AD/B737/303 Amdt 2 - Fuel Boost Pump Wiring

The central legal concept is an “Airworthiness Directive” (AD) under the Civil Aviation Regulations (or Civil Aviation Safety Regulations). An AD is a mandatory safety directive issued by CASA that requires particular inspection, modification, or operational restriction on an aircraft type to address an identified unsafe condition. Non-compliance with an AD renders an aircraft unairworthy; flying it would breach the maintenance and airworthiness provisions of the regulations and potentially expose the operator to enforcement action including suspension or cancellation of the aircraft’s certificate of airworthiness.

The directive introduces a hierarchy of technical standards. The primary source of the inspection and modification procedures is Boeing Alert Service Bulletin 737-28A1263 Revision 2. A service bulletin is a manufacturer-issued document that provides instructions for inspections, repairs, or modifications. It is not itself law, but when an AD makes compliance with a specific revision mandatory, that bulletin becomes binding. The directive also cross-references an earlier service bulletin, ASB 737-28A1120 (in its original issue and Revisions 1, 2, and 3, with associated Notices of Status Change). That earlier bulletin is used to determine compliance thresholds for certain aeroplanes based on whether the inspection or repair had already been performed.

The concept of “time in service” (TIS) is critical. TIS is measured in flight hours rather than calendar time, meaning the compliance clock runs only when the aircraft flies. This makes sense for wear-related wiring chafing, which is a function of vibration and fuel flow. However, it imposes a record-keeping burden: operators must track the exact hours on each affected aeroplane and schedule the inspection before the threshold is reached. The intervals are not trivial: 120 days for the initial inspection, but then 5,000 TIS for the first repeat and 15,000 TIS thereafter. For an aircraft that flies 2,000 hours per year, 15,000 hours is 7.5 years, so the repetitive inspection is relatively infrequent.

The directive also incorporates a legacy concept from the FAA system: “alternate method of compliance” (AMOC). The FAA may approve a different method of complying with the underlying AD, and CASA recognises that as acceptable for the Australian AD. This is a pragmatic delegation, but it means an Australian operator could be bound by an FAA AMOC that they never see. The directive says later revisions of the ASB approved by the FAA as an AMOC to FAA AD 2007-24-02 are acceptable. This is a limited delegation: it only covers that specific ASB and only if the FAA has formally approved it as an AMOC.

The concept of “report of findings” is unusual for a routine AD. Most ADs require the work to be done and logged, but here the operator must actively submit a report to the manufacturer of both positive and negative findings and send damaged parts. This suggests CASA and the FAA wanted to collect data on the actual extent of the wiring damage across the fleet. The requirement has a time limit of 30 days after inspection, but note that Amendment 1 deleted the “retrospective submittal of inspection reports” because the compliance time had passed. So this reporting is only for inspections performed after the effective date.

The directive directly applies to the registered operators of Boeing 737-100, 200, 200C, 300, 400, and 500 series aeroplanes. These are older-generation 737s (the “Classic” and earlier variants), not the Next Generation (737-600 to 900) or MAX series. In Australia, the affected fleet would include aircraft operated by major carriers (if they still operate these types), regional airlines, charter operators, freight carriers (the 200C is a convertible passenger/freighter), and possibly government or defence agencies if they operate civil-registered aircraft. As of 2008, Qantas had retired its 737-200s but still operated 737-300s and 400s at that time; Virgin Blue (now Virgin Australia) operated 737-700s and 800s which are not covered. Other operators like Jetstar (started 2004) operated A320s. So the Australian affected fleet was likely limited: a handful of 737-300/400 aircraft with legacy carriers or specialist operators.

The directive also indirectly affects maintenance organisations that hold the operator’s approved maintenance organisation (AMO) approval. They must have access to the latest service bulletin, train staff on the new sleeving installation procedure, procure the correct smaller-diameter sleeving, and accurately record inspections in the aircraft logbook. Parts suppliers benefit: they must stock the new sleeving. Boeing itself benefits as the manufacturer receives defect data and damaged parts, which may inform future design improvements.

A subtle cost falls on aircraft lessors. If an aircraft was on lease, the lessee (operator) must perform the work. But the lessor will want to see evidence of compliance before return or redelivery. The AD increases the cost of lease transitions and may reduce the residual value of aircraft that cannot be economically modified if the wiring is difficult to access.

