AD/CONVAIR/14 - Main Landing Gear Beam Webs

The AD organizes its safety mandate around a small set of technical thresholds, a mandated inspection method, and linked remedial options. Core concepts in the text are:

• Applicability: The AD applies to "Model 340 and 440 aircraft, and all such model aircraft converted to turbopropeller power." That phrasing makes the AD explicitly airframe- and conversion-specific rather than engine- or operator-specific.

• Affected components: The directive targets beam webs identified by part numbers P/N 340-1650551-7, -8, -53 and -54. The scope is limited to the MLG beam webs, not to other landing-gear items.

• Inspection procedure: Dye penetrant inspection in the “upper flange radius area” is mandated, and the AD requires use of General Dynamics 640 (340D) Service Bulletin No. 57-3 (17 April 1970) as the procedures reference. The AD therefore delegates technical execution details to the manufacturer’s SB, referencing particular sections for repair options (Section 2.(B)(3) and Section 2.(B)(4)).

• Decision thresholds by crack size and location: The AD sets three size/location bands with distinct outcomes:

  • Cracks exceeding 7 inches in total length and/or that extend more than 2 inches forward or aft of the P/N 340-8510109 MLG trunnion fitting require replacement "before further flight" (Requirement 3.a).

  • Cracks less than 2.75 inches long and oriented chordwise along the web flange bend radius may, at the operator’s choice, be stop-drilled (per SB 2.(B)(3)) and reinspected not more than every 50 hours TIS until reinforcement or replacement, or may be replaced outright (Requirement 3.b.(i) and 3.b.(ii)).

  • Cracks between 2.75 inches and 7 inches in length that do not extend beyond 2 inches forward or aft of the trunnion fitting may either be replaced or stop-drilled and reinforced per SB 2.(B)(4). If stop-drilled and reinforced, the web must be reinspected at intervals not to exceed 500 hours TIS until it is replaced (Requirement 4).

• Re-inspection and temporal controls: The AD sets an initial inspection deadline (50 hours TIS after 11 May 2006 unless the inspection was done in the previous 450 hours TIS) and recurring inspection caps (500 hours TIS generally, but 50 hours TIS for short-crack reinspections following stop-drilling).

• Relation to other instruments: The AD explicitly references General Dynamics SB No. 57-3 for inspection and repair methods and notes that FAA AD 70-12-01 Amdt 39-1000 is relevant.

These concepts create a rule structure that transforms observed physical measurements (crack length, orientation, and location relative to the trunnion fitting) into compulsory maintenance actions and discrete inspection cadences, with the manufacturer’s Service Bulletin supplying the technical how-to.

The AD’s affected parties are defined narrowly but with operational breadth. The explicit applicability line reads: "Model 340 and 440 aircraft, and all such model aircraft converted to turbopropeller power." This means:

• Aircraft owners and operators of Convair/General Dynamics Model 340 and Model 440 aeroplanes must comply. That includes both original piston-powered aircraft and any airframes of those models that have since been converted to turboprop power, because the AD’s applicability explicitly includes such conversions.

• Maintenance organisations, licensed aircraft maintenance engineers, and approved maintenance providers that perform structural inspections and repairs on these models will be directly engaged to carry out the specified dye penetrant inspections and any follow-up remedial work. The AD requires inspection “in accordance with General Dynamics 640 (340D) Service Bulletin No. 57-3,” which means the practical work will be performed by those able to implement the SB.

• Parts suppliers and logistics functions relevant to the specified beam web part numbers (P/N 340-1650551-7, -8, -53 and -54) will be affected by potential demand spikes if replacements are required. The AD also references another part number for reference location, the P/N 340-8510109 MLG trunnion fitting, which is used as a datum for the 2-inch forward/aft location threshold.

