{"id":"F2008L00151","name":"AD/B767/173 Amdt 1 - Thrust Reverser Directional Pilot Valve","slug":"ad-b767-173-amdt-1-thrust-reverser-directional-pilot-valve","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":72299,"registerId":"commonwealth-F2008L00151-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 767 Series Aeroplanes","sectionType":"division","heading":"Boeing 767 Series Aeroplanes","content":"### Boeing 767 Series Aeroplanes\n\n| AD/B767/173 Amdt 1 | Thrust Reverser Directional Pilot Valve | 3/2008 DM |\n| ------------------ | --------------------------------------- | --------- |\n\n| Applicability: | Model 767 series aeroplanes with General Electric CF6-80C2 series engines. |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. (a) For aeroplanes not modified in accordance with Boeing Service Bulletin (SB) 767-78-0063 or production equivalent carry out and successfully accomplish a functional test of the Directional Pilot Valve (DPV) of the thrust reversers to detect pneumatic leakage in accordance with Boeing Alert SB 767-78-0084 dated 21 October 1999.(b) For aeroplanes modified in accordance with Boeing SB 767-78-0063 or production equivalent carry out and successfully accomplish a functional test of the DPV of the thrust reversers to detect pneumatic leakage in accordance with Boeing Alert SB 767-78-0084 dated 21 October 1999.2. Repeat and successfully accomplish a functional test of Requirement 1(a).3. Repeat and successfully accomplish a functional test of Requirement 1(b).4. If any functional test required by Requirement 1, 2 or 3 of this Directive cannot be successfully carried out in accordance with the reference service bulletin, or if any discrepancy is detected during any functional test, repair in accordance with the Aircraft Maintenance Manual.5. Repeat Requirement 1 functional tests if any discrepancies have been corrected under Requirement 4 during compliance with requirement 1, 2 or 3.Production EquivalentFunctional tests accomplished in accordance with a production equivalent for aeroplanes modified during production, are acceptable as equivalent to the initial functional test required by Requirement 1(b) of this Directive. Therefore, in this case, compliance with Requirement 1(b) is not necessary.Later revisions of the above SB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2000-17-06 is considered acceptable for compliance with the equivalent requirements of this Directive.Note: FAA AD 2000-17-06 Amdt 39-11880 refers. |\n| Compliance: | For Requirement 1:(a) Remains unchanged as detailed in the original issue of this Directive as: Within 30 days after 5 June 2002 (the effective date of the original issue of this Directive), unless previously accomplished.(b) Remains unchanged as detailed in the original issue of this Directive as: With the exception of aeroplanes modified and functionally tested in accordance with a production equivalent, within 60 days after 5 June 2002, unless previously accomplished.For Requirement 2: At intervals not exceeding 1,000 flight hours.For Requirement 3: At intervals not exceeding 6,000 flight hours.For Requirement 4: Prior to further flight after the effective date of this Directive.For Requirement 5: Prior to further flight after the effective date of this Directive |\n| | This Amendment becomes effective on 23 January 2008. |\n| Background: | A possible leakage of the thrust reverser Directional Pilot Valve (DPV), due to a poppet valve being slightly jammed open or a leaking o-ring, has been identified by a report to the FAA as a latent failure of the fail-safe features of the thrust reverser system. The actions specified in this Directive are intended to ensure the integrity of the fail-safe features by preventing possible failure modes that could result in inadvertent deployment of the thrust reverser in flight.This amendment includes a statement approving the use of later FAA approved service bulletins which have been approved by the FAA as an AMOC to the referred FAA AD. There is no change to the requirements or compliance periods.The original issue of this AD became effective on 5 June 2002. |\n\n![](image.001.png) \nCharles Lenarcic \nDelegate of the Civil Aviation Safety Authority\n\n16 January 2008","sortOrder":0},{"sectionNumber":"AD/B767/173 Amdt 1","sectionType":"part","heading":"AD/B767/173 Amdt 1","content":"## AD/B767/173 Amdt 1","sortOrder":1},{"sectionNumber":"Thrust Reverser Directional Pilot Valve","sectionType":"part","heading":"Thrust Reverser Directional Pilot Valve","content":"## Thrust Reverser Directional Pilot Valve","sortOrder":2},{"sectionNumber":"3/2008 DM","sectionType":"part","heading":"3/2008 DM","content":"## 3/2008 DM","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope. The 2008 amendment explicitly states 'There is no change to the requirements or compliance periods' — it merely adds flexibility by accepting later FAA-approved versions of the referenced service bulletins as equivalent compliance methods. The safety intent (preventing inadvertent thrust reverser deployment) and the affected aircraft population remain identical to the original June 2002 directive."