AD/CESSNA 206/63 - Crew Seat Back Cylinder Lock Modification

The AD sets out a discrete set of technical and administrative concepts tied to a specific failure mode and a bounded fleet. The central technical concept is the crew seat back cylinder lock assembly. The AD identifies a structural failure mode in this assembly, specifically cracking or failure at the aft end area, and treats that failure as capable of producing uncontrolled seat-back movement and backward collapse during flight. The stated operational consequences are twofold: an abrupt pitch-up if a crew member holding the control yoke is involved, and potential difficulty exiting the aeroplane from an aft passenger seat after landing. The Background text supplies the causal narrative used to justify the mandatory measures.

The AD distinguishes three hardware configurations for the lock assembly: (a) aeroplanes without MK172-25-10A/B installed; (b) aeroplanes with MK172-25-10A/B installed; and (c) the corrective hardware MK172-25-10C as the preferred retrofit. Requirement 1 addresses aircraft without the A/B kits, requiring either installation of MK172-25-10C or fabrication of a steel lock rod/bar, following specific Cessna service bulletins. Requirement 2 addresses aircraft already fitted with MK172-25-10A or MK172-25-10B, requiring an installation inspection and either a log book entry if no issues are found or corrective actions if discrepancies exist.

A second main concept is reliance on manufacturer service bulletins and an FAA AD as the technical source documents. The AD repeatedly instructs compliance with Cessna Single Engine Service Bulletin SB04-25-01 Revision 4 dated 26 December 2006 for installation of MK172-25-10C and for inspections/corrective actions when A/B kits are present. It also references Cessna Single Engine Service Bulletin SB04-25-02 (Revision 1 dated 17 October 2005 or Revision 2 dated 5 June 2006) as the method for fabricating and installing a steel lock rod/bar. The AD explicitly notes that FAA AD 2007-05-10 Amdt 39-14971 and the two Cessna service bulletins are referred to in the directive.

A compliance-timing concept is employed that ties required action to the aircraft’s time-in-service at the effective date. This creates three compliance windows (4 months, 8 months, 12 months) corresponding to >1,000 TIS, 501-1,000 TIS, and 0-500 TIS respectively. For aircraft already fitted with MK172-25-10A/B, a much shorter window applies: an inspection within 30 days and any necessary corrective action before further flight after the inspection.

Record-keeping is a discrete administrative concept embedded in the AD. Where an inspection of an A/B installed kit reveals no discrepancies, the AD requires a log book entry showing compliance; that log book entry is the specified evidence of compliance and obviates further action per the text of Requirement 2(ii).

Finally, the AD is temporally bounded and administratively validated. The instrument includes an effective date of 11 April 2007, is dated 9 March 2007, and is presented under the signature of a CASA delegate, David Villiers. The document title is repeated in the source and is shown as AD/CESSNA 206/63, Crew Seat Back Cylinder Lock Modification, 5/2007 DM.

The AD affects owners and operators of the specific Cessna 206-series airframes listed in the Applicability box: Cessna 206H serial numbers 20608001 through 20608250 and Cessna T206H serial numbers T20608001 through T20608570. The wording of the Applicability is categorical: the directive applies to those airframes, and the Requirements are expressed in the imperative, which places obligations on those who operate or maintain the listed aircraft.

Maintenance organisations, licensed engineers and mechanics who perform the installation, fabrication, inspection, and corrective work specified by the AD are operationally affected because they must carry out work in strict accordance with the referenced service bulletins when completing the tasks mandated by the AD. The AD prescribes the exact Cessna service bulletin revisions and dates (SB04-25-01 Revision 4, dated 26 December 2006; SB04-25-02 Revision 1 dated 17 October 2005 or Revision 2 dated 5 June 2006) as the procedural authorities for installation, fabrication and inspection work. Those carrying out the work must therefore have access to and follow those specific documents.

