AD/AT 800/9 Amdt 4 - Engine Mount

The Directive sets out several core concepts that define what must be done and why. Applicability is narrowly defined: it applies to “Model AT‑802 and AT‑802A aircraft, serial numbers 0001 through 0227.” The operative inspection requirement is to carry out inspections “in accordance with Snow Engineering Co. SL No. 253 Revision C, dated 17 April 2008.” That Service Letter is the technical standard referenced; the Directive does not reproduce procedural detail of the SL, it makes compliance with the SL the mandated method.

The Directive differentiates aircraft by two structural conditions: engine mounts without gussets and engine mounts with gussets installed. It then layers a time‑in‑service distinction: aircraft with less than 5,000 hours time in service, and aircraft with 5,000 hours time in service or more. For each combination (gusset/no gusset, <5,000/≥5,000) the Compliance section sets an initial inspection trigger and a repetitive interval (for example, initial at 1,300 hours or within 100 hours after a specified date, then repeat every 300 hours for some categories; alternatively for ≥5,000 hours the repeats are at intervals not to exceed 100 hours). The Directive’s text repeats the same SL reference and compliance rule framework for both gusset and non‑gusset mounts, reflecting Amendment 3’s change noted in Background that repetitive inspections are required for all affected aircraft “with or without gussets installed.”

The Background records the causal facts that prompted the regulatory interventions: the FAA “received reports of cracked engine mounts,” including examples of cracked mounts below expected inspection times and a report of a crack through an installed gusset. The Background traces amendments 1-3: Amendment 1 reduced the initial compliance threshold to 1,300 hours after reports of cracks below prior thresholds; Amendment 2 required incorporation of gussets as a mandatory terminating action for repetitive inspections; Amendment 3 reinstated repetitive inspections even where gussets had been fitted because of a reported crack through a gusset. Amendment 4, the current text, corrects typographical errors in the Compliance section without changing technical requirements.

The Directive explicitly cross‑references FAA airworthiness directives (noting FAA AD 2009‑11‑05 Amdt 39‑15915 refers), thereby importing or aligning with related foreign regulatory action as part of the evidential or normative context. The effective date and signature are recorded: the Amendment becomes effective on 22 October 2009, and the instrument is signed by a CASA delegate (David Villiers, 4 September 2009).

The Directive affects owners, operators, maintenance providers and maintenance certifying staff responsible for Model AT‑802 and AT‑802A aircraft with serial numbers 0001 through 0227. The Applicability table explicitly limits the regulatory reach to those aircraft; it does not, in the text provided, extend to later serial numbers or to other Airtractor models. For each affected aircraft the operator must identify whether the engine mount has had gussets installed or not; that factual condition determines which compliance pathway and inspection intervals apply. The Directive also creates distinct operational obligations depending on an aircraft’s accumulated hours in service, because initial inspection scheduling and repetitive intervals differ for aircraft with less than 5,000 hours time in service and for aircraft with 5,000 hours or more.

Maintenance organisations and personnel tasked with performing the inspections are implicated because the Directive mandates compliance “in accordance with Snow Engineering Co. SL No. 253 Revision C, dated 17 April 2008.” The Service Letter provides the inspection methodology that must be used; hence any organisation that performs these inspections on the listed aircraft will need access to that SL and the competence to carry out the procedures it sets out. The Background also documents prior regulatory actions that would have affected the same stakeholder group: operators who incorporated gussets pursuant to Amendment 2 must nevertheless continue to submit the mounts to repetitive inspection as per Amendment 3.

The Directive does not list third parties such as insurers, passengers or airports; it identifies only aircraft by type and serial number and, through the inspection requirement, identifies the subset of technical service providers who must implement the inspection regime. The document does not specify exemptions, grandfathering arrangements beyond the compliance windows, nor does it specify processes for alternative means of compliance in the text provided.

Duties are explicit and procedural. The primary duty is to inspect engine mounts on affected aircraft “in accordance with Snow Engineering Co. SL No. 253 Revision C, dated 17 April 2008” (Requirement). That duty splits into four inspection pathways determined by two binary factors: (a) whether gussets have been installed, and (b) whether the aircraft has accumulated less than 5,000 hours time in service or 5,000 hours or more. For each pathway the Compliance section prescribes:

• For engine mounts without gussets, aircraft with less than 5,000 hours: “Initially, upon accumulating 1,300 hours time in service or within the next 100 hours time in service after 30 August 2007, whichever occurs later. Repetitively thereafter at intervals not to exceed 300 hours time in service.” For the same without gussets, aircraft with ≥5,000 hours: initial within the next 10 hours time in service after 30 July 2009 or within the next 100 hours time in service from the last inspection performed, whichever occurs later, and repetitively thereafter at intervals not to exceed 100 hours. The same structure is set for engine mounts with gussets: <5,000 hours initial at 1,300 or within next 100 hours after 30 July 2009, repeats every 300 hours; ≥5,000 hours initial within next 10 hours after 30 July 2009 or within next 100 hours from last inspection, repeats every 100 hours.

