AD/CONVAIR/13 - Main Landing Gear Trunnion Fittings

The Directive organises obligations around a small set of technical concepts and thresholds:

• Applicability scope: Model 340, Model 440 and any aircraft of those models converted to turbopropeller power (Applicability). All requirements apply only to those aircraft identified.

• Part specificity: inspections and actions apply to a single component defined by part number 340-8510109, the main landing gear trunnion fitting (Requirement 1, Requirement 3).

• Inspection standard: visual/dye-penetrant inspection is the mandated detection technique, to be carried out in accordance with a named manufacturer service bulletin , General Dynamics 640 (340D) Service Bulletin No. 57-4, dated 25 May 1970 (Requirement 1). The Directive thus operationally incorporates the technical content of that service bulletin as the inspection method.

• Crack-length thresholds and discrete remedies: the Directive uses defined crack-length thresholds to gate remedial options:

  • Any crack in the trunnion boss face or any crack exceeding 2 inches , mandatory replacement before further flight (Requirement 3(a)).
  • Cracks greater than 1 inch but less than 2 inches , either replace or stop-drill (0.25-inch) and reinspect daily until replacement (Requirement 3(b)).
  • Cracks 1 inch or less , either replace or stop-drill and reinspect at intervals not exceeding 50 hours time in service (Requirement 3(c)).
  • Stop-drill size exception: if insufficient clearance, a 0.1875-inch drill may be used instead of the 0.25-inch drill (Note 1).
  • Stop-drilled fittings are not a permanent fix; they must be replaced and a progressed crack may be stop-drilled again only if total length remains under 2 inches (Requirement 4).

• Timing architecture: an initial compliance window (50 hours TIS after effective date, unless an inspection was done within the prior 450 hours TIS), recurrent inspections every 500 hours TIS, immediate replacement before further flight for certain findings, and a 500-hour TIS replacement deadline for stop-drilled fittings from the initial stop-drilling event (Compliance 1-4).

• Cross-reference to FAA action: the Background notes that the FAA requires these inspections and the Directive references FAA AD 70-12-05 (Note 2 / Background). The Directive therefore sits alongside a corresponding FAA directive and relies on a manufacturer service bulletin as the technical inspection standard.

These concepts define a precise inspection-to-repair workflow: inspect per the service bulletin; measure detected cracks against stated thresholds; either replace immediately where indicated, or apply temporary mitigation (stop-drilling) with prescribed drill sizes and reinspection cadences; ensure replacement within a stated interval after stop-drilling, and repeat the inspection regime at set recurring intervals.

The Directive directly affects operators, owners, maintenance organisations, and engineers responsible for the airworthiness of Model 340 and Model 440 Convair aircraft, and any such aircraft converted to turbopropeller power (Applicability). The listed part number (340-8510109) narrows the scope to aircraft fitted with that specific main landing gear trunnion fitting; the presence or absence of that part on an aircraft will determine whether the Directive applies to that aircraft.

Who pays: the source does not state who bears the cost of inspections, repairs, tools, replacement fittings, or aircraft downtime. The operational implication is that aircraft operators or owners will typically fund compliance activities , inspections, stop-drilling, replacement parts and associated labour , because those are the activities required by the Directive (Requirements and Compliance). The Directive does not allocate funding or provide subsidies.

Who decides: the Directive sets technical choices and thresholds (inspect using General Dynamics Service Bulletin No. 57-4; permitted stop-drill sizes). It provides conditional options for remedial action (replace or stop-drill for certain crack lengths), thereby leaving the operator or maintenance organisation to elect either replacement or stop-drilling within the stated limits (Requirement 3(b)-(c)). However, where a crack exceeds 2 inches or where a crack appears in the trunnion boss face, the Directive prescribes replacement prior to further flight, removing choice in those scenarios (Requirement 3(a); Compliance 3). The Directive also prescribes the timing of repeat inspections and replacement after stop-drilling, which are mandatory.

