It also does not include an explicit AMOC process or contact details for variance requests.

• Reliance on referenced documents and approvals: The AD’s enforceability in practice depends on the referenced Fokker and Honeywell documents and EASA approvals; the AD requires adherence to those documents but does not contain their detailed procedures within its text.

Readers should therefore treat the AD as setting technical and documentation duties with specified compliance timing, enforceable through CASA’s usual regulatory oversight of airworthiness, even though the AD does not itself catalogue penalty mechanisms.

The AD situates itself within the broader international and national aviation regulatory framework by expressly referencing external standards and approvals. Interactions evident from the text include:

• Relationship to FAA SFAR 88 and JAA guidance: The background states the design review was conducted in accordance with guidelines related to FAA SFAR 88 (Fuel Tank Safety Program) and JAA INT/POL/25/12. Those documents are technical regulatory guidances addressing fuel tank safety and design reviews; the AD adopts the technical outcome of such a review as its factual basis. The AD does not republish those guidances but relies on their methodology and findings to justify the mandated actions.

• EASA approvals and cross-reference: The AD requires that the Fokker Services Accomplishment Instructions used for the FWC replacement be either SBF100-31-067 dated 31 January 2008 or a later revision approved by the European Aviation Safety Agency (EASA). The AD also refers to EASA AD 2008-0090 dated 13 May 2008. That cross-reference indicates the AD’s procedural compliance is tied to EASA’s approval processes for service documents, so EASA’s decisions about revisions bear on how operators can comply in practice.

• Manufacturer and OEM service bulletins: The AD makes Fokker Services SBF100-31-067 and MCNO F100-050 and Honeywell SB 80-0610-31-0003 operative instruments for compliance. These service documents are not law but become mandatory when an AD makes them the required method of compliance. The AD therefore converts manufacturer service instructions into regulatory obligations by reference.

• National regulatory enforcement: The AD is issued by the Civil Aviation Safety Authority (CASA) and the delegate signs it. The AD is thus a CASA instrument that must be complied with by Australian operators of the affected aircraft. The AD’s enforcement would operate through CASA’s statutory powers under the national aviation law framework, even though the AD text does not itself set out those statutory enforcement provisions.

• Interaction with continuing airworthiness and documentation regimes: The requirement to amend the AFM means the AD interacts with rules governing operational documentation and flight crew information. The AD does not specify training or approval for crews, but the AFM amendment obligation affects operational documentation that is often controlled under separate continuing airworthiness and operations regulations.

Constraints and dependencies

• EASA approvals: Use of later revisions of the Fokker Accomplishment Instructions requires EASA approval, making compliance contingent upon EASA’s regulatory processes.

• Service bulletin content: Because the AD mandates specific service documents, any inconsistencies between the required service bulletins and national procedures would need reconciliation through standard regulatory channels (for example, approval of methods or clarifications); the AD itself does not set out how to resolve such conflicts.

In sum, the AD converts manufacturer and EASA-approved technical procedures into mandatory corrective actions under CASA’s airworthiness oversight, creating a networked interaction between manufacturer instructions, EASA approvals, and national regulatory enforcement.

The instrument provided does not record any subsequent amendments to AD/F100/89 within its text. The AD itself cites certain dated service documents and other ADs and allows for the use of later EASA-approved revisions of the Fokker Accomplishment Instructions, but it does not list any internal amendments, corrigenda, or revision history for AD/F100/89. The specific dated references in the AD are:

• Fokker Services SBF100-31-067 dated 31 January 2008 , referenced as the Accomplishment Instructions for replacement of the FWC.

• Fokker Services Manual Change Notification - Operational Documentation (MCNO) F100-050 dated 31 January 2008 , referenced for AFM amendment.

• Honeywell Service Bulletin (SB) 80-0610-31-0003 dated 13 February 2008 , referenced as the modification procedure to bring legacy FWCs to P/N 80-0610-3-55 standard.

• EASA AD 2008-0090 dated 13 May 2008 , noted as a related AD.

The AD sets an effective date of 31 July 2008 and is signed by the CASA delegate on 13 June 2008. The AD text explicitly permits the use of a later revision of the Fokker Services Accomplishment Instructions provided that revision is approved by EASA. That built-in flexibility suggests a mechanism for amendment of the compliance method but does not itself constitute an amendment to AD/F100/89.