Pilots and crew are affected as the AD is driven by an identified safety risk in crew seat behaviour. The Background section states the operational hazard , uncontrolled movement and backward collapse of the seat back , and links that hazard to flight safety (abrupt pitch-up if a yoke is held) and to egress after landing. Those operational consequences implicate crew procedures and potentially the usability of the flight controls under an in‑flight failure of the seat back cylinder lock assembly, but the AD’s operational mitigation is hardware modification or inspection and corrective action.

Owners/operators are the parties required to evidence compliance; Requirement 2(ii) mandates a log book entry as proof where the inspection shows no discrepancies. The AD therefore affects record-keeping practices and operator administrative obligations. The AD’s Compliance section defines the time windows for mandatory action tied to the aeroplane’s time-in-service on the effective date. That creates different administrative timetables for different operators depending on their aircraft’s TIS at the effective date.

Finally, the AD implicitly affects supply and parts channels to the extent operators choose to install MK172-25-10C rather than fabricating a steel lock rod/bar. The AD offers both options, and maintenance providers will need access either to the manufacturer’s kit MK172-25-10C or the capability to fabricate and install a steel lock rod/bar following the service bulletin SB04-25-02 revisions named in the AD.

The AD establishes explicit duties, and it references specific procedural documents as the authorised means of compliance. The primary duties are:

• For aeroplanes without MK172-25-10A or MK172-25-10B installed: for each crew seat (pilot and co‑pilot), either install Modification Kit MK172-25-10C or fabricate and install a steel lock rod/bar. The directive specifies that MK172-25-10C installation must be performed following Cessna Single Engine Service Bulletin SB04-25-01 Revision 4 (26 December 2006), and that fabrication/installation of a steel lock rod/bar must follow Cessna Single Engine Service Bulletin SB04-25-02 Revision 1 (17 October 2005) or Revision 2 (5 June 2006) (Requirement 1).

• For aeroplanes that have MK172-25-10A or MK172-25-10B installed: perform an installation inspection for each crew seat, in accordance with SB04-25-01 Revision 4 (Requirement 2(i)). If no discrepancies are found, the operator must make a log book entry showing compliance with the AD and then no further action is required (Requirement 2(ii)). If discrepancies are found, the operator must carry out all necessary corrective actions in accordance with SB04-25-01 Revision 4 (Requirement 2(iii)).

Administrative duties include adherence to the compliance times set out in the Compliance section. For aircraft not already fitted with A/B kits, the compliance timing is tiered by TIS (over 1,000 hours: 4 months; 501-1,000 hours: 8 months; 0-500 hours: 12 months). For aircraft fitted with A/B kits, inspections must occur within 30 days of the effective date and corrective action, where needed, must be effected before further flight after inspection (Compliance).

The AD also establishes a duty to document compliance. Where an inspection finds no discrepancies (Requirement 2(ii)), the operator must make a log book entry showing compliance with this AD. The log book entry is presented as the record that compliance has been achieved and as the final administrative step for that branch of the instrument.

The AD’s text does not specify rights in the form of exemptions, alternatives, or appeal processes within the document itself. It does, however, afford a choice between two technical means of compliance for aeroplanes without A/B kits: either install MK172-25-10C or fabricate and install a steel lock rod/bar following the named service bulletin revisions. That choice is the only operationally recognisable "right" embedded in the directive , the operator may choose between the manufacturer kit or the fabrication route provided the fabrication follows the specified SB04-25-02 revisions.

All technical work is to be performed "in accordance with" the specific Cessna service bulletins and the FAA AD 2007-05-10 Amdt 39-14971 is referenced in the AD as part of the background and technical authority. The AD’s prescriptive references to those documents make strict conformity with the named revisions an implied duty for anyone relying on the AD for regulatory compliance.

The AD imposes time-limited duties (work within specified months or days tied to TIS or effective date) and a recording duty (log book entry) but does not, within the text shown, state procedures for approval of alternative methods of compliance or how to document equivalent compliance other than the log book entry in the one specific case. Users must therefore follow the exact references and timings laid out in the AD to fulfil the duties it sets.

