AD/PC-12/39 Amdt 1 - Autopilot & Flap Selection

The AD hinges on three principal regulatory concepts: temporary operating limitation, serial-numbered corrective actions, and terminating action via hardware modification.

Temporary operating limitation. The AD requires insertion of a Temporary Revision (TR No 11 or TR No 40) into Section 2 of the POH (Requirement 1). That temporary revision conveys an operational instruction , the original issue of the Directive required pilots to disengage the autopilot before selecting flaps to 40° , and is mandated before further flight after 19 May 2005. The AD treats that POH insertion as an interim risk-control measure pending completion of the hardware and wiring work specified in the Service Bulletin.

Serial-numbered corrective actions. The corrective work in Requirement 2 is explicitly allocated by Manufacturer Serial Number ranges. The AD distinguishes three overlapping MSN groups for discrete actions: actuator replacement (MSN 101-602), wire disconnection and stowage (MSN 321 and 401-620), and securing a circuit breaker with a specific safety clip (MSN 101-320 and 322-400). The use of MSNs creates a mosaic of obligations depending on an individual aeroplane’s serial number, rather than a uniform fleet-wide retrofit.

Terminating action. The AD sets a pathway to rescind the temporary POH limitation. Once the aircraft-specific items of Pilatus Service Bulletin 22-004 are accomplished, the operator must remove TR No 11 or TR No 40 from the POH immediately (Requirement 3). The hardware actions therefore function as terminating actions for the interim operational restriction.

Referential linkage. The AD delegates the technical steps to Pilatus Service Bulletin 22-004 (dated 21 December 2004). It also notes the FOCA Switzerland AD HB-2005-128, signalling that the Swiss authority has issued a related directive. The AD itself is issued under the Australian Civil Aviation framework and is signed by a Civil Aviation Safety Authority delegate.

Operational safety rationale. The background text states that the AD responds to a reported abrupt nose-down pitch that occurred after autopilot disconnection on an ILS approach with flaps at 40°. Investigations identified a possible out-of-trim condition that could reduce controllability of the aeroplane when autopilot is disengaged at that flap setting. The AD’s interventions are therefore designed to (1) mitigate immediate flight risk through the temporary POH limitation, and (2) remedy the underlying hardware/wiring conditions that could cause the out-of-trim condition.

Implementation timing. The AD sets near-term and medium-term deadlines: the temporary POH change is required before further flight after 19 May 2005; the hardware/wiring work must be completed before 31 December 2006; and the removal of the POH revisions is required immediately after completing the hardware work. The amendment becomes effective on 12 May 2005.

Directly affected parties are the registered owners, operators and maintenance organisations responsible for Pilatus PC-12 and PC-12/45 aeroplanes with Manufacturer Serial Numbers 101 through 620 inclusive. The AD’s Applicability line states: "All Model PC-12 and PC-12/45 aeroplanes, Manufacturer Serial Numbers (MSN) 101 thru MSN 620 inclusive." This identifies the entire affected cohort.

Within that cohort different operators have different obligations depending on MSN. For example:

• Operators of MSN 101-602 inclusive must replace the pitch actuator P/N 985.92.03.161 with P/N 985.92.03.164 (Requirement 2a).
• Operators of MSN 321 and MSN 401-620 inclusive must disconnect, de-pin and cap wire C97C22 at terminal block TB260-13/H and stow it (Requirement 2b).
• Operators of MSN 101-320 and MSN 322-400 inclusive must secure circuit breaker CB906 with safety clip P/N 110.88.07.065 (Requirement 2c).

Pilots of affected aeroplanes are also affected in their operational practice. The AD mandates an immediate POH insertion of a temporary revision into Section 2 of the POH (Requirement 1) which, as stated in the Background, included an instruction to disengage the autopilot before a flap selection of 40° is made. That imposed POH change alters normal operating procedures until the terminating hardware work is done and the temporary revision is removed.

Maintenance organisations and engineers who carry out the required modifications are affected operationally and commercially. The AD directs that the corrective actions be accomplished "in accordance with Pilatus Service Bulletin 22-004 dated 21 December 2004" (Requirement 2). That ties the maintenance work to a manufacturer-prescribed method, parts and procedures.

Manufacturers or parts suppliers are indirectly affected because the AD requires specific part numbers: replacement pitch actuator P/N 985.92.03.164 and safety clip P/N 110.88.07.065. The AD therefore creates demand for those parts among the affected MSNs.