The Directive also contains a note that “FAA AD 2009‑11‑05 Amdt 39‑15915 refers,” which indicates that related FAA directives are part of the normative context, and the Background records that incorporation of gussets was previously a mandatory terminating action under Amendment 2, but Amendment 3 and the present text require repetitive inspections regardless of gusset installation. The present Amendment 4 corrects typographical errors in certain Compliance paragraphs and expressly states the compliance times remain unchanged.

Rights are not expressly articulated in the text. There is no express provision in the supplied instrument for alternative methods of compliance, appeals, waivers, or monetary compensation. The instrument does record the effective date (22 October 2009) and the responsible CASA delegate, which provides an administrative point of contact implicitly for enforcement or queries, but the Directive as supplied does not set out procedural rights for affected parties.

Operators therefore hold the duty to: (1) determine applicability for their airframes (serial number check), (2) determine whether gussets are installed, (3) ascertain hours‑in‑service to establish which compliance schedule applies, and (4) conduct inspections under Snow Engineering SL No. 253 Rev C within the specified initial window and at the required repetitive intervals. Any other rights, such as relief or alternative compliance mechanisms, are not enumerated in this text.

The text provided does not specify statutory penalties, monetary fines, or criminal sanctions for non‑compliance. The instrument is presented as an Airworthiness Directive (AD/AT 800/9 Amdt 4) issued by the Civil Aviation Safety Authority’s delegate (signed David Villiers), and it states an effective date (“This Amendment becomes effective on 22 October 2009”). As drafted, the Directive creates mandatory inspection obligations for the named aircraft and cross‑references an FAA AD, but the Directive itself does not set out an enforcement mechanism or penalty schedule within the supplied pages.

Because the document is an AD (as labelled), it functions as a mandatory safety requirement; however, any specific enforcement process, supervisory checks, or consequences for failing to comply are not contained in the text given. The Background explains the safety rationale for the inspections,reports of cracked engine mounts and a case of a crack through an installed gusset,but it does not translate that rationale into an enforcement rubric or sanctions. The only administrative markers present are the signature and the effective date.

Readers should therefore note that the Directive leaves enforcement details out of the text supplied. If enforcement, sanctioning powers, or certification consequences are relevant for operational or legal planning, the absence of such provisions in the instrument means the operator must consult the broader regulatory framework administered by CASA or the relevant civil aviation legislation and regulations to determine the consequences of non‑compliance. The Directive itself, as supplied, imposes the inspection obligations and records the effective date; it does not enumerate penalties or enforcement steps within this document.

The Directive directly references and situates itself alongside related FAA airworthiness directives: it includes a note that “FAA AD 2009‑11‑05 Amdt 39‑15915 refers,” and the Background refers to FAA AD 2007‑13‑17 and FAA AD 2008‑10‑12 as antecedent actions that influenced prior amendments. Those cross‑references indicate the Directive aligns with or takes account of foreign regulator findings and actions as part of its technical and factual basis. The Directive also mandates compliance with an external technical standard, “Snow Engineering Co. SL No. 253 Revision C, dated 17 April 2008,” by making that Service Letter the required inspection procedure. That creates a direct normative link between CASA’s Directive and the technical content of an external engineering Service Letter.

Within the document itself there is no express statement of interaction with Australian statutory provisions, administrative law, or the broader Civil Aviation Safety Regulations. The Directive’s status as an airworthiness directive issued by CASA’s delegate implies it sits within the CASA regulatory regime, but the text does not reproduce enabling statutes, certification rules, or administrative appeal channels. The Background narrative traces how successive amendments modified inspection timing and terminating actions; Amendment 2 had made gusset incorporation a mandatory terminating action for repetitive inspections, yet later evidence (a gusset cracked through) caused Amendment 3 to require repetitive inspections whether gussets were fitted. Amendment 4 corrects typographical errors without changing technical requirements. These iterative changes show how the Directive’s requirements are conditional on technical findings and cross‑referenced foreign directives.

Because the instrument references the FAA ADs and the Snow Engineering Service Letter, operators must interpret their compliance obligations in light of those documents; the Directive makes the SL the operational method, and the FAA AD references provide background and perhaps parallel regulatory requirements in other jurisdictions. The supplied text does not indicate how conflicts between the SL, FAA ADs and other CASA instruments are to be resolved; it simply prescribes compliance with the specified SL and states the relationship to FAA advisories. If operators need to understand legal effect across jurisdictions or whether alternative maintenance practices satisfy the Directive, they must consult CASA’s broader regulatory framework or seek clarification from CASA, since those procedural interactions are not set out in this Directive.