• Operators whose aircraft have previously complied with an earlier inspection within the last 450 hours TIS before 11 May 2006 are affected differently: the initial inspection deadline is conditional on prior work. The AD states that unless the initial inspection is already accomplished, the inspection must be done “within 50 hours time in service after 11 May 2006 unless accomplished within the last 450 hours time in service.” That creates a conditional compliance cohort , operators who have recently inspected may not need to perform a fresh initial inspection within the 50-hour window.

• Regulators and airworthiness authorities (primarily the Civil Aviation Safety Authority, as the signing instrument shows) are the issuing and monitoring entities. The AD is signed by the Delegate of CASA and sets obligations on the operator community; it also notes an FAA AD for cross-reference.

Who pays and who decides, as the AD sets it up: the operators ultimately pay for inspections, stop-drilling, reinforcement and/or beam web replacement; maintenance organisations execute the work under the SB; and the decision between the allowed remedial options is governed by measured crack characteristics meeting the thresholds set out in the directive. The AD ties decisions directly to objective measurements (length, orientation, location) rather than leaving them to subjective judgement.

The AD sets duties in functional, measurable terms and delegates technical execution to a manufacturer service bulletin. The duties are:

• Duty to inspect: Aircraft operators must inspect the specified MLG beam webs (P/N 340-1650551-7, -8, -53 and -54) for crack indications "in the upper flange radius area" using dye penetrant inspection procedures "in accordance with General Dynamics 640 (340D) Service Bulletin No. 57-3, dated 17 April 1970" (Requirement 1). This is the foundational duty from which other duties flow.

• Duty to meet initial and recurring timing limits: The initial inspection must be performed within 50 hours TIS after 11 May 2006 unless the inspection already was done within the previous 450 hours TIS. Subsequent inspections must be done at intervals "not to exceed 500 hours time in service" (Compliance paragraphs 1 and 2). For webs that have been stop-drilled following detection of small cracks, reinspections must be performed at intervals "not to exceed 50 hours time in service" until reinforcement or replacement (Compliance 3.b.(i) and Requirement 3.b.(i)).

• Duty to take corrective action according to objective criteria: Where cracks are found the AD compels action according to the measured extent and position of the damage:

  • Replacement before further flight is mandatory where cracking “exceeds 7-inches total length and/or extends more than 2-inches forward or aft of the P/N 340-8510109 MLG trunnion fitting” (Requirement 3.a). The phrase “before further flight” is an unequivocal operational restriction tied to the presence of this category of damage.

  • For cracks less than 2.75 inches and chordwise, the operator must either stop-drill and reinspect per SB Section 2.(B)(3) at intervals not exceeding 50 hours TIS until reinforcement or replacement, or replace the web (Requirement 3.b.(i) and (ii)).

  • For cracks between 2.75 and 7 inches that remain within 2 inches of the trunnion fitting, the operator must either replace the beam web or stop-drill and reinforce per SB Section 2.(B)(4), and if reinforced must reinspect per the 500-hour cap until replacement (Requirement 4).

• Duty to follow the Service Bulletin procedures where the AD references them: The AD does not reproduce the detailed stop-drilling or reinforcement instructions; it requires work "in accordance with" the identified sections of SB No. 57-3. That allocates technical compliance to the SB’s content.

The AD does not enumerate explicit rights of appeal, nor does it include procedural exceptions or approvals within its text. It does note the FAA AD 70-12-01 Amdt 39-1000 as a referent. Rights that could be relevant in practice (for example, to seek an alternative method of compliance or to request relief) are not specified in the AD text itself. The text does, however, create operational rights of choice within constrained options: for small (less than 2.75-inch) cracks, the operator has a choice between stop-drill-and-reinspect versus immediate replacement; for the mid-band (2.75 to 7 inches) the operator can choose replacement or stop-drill-and-reinforce.

Who decides: measurable outcomes drive the decision tree. The maintenance inspector or authorised engineer will measure crack length, orientation and location and apply the AD’s objective thresholds to reach the prescribed remedial path. The AD requires using the manufacturer’s SB for the technical steps, so maintainers decide how to implement technical repairs within that SB’s specifications.