The directive disproportionately burdens small operators with limited engineering support. Larger airlines with dedicated continuing airworthiness management organisations (CAMOs) can absorb the cost. A small charter operator with a single 737-200 may need to contract the work to a third party, find a hangar slot, and possibly order parts from the US. The 120-day compliance period is short for an operator without in-house capability.

The background references a fatal fuel tank explosion on a 727-200F, which is a different aircraft type but shares a similar fuel boost pump installation. This illustrates that the AD is not a response to a known Australian incident but a reaction to international data. The cost-benefit trade-off is not discussed in the directive. The compliance costs are borne entirely by private operators, while the safety benefit (reducing a low-probability, high-consequence event) is diffuse. An operator who has never seen wiring chafing may view this as an expensive precaution. However, the legal obligation is absolute: non-compliance exposes the operator to enforcement, even if the risk is remote.

The primary duty is on the registered operator to ensure that each affected aeroplane is inspected, modified, and reported upon in accordance with the specified compliance times. This duty is ongoing: when the repetitive inspection interval (15,000 TIS) next falls due after the initial action, the operator must perform the inspection again and, if necessary, replace the sleeving. The duty does not extinguish after one compliance.

A secondary duty rests with maintenance personnel. They must perform the detailed inspection in accordance with the Accomplishment Instructions of ASB 737-28A1263 Revision 2. If they deviate from those instructions, the inspector may not be deemed to have complied, and the operator could be non-compliant. The directive does not explicitly require the use of a licensed aircraft maintenance engineer (LAME), but the Civil Aviation Regulations require that certain maintenance be performed or supervised by a LAME or an appropriately authorised person. The AD does not create an exception.

The duty to send damaged parts to the manufacturer is a reporting obligation that goes beyond typical maintenance logging. It means the operator must package, document, and ship potentially hazardous materials (fuel-soaked wiring) to Boeing. This imposes a logistics cost and potential customs paperwork if the parts are sent overseas. The directive does not state who pays shipping; presumably the operator bears that cost.

The operator has a right to use alternative methods of compliance (AMOCs) but only those specifically recognised by the directive. The directive accepts later revisions of ASB 737-28A1263 that the FAA has approved as an AMOC to FAA AD 2007-24-02. The operator cannot invent its own AMOC or use an unapproved revision. For example, if Boeing issues Revision 3 of the ASB but the FAA has not yet approved it as an AMOC to the FAA AD, the operator cannot use Revision 3 for compliance with this AD. This creates a catch-up risk: operators must monitor the FAA’s AMOC approvals.

The operator also has a right to rely on previously completed actions. The directive states that actions accomplished before 31 August 2007 in accordance with the original issue of ASB 737-28A1263 (dated 19 February 2007), or actions before 13 March 2008 in accordance with Revision 1, are considered acceptable for compliance with corresponding actions in this Amendment. This is a grandfathering provision to avoid requiring rework of earlier compliant work. However, note that the inspection thresholds for Requirement 1 are based on whether an inspection or repair was done in accordance with the other service bulletin (ASB 737-28A1120). So there are two different grandfathering regimes in one AD: one for the immediate action (ASB 28A1263) and one for the baseline inspection history (ASB 28A1120). This is easy to confuse.

The operator has the right to operate the aircraft during the compliance period (subject to the 120-day or 5,000-hour window) and for the full repetitive interval (15,000 hours). The AD does not ground the aircraft immediately; it sets future deadlines. However, if the inspection reveals damage, the operator must do the modification before further flight, which could cause a delay at an inconvenient location.

The source text does not specify penalties. However, under the Civil Aviation Act 1988, non-compliance with a CASA-issued AD is a serious breach of the airworthiness requirements. The aircraft concerned could be deemed unairworthy, and operating it would be a breach of regulation 42ZC and similar rules. Penalties for operating an unairworthy aircraft can include fines of up to 200 penalty units (then about $22,000) for an individual and 1,000 penalty units (about $110,000) for a body corporate, plus potential suspension or cancellation of the air operator’s certificate or certificate of registration. Repeat or wilful breaches could attract criminal prosecution.