The Background paragraph summarises the sequence of amendments leading to the current Amendment 4 and the reasons for each change. The chain is as follows, as recited in the Directive:

• Original issue: The FAA received reports of cracked engine mounts. Those cracks, unless detected and corrected, “could result in failure of the engine mount and possible separation of the engine from the aircraft.” This safety concern prompted the initial AD requiring inspections.

• Amendment 1: Prompted by reports of two Model AT‑802A aircraft with cracked engine mounts occurring below the initial compliance time. The FAA determined an earlier initial inspection threshold was required, moving the initial inspection to when the aircraft reaches a total of 1,300 hours time in service.

• Amendment 2: Retained the inspection actions of FAA AD 2007‑13‑17 and required “incorporation of engine mount gussets as a mandatory terminating action for the repetitive inspection requirement.” That is, Amendment 2 made fitting gussets a way to stop the repetitive inspection requirement.

• Amendment 3: Prompted by a report of a Model AT‑602 aircraft with a crack completely through the gusset that had been installed as required in FAA AD 2008‑10‑12. As a consequence, Amendment 3 required repetitive inspections of engine mounts for all previously affected aircraft whether or not gussets were installed. Thus Amendment 3 reversed the terminating‑action effect of gusset installation triggered by Amendment 2.

• Amendment 4 (the current instrument): Issued to correct minor typographical errors in Compliance section paragraphs 1.b. and 2.b., and the text explicitly states there is no change to the technical requirements. Amendment 4 becomes effective on 22 October 2009, and the document is dated by the CASA delegate as 4 September 2009.

The Directive repeatedly notes specific calendar reference points and windowing language in the Compliance section (for example, references to “30 August 2007” and “30 July 2009”), reflecting the history of prior amendments and their implementation timelines. The Background ties each amendment to empirical reports of cracks,first below prior inspection times, then failure despite gusset installation,explaining why inspection cadence and the role of gussets evolved across amendments.

The supplied Directive contains no litigation history, case citations or references to judicial or administrative proceedings. The document’s Background describes safety reports and administrative amendments prompted by engineering findings and FAA directives, but it does not record any disputes, appeals, or legal challenges to the AD or its amendments.

Given the absence of litigation material in the text, there is no source‑grounded litigation history to report. Practitioners seeking to know whether this Directive has been the subject of judicial review, enforcement litigation, or appeals would need to consult court records, administrative rulings, or CASA files outside of the text provided, because none of those matters are mentioned in the instrument itself.

The Directive contains several precise details that can cause operational confusion if read cursory, and the Background highlights earlier misunderstandings that led to amendment cycles. Concrete gotchas in the text include:

• Applicability is narrowly serial‑number specific. The instrument applies only to “Model AT‑802 and AT‑802A aircraft, serial numbers 0001 through 0227.” Operators must verify serial numbers; aircraft of the same model but outside that serial range are not covered by this Directive as written.

• Dual branching by gusset status and hours in service. The Compliance section splits obligations across two axes: (1) whether gussets are installed, and (2) whether the aircraft has accumulated less than 5,000 hours, or 5,000 or more. Getting the branch wrong changes both the initial inspection window and the repetitive interval (300 hours for some categories, 100 hours for higher hours categories). Operators must confirm both facts before scheduling inspections.

• Complex initial windows referencing calendar dates and hours. The initial inspection triggers are expressed as “upon accumulating 1,300 hours time in service or within the next 100 hours time in service after 30 August 2007, whichever occurs later” (or similar wording tied to 30 July 2009 for other clauses). The Directive also contains initial windows for ≥5,000 hours that require inspections “within the next 10 hours time in service after 30 July 2009, or within the next 100 hours time in service from the last inspection performed, whichever occurs later.” Those layered conditions produce multiple permutations that must be interpreted precisely to avoid missed mandatory windows.

• Repetitive inspections despite gusset installation. Amendment 2 had made gussets a terminating action, but Amendment 3 (and the current text) require repetitive inspections for all previously affected aircraft whether or not gussets were fitted, because of reported gusset failures. Operators who fitted gussets expecting that to end inspection obligations must note the Directive’s later change requiring ongoing inspections.

• Typographical corrections may obscure intent. This Amendment 4 was issued to correct typographical errors in paragraphs 1.b. and 2.b. The text asserts no change to technical requirements, but operators should confirm that the corrected wording in the current Directive aligns with prior compliance records and maintenance planning to avoid inadvertent non‑compliance due to reading an earlier faulty text.

• External technical standard reliance. Mandatory compliance is specified “in accordance with Snow Engineering Co. SL No. 253 Revision C, dated 17 April 2008.” The Directive does not reproduce the SL’s procedures or acceptance criteria; failure to obtain, interpret and implement that SL correctly may lead to ineffective inspections. The Directive also refers to FAA ADs for background and related actions; practitioners must ensure they are implementing the Service Letter procedures the Directive mandates, not merely following FAA AD text.