Regulatory authorities are affected administratively in the sense that the AD is a regulatory instrument signed by a Civil Aviation Safety Authority delegate (James Coyne) and takes effect 12 May 2005. The AD also references the Swiss FOCA AD HB-2005-128, which indicates cross-jurisdictional regulatory coordination; however, the AD itself applies to aircraft within the Australian regulatory domain for which CASA’s delegate issued the AD.

Who pays. The text itself does not allocate costs, but by prescriptive effect the operators and maintenance providers will incur direct costs for parts, labour and downtime necessary to comply with Requirement 2, while pilots must operate under the temporary POH limitation prior to the terminating action. These cost-bearing relationships derive from who legally controls and maintains the aircraft (owners/operators) and from the AD’s instruction that the work be done in accordance with the Pilatus service bulletin.

The AD prescribes mandatory duties, and the rights available under the text are procedural , namely, the right to remove the temporary POH revision once the terminating action has been accomplished. The AD’s operative duties are set out as three numbered Requirements.

Duty 1 , Temporary POH amendment (Requirement 1). If not previously done, the operator must amend the Pilot’s Operating Handbook by inserting either Temporary Revision No 11 (Report No 02211) or TR No 40 (Report 01973-001) into Section 2 of the POH. The AD sets the compliance timing for this duty "Before further flight after 19 May 2005." This creates an immediate limitation on operations for aircraft that had not already implemented the TR.

Duty 2 , Accomplish Service Bulletin actions (Requirement 2). Operators must accomplish the actions listed in Pilatus Service Bulletin 22-004 dated 21 December 2004. The three discrete actions are allocated by MSN ranges and specify exact parts and wiring connections. The completion deadline for these actions is "Before 31 December 2006." The AD thus imposes an affirmative maintenance duty to modify hardware/wiring in accordance with the manufacturer’s bulletin.

Duty 3 , Removal of temporary TR (Requirement 3). Once the work required by Requirement 2 is completed, the operator must remove TR No 11 or No 40 from the POH "immediately following accomplishment of Requirement 2." That is presented as the terminating action which returns the POH to its prior state.

Rights arising from the AD. The AD provides the right to resume normal POH operation after the terminating actions are completed. There is no express appeal, exemption or variation mechanism contained within the text itself. The AD does not specify alternative means of compliance or equivalent level of safety provisions within its own wording. The AD does, however, rely on Pilatus Service Bulletin 22-004 to define the technical method of compliance.

Procedural and timing constraints. The AD prescribes precise timing for each duty: Requirement 1 before further flight after 19 May 2005; Requirement 2 before 31 December 2006; Requirement 3 immediately after Requirement 2 is accomplished. Those temporal constraints create a window during which aircraft must operate under the temporary POH limitation until hardware work is done.

Scope limits and serial-number differentiation. Duties are not uniform across the fleet but differ by MSN. An operator must check its aeroplane MSN to identify which specific actions from the Service Bulletin apply. The AD’s formatting shows discrete cohorts: 101-602, 321 and 401-620, and 101-320 and 322-400 inclusive. The AD thereby imposes duties that vary by aircraft rather than by model alone.

References and delegated compliance. The AD explicitly directs that Requirement 2 be accomplished "in accordance with Pilatus Service Bulletin 22-004 dated 21 December 2004." That creates a duty to follow the manufacturer-prescribed procedures and parts for the corrective actions. The AD itself does not describe the detailed technical steps beyond listing which action applies to which MSN; the Service Bulletin supplements the AD by providing the procedural detail.

The AD text does not specify civil or criminal penalties, nor does it include an enforcement clause within the document itself. The AD spells out compliance timings and required actions , for example, Requirement 1 must be done "Before further flight after 19 May 2005," Requirement 2 "Before 31 December 2006," and Requirement 3 "Immediately following accomplishment of Requirement 2." The AD is signed by a delegate of the Civil Aviation Safety Authority, which indicates formal regulatory origination and effectivity ("This Amendment becomes effective on 12 May 2005").

Because the AD contains no express penalty provisions, the directive leaves a gap in the text between mandated actions and an explicit enforcement mechanism. That absence is material for operators and maintenance organisations because the AD nonetheless imposes strict compliance windows and technical instructions. The practical enforcement consequences are not stated in the instrument; any enforcement or sanctions that may occur for non-compliance are not detailed in the AD itself.

This gap introduces a compliance risk. Operators must comply with the timelines and technical requirements set out in the AD, but the AD does not set out a process for seeking extensions, exemptions, or alternate means of compliance within its text. The AD also does not specify record-keeping requirements or documentary proof of compliance. The absence of those procedural details may create operational uncertainty for owners and maintenance organisations who must plan parts procurement and maintenance scheduling to meet the deadlines.