CASA has enforcement discretion. The directive is specific and prescriptive, so technical non-compliance is easy to prove: an inspector can check the aircraft logbook for a sign-off referencing the correct ASB revision and the compliance time. If the inspection was done using the wrong revision, or at the wrong interval, the operator is non-compliant. The report of findings to the manufacturer is also enforceable; if the operator fails to submit the report within 30 days, that is a separate breach.

The risk for maintenance organisations is that they may be implicated if they sign off work incorrectly. Under the Civil Aviation Safety Regulations, an AMO that certifies maintenance that does not meet the AD requirements can face suspension or revocation of its approval, in addition to financial penalties. The AD does not impose criminal liability directly, but the underlying regulations do.

One interesting point: the directive accepts actions done in accordance with earlier revisions of the ASB if completed before certain dates. This means an operator could have done the work in 2007 using the original ASB, and that is fine for this Amendment. But if the operator uses the original ASB after 13 March 2008, that would not be acceptable because the directive specifies Revision 2. So an AME who relies on a downloaded copy of the original ASB would cause the operator to be non-compliant. This is a common trap in AD compliance: the revision level matters.

The penalty exposure extends beyond direct fines. An engine or fuel system failure attributable to non-compliance could lead to civil liability. Insurers may refuse cover for an incident on an aircraft that was not AD-compliant. In the worst case, a fuel tank explosion could cause loss of life, and the operator could face criminal negligence charges or massive compensatory damages. The directive does not create a private right of action, but it sets a standard of care that a court could use in negligence.

Enforcement is also possible through the aircraft maintenance release (or certificate of release to service). Without a valid release, the aircraft cannot be flown. The maintenance organisation is the gatekeeper. In practice, the deterrent effect of the AD is high because the regulator can issue a Grounding Order if it believes an aircraft is unairworthy due to non-compliance. The directive itself does not include a grounding provision, but the underlying law does.

This Airworthiness Directive sits within a hierarchical regulatory framework. At the top is the Civil Aviation Act 1988, which empowers CASA to issue ADs. The Civil Aviation Regulations 1988 (and later the Civil Aviation Safety Regulations 1998) contain the detailed rules on airworthiness, including the requirement that aircraft be maintained in accordance with the manufacturer’s instructions and any applicable ADs. The directive is therefore legislative in character, not merely advisory.

The directive explicitly interacts with two Boeing service bulletins: ASB 737-28A1120 (the earlier one used for threshold determination) and ASB 737-28A1263 (the main one for the current action). While service bulletins are not law, the AD incorporates them by reference. That means any change to the bulletin could affect legal compliance without the AD itself being amended. The directive recognises this by allowing later FAA-approved revisions of the ASB to be used. But it does not automatically adopt all future revisions; only those approved as AMOCs by the FAA.

There is a cross-border interaction with FAA AD 2007-24-02. That FAA AD covers the same unsafe condition on US-registered 737s. The Australian AD explicitly references it and makes the FAA’s AMOC approvals effective for Australian compliance. This is a form of regulatory harmonisation that reduces duplication for operators that fly aircraft on both registries. However, it also means that a Boeing revision rejected by the FAA would also be rejected in Australia, even if CASA might have a different view. The directive creates dependency on a foreign regulator’s assessment.

The directive also supersedes three earlier Australian ADs: AD/B737/119 Amdt 3, AD/B737/121 Amdt 2, and AD/B737/138 Amdt 1. Those older ADs presumably addressed related wiring issues on the same aircraft types, and this AD consolidates and updates the requirements. Operators must ensure they no longer rely on the earlier ADs for the fuel boost pump wiring; they should remove references from their maintenance schedules. This supersession effect is important: if an AD is cancelled but its requirements are not repeated in the new AD, those requirements cease to be mandatory. Here, all relevant requirements are carried forward into the new AD.

There is no indication of interaction with state or territory laws, like workplace health and safety. However, the fuel system work may involve hazardous materials that trigger state regulations for handling and disposal. The AD does not address those; the operator must comply separately with environmental laws for the disposal of fuel-soaked parts.

From an international law perspective, Australia is a signatory to the Chicago Convention, which obliges member states to ensure that aircraft registered in their territory meet airworthiness standards at least as stringent as those in Annex 8. The AD is consistent with that obligation. It mirrors the US AD, so it aligns with the international standard set by the FAA as the state of design.