The document provided does not set out specific penalties, fines, or enforcement procedures within its text. The AD states its effective date (11 April 2007) and is signed by a delegate of the Civil Aviation Safety Authority, David Villiers, but it contains no express penalty schedule or administrative sanction clause within the contents supplied. The AD’s Compliance section imposes mandatory actions and deadlines but does not, in the material presented, describe the enforcement mechanisms that CASA might use to ensure compliance, nor does it prescribe fixed monetary penalties or criminal sanctions in the AD text itself.

The AD does, however, set out duties whose fulfilment requires documentary evidence in the form of a log book entry where an inspection finds no discrepancies (Requirement 2(ii)). That log book entry is the explicit record the AD requires as evidence of compliance in that circumstance. The AD also imposes mandatory hardware installation, fabrication or inspection and corrective action obligations, with specified service bulletin procedures to be followed. The presence of those mandatory actions and the documentary requirement means that, operationally, an operator who fails to comply would lack the prescribed evidence of compliance in the ways the AD specifies.

Because the AD refers to FAA AD 2007-05-10 and to Cessna service bulletins as the procedural authority to be followed, failure to follow those referenced documents as directed by the AD would amount to non‑compliance with the AD’s requirements as written. The AD does not, in the provided text, specify whether evidence of compliance must be lodged with CASA or simply retained in the aircraft records, though the log book entry requirement implies retention within the maintenance records and continuation records that operators normally hold.

In summary, the AD imposes mandatory technical and record-keeping duties, but the supplied text contains no express penalty table or administrative enforcement procedures. The absence of such details in the AD text as provided means that any further information on penalties and enforcement would need to be located in other regulatory instruments or CASA enforcement policies, which are not reproduced in the source material used here.

The AD explicitly references other prescriptive documents as the technical means by which compliance must be achieved. The text states that FAA AD 2007-05-10 Amdt 39-14971 and Cessna Service Bulletins SB04-25-01 and SB04-25-02 are referred. That cross-reference embeds an interaction: the Australian AD requires compliance by directing the work be performed "in accordance with" the named FAA AD and Cessna service bulletin revisions. The AD therefore binds Australian operators to procedures and amendment versions specified by the manufacturer and the FAA AD as the acceptable method of correction for the identified unsafe condition.

The AD’s reliance on specific service bulletin revisions and dates creates a textual dependency between this instrument and those external documents. For example, installation of MK172-25-10C must follow SB04-25-01 Revision 4 dated 26 December 2006. Fabrication and installation of a steel lock rod/bar must follow SB04-25-02 Revision 1 (17 October 2005) or Revision 2 (5 June 2006). Inspections and corrective actions for aircraft with MK172-25-10A/B must follow SB04-25-01 Revision 4. Because the AD names those revisions and dates, an operator relying on a different revision cannot claim compliance with the AD unless the AD or another authoritative instrument explicitly accepts that revision, which the AD does not do in the supplied text.

The AD also references FAA AD 2007-05-10 Amdt 39-14971. That indicates an operational interaction between this Australian AD and the FAA’s regulatory action, insofar as both documents address the same unsafe condition and the Australian AD incorporates the FAA AD as a reference. The AD is not a verbatim reproduction of the FAA AD but refers operators to it; the Australian directive therefore stands as the national regulatory instrument that incorporates, by reference, technical material from the FAA and the aircraft manufacturer.

The AD does not mention or quote any Australian Civil Aviation Regulations, civil penalties, or processes for seeking an alternative method of compliance (AMOC) within its text as provided. It also does not mention how the AD is to be recorded in national registries or how CASA will track compliance. Those interactions, if they exist, are outside the scope of the supplied document. What is clear in the text is that compliance under the AD must be demonstrated by following the specific service bulletins and, where applicable, recording the result in the aircraft log book as required.