What behaviour changes: affected parties must incorporate the dye-penetrant inspection technique specified into maintenance schedules, perform initial inspections within the time windows provided, execute reinspection intervals not exceeding 500 hours TIS, implement stop-drilling when chosen within the permitted parameters, and plan for replacement either immediately (where required) or within the 500-hour TIS window after stop-drilling. The Directive also requires daily reinspections if stop-drilling is used to manage cracks between 1 inch and 2 inches until replacement (Requirement 3(b)). These requirements change maintenance planning, spare parts inventory (need for replacement trunnion fittings), and aircraft availability.

Ancillary participants: maintenance organisations responsible for performing dye-penetrant inspections in accordance with the referenced General Dynamics service bulletin will be engaged. The Directive may require specialised inspection equipment and trained personnel familiar with the service bulletin method and with measuring and documenting crack lengths relative to the thresholds given.

Excluded parties: aircraft that are not Model 340 or Model 440, and that do not use part number 340-8510109, are outside the Directive’s applicability as stated. The Directive does not extend to other components of the landing gear or to other part numbers unless those are explicitly covered by additional directives or service bulletins.

Key duties under the Directive are precisely stated and time-bound. They fall into inspection duties, conditional remedial duties and timing duties.

Inspection duties

• Conduct a dye-penetrant inspection for crack indications in the outboard fitting face and inboard boss area, focusing primarily on the upper area of the fitting above the boss radius, in accordance with General Dynamics 640 (340D) Service Bulletin No. 57-4, dated 25 May 1970 (Requirement 1). This is the mandated detection method.

Conditional remedial duties

• If no cracks are detected on inspection, repeat the inspection in accordance with the inspection interval regime set by the Directive (Requirement 2).
• If cracks are detected, apply one of the explicit remedial paths:
  • Replace the fitting before further flight where cracking exceeds 2 inches or where a crack is detected in the trunnion boss face (Requirement 3(a); Compliance 3).
  • If cracking is greater than 1 inch but less than 2 inches, either replace the fitting or stop-drill using a 0.25-inch drill and reinspect daily for crack growth until the fitting is replaced (Requirement 3(b)).
  • If cracking is 1 inch or less, either replace the fitting or stop-drill using a 0.25-inch drill and reinspect for crack growth at intervals not to exceed 50 hours time in service (Requirement 3(c)).
• The Directive allows a smaller drill (0.1875-inch) where 0.25-inch cannot be used due to insufficient clearance (Note 1).
• Replace stop-drilled fittings; if a crack progresses beyond a stop-drilled hole it may be stop-drilled again only if the total crack length is less than 2 inches; the fitting must be replaced if a crack progresses to 2 inches or more in length (Requirement 4).

Timing duties (Compliance)

• Perform the initial inspection within 50 hours time in service after 11 May 2006 unless the inspection was already accomplished within the previous 450 hours time in service (Compliance 1).
• Repeat the inspection at intervals not to exceed 500 hours time in service (Compliance 2).
• If replacement is required because of crack findings that meet the Criterion in Requirement 3(a), replacement must occur before further flight (Compliance 3).
• Replace any stop-drilled fitting within 500 hours time in service from the initial stop-drilling (Compliance 4).

Rights and operator choices

• For cracks of specified sizes (<=1 inch, >1 inch and <2 inches), operators have the option to either replace the fitting immediately or to perform the permitted temporary repair (stop-drilling) and comply with reinspection cadences (Requirement 3(b)-(c)). The Directive therefore leaves an operational choice regarding whether to accept temporary mitigation and planned replacement, or to incur replacement immediately, subject to the limits and timing rules set out.
• Note 1 grants an operational choice in drill size where clearance prevents the use of the nominal 0.25-inch drill, allowing a 0.1875-inch drill instead.