The source document provides a brief legislative history. The original issue of AD/B737/303 became effective on 5 July 2007. That original issue superseded three earlier ADs: AD/B737/119 Amdt 3, AD/B737/121 Amdt 2, and AD/B737/138 Amdt 1, which were cancelled. Amendment 1 of this directive became effective on 31 August 2007. Amendment 1 corrected a typographical error in FAA AD 2007-11-07 (which itself corrected a cross-reference). Specifically, the repetitive inspection interval was changed from flight cycles to hours time in service (TIS), and the requirement for retrospective submittal of inspection reports was deleted because the compliance time had already passed. All other aspects remained unchanged.

Amendment 2 (the version analysed here) becomes effective on 13 March 2008. It follows a superseding AD being issued by the FAA. This Amendment reduces the inspection threshold for certain aeroplanes and, to avoid confusion, bases the threshold on the completion of service bulletin inspections rather than on previous AD compliance. The background states that this change was made because the past compliance deadlines for the earlier ADs had passed, so tying thresholds to service bulletin actions rather than AD actions was clearer for operators.

The three earlier superseded ADs (AD/B737/119, 121, and 138) are not described in the source, but they likely addressed earlier versions of the same fuel boost pump wiring issue, possibly for specific model ranges or with less stringent requirements. Their cancellation means that any ongoing compliance obligations under those ADs are now subsumed by the current directive. However, operators must ensure that actions previously completed under those ADs are still valid under the new thresholds. The directive grandfathers actions done under certain revisions of ASB 737-28A1120 as listed in Table 1, but not necessarily any work done under the older ADs themselves. So if an operator performed an inspection only because an old AD required it, but not in accordance with the ASB, that work may not count for the compliance threshold of this AD.

There is no mention of any consultation process or cost-benefit analysis in the source. The directive appears to be a routine safety amendment, not a controversial new imposition.

The source text does not mention any litigation history. It is extremely rare for an individual airworthiness directive to be the subject of litigation in Australia. The Civil Aviation Act provides for merits review of CASA decisions through the Administrative Appeals Tribunal, but that typically applies to decisions like issuing, suspending, or cancelling licences and certificates, not to the making of a legislative AD. Judicial review of an AD would be possible in the Federal Court on administrative law grounds (e.g., ultra vires, unreasonableness, procedural fairness), but the threshold is high. The directive is a legislative instrument, so it is not subject to challenge as a decision affecting an individual unless it specifically directs a particular operator.

No cases are cited in the directive. There are no reported Australian cases specifically about AD/B737/303 or the fuel boost pump wiring issue. Internationally, the underlying wiring defect may have been a factor in litigation following the 727 fuel tank explosion, but that would be in US courts and not directly relevant to the Australian AD.

The directive is a technical safety regulation that has likely been complied with without challenge. The aviation industry generally accepts ADs as a cost of doing business. The only litigation risk would be if CASA attempts to enforce the AD against an operator that disputes its applicability or the reasonableness of the compliance time, but that would be unusual. The operator would likely prefer to negotiate a compliance extension rather than go to court.

From an analyst’s perspective, the absence of litigation does not mean the AD is uncontroversial; it means the costs of compliance are lower than the costs of fighting CASA. The directive is narrow, clear, and based on an FAA equivalent, so it lacks the ambiguity that often triggers litigation. However, if an operator suffered economic loss due to a forced grounding because the new sleeving was not available, there might be a claim against Boeing for supply failure, but that is contract law, not aviation regulation.

Several features of this directive are easy to overlook or misapply. First, the distinction between two different service bulletins. The compliance thresholds for Requirement 1 depend on whether an inspection or repair was done in accordance with ASB 737-28A1120 (the earlier bulletin for pump wiring on other models?), not ASB 737-28A1263 (the current bulletin). The table lists versions of ASB 737-28A1120 from 1998 to 2001. An operator with a 737-300 may never have performed ASB 737-28A1120 because that bulletin may have applied to different line numbers or configurations. If no such inspection was done, the compliance threshold is the general one: 120 days from the effective date, or 5,000 total hours TIS. But paragraph (c) for 737-200C says “whichever occurs later and thereafter at intervals not to exceed 15,000 hours TIS” referencing the last inspection done under any version of ASB 737-28-1120. So the operator must identify whether that ASB ever applied to its aircraft and whether it was done. This is a research burden.