• No penalties specified here. The absence of an express penalty clause in the supplied text does not remove the mandatory nature of the inspections, but it means that the practical consequences for non‑compliance are not addressed in this document and must be determined from the broader regulatory framework.

Follow the Directive’s procedural steps strictly and document compliance clearly. The Directive’s requirements are concrete and procedural; practitioners should implement the following source‑grounded workflow:

1. Applicability check. Confirm the aircraft’s model and serial number. The Directive applies to “Model AT‑802 and AT‑802A aircraft, serial numbers 0001 through 0227.” If the aircraft is outside that serial‑number range, this AD as written does not apply.

2. Factual categorisation. For each affected aircraft determine (a) whether the engine mount has had gussets installed and (b) the current total hours time in service (to ascertain whether it is less than 5,000 hours or 5,000 hours or more). Those two facts determine which Compliance paragraph applies.

3. Obtain the mandated technical procedure. Acquire Snow Engineering Co. SL No. 253 Revision C, dated 17 April 2008, and follow it exactly. The Requirement section makes compliance with that SL mandatory; the Directive contains no technical alternative within the text provided.

4. Apply the correct initial inspection window and repetitive interval. Use the Compliance language for the relevant branch:

   • For engine mounts without gussets, aircraft with less than 5,000 hours: initially upon accumulating 1,300 hours time in service or within the next 100 hours time in service after 30 August 2007, whichever occurs later; repeat at intervals not to exceed 300 hours time in service.
   • For engine mounts without gussets, aircraft with 5,000 hours or more: initially upon accumulating 5,000 hours time in service or within the next 10 hours time in service after 30 July 2009, or within the next 100 hours time in service from the last inspection performed, whichever occurs later; repeat at intervals not to exceed 100 hours time in service.
   • For engine mounts with gussets installed, aircraft with less than 5,000 hours: initially upon accumulating 1,300 hours time in service or within the next 100 hours time in service after 30 July 2009, whichever occurs later; repeat at intervals not to exceed 300 hours time in service.
   • For engine mounts with gussets installed, aircraft with 5,000 hours or more: initially upon accumulating 5,000 hours time in service or within the next 10 hours time in service after 30 July 2009, or within the next 100 hours time in service from the last inspection performed, whichever occurs later; repeat at intervals not to exceed 100 hours time in service. Carefully apply the “whichever occurs later” language and the calendar reference points in scheduling.

5. Record inspections and findings. The Directive mandates inspections but does not provide the record‑keeping format. Best practice consistent with airworthiness processes is to record the date, aircraft hours at inspection, whether gussets are present, the SL procedures followed (SL No. 253 Rev C), and any corrective actions taken. Although the Directive does not specify documentation requirements, maintaining auditable records is necessary to demonstrate compliance.

6. Implement corrective actions per SL. If the Snow Engineering Service Letter prescribes repair, replacement or further action upon finding cracks or defects, follow those prescribed remedies. The Directive’s Background emphasises that cracking could lead to engine mount failure and possible separation of the engine; the Directive therefore implicitly requires corrective action consistent with the SL when defects are found.

7. Maintain awareness of prior amendment context. Operators who fitted gussets as a terminating action under Amendment 2 must note the Amendment 3 outcome,repetitive inspections are required even for gusseted mounts. Ensure maintenance planning reflects the current Directive’s requirement for repetitive inspections.

8. Check effective date and transitional windows. The Amendment becomes effective on 22 October 2009. Pay attention to the initial inspection windows that reference specific dates (30 August 2007 and 30 July 2009) and to the “within the next X hours” language attached to those dates. If inspections were already performed pursuant to earlier ADs, the Compliance text allows for “within the next 100 hours time in service from the last inspection performed” in certain branches; apply that clause where relevant.

9. Seek clarification where needed. The Directive references FAA ADs and an external Service Letter for technical procedure but does not provide penalty or alternate compliance mechanisms. If there is uncertainty about whether a particular inspection method meets the SL’s requirement, or about the interplay of prior inspections and initial windows, obtain clarification from CASA or the appropriate delegated authority.

10. Treat the Directive as mandatory. The instrument is an airworthiness directive signed by a CASA delegate and is effective from the date specified; follow its requirements as part of the aircraft’s continuing airworthiness obligations.

This compliance sequence is drawn solely from the text of the Directive (Applicability, Requirement, Compliance, Background and effective date). The Directive does not set out alternative compliance processes, exemption mechanisms, or penalties within the supplied document; implementers should therefore proceed on the basis that inspections per Snow Engineering SL No. 253 Rev C and scheduled as the Compliance section prescribes are mandatory for affected aircraft.