In short, the AD interacts with external technical and regulatory instruments by explicit reference and incorporation of specific FAA and manufacturer service bulletin documents and revisions. Any legal effects flowing from that interaction (for example the acceptability of alternative service bulletin revisions or deviations) are not detailed within the AD text provided.

The source contains limited explicit amendment history for the AD itself, but it does record key dates and referenced revision numbers for the technical service bulletins that the AD mandates. The AD is presented as AD/CESSNA 206/63, with the notation 5/2007 DM, which signals the AD numbering and the year. The AD document is dated 9 March 2007 and is shown as becoming effective on 11 April 2007. Those dates are the only explicit temporal markers for this AD in the supplied text.

The AD instructs work to be performed in accordance with Cessna Single Engine Service Bulletin SB04-25-01 Revision 4, dated 26 December 2006, and Cessna Single Engine Service Bulletin SB04-25-02 Revision 1, dated 17 October 2005, or Revision 2, dated 5 June 2006. Those revision dates are material because the AD requires compliance with those specific revisions. The inclusion of those revision numbers and dates functions as part of the AD’s amendment-referenced history for the technical procedures it prescribes.

The AD also references FAA AD 2007-05-10 Amdt 39-14971. The FAA AD number and amendment detail, as cited, indicate the FAA action that the Australian AD references for background and technical correlation. The AD’s text states that FAA AD 2007-05-10 Amdt 39-14971 and the two Cessna service bulletins "refer", which anchors this AD to those external documents at the time the AD was issued.

The source shows the AD title and metadata multiple times including repeated headings "AD/CESSNA 206/63", "Crew Seat Back Cylinder Lock Modification", and "5/2007 DM". The repetition indicates the document identity and edition. There is no explicit record in the supplied text of any later amendment to this AD, nor is there any notation of prior versions of the AD itself. The AD’s internal references to specific service bulletin revisions, however, imply a dependency on the revision history of those service bulletins; that history is partially recorded in the AD by listing the acceptable SB04-25-02 revisions (Revision 1 or Revision 2) and by mandating Revision 4 of SB04-25-01.

If an operator needs to know whether later revisions of the service bulletins or later ADs supersede this AD, that information is not contained in the supplied text; the AD as presented binds operators to the named revisions and effective date. The signatory block indicates that David Villiers, as a CASA delegate, executed the AD on 9 March 2007 and set the effective date as 11 April 2007, which is the administrative amendment history available in the document.

The supplied AD text contains no information about any litigation, disputes, judicial review, or administrative appeal related to this AD. There are no case names, no references to court decisions, and no mention of any challenges to the AD’s content or to the technical measures it prescribes. The only legal-adjacent references in the document are to FAA AD 2007-05-10 and to Cessna service bulletins; neither of those references in this text is accompanied by any litigation history.

Because the source provided contains no litigation history, one cannot cite any judicial pronouncements, administrative determinations, or case law that interpret or apply this instrument based on the material available. The AD does not set out any statutory appeals mechanism or note any pending legal proceedings. The document stands as an administrative directive signed by a CASA delegate and effective on a stated date, with no internal record of subsequent litigation or challenge.

Where a practitioner needs litigation history or precedents about interpretation, enforcement, or disputes concerning this AD, that information is not present in the instrument supplied and would therefore need to be sought in external legal or regulatory records. The AD itself contains no such records or annotations.

The AD’s brevity and reliance on external service bulletins create several practical pitfalls and traps for unwary operators and maintainers; these are all identifiable within the instrument’s text.

1. Narrow serial number applicability. The AD applies only to Cessna 206H serials 20608001 through 20608250 and Cessna T206H serials T20608001 through T20608570. Operators of airframes outside these ranges are not covered by this specific instrument; conversely, operators of airframes within these serial number ranges must comply. A misreading of serial ranges could lead to non‑compliance or unnecessary work.

