AD/LYC/110 Amdt 1 - Crane / Lear Romec Rotary Fuel Pump Relief Valve Attachment Screws

AD/LYC/110 Amdt 1 is a mandatory airworthiness directive issued by the Civil Aviation Safety Authority (CASA) that imposes a series of torque check inspections and visual inspections on certain Textron Lycoming reciprocating engines fitted with specific Crane/Lear Romec rotary fuel pumps. The directive requires the operator or maintainer to inspect the relief valve attaching screws on the fuel pump for correct torque as specified in Lycoming Service Bulletin (SB) 529B, and to visually examine the pump for any fuel leakage or loose or missing screws. The initial torque check must be accomplished within 10 hours time-in-service (TIS) or 30 days from the effective date of the directive (17 March 2005), whichever occurs first. After that, a follow-up torque check must be performed repetitively at 55-hour TIS intervals or 6 months, whichever occurs first, until the accumulation of 110 hours TIS since the torque last remained within the SB specifications. Once that 110-hour threshold is reached, the obligation continues as a repetitive torque check at 55-hour TIS intervals. The directive also requires a concurrent visual inspection for fuel leakage at each 55-hour interval.

The directive is grounded in a safety concern: loose or missing relief valve attachment screws can cause fuel leaks, leading to engine failure, engine fire, and potential damage to or loss of the aircraft. The background states that Amendment 1 was issued in response to a review of an AD application that requested an inspection interval of 55 hours or a 10 per cent tolerance. This version supersedes CASA AD/FSM/25 Amendment 4 and is based on the United States Federal Aviation Administration’s AD 2003-14-03. The directive is not a standalone statute; it operates as a legislative instrument under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations. It is legally binding on all affected aircraft operators and maintenance organisations in Australia.

The directive also provides a terminating action: installation of a modified fuel pump (identified by a “/M” after the part number) ends all inspection requirements. Importantly, replacing a pump with an unmodified unit (without the “/M” suffix) restarts the entire inspection cycle from the beginning. This places a recurring compliance burden on operators who do not elect to install the terminating modification.

The central concept is the airworthiness directive (AD) itself: a mandatory regulatory instrument that requires specific maintenance actions on certified aircraft, engines, or components to correct an unsafe condition. AD/LYC/110 Amdt 1 is a “repeat inspection” AD, meaning it demands periodic checks rather than a one-time fix. The key technical concept is the torque check inspection of the relief valve attaching screws on the rotary fuel pump. Torque is the rotational force applied to a fastener; the inspection measures whether each screw is tightened to the value specified in Lycoming SB 529B. If the torque is below specification, the screws must be retightened to the correct value in accordance with that service bulletin.

The directive applies to time-in-service (TIS) as the primary compliance interval. TIS is the total operating time of the engine since new, overhaul, or last inspection, measured in hours. The directive also uses a calendar interval of 30 days or 6 months, whichever occurs first, so grounding periods or low-utilisation aircraft do not escape the requirement.

Another central concept is the distinction between unmodified and modified fuel pumps. Unmodified pumps are those without the “/M” suffix in the part number, and they are subject to all inspection requirements. Modified pumps (with “/M”) have been altered by the manufacturer to correct the underlying design issue, and their installation constitutes terminating action: no further torque checks are required. The directive’s applicability table enumerates specific pump series: RG9080, RG9570, and RG17980, each linked to a set of Textron Lycoming part numbers. Only pumps in that table are caught; pumps from other series or with different part numbers are not subject to this AD.

The Lycoming SB 529B is the procedural document that details how to perform the torque check, what torque value to apply, and any specific tooling or technique required. The AD incorporates that SB by reference. The follow-up inspection and repetitive inspection concepts are defined by the cumulative TIS since the torque last remained within the SB specification. The follow-up phase ends after 110 hours of stable torque; after that, the inspection continues at 55-hour intervals but is no longer called a “follow-up”. Practitioners must track these intervals precisely, because using an unmodified replacement pump resets the clock.

The directive directly affects owners, operators, and maintenance organisations of aircraft that are fitted with any of the listed Textron Lycoming reciprocating engines and Crane/Lear Romec rotary fuel pumps. The engine models covered are: IO-320, LIO-320, IO-360, HIO-360, TIO-360, LTIO-360, GO-435, GO-480, IGO-480-A1B6, IO-540, IGO-540, AEIO-540, HIO-540, TIO-540, LTIO-540, TIGO-541, IO-720, and TIO-720. These engines are common on light single-engine and twin-engine piston aircraft, including many Cessna, Piper, Beechcraft, and homebuilt types. The fuel pump series caught are RG9080, RG9570, and RG17980, with specific part numbers listed in the cross-reference table. Pumps that have been modified (with “/M” suffix) are excluded from the directive.