Because the AD text does not record any amendments to the directive itself, readers should treat the AD as issued in the form provided, with the procedural allowance that later EASA-approved revisions of the specified Fokker document may be used in place of the dated SBF100-31-067. Any actual later amendment to AD/F100/89 would need to be sought in CASA’s public AD listings or regulatory gazette where AD revisions and superseding directives would be published; no such information is contained in the instrument text provided.

The AD text contains no reference to litigation, legal challenge, or judicial decisions relating to AD/F100/89. It mentions EASA AD 2008-0090 and specifies manufacturers’ service documents, but it does not cite any court cases, appeals, or reviews. The document is an administrative regulatory instrument signed by a CASA delegate; the AD itself does not record any legal disputes or litigation outcomes.

Because the source text provides no litigation history, there is no basis in this instrument to cite cases, appeals or disputes arising from AD/F100/89. If a reader requires information on judicial or administrative proceedings that may have arisen from this AD, they will need to consult CASA’s records, legal databases, or court registries outside this document. The AD’s silence on litigation means the instrument should be read as a stand-alone regulatory mandate without recorded legal contestation in the text provided.

Several operational and compliance traps arise from the AD’s specific language and references; careful attention to detail is necessary to avoid non-compliance or unintended consequences.

1. Applicability nuances: The AD applies automatically to "F28 Mark 0100 aircraft, all serial numbers," and to a specified list of F28 Mark 0070 serial numbers only "fitted with centre wing fuel tank." Failure to verify whether a given Mk 0070 has that tank could lead an operator to misapply the AD. Operators must check configuration and serial numbers precisely against the list in the AD before undertaking or deferring the mandated actions.

2. Exact part numbers matter: The AD singles out P/N 80-0610-3-45 and P/N 80-0610-3-50 as the legacy units, and P/N 80-0610-3-55 as the compliant unit. Installations, inventory management and purchase orders must reference these exact P/Ns; substituting a superficially similar part without confirming the P/N and applicable modifications risks non-compliance.

3. Concurrent AFM amendment requirement: Requirement 2 must be done concurrently with Requirement 1. Replacing the hardware but delaying or omitting the AFM amendment would not satisfy the AD. Operators must plan maintenance scheduling and documentation updates together.

4. Post-compliance replacement prohibition: After an aircraft has complied with Requirements 1 and 2, installers must not fit legacy P/N units as replacements unless they have been modified per Honeywell SB 80-0610-31-0003. This is a continuing restriction and affects maintenance planning for spare units. Maintaining an inventory of unmodified legacy FWCs for spare use is not permissible on a compliant aircraft.

5. Approved-method caveat: The AD requires that replacement be done "in accordance with the Accomplishment Instructions of Fokker Services SBF100-31-067 dated 31 January 2008 or later revision approved by the European Aviation Safety Agency (EASA)." Using a later revision without EASA approval would not meet the AD’s condition. Operators must confirm EASA approval status of any later revision before relying on it.

6. Software version and functional change: The background describes the software update V13.55 that shortens the centre wing fuel tank low pressure alert from 15 minutes to 60 seconds. This represents an operational change that might affect crew response expectations and maintenance test procedures. The AFM amendment is intended to ensure operational documents reflect that changed behaviour. Failure to integrate AFM changes with crew briefings and maintenance checklists could cause confusion.

7. Timing and scheduling: The compliance period for Requirement 1 is 36 calendar months after the AD's effective date (31 July 2008). Though the window appears generous, fleet operators must schedule downtime for each affected aircraft and ensure parts availability; delays in parts supply or maintenance capacity could compress operator scheduling flexibility and jeopardise compliance timing.

8. Reference dependencies: The AD refers to external documents (Fokker SBF100-31-067, MCNO F100-050, Honeywell SB 80-0610-31-0003, and EASA AD 2008-0090). Those documents contain the technical steps required; the AD does not include detailed instructions. Operators must obtain, retain and follow those documents; failing to use the exact referenced or EASA-approved documents is a compliance risk.

9. Record-keeping expectations: While the AD does not lay out specific record-keeping instructions, evidence of compliance in maintenance records and AFM amendments will be critical during regulatory inspections. Operators should ensure traceability of part P/Ns, serials, and evidentiary documentation that the procedures were executed per the referenced service instructions.

10. Narrow scope does not mean low risk: The AD targets a subset of Fokker types and serial numbers, but the background claims the condition could lead to fuel tank explosion with catastrophic outcomes. Operators of non-listed aircraft should not assume immunity without confirming their aircraft configuration and whether a similar vulnerability exists; conversely, listed operators must treat the AD obligations as binding.