},"complexity_factors":["Multiple conditional pathways based on aircraft modification status (modified vs unmodified per Boeing SB 767-78-0063)","Cross-references to external technical documents: Boeing Alert SB 767-78-0084, Boeing SB 767-78-0063, FAA AD 2000-17-06, and Aircraft Maintenance Manual","Nested compliance timelines: original 2002 deadlines plus ongoing repetitive intervals (1,000 vs 6,000 flight hours)","Exception handling: specific provisions for 'production equivalent' modifications and later FAA-approved AMOCs (Alternate Methods of Compliance)","Circular logic in Requirement 5 (retesting after repairs under Requirement 4)","Dense tabular formatting with fragmented sentence structures in the original text"],"plain_english_summary":"This AD mandates functional testing of the Directional Pilot Valve (DPV) in thrust reverser systems on Boeing 767s with GE CF6-80C2 engines to detect pneumatic leaks that could lead to unintended reverser deployment. Tests must be done soon after the AD and repeated at specified flight-hour intervals; defects must be fixed and retested before flight.\n\nA 2008 amendment allows using later FAA‑approved Boeing service bulletins for compliance but doesn’t change the safety requirements."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"This amendment does not broaden or narrow the technical obligations imposed by the original Airworthiness Directive. It retains the same testing requirements, intervals and repair-before-flight mandates (Requirements 1–5) and explicitly states there is no change to compliance periods. The only substantive change in this amendment is administrative: it approves the use of later revisions of the Boeing service bulletin where those revisions have been accepted by the FAA as an Alternate Method of Compliance (AMOC) to FAA AD 2000-17-06, clarifying acceptable compliance paths rather than altering the AD's operational scope."},"complexity_factors":["Multiple conditional paths: Requirement 1 is split into 1(a) (unmodified aeroplanes) and 1(b) (aeroplanes modified by SB 767-78-0063 or production equivalent).","Different recurring intervals depending on modification status: 1,000 flight hours (Requirement 2) vs 6,000 flight hours (Requirement 3).","Cross-references to external documents: Boeing Alert SB 767-78-0084, Boeing SB 767-78-0063, Aircraft Maintenance Manual, and FAA AD 2000-17-06.","Allowance for 'production equivalent' tests and for later SB revisions approved as FAA AMOCs — introduces conditional acceptability based on external regulator approval.","Explicit repair and re-test requirements tied to AMM (Requirement 4 and 5) create an operational dependency on the AMM's detail and interpretation.","Administrative note that the amendment does not change substantive requirements but approves later FAA AMOCs — creates a narrow administrative layer without changing technical obligations."],"plain_english_summary":"**What this instrument does (mechanics)\n\n- Requires functional testing of the thrust reverser Directional Pilot Valve (DPV) on Boeing 767 aeroplanes fitted with General Electric CF6-80C2 engines. The test must follow Boeing Alert Service Bulletin (SB) 767-78-0084 dated 21 October 1999. (Requirement 1)\n- Distinguishes between aeroplanes that were modified in-service under Boeing SB 767-78-0063 (or a production equivalent) and those that were not. There are separate initial compliance windows for each group. (Requirement 1(a) and 1(b))\n- Requires repeating the functional test at recurring intervals: for aeroplanes not modified by SB 767-78-0063, every 1,000 flight hours (Requirement 2); for aeroplanes modified under that SB or production equivalent, every 6,000 flight hours (Requirement 3).\n- If any test cannot be completed successfully or any discrepancy is found, the aircraft must be repaired in accordance with the Aircraft Maintenance Manual (AMM) and the affected test(s) repeated before further flight. (Requirements 4 and 5)\n- Allows tests done to production-equivalent standards during manufacture to substitute for the initial test for production-modified aeroplanes, so those aeroplanes do not need the initial Requirement 1(b) test.