2. Tiered compliance windows tied to TIS. The clock for compliance is the aircraft’s hours time-in-service on the AD’s effective date. The AD creates three distinct time windows (4 months, 8 months, 12 months) depending on whether the aeroplane has >1,000 TIS, 501-1,000 TIS or 0-500 TIS on the effective date. If an operator miscalculates TIS on the effective date (11 April 2007 per the AD), they may miss the correct deadline. The AD explicitly ties the required action start date to that effective date.

3. Short inspection window for A/B‑fitted aircraft. Aircraft that already have MK172-25-10A or MK172-25-10B installed must have an installation inspection within 30 days of the effective date and must complete corrective actions before further flight if discrepancies are found. The 30-day window is short and requires prompt scheduling.

4. Choice of technical route with strict procedural references. For aircraft without MK172-25-10A/B, operators may either install MK172-25-10C or fabricate a steel lock rod/bar. Fabrication must be done in accordance with SB04-25-02 Revision 1 or Revision 2; installation must be done in accordance with SB04-25-01 Revision 4. The AD names exact SB revisions and dates. Using a different revision or a different fabrication method not called out may not satisfy the AD as written.

5. Log book entry as the compliance record for one branch. For A/B‑fitted aircraft where the inspection reveals no discrepancies, the AD requires a log book entry showing compliance and states that no further action is required. That log book entry is the AD’s prescribed evidence of compliance in that circumstance. Failure to create or retain such an entry would leave the operator without the specific compliance evidence the AD mandates.

6. Ambiguity or repetition in the Compliance section. The Compliance section includes phrasing that repeats "Before further flight after the inspection required in paragraph 2(i) of this AD" more than once; this duplication could introduce minor parsing uncertainty for a reader but does not change the substantive duty that corrective action must be completed prior to further flight after inspection.

7. Dependence on external documents not reproduced in the AD. The AD directs operators to Cessna service bulletins and references an FAA AD. Those external documents contain the technical steps and drawings necessary for installation, fabrication, inspection and corrective action. Operators must obtain and follow those documents exactly as referenced. Misapplying a later or earlier revision, or using a different fabrication drawing, risks non‑compliance with the AD.

8. No penalty detail in the AD. The instrument does not detail enforcement or penalties. That absence does not mean enforcement will not occur; it simply means that any enforcement mechanism or penalty regime is not contained in the AD text itself. Operators should not assume the absence of penalty detail negates the mandatory nature of the AD.

9. Multiple affected items per aircraft. The AD requires the action "for each crew seat (pilot and co-pilot)". That means two discrete installations/inspections per aeroplane. Overlooking either seat would amount to partial compliance.

10. Workforce and parts scheduling. The AD allows either kit installation or fabrication; the latter requires a maintenance organisation with fabrication capability and the exact SB instructions. Scheduling and parts availability are operational risks implicit in the AD but made material by the specific timelines the AD sets.

These gotchas arise directly from the AD’s wording and its design as a short directive that delegates technical method to external service bulletins. They emphasise the need for precise reading of serial ranges, TIS cutoffs, specified SB revisions and dates, the short 30-day inspection window for certain aircraft, and the log book entry requirement as the documentary evidence of compliance in the inspection-no-discrepancy scenario.

The AD provides a clearly structured path to compliance; the following is a step-by-step rendition of the required actions, grounded in the exact wording of the AD.

1. Identify applicability. Confirm whether the aeroplane falls within the serial number ranges listed in the Applicability: Cessna 206H serial numbers 20608001 through 20608250, or Cessna T206H serial numbers T20608001 through T20608570. If the aircraft is not within these serial numbers, this AD does not apply as written.

2. Determine the aircraft’s time-in-service (TIS) on the AD’s effective date. The AD becomes effective on 11 April 2007. Record the TIS on that date, because the required compliance deadline depends on that figure:

   • If TIS > 1,000 hours, perform the required action within the next 4 months after the effective date.
   • If TIS is 501-1,000 hours, perform the required action within the next 8 months after the effective date.
   • If TIS is 0-500 hours, perform the required action within the next 12 months after the effective date. These timings are set out in the Compliance section.