The AD specifies the precise actions and the acceptable methods for compliance. Compliance should be managed as a project involving airworthiness, maintenance planning and documentation control. Below is a practical compliance checklist, strictly limited to mandates and references contained in the AD.

1. Confirm applicability

   • Verify whether each aircraft in your fleet is an F28 Mark 0100 (all serial numbers included) or one of the listed F28 Mark 0070 serial numbers.
   • Confirm whether the listed Mk 0070 aircraft are fitted with a centre wing fuel tank, as the AD’s applicability for Mk 0070 serials is conditional on that configuration.

2. Acquire required service documentation

   • Obtain Fokker Services SBF100-31-067 dated 31 January 2008, and Fokker Services MCNO F100-050 dated 31 January 2008, or check for later revisions of SBF100-31-067 that are approved by EASA.
   • Obtain Honeywell SB 80-0610-31-0003 dated 13 February 2008 for any modification of legacy FWCs that you intend to return to service after compliance as a replacement.
   • Consult EASA AD 2008-0090 (13 May 2008) as a referenced background instrument.

3. Plan the FWC replacement or modification

   • For each affected aircraft, plan to remove any FWC with P/N 80-0610-3-45 or P/N 80-0610-3-50 and install an FWC modified to P/N 80-0610-3-55.
   • Decide whether to procure pre-modified replacement units (P/N 80-0610-3-55) or to modify existing units in accordance with Honeywell SB 80-0610-31-0003. Either path is permitted: replacement with P/N 80-0610-3-55 units per Fokker SBF100-31-067 as the primary method, or modification via Honeywell SB when re-installing legacy units post-compliance as per Requirement 3.

4. Schedule maintenance within the compliance window

   • The AD requires completion of Requirement 1 within 36 calendar months of the effective date (effective date 31 July 2008). Schedule aircraft downtime, parts procurement, and maintenance resources accordingly.
   • Ensure Requirement 2 (AFM amendment) is executed concurrently with the hardware replacement.

5. Execute replacement/modification in accordance with approved instructions

   • Perform the work strictly according to the Accomplishment Instructions of Fokker Services SBF100-31-067 dated 31 Jan 2008, or a later EASA-approved revision. Verify that the revision used is approved by EASA if not the dated one.
   • If modifying legacy units to the P/N 80-0610-3-55 standard for subsequent installation, follow Honeywell SB 80-0610-31-0003 dated 13 Feb 2008.

6. Amend AFM and operational documentation

   • Concurrent with the FWC replacement, amend the AFM per Fokker Services MCNO F100-050 dated 31 January 2008, or insert AFM pages supplied by Fokker Services.
   • Ensure flight crew are briefed on the AFM changes and that any operational and maintenance procedures affected by the shortened low pressure alert delay (15 minutes to 60 seconds per software V13.55) are updated in relevant checklists and procedures.

7. Post-installation checks and records

   • Conduct required functional checks and tests per the Accomplishment Instructions to confirm the FWC is functioning to the P/N 80-0610-3-55 standard and that the low pressure alert timing aligns with the V13.55 behaviour.
   • Record the replacement/modification actions, part numbers installed, serial numbers, service bulletin references used, and AFM amendments in the aircraft’s maintenance and continuing airworthiness records.

8. Spare parts and future maintenance

   • After completing Requirements 1 and 2 for an aircraft, do not install FWC units P/N 80-0610-3-45 or P/N 80-0610-3-50 as replacements unless those units have been modified per Honeywell SB 80-0610-31-0003. Manage spares inventory accordingly to retain only compliant spares for use on modified aircraft or ensure unmodified spares are used only on aircraft not subject to the AD where appropriate.

9. Liaison with regulators and OEMs

   • If in doubt about EASA approval status for later revisions of Fokker documentation, obtain written confirmation from EASA or CASA before relying on a later revision for compliance.
   • Maintain communication with Fokker Services and Honeywell for availability of parts, modification services, and approved documentation.

10. Evidence of compliance for oversight

• Keep a clear audit trail: maintenance orders, work cards, SB compliance records, AFM amendment pages and insertion records, signatures of certifying staff, and any EASA approval paperwork if a later revision was used. Those documents will be needed for regulatory inspections and to demonstrate that the AD’s requirements were met.

This checklist follows only the steps and references the AD itself makes mandatory. It does not invent alternative compliance routes. If an operator seeks a different method of compliance or an extension, that would typically be addressed through the regulator’s procedures for alternative means of compliance or approvals; such processes are not described in the AD text provided and must be pursued through CASA or EASA channels outside the AD document.