The AD text supplied does not set out specific monetary penalties, criminal sanctions or administrative fines for non-compliance. What the instrument does state, in the source text, is that it "becomes effective on 11 May 2006" and that it is issued by a Delegate of the Civil Aviation Safety Authority (signed by David Villiers). From the text that is present, the enforcement footprint is therefore limited to the issuing authority and the effective date; the AD itself prescribes mandatory actions but does not recite the enforcement mechanisms or penalty provisions within its wording.

Practical enforcement implications derivable from the document are procedural rather than punitive in the AD text (i.e. mandatory inspection and repair actions with specified deadlines). The instrument explicitly sets mandatory timing and technical requirements , initial inspection within 50 hours TIS unless already done within 450 hours, recurring inspection limits (500 hours TIS generally; 50 hours TIS for small-crack reinspections while awaiting replacement or reinforcement), immediate grounding until replacement for cracks exceeding 7 inches or extending beyond 2 inches of the trunnion fitting ("replace the beam web before further flight"), etc. These directives establish operational restraints that, in the normal course, are actionable by the regulator through the civil aviation safety framework.

The AD text also cross-references FAA AD 70-12-01 Amdt 39-1000 and a manufacturer service bulletin (General Dynamics SB No. 57-3). The AD delegates technical repair content to the SB and references the FAA AD as context. The AD therefore creates a compliance duty that is both prescriptive (the actions that must be taken) and time-bound (the inspection windows and reinspection intervals). The text does not specify the administrative process for demonstrating compliance, record-keeping obligations, or how CASA will monitor or verify compliance; nor does it reproduce the regulatory enforcement provisions that may exist elsewhere in aviation law.

In short, the AD sets mandatory technical and temporal duties and identifies the issuing authority; it does not itself contain a schedule of penalties or an enforcement procedure within its printed text.

The AD explicitly interacts with and references other regulatory and technical instruments. Two primary cross-references appear in the source:

• Manufacturer Service Bulletin: The inspection method and certain repair procedures are explicitly required "in accordance with General Dynamics 640 (340D) Service Bulletin No. 57-3, dated 17 April 1970." The AD thereby makes the content of that SB part of the compliance architecture. In practice, this means the AD’s legal mandate is operationalised by following the SB’s detailed procedures , the AD sets the objective requirements and the SB supplies the procedural techniques (for example, how to stop-drill and reinforce, per Section 2.(B)(3) and Section 2.(B)(4) of the SB).

• FAA Airworthiness Directive: The AD contains a note that "FAA AD 70-12-01 Amdt 39-1000 refers." That establishes a transnational regulatory linkage. The FAA AD is indicated as relevant context, and the Australian AD references it for background. The text does not specify derivative effects such as reciprocal acceptance or mutual recognition, but the mention signals that the FAA issued related requirements historically and that CASA considered that FAA material relevant.

This AD is an instrument issued by the Civil Aviation Safety Authority (signed by a CASA delegate), so its primary legal interaction is with the broader statutory and regulatory aviation safety framework administered by CASA. The AD imposes mandatory actions on operators of the applicable aircraft types; while the AD text does not reproduce wider regulatory provisions, it creates compliance duties that, in practice, will sit alongside certificate-holding obligations, maintenance release rules, and airworthiness certification regimes that typically exist in aviation regulatory systems.

Because the AD requires adherence to a manufacturer’s SB, the AD also places operators in a regime where compliance is a blend of regulator-issued mandatory requirements and manufacturer-provided technical instructions. Where the AD prescribes actions "in accordance with" the SB, the SB’s technical content effectively becomes the method by which the regulatory requirement is satisfied. The AD does not specify an alternative method of compliance, nor does it include wording about seeking approval for alternate repairs or methods; the AD also does not lay out how its requirements interact with other specific domestic statutes or regulations outside the aviation safety system.