3. Ascertain current hardware configuration. Check whether MK172-25-10A or MK172-25-10B is already installed on the crew seat back cylinder lock assembly.

   • If MK172-25-10A or MK172-25-10B is not installed, follow the path in Requirement 1.
   • If MK172-25-10A or MK172-25-10B is installed, follow the path in Requirement 2.

4. Requirement 1 path (A/B not installed): For each crew seat (pilot and co‑pilot), either:

   • Install Modification Kit MK172-25-10C following Cessna Single Engine Service Bulletin SB04-25-01 Revision 4 dated 26 December 2006; or
   • Fabricate and install a steel lock rod/bar following Cessna Single Engine Service Bulletin SB04-25-02 Revision 1 dated 17 October 2005, or Revision 2 dated 5 June 2006. Ensure that the work follows the exact SB revision specified in the AD. Complete the action within the TIS-tiered compliance window described in step 2.

5. Requirement 2 path (A/B installed): For each crew seat, perform an installation inspection in accordance with Cessna SB04-25-01 Revision 4 dated 26 December 2006. Complete that inspection within 30 days after the effective date of the AD. After inspection:

   • If no discrepancies are found, make a log book entry showing compliance with this AD. The AD states that no further action is required in that case.
   • If discrepancies are found during the inspection, make all necessary corrective actions in accordance with SB04-25-01 Revision 4. The AD states these corrective actions must be completed before further flight following the inspection.

6. Record the compliance actions. Where the AD requires a log book entry (Requirement 2(ii)), create and retain the entry in the aircraft maintenance log book. For other actions, while the AD does not prescribe a specific form of external submission, retaining records of installation certificates, maintenance release signatures, references to the specific SB revision used and dates of completion will be necessary to evidence compliance in operational or regulatory checks.

7. Use the exact referenced documents. The AD explicitly requires following SB04-25-01 Revision 4 for installation of MK172-25-10C and for inspections and corrective actions if A/B kits are present. For fabrication of a steel lock rod/bar, use SB04-25-02 Revision 1 or Revision 2 as named. Do not substitute other documentation or unapproved procedures if you intend to rely on the AD for regulatory compliance.

8. Address dual‑seat requirement. The AD requires the action for each crew seat, so plan for two installations or two inspections per aeroplane.

9. Verify final status before flight. For any aeroplane where corrective actions were required following an inspection, ensure that all corrective actions required by SB04-25-01 Revision 4 are completed and signed off prior to the next flight, as the AD states corrective action must be made "before further flight."

10. Keep technical references available. Maintain copies or accessible records of the referenced documents: FAA AD 2007-05-10 Amdt 39-14971 (as cited), Cessna SB04-25-01 Revision 4 (26 December 2006), and Cessna SB04-25-02 Revision 1 (17 October 2005) or Revision 2 (5 June 2006).

The AD supplies a limited set of options for compliance (kit installation or fabrication) and a prescribed inspection and corrective action path for aircraft already modified with earlier kits. Compliance is evidenced by maintenance completion sheets and the specific log book entry where the inspection finds no discrepancies. Because the AD directs compliance with exact service bulletin revisions and dates, conforming exactly to those documents is a practical necessity. Failure to perform the required work within the specified TIS-based periods or failure to create the required log book entry where applicable would leave the operator without the compliance evidence the AD mandates.

In operational terms, compliance requires co-ordination among the aircraft owner/operator, a licensed maintenance provider that can either install the MK172-25-10C kit or fabricate the steel lock rod/bar per the SB instructions, and the person authorised to sign the log book entry or maintenance release after completion. The AD’s effective date, 11 April 2007, is the reference point for compliance timing, and the AD’s Background section explains the safety rationale that makes these steps mandatory.