Second, the modification (requirement 2) must be done before further flight following the inspection. That means if the inspection reveals damage or if the operator simply decides to do the modification proactively (which the directive requires anyway), the aircraft must be grounded until the new sleeving is installed. For an operator with a tight schedule, this could cause a cancellation or delay. The directive does not allow any grace period for the modification.

Third, the reporting requirement (requirement 3) is within 30 days after the inspection. This is a separate time limit from the modification. If the operator does the inspection, then takes 45 days to install the new sleeving and then sends the report, the report is late. The report must be sent even if no damage was found (positive findings). The operator must also send damaged parts to the manufacturer. This is unusual: typically damaged parts are retained for investigation or scrapped. The cost of shipping fuel-soaked wiring, which may be classified as hazardous waste, could be significant.

Fourth, the directive’s recognition of later FAA-approved revisions of ASB 737-28A1263 creates a trap for operators who update their maintenance procedures. If the FAA approves Revision 3, it is acceptable for Australian compliance. But if the FAA approves a different ASB altogether, or if Boeing issues a revision that the FAA does not approve as an AMOC (maybe it is a minor editorial change), then using that revision would not comply. The operator must verify the FAA’s approval status. The directive does not require CASA to publish a list of approved revisions; it relies on the operator to monitor FAA actions.

Fifth, the grandfathering provision for earlier actions is date-specific: actions before 31 August 2007 using the original ASB 737-28A1263 are fine; actions before 13 March 2008 using Revision 1 are fine. But if an operator did the inspection and modification on 12 March 2008 using Revision 1, that is grandfathered. If the same operator did the same work on 14 March 2008 using Revision 1, it is not compliant. The difference is one day, but the directive is absolute.

Sixth, the compliance times are in hours time in service (TIS) not calendar days, except the initial 120 days. The 15,000-hour interval could be considerably longer than 120 days for a low-utilisation aircraft. But the initial 120 days is a strict calendar deadline. An operator with an aircraft in storage or undergoing heavy maintenance might let the 120-day window expire without noticing. That would be a breach.

Seventh, the directive applies to model 737-200C series aeroplanes separately in paragraph (c) with a slightly different trigger: within 120 days after the effective date of the original issue of this Directive (5 July 2007), or within 5,000 hours TIS since the last inspection done under ASB 737-28-1120. For the original issue, the 120-day window from 5 July 2007 has long passed. So for a 737-200C that was not inspected under ASB 737-28-1120 before 5 July 2007, the compliance time would have been 120 days from 5 July 2007, which is now past. This amendment does not change that; it merely adds a separate threshold for the new inspection. The operator must be careful not to assume that the new 120-day period from 13 March 2008 applies to the 200C series. Actually, the compliance table for Requirement 1 lists three bullets: (a) for models 737-100 through -500 lines 1-3072, (b) for lines 3073 and subsequent, and (c) for 200C series. Paragraph (c) references the original issue effective date. So the 200C series has a different baseline for the last inspection done under ASB 737-28-1120. This is a significant gotcha: the 200C series may have already been required to do the inspection under the original directive, and now the new amendment might require an earlier repeat if the original inspection was done long ago. The operator must calculate from the earlier date.

Eighth, the directive’s background says Amendment 2 “reduces the inspection threshold for certain aeroplanes.” The source does not specify which aeroplanes. The reduction likely applies to the line number threshold, perhaps bringing more aircraft into the earlier compliance deadline. But this is ambiguous and operators must examine the fine print of their line numbers against the new thresholds.

An operator of an affected Boeing 737 should take the following steps to ensure compliance with AD/B737/303 Amdt 2:

1. Identify all aircraft on the operator’s registration that are Boeing 737-100, 200, 200C, 300, 400, or 500 series aeroplanes. Obtain the aircraft’s line number (a manufacturer’s sequential production number) and total time in service (TIS) in hours at the effective date of 13 March 2008. Determine whether the aircraft is a 737-200C series.