Documentation and method incorporation

• The duty to inspect in accordance with the named General Dynamics service bulletin effectively requires maintenance documentation and procedures to reflect that bulletin’s method. Operators and maintenance organisations must therefore incorporate that service bulletin’s dye-penetrant procedure into their maintenance practice for the affected aircraft (Requirement 1).

The Directive prescribes specific technical steps and discrete timing obligations; it does not specify ancillary rights such as funding or dispute-resolution mechanisms. The choice points provided (replace versus stop-drill) are real but constrained by mandatory thresholds and timing for replacement.

The text of the Directive sets mandatory actions and deadlines but does not set out penalties, civil fines, criminal sanctions or an enforcement regime within the instrument itself. The compliance section specifies when inspections and replacements must be performed: initial inspection timing (within 50 hours TIS after 11 May 2006 unless an inspection occurred within the last 450 hours), recurring inspection intervals (not to exceed 500 hours TIS), replacement before further flight where a replacement threshold is met, and replacement of stop-drilled fittings within 500 hours TIS of the initial stop-drilling (Compliance 1-4). These are framed as requirements.

What the Directive does not say

• The Directive does not state any monetary penalties, licence suspensions, administrative sanctions, or criminal penalties for non-compliance in its text. It similarly does not describe the mechanism by which compliance will be audited, nor any enforcement process (for example, notices, infringement processes or enforcement timelines). The source is silent on those matters.

Operational enforcement risk to operators

• Because the Directive prescribes mandatory airworthiness actions and effective dates, operational risk to the aircraft operator for non-compliance exists in practice: an aircraft returned to service with unaddressed cracks that contravene the Directive will be operating contrary to the Directive’s requirements. The Directive itself does not spell out how that operational non-compliance will be detected or what administrative measures will follow; the instrument is limited to technical requirements and timing.

Cross-reference to FAA action

• The Background notes that the FAA requires inspections to detect cracks and prevent failure of the main landing gear trunnion fittings, and Note 2 refers to FAA AD 70-12-05. The Directive therefore aligns with an existing FAA directive, which implies harmonisation of inspection expectations across jurisdictions, but it does not itself specify penalties or enforcement steps derived from FAA ADs.

In short, the Directive imposes mandatory technical duties within prescribed times. It contains no express penalty provisions in its text; enforcement mechanisms and sanctioning processes are not described in the instrument provided.

The Directive references and incorporates two external instruments as technical and regulatory touchpoints, indicating specific interactions rather than general statutory cross-effects:

• Manufacturer service bulletin: Requirement 1 mandates dye-penetrant inspections "in accordance with General Dynamics 640 (340D) Service Bulletin No. 57-4, dated 25 May 1970." That incorporation creates an operational interplay between the Directive and the manufacturer service bulletin: operators must follow the service bulletin’s inspection methodology when complying with the Directive. The Directive does not reproduce the service bulletin’s content in full, but it relies on that document for the technical inspection procedure, thereby making the service bulletin a practical normative companion to the Directive.

• FAA Airworthiness Directive: Note 2 states "FAA AD 70-12-05 refers." The Background mentions that the FAA requires inspections to detect cracks and prevent failure of the trunnion fittings. This indicates cross-jurisdictional alignment: CASA’s Directive corresponds to an FAA AD on the same issue. The instrument therefore interacts with, and echoes, FAA regulatory action, providing consistent expectations for aircraft types that may operate in multiple jurisdictions.

What the Directive does not do or claim

• The text does not expressly reference any Australian statutes, civil aviation regulations, or enforcement powers beyond its own requirements. It does not describe how it sits within the broader Australian civil aviation regulatory framework, nor does it state the statutory authorising provision for issuing the Directive. It also does not identify any inconsistencies or conflicts with other Australian laws or regulatory instruments.

Operational implications of those interactions

• Following the Directive necessarily requires engagement with manufacturer documentation (Service Bulletin No. 57-4) and awareness of the FAA AD it references (FAA AD 70-12-05). Maintenance and compliance programs will therefore need to incorporate both external documents into their compliance filings and maintenance procedures, as these are the technical sources the Directive cites as authoritative for inspection technique and the safety rationale.

