{"id":"F2006B02984","name":"AD/B737/82 Amdt 2 - Thrust Reverser Sync-Lock System Test","slug":"ad-b737-82-amdt-2-thrust-reverser-sync-lock-system-test","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42343,"registerId":"commonwealth-F2006B02984-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/82 Amdt 2 - Thrust Reverser Sync-Lock System Test","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n![](image.002.png)  \nBoeing 737 Series Aeroplanes\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/B737/82 Amdt 1 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nAD/B737/82\n\nAmdt 2\n\n  \nThrust Reverser Sync-Lock System Test 7/2000\n\nApplicability: All Boeing 737-300, \\-400, and \\-500 series aircraft fitted with thrust reverser sync- locks in accordance with Boeing Service Bulletin 737-78-1053.\n\nRequirement: 1. Revise respective Boeing 737 systems of maintenance to include a periodic functional test of the thrust reverser sync lock-system that meets the intent of the test specified in FAA AD 94-21-05 Revision 1 Amdt 39-9314 on page 2 titled “Thrust Reverser Sync-Lock Integrity Test”. The following amendments shall be included in the FAA AD Sync-Lock Integrity Test.\n\nAmend paragraph B. (2) to read “Make sure both thrust reverser sleeves did not move aft more than 0.08 inches.”\n\nAmend paragraph B. (4) to read ” Make sure that both reverser sleeves move aft a minimum of 0.15 inches, but not more than 1.25 inches.”\n\nNote 1: Boeing All Operator Message M-7272-94-6132 dated 19 December 1994 advises FAA approval of two alternate Means of Compliance to FAA AD 94-21-05 R1.\n\n2. Functionally test the thrust reverser sync-lock system in accordance with the test introduced by Requirement 1 of this Directive.\n\nIf any discrepancy is found during this test either rectify the defect before further flight or operate the aircraft in accordance with an approved MEL. Operation under the provisions and limitations of an MEL is permitted provided the failed sync-lock system is deactivated and in the locked position.\n\nCompliance: 1. Upon incorporation of Boeing Service Bulletin 737-78-1053 on any aircraft.\n\n2. Within 4000 hours time in service since the incorporation of Boeing Service Bulletin 737-78-1053, or within 4000 hours time in service after 2 February 1995, whichever occurs later. Thereafter, reinspect at intervals not exceeding 4000 hours time in service.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nNote 2: AD/B737/81 Amdt 1 mandated compliance with Boeing Service Bulletin 737- 78-1053R1, R2 or R3 by 31 December, 1999.\n\nNote 3: FAA AD 94-21-05 R1 Amdt 39-9314 refers and revises 94-21-05 Amdt 39-\n\n9047.\n\nThis Amendment becomes effective on 13 July 2000.\n\nBackground: The original Directive was issued to introduce a periodic functional test of the thrust reverser sync-lock system. The sync-lock system was introduced as part of an on- going design review of thrust reverser systems following an accident that was attributed to an uncommanded in-flight deployment of a thrust reverser.\n\nAmendment 1 issued in November 95 raised to reflect a minor editorial revision to the original FAA AD and make reference to an approved alternate test.\n\nAmendment 2 was issued to clarify and include FAA approved changes to the FAA Sync-Lock Integrity Test Procedures and Reference latest FAA AD and Boeing message dated 19 December 1994.\n\nAmendment 1 of this Airworthiness Directive became effective on 9 November 1995.\n\nThe original issue of this Airworthiness Directive became effective on 2 February 1995.\n\n![Signature of Eugene Paul Holzapfel, Delegate of the Civil Aviation Safety Authority.](image.003.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 31 May 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 14 June 2000.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"The legislation maintains its original scope. It remains focused on the specific safety issue of thrust reverser sync-lock testing for Boeing 737-300/400/500 series aircraft. Amendment 2 does not expand the applicability to other aircraft types or introduce new substantive safety requirements beyond clarifying the testing procedures and measurements. The amendments are refinements to the testing methodology rather than scope expansion."},"complexity_factors":["Multiple amendment layers (original 1995, Amendment 1 1995, Amendment 2 2000) with cross-references between them","Incorporation by reference of external documents (FAA AD 94-21-05 Revision 1, Boeing Service Bulletin 737-78-1053, Boeing All Operator Message M-7272-94-6132) without reproducing their full text","Conditional compliance dates with 'whichever occurs later' logic","Specific technical measurements requiring precise interpretation (0.08 inches, 0.15-1.25 inches)","Alternative compliance pathways (repair vs. MEL operation with deactivation requirements)","Applicability limited to specific aircraft series with specific equipment configurations"],"plain_english_summary":"This CASA Airworthiness Directive targets Boeing 737-300/-400/-500s fitted with thrust-reverser sync-locks, requiring maintenance manuals to be updated and a specific functional test (with tightened movement tolerances) to be performed on installation and every 4,000 flight hours thereafter. Failures must be repaired before flight or managed under strict MEL conditions with the sync-lock deactivated and locked. It tightens safeguards introduced after an accident to prevent dangerous in‑flight uncommanded thrust‑reverser deployment."