\n- Accepts later revisions of the referenced Boeing service bulletins if those later revisions have been approved by the United States FAA as an Alternate Method of Compliance (AMOC) to FAA AD 2000-17-06. (final paragraph)\n\n**Who this affects\n\n- Primary: Operators/owners of Boeing 767 series aeroplanes equipped with GE CF6-80C2 engines.\n- Secondary: Approved maintenance organisations and technicians who must perform the functional DPV tests and any repairs to the AMM standard. Independent MROs can perform the work if they are authorised to carry out the mandated tests/repairs.\n\n**Why it matters (official purpose, then practical trade-offs)\n\n- Stated purpose: The directive aims to prevent a latent failure mode in the thrust reverser system (a leaking or jammed DPV poppet valve or o-ring) that could defeat fail-safe features and potentially cause inadvertent thrust reverser deployment in flight. The background text explains the action is intended to ensure integrity of the fail-safe features (Background).\n\n- Practical trade-offs and implementation issues:\n - Who pays: Aircraft operators bear the cost of tests, any repairs, parts and associated down-time. (Requirements 1–5)\n - Operational cost: For unmodified aeroplanes, more frequent testing (every 1,000 flight hours) creates higher recurring maintenance labour and potential downtime than for modified aeroplanes (every 6,000 flight hours). (Requirements 2 and 3)\n - Scheduling and utilisation: Tests and any corrective repairs may cause aircraft out-of-service time and can affect crew scheduling and utilisation. Repairs that require removal/parts could lead to AOG events and higher short-term costs.\n - Compliance burden: Operators must track flight hours per aircraft, record test completion, and ensure repairs meet the AMM before return to service. The AD references external documents (Boeing SB 767-78-0084 and SB 767-78-0063, and FAA AD 2000-17-06) which the operator must obtain and follow, adding paperwork and potential interpretation needs. (Requirement 1 and final paragraph)\n - Discretion and approvals: The AD accepts later Boeing SB revisions only if approved by the FAA as an AMOC; this gives regulators (FAA and CASA by acceptance) control over which service instructions qualify as compliant methods. That central approval reduces operator discretion but provides a clear accepted compliance path. (final paragraph)\n - Effects on market/service providers: The requirement creates predictable demand for testing and potential DPV repairs. Independent maintenance organisations that are approved to perform the tasks can compete for this work; specialised parts suppliers (o-rings, poppet valves) may see increased demand.\n - Risk of substitution/unintended consequences: If testing is interpreted or performed inconsistently, there is risk of false positives (unnecessary repairs) or false negatives (missed defects). The AD mitigates this by requiring repairs to the AMM and accepting FAA-approved AMOCs for service bulletin revisions.\n\n**What changes mechanically compared with the original text of the AD (if any)\n\n- This Amendment (Amdt 1) adds an explicit statement that later revisions of the referenced Boeing service bulletin are acceptable where the FAA has approved them as an AMOC to FAA AD 2000-17-06. The amendment states there is no change to the substantive requirements or compliance periods. (Background; final paragraph)\n\n**Behavioural summary — who decides, who acts, and what changes\n\n- Operators decide scheduling and fund tests/repairs; approved maintenance organisations and technicians carry out tests and repairs following Boeing SB 767-78-0084 and the AMM. Regulatory acceptance (FAA AMOC and CASA notice) decides which later SB revisions are acceptable. The practical change in daily operations is recurring mandatory functional testing of the DPV at the specified flight-hour intervals and mandatory repair and re-test before further flight if failures or discrepancies are found. (Requirements 1–5)"},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b767-173-amdt-1-thrust-reverser-directional-pilot-valve","history":"/api/acts/ad-b767-173-amdt-1-thrust-reverser-directional-pilot-valve/history","analysis":"/api/acts/ad-b767-173-amdt-1-thrust-reverser-directional-pilot-valve/analysis","conflicts":"/api/acts/ad-b767-173-amdt-1-thrust-reverser-directional-pilot-valve/conflicts","importantCases":"/api/acts/ad-b767-173-amdt-1-thrust-reverser-directional-pilot-valve/important-cases","documents":"/api/acts/ad-b767-173-amdt-1-thrust-reverser-directional-pilot-valve/documents"}}