• Where operators already complied with the FAA AD or the General Dynamics Service Bulletin within the periods noted, such prior compliance affects the timing imposed by Compliance 1 (initial inspection due within 50 hours TIS after 11 May 2006 unless inspection was already accomplished within the last 450 hours TIS). The Directive therefore interacts practically with prior maintenance history, including compliance with prior FAA or manufacturer instructions.

Because the Directive is itself a discrete airworthiness directive referencing the manufacturer’s service bulletin and an FAA AD, the direct interactions are to those instrumentary sources rather than to other named Australian statutes or regulations in the text provided.

The text supplied does not record any amendments to AD/CONVAIR/13. What the instrument does state about history:

• Effective date: The Directive becomes effective on 11 May 2006 (effective date line). This is the operative commencement date for the compliance timing requirements set out under the Compliance heading.

• Issuance date and signer: The Directive is dated 29 March 2006 and is signed by David Villiers, Delegate of the Civil Aviation Safety Authority. That is the only formal administrative metadata present in the text beyond the effective date.

Absence of amendment log

• There is no amendment log, no prior versions, no subsequent revisions, and no rescission language included in the provided text. The instrument does not indicate whether this AD replaces or supersedes any previous CASA instrument, nor does it list any later variations, extensions, or revocations.

Implication for records

• Because the Directive references earlier documents (notably General Dynamics Service Bulletin No. 57-4, dated 25 May 1970, and FAA AD 70-12-05), a complete compliance history for a specific aircraft will require operators to maintain records showing the dates of any prior inspections done in accordance with those earlier instruments, since such prior compliance can alter the initial inspection timing (Compliance 1). The Directive itself, however, does not record any carried-over compliance credits beyond the single allowance in Compliance 1 for inspections within the previous 450 hours TIS.

If an operator or maintenance organisation requires evidence of amendments, revocations, or subsequent related directives, that information does not appear in the text provided and would need to be sourced from CASA records or later issuances not included here.

The supplied instrument contains no reference to litigation, court decisions, administrative appeals, or disputes arising from AD/CONVAIR/13. The document does not list any legal challenges to the Directive, any enforcement proceedings, or any case names. The Background references FAA action but does not refer to litigation under that FAA AD.

Consequences of absence

• Because the Directive’s text contains no litigation history, there is no record in the provided source of contested interpretation, judicial review, or precedential case law that construes the requirements, thresholds or timing provisions of this Directive. The instrument stands as a technical regulatory requirement without an attached litigation narrative in the provided material.

What this means for practitioners

• Practitioners looking for judicial or administrative interpretations of the Directive’s language, enforcement scope, or interaction with other regulatory instruments will not find such material in the Directive itself. Any search for litigation or precedent would need to go beyond the supplied text to CASA enforcement records, administrative tribunals, or courts, none of which are referenced in this document.

The Directive contains several technical and drafting features that can create risk of misinterpretation or operational oversight if taken at face value without careful reading. These are specific, source-derived cautions.

Applicability specificity

• The Directive applies only to Model 340 and 440 aircraft, and converted versions (Applicability). Failure to verify the aircraft model and whether the trunnion fitting is part number 340-8510109 risks either overcompliance (doing unnecessary inspections) or undercompliance (failing to inspect aircraft that are in scope). Operators must verify both model and part number before applying the Directive.

Initial inspection timing caveat

• Compliance 1 requires an initial inspection "within 50 hours time in service after 11 May 2006 unless accomplished within the last 450 hours time in service." This language creates two windows: (a) if an inspection meeting Requirement 1 was done within the prior 450 hours TIS before 11 May 2006, the operator may not need to do another inspection within 50 hours TIS after 11 May 2006; (b) if not, the operator must inspect within 50 hours TIS after 11 May 2006. Misreading this clause could lead to unnecessary immediate inspections or missed deadlines. Operators must check maintenance records for an inspection conducted within the 450 hours prior to 11 May 2006.