The primary compliance burden falls on Licensed Aircraft Maintenance Engineers (LAMEs) and approved maintenance organisations (AMOs) that perform scheduled inspections. They must obtain Lycoming SB 529B, apply the correct torque measurement procedure, record results, and ensure that the TIS and calendar triggers are met. The operator or owner is ultimately responsible for ensuring the aircraft remains airworthy, which includes compliance with all applicable ADs. Failure to comply can lead to grounding and enforcement action.

The directive also affects purchasers and sellers of aircraft or engines with these pumps. A prospective buyer must verify that the AD has been complied with, and that if unmodified pumps are installed, the inspection history is current. The directive may also affect insurers and finance lessors, as non-compliance can void insurance policies or breach lease terms. Manufacturers Textron Lycoming and Crane/Lear Romec are indirectly affected: the AD relies on their service bulletin and modified-pump parts to provide a terminating solution. The directive does not impose duties on manufacturers, but it creates demand for the modified pump parts.

Importantly, the directive applies only to aircraft on the Australian register or operated under an Australian air operator’s certificate. Aircraft imported from the United States may have complied with the equivalent FAA AD, but CASA requires its own AD to be satisfied. Operators with foreign-registered aircraft temporarily in Australia may need to check whether the directive applies under bilateral arrangements.

The directive imposes several clear duties on the person responsible for the continuing airworthiness of the affected aircraft. The first duty is to perform an initial torque check inspection within 10 hours TIS or 30 days from the effective date (17 March 2005), whichever occurs first. If the torque of any relief valve attaching screw does not meet the specification in Lycoming SB 529B, the screws must be tightened to the required value in accordance with that SB. The second duty is to conduct a follow-up torque check inspection repetitively at 55-hour TIS intervals or 6 months, whichever occurs first, until 110 hours TIS have accumulated with the torque remaining within the SB specification during each check. The third duty is to continue with repetitive torque check inspections at 55-hour TIS intervals after the 110-hour condition is satisfied. Additionally, at each inspection interval, the pump must be visually inspected for fuel leakage in the area of the relief valve and for loose or missing attachment screws. The visual inspection does not require a torque measurement but must look for evidence of leak paths.

A critical duty arises when a fuel pump is replaced with an unmodified pump (one without the “/M” suffix). In that case, the entire initial and follow-up inspection cycle must be repeated, regardless of any previous compliance history. This means that an operator who cannot or does not install a modified pump faces perpetual recurrence of the 55-hour inspections.

The directive also confers a limited right: installation of a modified pump (with “/M” after the part number) constitutes terminating action. Once a modified pump is fitted, all inspection requirements of this AD cease for that pump. The operator may choose to upgrade at any time to end the recurring compliance burden. The directive does not specify who bears the cost of the modification, but the right to terminate by modification is explicit.

The directive does not grant any right to apply for an alternative method of compliance (AMOC) within its own text, but under the broader CASA framework, an operator may request an alternative means of compliance if it provides an equivalent level of safety. The directive does not prohibit such requests; the power lies in the underlying regulations.

The text of AD/LYC/110 Amdt 1 does not itself prescribe any penalty or fine. It is a legislative instrument issued by a delegate of CASA under the Civil Aviation Act 1988. The enforcement framework for airworthiness directives is found in the general aviation safety legislation. Failure to comply with a mandatory AD is a breach of the Civil Aviation Safety Regulations (CASR), specifically regulations dealing with the operation of aircraft that do not meet applicable airworthiness requirements. Under CASR Part 42 and Part 145, the operator or certificate holder is responsible for ensuring that all directives are complied with before flight.

CASA’s enforcement options include: issuing a direction to ground the aircraft until compliance is achieved; suspending or revoking the aircraft’s certificate of airworthiness; imposing civil penalties (maximum amounts are set by regulation and can be substantial); and in serious cases initiating criminal prosecution for operating an unairworthy aircraft. The practical risk for most operators is a grounding notice that prevents any further flight until the torque check is performed. For commercial operators, that can cause significant financial disruption. Additionally, non-compliance can void insurance policies and expose the operator to civil liability in the event of an accident.

The directive is enforceable against the operator and the maintenance organisation if either knowingly neglects the requirement. The directive’s language is mandatory: the requirement says “perform” and “visual inspect”. There is no discretion to skip or extend intervals beyond what is stated. The background indicates the inspections are intended to prevent fuel leaks that could cause engine failure and fire, so CASA is likely to treat non-compliance seriously.