The AD does, however, provide a clear compliance pathway and terminating action. The removal of the temporary POH revision is expressly linked to completion of the Service Bulletin items, which gives operators a discrete end-point for restoring normal operating limits. The AD’s effective date and the signature by a CASA delegate indicate formal regulatory authority behind the document even though no penalties are enumerated.

In practice, affected parties should note the textual absence of explicit enforcement or penalty language in the AD, and ensure they retain contemporaneous records documenting compliance with Requirements 1, 2 and 3. The AD’s own wording, including its effective date and compliance deadlines, creates a mandatory regime; how any non-compliance would be dealt with is not contained within the text provided.

The AD expressly interacts with a manufacturer service bulletin and with another national airworthiness directive, and it operates by requiring amendments to the Pilot’s Operating Handbook, which is a component of aircraft operating documentation.

Interaction with Pilatus Service Bulletin 22-004. The AD delegates technical compliance to Pilatus Service Bulletin 22-004 dated 21 December 2004. Requirement 2 instructs operators to "Accomplish the following actions in accordance with Pilatus Service Bulletin 22-004 dated 21 December 2004." That means the AD and the Service Bulletin function together: the AD provides the regulatory mandate and deadlines while the Service Bulletin specifies the method of compliance and the technical details (such as how to replace the pitch actuator, how to disconnect and stow wire C97C22, and how to secure circuit breaker CB906 with the specified safety clip). The AD therefore incorporates the Service Bulletin by reference as the technical standard.

Interaction with Pilot’s Operating Handbook (POH). Requirement 1 mandates insertion of a Temporary Revision into Section 2 of the POH, and Requirement 3 mandates the removal of that TR after the Service Bulletin work is done. The POH is an operational document; the AD therefore changes operating limitations via the POH and then restores them when the terminating action is completed. This establishes an interaction between regulatory compliance and operational documentation.

Cross-jurisdictional reference. The AD notes "FOCA Switzerland AD HB-2005-128 refers." That identifies a formally related measure by the Swiss Federal Office for Civil Aviation and implies coordinated regulatory action across jurisdictions for the same technical problem. The AD does not detail the content of the FOCA AD within the text; it only references it. The presence of that reference indicates interplay between Australian regulatory action and foreign airworthiness directives concerning the same aeroplane type.

No other statutory cross-references. The AD does not itself cite other specific Australian statutes, regulations or penalties. It is a standalone airworthiness directive that prescribes technical and operational steps; any interaction with broader aviation law, safety regulation, or enforcement frameworks is not specified in the text provided. The AD’s effective date and CASA delegate signature show it as a regulatory instrument, but the AD does not contain explicit cross-references to enforcement provisions in civil aviation statutes within the text given.

Operational and contractual implications. By imposing a mandatory POH revision and hardware modification, the AD can affect contractual obligations in aviation operations and maintenance supply chains. The AD requires use of specific part numbers and a Pilatus service bulletin; that will interact with procurement contracts, maintenance authorisations and technical records. The AD does not itself amend or reference maintenance record-keeping requirements, but compliance with the AD will typically require operators and maintenance organisations to update maintenance logs, POH copies, and possibly MEL/dispatch procedures to reflect the temporary limitation and its subsequent removal.

The AD document itself summarises prior procedural steps and provides effective dates for the original issue and the amendment. Key historical elements in the AD text:

Original issue. The AD notes that "The original issue of this Directive required, as a temporary measure, revision of the Limitations Section of the POH to include an instruction to disengage the autopilot before a flap selection of 40° is made." That original Directive became effective on 11 February 2004. The AD therefore has a track record: an initial, time-limited POH limitation was issued earlier.

Amendment purpose and effectivity. This instrument is an amendment to that original Directive; it is labelled "AD/PC-12/39 Amdt 1" and becomes effective on 12 May 2005. The AD’s own heading indicates it is an amendment to AD/PC-12/39. The amendment "limits the MSN effectivity and at the same time, introduces a terminating action which allows the removal of the temporary POH revisions." In other words, where the original AD imposed a temporary POH limitation broadly, the amendment narrows the serial-number scope and provides a manufacturer-prescribed corrective set of actions that, when completed, terminate the POH restriction.

Dates and timelines included in the amendment. The amendment sets a short-term compliance date for the temporary POH revision: Requirement 1 must be done "Before further flight after 19 May 2005." The amendment itself is effective 12 May 2005. The amendment sets a longer-term deadline for the corrective work: Requirement 2 must be completed "Before 31 December 2006." The removal of the TR under Requirement 3 is immediate upon completion of the Service Bulletin work.