Finally, the AD’s reference to part numbers and to configuration (including conversions to turbopropeller power) means that aircraft that are otherwise certificated or modified under different approvals are still captured by this directive if they meet the stated applicability. The AD therefore applies across the type population irrespective of engine conversion status.

The AD text carried the identifier AD/CONVAIR/14 and the date marker 5/2006. The instrument contains a specific effective date and a signature block that indicates its issuance by a CASA delegate on 29 March 2006, with the AD becoming effective on 11 May 2006. The AD header repeats "AD/CONVAIR/14" and "Main Landing Gear Beam Webs" with the date "5/2006."

Within the text provided there are no listed prior amendments to this AD, and no history of earlier or later revisions provided. The AD itself references FAA AD 70-12-01 Amdt 39-1000, which may be a much older instrument, but the supplied AD does not record any internal amendment history (for example, an amendment table or supersession note). The only date stamps present in the source are:

• Service Bulletin date: General Dynamics 640 (340D) Service Bulletin No. 57-3 dated 17 April 1970, which the AD incorporates by reference for procedures.

• Signing date: 29 March 2006 (signature by David Villiers, Delegate of the Civil Aviation Safety Authority).

• Effective date: 11 May 2006 (explicit “This Airworthiness Directive becomes effective on 11 May 2006”).

The AD’s identifier and the effective date together indicate that this AD was issued in the context of CASA’s 2006 AD issuance cycle (as evidenced by the "5/2006" tag). No subsequent revisions, amendments, cancellations, or corrigenda appear in the text provided. If users require a full amendment trail (for example, whether this AD was later superseded or incorporated into another instrument), they will need to consult the issuing authority’s consolidated AD registry or later records; nothing of that character is included in the supplied source.

The text supplied contains no litigation history. There are no references to court challenges, appeals, judicial interpretations, or litigation outcomes connected to AD/CONVAIR/14 within the instrument itself. The AD is procedural and technical in its content and does not cite case authorities, nor does it reference judicial review processes or specific contested determinations.

Because the AD references FAA AD 70-12-01 Amdt 39-1000 and a manufacturer Service Bulletin, there is potential for disputes in practice (for example, over the interpretation of SB repair instructions, or over whether a particular crack meets the AD thresholds), but the source contains no record of such disputes or of litigation arising from the directive. Users seeking any litigation or administrative challenge history would need to consult CASA records, court databases or industry bulletins , that material is not present in the AD text provided.

In the AD text itself, the administrative provenance is recorded: it is signed by a CASA delegate and dated; however, the document contains no narrative of contestation, review, or legal challenge.

The AD contains several technical and procedural specifics that can create operational pitfalls if overlooked. These are precise, measurable items from the text that commonly cause compliance errors:

• Parts specificity: The AD applies only to beam webs P/N 340-1650551-7, -8, -53 and -54. If an operator or maintainer inspects the wrong part number, that work will not satisfy the AD. Confirm the part number physically before declaring compliance.

• Datum for the 2-inch forward/aft threshold: The AD uses the P/N 340-8510109 MLG trunnion fitting as the reference point for the 2-inch forward or aft criterion. Properly locating that fitting on the airframe and measuring relative to it is necessary to determine whether a crack exceeds the location threshold that triggers mandatory replacement.

• Orientation and crack-length bands: The AD relies on crack orientation as well as length. For small cracks (less than 2.75 inches) the text requires that the crack be "orientated in a wing chordwise direction along the web flange bend radius" to qualify for the stop-drill-and-reinspect option. A crack of similar length but different orientation may not meet the same option. Maintenance inspectors must therefore record both orientation and length precisely.

• Multiple numerical thresholds: There are three different length thresholds with differing consequences: less than 2.75 inches (possible stop-drill and reinspect or replace), between 2.75 and 7 inches (replace or stop-drill and reinforce), and greater than 7 inches (replace before further flight). Mis-measuring or rounding could move a crack into a different regulatory outcome. The AD includes “total length” for the >7 inch threshold; clarity on whether multiple short cracks summing to more than 7 inches is treated as “total length” is not further elaborated in the AD, so conservatively record measurements and consult the SB.