While the AD does not specify record-keeping requirements, standard practice under the CASR mandates that all maintenance actions, including AD compliance, be entered into the aircraft’s maintenance records. Failure to document the torque check may itself be an offence under maintenance record-keeping provisions. The directive’s Note 3 reinforces that replacement with an unmodified pump requires repeating the initial and follow-up inspections, so careful tracking of part numbers and modifications is essential.

AD/LYC/110 Amdt 1 interacts with several other regulatory instruments. Most directly, it is stated to be based on FAA Airworthiness Directive 2003-14-03. The FAA AD is the equivalent US directive covering the same unsafe condition. For aircraft imported from the United States or operating under a bilateral airworthiness agreement, compliance with the FAA AD may be recognised in Australia, but CASA has issued its own directive to ensure enforcement under Australian law. The Note 2 reference indicates that the CASA AD “refers” to the FAA AD, likely meaning that the technical content (such as the torque specifications) derives from the FAA version. Practitioners should be aware that the CASA AD may have slightly different compliance dates or wording, and the CASA version is the controlling law for Australian-registered aircraft.

The directive supersedes CASA AD/FSM/25 Amendment 4. That earlier directive likely covered the same issue but has been replaced. Any aircraft that had previously complied with AD/FSM/25 Amdt 4 now must comply with the new AD. The new AD may impose different intervals or additional actions.

The directive incorporates Lycoming Service Bulletin 529B by reference. The SB is a proprietary document that must be obtained from the engine manufacturer. The AD does not reproduce the SB; the person performing the inspection must have access to it. Non-compliance with the SB details is effectively non-compliance with the AD.

Under the broader legal framework, the AD sits within the hierarchy of the Civil Aviation Act 1988 and Civil Aviation Safety Regulations 1998. Regulations Part 42 (Continuing Airworthiness) and Part 145 (Maintenance Organisations) impose the general duty to maintain aircraft in an airworthy condition. An AD is a specific direction that supplements those general duties. The AD may also interact with the Australian Technical Standard Order (ATSO) or Civil Aviation Orders applicable to the specific engines and pumps.

If the engine or pump is installed in an aircraft operated under a Part 121 (air transport) or Part 135 (charter) certificate, the operator’s approved maintenance program must incorporate the AD. The CASA may also issue an airworthiness bulletin or other guidance to assist compliance. There is no indication in the AD of interaction with state or territory laws, or with other Commonwealth legislation such as work health and safety. However, in the event of an accident, the AD may be relevant in or as evidence of the required standard of maintenance.

AD/LYC/110 Amdt 1 is an amendment to an original directive. The original issue became effective on 17 February 2005. This amendment becomes effective on 17 March 2005, exactly one month later. The background states that the amendment was issued in response to a review of an AD application that requested an inspection interval of 55 hours or a 10 per cent tolerance. The original directive presumably had different intervals or other requirements that were revised. The nature of the application is not further described, but it likely came from an operator or industry body seeking a longer interval or more flexibility.

The amendment also clarifies that this version supersedes CASA AD/FSM/25 Amendment 4. That earlier directive is no longer in effect. The relationship between AD/FSM/25 and AD/LYC/110 is not detailed, but it is likely that AD/FSM/25 covered a different component or had broader scope, and this AD narrows or replaces it for these specific pumps.

The document is titled “AD/LYC/110 Amdt 1”. The numbering suggests it is the first amendment to Directive number 110 in the Lycoming series. The “3/2005” in the sidebar likely indicates the publication number or year and month. The signature block shows James Coyne as Delegate of CASA, dated 4 February 2005. The AD was thus signed about six weeks before becoming effective.

No further amendments are mentioned. The source does not indicate whether later amendments have been issued. For practitioners, it is essential to check the current version of the AD, because the text provided may have been superseded by later amendments or by a new directive. The amendment history within this document is limited to the original issue and one amendment.

The source text contains no reference to any litigation, court decisions, or administrative appeals concerning this AD. No cases are mentioned in the applicability table, requirements, or background section. It is possible that the underlying FAA AD or the CASA AD/FSM/25 may have been challenged, but this specific instrument does not record any litigation history.

Given that the directive is a technical safety regulation based on a known failure mode (loose relief valve screws), it is typical for such ADs to be issued without litigation. Operators who disagree with the mandatory action may apply for an alternative means of compliance, but that is an administrative process rather than litigation. The absence of cited cases does not mean no legal challenge ever occurred; it simply means the source does not provide that information.