Reference to related foreign AD. The amendment notes that FOCA Switzerland AD HB-2005-128 "refers," indicating the existence of a parallel Swiss action in the amendment’s provenance. The amendment therefore sits in a sequence: original AD (effective 11 February 2004), followed by this Amendment 1 (effective 12 May 2005) that narrows scope and provides terminating actions.

Signature and delegate authority. The amendment bears the signature of James Coyne, "Delegate of the Civil Aviation Safety Authority," dated 31 March 2005. That signature line documents the authority and date at which the AD was signed, which precedes the formal effective date.

No further amendments are recorded in the text provided. The AD records only the original issue date and the amendment effective date and describes the functional changes effected by the amendment relative to the original Directive. There is no additional amendment history within the supplied text.

The supplied AD text contains no references to litigation, court decisions, judicial review or administrative appeals. The document reports facts, compliance requirements and dates, and includes a background statement about an incident investigation leading to the AD, but it does not mention any legal challenges to the Directive or related proceedings.

Specifically, the text describes the Swiss FOCA investigation that identified a risk of abrupt nose-down pitch when autopilot is disconnected at 40° flaps, and it recounts the administrative steps taken: an original Directive with a temporary POH revision, and this Amendment 1 which limits MSN scope and provides terminating actions. The AD’s signature block identifies a CASA delegate as the issuing authority. Beyond that, no litigation history or references to cases, tribunals or appeals mechanisms appear in the AD text.

Due to the absence of litigation references, readers seeking legal precedents, judicial interpretations of ADs, or case law applications of this AD will find none within the document itself. Any analysis of enforcement outcomes, disputed compliance, or successful challenges to similar airworthiness directives is outside the scope of the text provided because no such events are recorded here.

Precision on MSNs and overlapping ranges. The AD imposes different physical actions for overlapping MSN ranges. For example, MSN 321 appears in the list for wire disconnection (MSN 321 and MSN 401-620) while MSN 322 is listed separately in the circuit-breaker security cohort (MSN 322-400 inclusive). Operators must verify the exact MSN of their aircraft to determine which specific requirements apply. Misreading the ranges could lead to incomplete compliance.

Exact part numbers and identifiers are required. The AD specifies exact Part Numbers and identifiers: pitch actuator to be replaced from P/N 985.92.03.161 to P/N 985.92.03.164; wire C97C22, terminal block TB260-13/H; circuit breaker CB906 to be secured with safety clip P/N 110.88.07.065; and the TR numbers are TR No 11 (Report No 02211) or TR No 40 (Report 01973-001). Failure to use the specified part numbers or to act at the specified wiring and terminal locations may render the corrective action non-compliant with the AD because Requirement 2 is to be accomplished "in accordance with Pilatus Service Bulletin 22-004 dated 21 December 2004," which will be precise about parts and methods.

Timing sequencing pitfall. Requirement 1 must be accomplished "Before further flight after 19 May 2005." If an operator delays the Service Bulletin work, the aeroplane will need to retain the temporary POH revision for potentially up to the entire window until 31 December 2006. That creates an operational state in which the aircraft must be flown under the limitation. Operators should note that Requirement 3 requires removal of the TR "Immediately following accomplishment of Requirement 2," so the TR is not to be removed until the terminating action is done.

Partial applicability within the fleet. Because different MSNs require different items from the Service Bulletin, an operator with multiple aeroplanes in the 101-620 range will have to manage a matrix of actions, parts and scheduling for each airframe. Supply constraints on the specific actuator P/N and safety clips or disconnect connectors for the specified wire could lead to staggered compliance and uneven fleet availability.

The AD does not state alternate compliance paths. The Directive mandates compliance by reference to Pilatus Service Bulletin 22-004 but does not articulate an alternative means of compliance within the text. If an operator believes there is an equivalent method that achieves the same level of safety, that path is not described in the AD itself.

No explicit record-keeping or enforcement text. The AD prescribes actions and deadlines but does not include requirements for documenting compliance within the AD text. That absence is a practical gotcha because operators typically need documentary proof of compliance when conducting audits, inspections or showing conformity to regulators. The AD’s omission of explicit record-keeping instructions may lead to divergent practices among operators concerning what evidence to retain.

Operational implications for flight crews. The background notes that the original Directive required pilots to disengage the autopilot before a flap selection of 40°. If crews are accustomed to different autopilot/flap interaction procedures, the temporary POH revision may require immediate changes to SOPs and training for line pilots and dispatchers until the terminating action is completed.

Interpreting "remove TR immediately." Requirement 3 states that TR No 11 or No 40 must be removed "immediately following accomplishment of Requirement 2." Operators should interpret "immediately" conservatively and update the POH and any flight crew operating documents without delay, ensuring that the work is properly documented so that the removal is traceable.