• Stop-drill repeatability: The AD permits repeat stop-drilling if cracks propagate beyond a stop-drill hole "providing the crack length remains within the above stated limits." That allows iterative stop-drilling in some circumstances, but operators must track cumulative crack length and maintain it within the applicable band; otherwise the AD’s mandatory replacement requirements kick in.

• Timing interplay: The initial inspection window is conditional: if the initial inspection has not been accomplished, it must happen within 50 hours TIS after 11 May 2006 "unless accomplished within the last 450 hours time in service." Operators may misinterpret this and either miss the 50-hour window or re-do an inspection unnecessarily. Determine whether a qualifying inspection was indeed accomplished within the prior 450 hours to avoid redundant work or missed deadlines.

• Different reinspection cadences: The AD sets two distinct reinspection intervals. Following a clear no-crack inspection, repeat inspections are at "intervals not to exceed 500 hours time in service." In contrast, for small cracks addressed by stop-drilling the reinspections are "not to exceed 50 hours TIS" until reinforcement or replacement. For reinforced beams (Requirement 4), reinspections are at intervals not to exceed 500 hours TIS until replacement. Mixing up these cadences can leave an aircraft out of compliance.

• Dependence on Service Bulletin sections: The AD requires specific sections of SB No. 57-3 for stop-drilling and reinforcement (Section 2.(B)(3) and Section 2.(B)(4)). The AD does not reproduce these instructions. If the SB version in hand differs from the 17 April 1970 edition, or if the relevant sections are ambiguous, maintainers must confirm that they are following the exact SB version required by the AD.

• “Before further flight” for >7-inch or offset cracks: Where the AD requires replacement "before further flight," operators must not operate the aircraft until the replacement is carried out and signed off. Failure to interpret "before further flight" strictly can result in a compliance breach.

• Conversion status: The AD explicitly includes aircraft "converted to turbopropeller power." If an operator has a modified or variably configured aircraft, confirm that the AD applies and that the parts in question remain the same post-conversion. Do not assume conversion removes applicability.

• Recordation and evidence: The AD does not specify record-keeping requirements in the text provided, but operational auditors and regulators will typically expect evidence of inspections and repairs. Maintain clear documentation linking inspections to the AD's thresholds and SB actions.

• Cross-reference to FAA AD: The AD notes that "FAA AD 70-12-01 Amdt 39-1000 refers." Operators must not assume that following the FAA AD alone satisfies the CASA AD if there are differences in wording or timing; check both instruments and the stated SB to ensure compliance with the Australian AD.

These technical micro-details are the likely sources of inadvertent non-compliance. The AD’s reliance on precise measurements, orientation, part numbers and SB sections means that administrative attention to technical detail is necessary.

The AD prescribes a clear sequence of actions tied to measured outcomes. The following practical compliance steps map the AD’s text into an operational checklist. Each step cites the applicable AD requirement in parentheses.

1. Confirm applicability: Verify whether the aircraft is a Convair/General Dynamics Model 340 or Model 440, including those converted to turbopropeller power. Confirm that the MLG beam webs on the aircraft carry one of the listed part numbers: P/N 340-1650551-7, -8, -53 or -54 (Applicability paragraph).

2. Obtain the referenced Service Bulletin: Acquire General Dynamics 640 (340D) Service Bulletin No. 57-3 dated 17 April 1970. The AD requires inspections and certain repair procedures "in accordance with" that SB, and specific SB sections are referenced for stop-drilling and reinforcement (Requirement 1; Requirements 3 and 4).

3. Schedule the initial inspection: If the inspection has not already been done within the last 450 hours TIS, schedule and perform the dye penetrant inspection within 50 hours TIS after 11 May 2006 (Compliance 1). If an inspection was done within the last 450 hours TIS, that earlier inspection satisfies the initial timing condition; record the date and TIS to prove compliance.