2. For each aircraft, determine the correct compliance time for Requirement 1 (the detailed inspection). This requires consulting the table of ASB 737-28A1120 versions. Check the aircraft maintenance records to see if an inspection or repair under any version of ASB 737-28A1120 (original, Revision 1, 2, or 3, including any NSC) has ever been performed. If yes, note the TIS at that last inspection or repair. If no, then the baseline is the aircraft’s first flight (zero hours).

3. For aircraft with line numbers 1 through 3072 inclusive (excluding 200C), calculate the later of: (a) 120 days after 13 March 2008, or (b) 5,000 hours TIS after the last ASB 737-28A1120 inspection or repair. The inspection must be performed by that date or before that TIS accumulation, whichever is earlier in practice. After that initial inspection, the repetitive interval is not to exceed 15,000 hours TIS.

4. For aircraft with line numbers 3073 and subsequent, the calculation depends on whether the ASB 737-28A1120 inspection or repair has been done as of 13 March 2008. If it has been done, use the same “120 days or 5,000 TIS later” formula. If it has not been done, the inspection must be done before accumulating 5,000 total hours TIS, or within 120 days after 13 March 2008, whichever occurs later. Again, thereafter every 15,000 TIS.

5. For 737-200C series aeroplanes, paragraph (c) refers to the original issue effective date (5 July 2007). So use that date in the calculation: within 120 days after 5 July 2007, or 5,000 hours TIS since the last ASB 737-28-1120 inspection, whichever later. This may already be overdue; if so, the aircraft must be grounded until the inspection is done. The repetitive interval remains 15,000 TIS.

6. Obtain a copy of Boeing Alert Service Bulletin 737-28A1263 Revision 2, dated 10 August 2007. Ensure maintenance personnel have the correct revision. Do not use Revision 1 after 13 March 2008 (unless the work was done before that date). If using a later revision, verify that the FAA has approved it as an Alternate Method of Compliance to FAA AD 2007-24-02.

7. Perform the detailed inspection of the fuel boost pump wiring sleeve and wire. Follow the Accomplishment Instructions precisely. Document any damage found. If damage is found, perform related investigative and corrective actions as per the ASB.

8. Before further flight after the inspection, install new, smaller-diameter sleeving on the fuel boost pump wiring. Again, follow the ASB instructions. The aircraft must not fly between the inspection and the installation of the new sleeving.

9. Within 30 days of completing the Requirement 1 inspection, prepare a report of findings. Include the aeroplane serial number, number of landings and flight hours, whether any discrepancies were found and their description. Ship any damaged parts to Boeing as described in the ASB. There is no stated exemption for sending parts if no damage was found; the directive says “send any damaged parts” but does not require sending undamaged parts.

10. Update the aircraft maintenance logbook with entries referencing AD/B737/303 Amdt 2, the specific requirement number, the ASB revision used, and the date and TIS of the action. Also update the maintenance schedule to reflect the new repetitive inspection at intervals not exceeding 15,000 hours TIS.

11. Review the superseded ADs (AD/B737/119, 121, 138) to ensure no residual obligations remain. Cancel any maintenance schedule tasks that refer to the old ADs.

12. Monitor CASA and FAA publications for any subsequent amendments to this AD or approval of later ASB revisions. If the FAA approves a new revision, the operator may voluntarily use it to comply, but should check whether it changes the repetitive interval or adds new requirements.

13. For leased aircraft, coordinate with the lessor to ensure the modification is approved under the lease and that the cost is allocated per the contract. If the operator has multiple aircraft, consider scheduling the work during regular maintenance checks to minimise downtime, but be mindful that the initial 120-day calendar window may not align with future checks. Use a maintenance planning tool to track each aircraft’s TIS to avoid exceeding the 15,000-hour interval.

14. If the operator cannot meet the compliance deadline due to parts unavailability or other constraints, they may apply to CASA for an extension or exemption under the Civil Aviation Act. However, the directive does not provide a standard process for that. Such requests should be in writing and demonstrate that the safety risk is mitigated (e.g., the aircraft has low utilisation or previous inspections showed no chafing).

15. Finally, train all relevant maintenance personnel on the difference between ASB 737-28A1120 and ASB 737-28A1263, and ensure they understand that actions under the former are only used to set the compliance threshold, not to meet the current inspection requirement. Do not confuse the two.