Cross-reference to FOCA AD. The AD notes "FOCA Switzerland AD HB-2005-128 refers." Operators should be aware that parallel or differing requirements may exist in other jurisdictions and that compliance with the Pilatus Service Bulletin and removal of the TR might interact with foreign AD requirements if an aircraft is operated internationally.

Follow the AD’s three Requirements in order, verify aircraft MSN applicability, and document completion.

1. Verify applicability by MSN. Confirm the aeroplane’s Manufacturer Serial Number is within the AD’s scope: MSNs 101 through 620 inclusive. Determine which specific Requirement 2 items apply by checking the aircraft’s exact MSN against the AD’s delineation (Requirement 2a, 2b, 2c).

2. Insert the Temporary Revision into the POH (Requirement 1). If the POH does not already contain TR No 11 (Report No 02211) or TR No 40 (Report 01973-001) in Section 2, insert one of those TRs. The AD requires this to be done "Before further flight after 19 May 2005." Ensure flight crews are briefed on the temporary operating instruction contained in the TR, which the Background describes as an instruction to disengage the autopilot prior to a flap selection of 40°.

3. Accomplish the Service Bulletin work (Requirement 2). Conduct the actions "in accordance with Pilatus Service Bulletin 22-004 dated 21 December 2004." Apply the correct action by MSN:

   • For MSN 101-602 inclusive: replace pitch actuator P/N 985.92.03.161 with pitch actuator P/N 985.92.03.164. This is the terminating actuator replacement for the majority of the fleet.
   • For MSN 321 and MSN 401-620 inclusive: disconnect wire C97C22 from terminal block TB260-13/H, remove the end connector from the wire, then cap and stow the wire.
   • For MSN 101-320 and MSN 322-400 inclusive: secure circuit breaker CB906 with safety clip P/N 110.88.07.065.

   Schedule and procure the correct parts and tools per Pilatus Service Bulletin 22-004. Complete these actions before 31 December 2006. Ensure that maintenance personnel perform the work in accordance with the Service Bulletin’s procedural and safety steps.

4. Remove the Temporary Revision from the POH (Requirement 3). Once the applicable Service Bulletin work is completed on the aircraft, remove TR No 11 or TR No 40 from Section 2 of the POH immediately after the work is finished, as the AD directs. This restores the POH to its pre-TR state.

5. Record and retain evidence of compliance. While the AD text does not prescribe record-keeping steps, the AD imposes mandated technical work and POH changes. To demonstrate compliance, retain the following:

   • A maintenance release or sign-off showing the Service Bulletin work was done and specifying parts used, part numbers installed, and work completion date.
   • A copy of the POH before and after TR insertion and a dated record showing the insertion and later removal of TR No 11 or TR No 40.
   • Photographic evidence where practical (e.g., showing the installed safety clip or the capped and stowed wire), and part tag documentation for the replaced pitch actuator.
   • Any communications with the manufacturer or regulatory authority regarding the Service Bulletin or completion status.

6. Coordinate flight operations for temporary limitation. Until Requirement 2 is completed for a given aircraft, operate under the temporary POH instruction. Brief crews on the change, update dispatch and training materials as necessary, and factor possible downtime into flight scheduling.

7. Cross-check foreign ADs and regulatory expectations. The AD notes a reference to FOCA Switzerland AD HB-2005-128. If the aircraft is operated internationally or under a foreign registry, ensure that compliance with Pilatus Service Bulletin 22-004 and removal of the TR conforms with any foreign ADs or airworthiness authority requirements.

8. Plan for parts, labour and scheduling. The AD requires specific parts (actuator P/N changes and safety clip P/N) and wiring work. Operators should plan procurement and maintenance scheduling so that Requirement 2 is completed well before the 31 December 2006 deadline where possible, to minimise the time aircraft must operate under the temporary POH restriction.

9. Use the Service Bulletin as the technical standard. The AD explicitly ties Requirement 2 to Pilatus Service Bulletin 22-004 dated 21 December 2004. Follow the Service Bulletin’s step-by-step instructions and safety precautions when performing the work.

10. Treat the AD as regulatory direction. The AD is an airworthiness directive with an effective date of 12 May 2005 and a signature by a CASA delegate. Although the AD text does not set out penalties or enforcement mechanisms, the operator must comply with the Requirements and the specified timings. Keeping contemporaneous, well-organised evidence of compliance will mitigate operational and regulatory uncertainty.

By following these steps and documenting each stage, an operator will align with the AD’s procedural requirements: interim POH change, Service Bulletin technical actions by specific MSNs, and removal of the TR immediately after completing the corrective work.