Particularity of the inspection method

• Requirement 1 mandates inspection "in accordance with General Dynamics 640 (340D) Service Bulletin No. 57-4, dated 25 May 1970." The service bulletin is the mandated method. If a maintenance organisation uses an alternative dye-penetrant procedure or another NDT method, that may not satisfy the Directive unless the alternative is demonstrably equivalent and accepted under the governing airworthiness authority , the Directive itself does not provide a process for accepting alternatives.

Crack measurement precision and enforcement

• The remedial rules hinge on crack-length bands: <=1 inch, >1 inch but <2 inches, >=2 inches or any crack in the trunnion boss face. Accurate measurement and documentation of crack lengths are therefore critical. Differences in measurement technique, tool calibration, or rounding could change the remedial path from stop-drilling and inspection to mandatory replacement before further flight.

Stop-drill size and clearance exception

• Requirement 3(b)-(c) nominally requires a 0.25-inch stop-drill; Note 1 permits a 0.1875-inch drill where insufficient clearance precludes the 0.25-inch drill. Maintenance personnel must assess clearance and document why the smaller drill was used. The Directive does not specify what constitutes "insufficient clearance" or how to document that determination, so clear maintenance records are advisable to evidence compliance with Note 1.

Temporary nature of stop-drilling and replacement timelines

• Stop-drilling is explicitly a temporary mitigation (Requirement 4 and associated paragraphs). Stop-drilled fittings must be replaced, and Compliance 4 requires replacement within 500 hours TIS from the initial stop-drilling. Operators that treat stop-drilling as a long-term solution risk breaching this timing requirement. Additionally, where a stop-drilled crack progresses, it may be stop-drilled again only if total length remains less than 2 inches; otherwise replacement is required. Daily reinspections are mandated for stop-drilling in the >1 inch but <2 inch band until replacement (Requirement 3(b)), which imposes a continuous monitoring burden during that interval.

Replacement before further flight condition

• If a crack exceeds 2 inches or is in the trunnion boss face, the Directive requires replacement "before further flight" (Requirement 3(a); Compliance 3). That is an absolute restriction: the aircraft should not be flown until the part is replaced. Operators must plan for spares and logistical arrangements accordingly.

Record-keeping and traceability

• The Directive references prior inspections within the last 450 hours TIS that affect initial inspection timing. Accurate prior inspection records are therefore essential to determine compliance timelines. The Directive itself does not provide a prescribed record form, but operators must maintain records demonstrating the date and method of inspections and the measurements observed.

No penalties or enforcement process in the text

• The Directive does not set out penalties or enforcement mechanisms. Operators should nonetheless treat the Directive as mandatory; absence of explicit penalties in the text does not negate the operational safety obligations implied. Where certainty about enforcement or acceptance of equivalent procedures is required, operators may need to seek clarification from CASA or the relevant aviation authority.

Interplay with FAA and service bulletin

• The Directive requires adherence to a 1970 service bulletin and references an FAA AD. Practitioners should not assume contemporary service practices supersede the service bulletin unless an authorised amendment or alternative is issued; the Directive itself prescribes the particular service bulletin as the inspection method.

This section sets out a practical, source-grounded compliance checklist and operational steps strictly derived from the Directive. Follow the Directive’s numbered Requirements and Compliance items exactly.

1. Confirm applicability

   • Verify the aircraft is Model 340 or Model 440, or a Model 340/440 converted to turbopropeller power (Applicability).
   • Confirm the fitted main landing gear trunnion fitting is part number 340-8510109. The Directive applies only to that part number (Requirement 1).