4. Perform the inspection per the SB: Conduct dye penetrant inspection of the MLG beam web "upper flange radius area" using the exact procedures set out in SB No. 57-3 (Requirement 1). Document the inspection method, who performed it, the date, and TIS at inspection.

5. Measure and record crack characteristics: For any indications, measure total crack length, record crack orientation (specifically whether it is "orientated in a wing chordwise direction along the web flange bend radius") and measure the crack’s location relative to the P/N 340-8510109 MLG trunnion fitting to see whether it extends more than 2 inches forward or aft (Requirements 3 and 4).

6. Apply the AD’s outcome rules:

   • If no cracks are detected, repeat inspections at intervals not to exceed 500 hours TIS (Compliance 2).

   • If cracks exceed 7 inches in total length and/or extend more than 2 inches forward or aft of the P/N 340-8510109 trunnion fitting, replace the beam web before further flight (Requirement 3.a; Compliance 3).

   • If cracks are less than 2.75 inches long and oriented chordwise along the flange bend radius, either:

     a) Stop-drill the crack per Section 2.(B)(3) of SB No. 57-3 and reinspect for further crack propagation at intervals not to exceed 50 hours TIS until the beam is reinforced in accordance with Requirement 4 or replaced in accordance with Requirement 3.a; or

     b) Replace the beam web (Requirement 3.b.(i) and (ii); Compliance 3.b.(i)).

   • If cracks are between 2.75 and 7 inches in length and do not extend beyond 2 inches forward or aft of the trunnion fitting, either replace the beam web or stop-drill and reinforce in accordance with Section 2.(B)(4) of SB No. 57-3. If stop-drilled and reinforced, reinspect at intervals not to exceed 500 hours TIS until replacement (Requirement 4).

   • If cracks propagate beyond a stop-drill hole, stop-drilling may be repeated provided the crack length remains within the AD’s stated limits (AD text note).

7. Abide by "before further flight" constraints: Where replacement is mandated "before further flight" (Requirement 3.a), do not release the aircraft to service until the replacement has been performed and signed off by an authorised maintenance release authority.

8. Track reinspection cadences: Maintain a maintenance schedule that enforces the different reinspection intervals: 50 hours TIS for stop-drilled small cracks until reinforcement/replacement; 500 hours TIS for general reinspections and for reinforced beams until replacement.

9. Maintain documented evidence: Although the AD text does not specify record-keeping mechanics, maintain clear records of the inspection findings, measurements of cracks, SB procedures followed, dates, TIS at inspection, nature of remedial action (stop-drill, reinforcement, replacement), and signatures of authorised personnel. This is necessary to demonstrate compliance against the AD’s explicit deadlines and thresholds.

10. Part procurement planning: If replacements are anticipated (especially where cracks exceed thresholds), plan for part acquisition for P/N 340-1650551-7, -8, -53 or -54 beam webs and for any reinforcement kit or hardware specified by SB No. 57-3. The AD’s remedial options create potential short-term supply demand that operators should manage.

11. Consult the FAA AD and SB for technical clarifications: The AD notes that FAA AD 70-12-01 Amdt 39-1000 refers. Use the FAA AD and the manufacturer SB as technical references where the Australian AD invokes them, but ensure that the maintenance practices implemented are tailored to satisfy the Australian AD’s literal requirements.

12. Escalate ambiguous cases: Where measurements are close to threshold boundaries or where the SB’s instructions are unclear, consider seeking technical clarification from the manufacturer or an authorised engineering representative. The AD itself does not provide an alternative method of compliance within the text; follow the SB instructions and document any technical rationale for repair choices.

Following these steps will map the AD’s prescriptive requirements into concrete operational work. Keep careful measurement records because the AD’s remedial route is triggered by objective measurements (length, orientation and position relative to P/N 340-8510109). Where replacement is required "before further flight," ensure that the aircraft is grounded until compliant repairs are completed and certified.