The directive references both FAA AD 2003-14-03 and CASA AD/FSM/25 Amendment 4 as prior instruments. Those earlier directives might have been the subject of petitions for review in the United States or Australia, but again, the source is silent. For the purposes of this deep dive, we must note that no litigation history is provided in the source.

Practitioners should be aware that airworthiness directives are generally upheld by courts if challenged, because they are based on a factual finding of an unsafe condition and are issued under broad ministerial delegation. However, an operator could seek judicial review on procedural grounds (e.g., if the AD is arbitrary or not supported by evidence), but no such challenge is recorded in this document.

Several aspects of this AD can trap unwary operators and maintainers. First, the terminating action is only effective if the pump is modified. Many operators may assume that simply replacing an old pump with a new unmodified unit ends the requirement, but Note 3 explicitly states that replacement with an unmodified pump restarts the initial and follow-up inspections. The only way to escape the 55-hour cycle permanently is to install a pump with “/M” in the part number. If a modified pump is not available or is more expensive, the operator faces indefinite recurring inspections.

Second, the compliance times are tight and use “whichever occurs first” triggers. The initial check must be done within 10 hours TIS or 30 days, not the longer of the two. A low-utilisation aircraft that flies only once a month could easily exceed 30 days, so the calendar trigger bites. Similarly, the follow-up is at 55 hours or 6 months. After 110 hours of stable torque, the interval remains 55 hours, so the cycle never ends until modification.

Third, the torque check must follow Lycoming SB 529B exactly. The SB may require specific tools (e.g., a calibrated torque wrench, possibly a crow’s foot adapter, and a specific tightening sequence). Using the wrong tool or incorrect torque value constitutes non-compliance. The SB is not included in the AD; the operator must obtain it separately. This can be a trap if the maintenance organisation does not have the SB on hand.

Fourth, the visual inspection is separate from the torque check. It must check for fuel leakage in the relief valve area, which may require cleaning the pump or using a mirror. Leakage signs may be subtle. The AD does not specify what to do if leakage is found beyond the torque check; presumably, corrective action would be needed, but the AD only says to tighten screws if torque is low. A leak with correct torque might require pump replacement.

Fifth, record-keeping is critical but not detailed in the AD. The operator must track TIS of the pump and each torque check result to prove that 110 hours of stable torque have accumulated. If records are lost or incomplete, the operator may have to start the cycle over. The AD also does not specify how to document torque values; but standard maintenance practice requires it.

Sixth, the engine applicability list is wide but not exhaustive. Engines like the IO-540 are covered, but specific variants may have different pump part numbers. The cross-reference table must be consulted for each pump. If a pump part number is not listed, the AD does not apply to that pump, even if it is a similar series. Practitioners should verify the exact part number on the data plate.

Compliance with AD/LYC/110 Amdt 1 requires a methodical approach integrated into the aircraft’s maintenance program. The following steps assume the aircraft has an affected engine and pump.

1. Identify applicability: Verify the engine model is one listed (e.g., IO-360, IO-540). Find the fuel pump part number on the pump data plate. Cross-reference it in the table to confirm it is a caught pump. If the pump has “/M” after the part number, no further action is needed - the AD does not apply.

2. Obtain Lycoming SB 529B: The SB is essential for the torque specification and the inspection procedure. Contact Textron Lycoming or download it from the manufacturer’s technical portal. The SB may also include figures and tolerances.

3. Initial torque check: Within 10 hours TIS or 30 days of 17 March 2005 (whichever occurs first), have a licensed aircraft maintenance engineer perform the torque check on each relief valve attaching screw. Use the correct tool and torque value per SB 529B. Record the torque value for each screw. If any screw does not meet the minimum torque, tighten it to the specified value.

4. Visual inspection: At the same time, visually inspect the pump in the area of the relief valve for any evidence of fuel leakage and for loose or missing screws. Document findings.

5. Follow-up inspections: Repeat the torque check and visual inspection at intervals not exceeding 55 hours TIS or 6 months, whichever occurs first. Continue until 110 hours TIS have accumulated since the last time the torque remained within specification (i.e., since a check where all screws met the torque without needing tightening). Keep a running log of TIS and torque results.

6. After 110 hours of stable torque: Once 110 hours TIS have passed with all torque checks meeting specification, continue the repetitive inspections at 55-hour TIS intervals (the calendar option also applies). These remain mandatory indefinitely unless the pump is modified.

7. If pump replacement is needed: If an unmodified pump is installed as a replacement (any pump without “/M” suffix), the compliance cycle resets. Perform the initial torque check within 10 hours TIS or 30 days of installation, then follow the follow-up cycle. If a modified pump is installed (with “/M”), no further inspections under this AD are required for that pump. Record the pump part number and modification status.