2. Schedule the initial inspection within the correct window

   • Check maintenance records for any inspection that was accomplished in accordance with General Dynamics 640 (340D) Service Bulletin No. 57-4, dated 25 May 1970, within the 450 hours time in service prior to 11 May 2006. If such an inspection exists, an immediate repeat within 50 hours TIS after 11 May 2006 is not required (Compliance 1).
   • If no qualifying inspection exists, schedule and perform the initial dye-penetrant inspection within 50 hours time in service after 11 May 2006 (Compliance 1, Requirement 1).

3. Use the specified inspection method

   • Perform a dye-penetrant inspection directed at crack indications in the outboard fitting face and inboard boss area, concentrating on the upper area of the fitting above the boss radius, and do so in accordance with General Dynamics Service Bulletin No. 57-4 (Requirement 1). Ensure personnel are trained in the service bulletin’s dye-penetrant procedures.

4. Document inspection findings with exact measurements

   • Measure any crack indications found and document lengths. Categorise crack findings against the Directive thresholds:
     • crack in boss face = replacement required before further flight (Requirement 3(a));
     • crack >2 inches = replacement required before further flight (Requirement 3(a));
     • crack >1 inch and <2 inches = either replace or stop-drill (0.25-inch), then reinspect daily until replacement (Requirement 3(b));
     • crack <=1 inch = either replace or stop-drill (0.25-inch) and reinspect at intervals not to exceed 50 hours TIS (Requirement 3(c)).

5. Apply remedial options consistently and timely

   • Where replacement is chosen, replace the fitting per best practice and ensure the aircraft is not returned to flight if the Directive required a replacement before further flight (Compliance 3).
   • Where stop-drilling is chosen:
     • Use a 0.25-inch drill as the first choice (Requirement 3(b)-(c)).
     • If insufficient clearance prevents 0.25-inch drill use, document the clearance issue and use a 0.1875-inch drill (Note 1).
     • If crack length is >1 inch and <2 inches, conduct daily reinspections for crack growth until replacement (Requirement 3(b)).
     • If crack length is <=1 inch and stop-drilling is used, reinspect at intervals not exceeding 50 hours TIS (Requirement 3(c)).
     • Replace the stop-drilled fitting within 500 hours TIS from initial stop-drilling (Compliance 4).

6. Reinspection programme

   • If no cracks were detected initially, repeat the inspection at intervals not to exceed 500 hours time in service (Requirement 2; Compliance 2).
   • Where stop-drilling is used, adhere to the specified reinspection frequency (daily or <=50 hours TIS) until replacement, and update records accordingly.

7. Progressive damage handling

   • If a stop-drilled crack progresses beyond the initial stop-drilled hole, another stop-drill may be performed only if the total crack length remains less than 2 inches. Replace the fitting if the crack reaches 2 inches or more (Requirement 4).

8. Record-keeping

   • Maintain records of inspection dates, service bulletin reference, personnel who performed inspection, measurements of any cracks, stop-drill actions (including drill size and justification for using 0.1875-inch drill where applicable), reinspection dates and outcomes, and replacement actions including part numbers and serial numbers. These records will evidence compliance with the timing allowances in Compliance 1 and the replacement deadlines in Compliance 4.

9. Operational restrictions

   • Treat any finding that requires replacement before further flight as a prohibition on further flight until replacement is completed (Requirement 3(a); Compliance 3). Ensure flight operations are not scheduled until the replacement is installed and logged.

10. Integrate into maintenance planning

    • Incorporate the recurring inspection interval (every 500 hours TIS) into the maintenance schedule for each affected aircraft. Ensure spare part availability planning reflects the requirement to replace stop-drilled fittings within 500 hours TIS of the initial stop-drilling.

By following this stepwise compliance checklist based on the Directive’s Requirements and Compliance provisions, maintenance organisations and operators can align inspection, documentation and remedial actions with the instrument’s technical and timing obligations. The Directive does not prescribe forms or reporting procedures; maintain clear, auditable records to demonstrate compliance with the windows and thresholds stated.