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Amendment 2 clarifies and updates the originally mandated periodic test to align with FAA‑approved changes and a Boeing operator message. It does not broaden the class of affected aircraft beyond those fitted per Boeing Service Bulletin 737-78-1053, nor does it add new types of obligations beyond refining test procedures, numeric criteria, and timing. Therefore the AD's scope remains the same in substance — periodic functional testing of the thrust reverser sync-lock system — but it tightens and clarifies the test requirements by adopting FAA/Boeing-specified changes (Requirement; Background; Notes 1 and 3)."},"complexity_factors":["Short, single-subject AD (limited length)","Cross-reference to FAA AD 94-21-05 R1 and Boeing Service Bulletin 737-78-1053 (external documents required to implement)","Two specific numeric amendments to the FAA test (precision tolerances: 0.08 in, 0.15 in, 1.25 in)","Conditional compliance timing (whichever occurs later between 4,000 hours after SB incorporation or 4,000 hours after 2 Feb 1995)","Allowance for operation under an approved MEL with conditions (creates a branch in operator responses)","Notes and prior amendment history referenced (multiple amendments and messages to consider)"],"plain_english_summary":"**What this directive changes (mechanically)**\n\n- Applies to: Boeing 737-300, -400 and -500 series aircraft that have had thrust reverser \"sync-locks\" installed per Boeing Service Bulletin 737-78-1053 (\"Applicability\").\n\n- Adds a new required maintenance action: revise each aircraft's Boeing 737 maintenance schedule to include a periodic functional test of the thrust reverser sync-lock system that follows the intent of the FAA test called the \"Thrust Reverser Sync-Lock Integrity Test\" (\"Requirement\" 1). The AD also amends two numeric checks in that FAA test: (a) verify neither thrust reverser sleeve moves aft more than 0.08 inches (amended B.(2)); (b) verify both sleeves move aft at least 0.15 inches but no more than 1.25 inches (amended B.(4)).\n\n- Perform the functional test in service as required (\"Requirement\" 2). If the test finds a problem, either fix it before the aircraft next flies or use an approved Minimum Equipment List (MEL) procedure to continue operations provided the failed sync-lock system is deactivated and physically locked (Requirement 2).\n\n- Timing: the test requirement becomes part of the maintenance program once Boeing SB 737-78-1053 is incorporated on an aircraft. The first test is required within 4,000 flight hours after incorporation of that service bulletin, or within 4,000 hours after 2 February 1995, whichever is later. Thereafter, repeat at intervals of no more than 4,000 hours time in service (\"Compliance\").\n\n**Why CASA says this was introduced (stated purpose)**\n\n- The AD is intended to introduce and standardise a periodic functional check of the thrust reverser sync-lock system. The background states this system was introduced after an accident attributed to an uncommanded in‑flight deployment of a thrust reverser. Amendment 2 updates and clarifies the test to align with FAA-approved changes and a Boeing operator message.\n\n**Who this affects and who pays**\n\n- Affected parties: operators/owners of Boeing 737-300/-400/-500 aircraft fitted with the specified sync-lock modification. Maintenance organisations that hold or prepare the aircraft's Boeing 737 maintenance program must amend it to include the test (Applicability; Requirement 1).\n\n- Who pays: aircraft operators and their maintenance providers pay for incorporation of the Boeing service bulletin (if not already done), the labour and tooling to perform the periodic sync-lock test, and any corrective maintenance identified by the test. If operators choose to dispatch under the MEL instead of repairing the defect immediately, they may incur operational costs (reduced dispatch reliability, flight restrictions) and must ensure the sync-lock is deactivated and locked.\n\n**Behavioural and operational effects (mechanical incentives & constraints)**\n\n- Operators must include the test in their maintenance program and carry out the test every 4,000 hours. This increases scheduled maintenance workload and creates a recurring inspection cost.\n\n- If a discrepancy is found, there are two mechanical paths: (a) repair before further flight (increases downtime and direct maintenance cost); or (b) operate under an approved MEL with the system deactivated and locked (reduces immediate repair cost but imposes operational limits and safety mitigations). The MEL route creates an incentive to delay repairs when operators prioritise flight availability, at the cost of operating under limitations.\n\n- The AD relies on existing FAA procedures and a Boeing operator message for the test method; this cross-references foreign regulatory material and OEM guidance (Requirement 1, Note 1). That reliance concentrates technical decision-making on Boeing and FAA-prescribed test parameters, while CASA enforces incorporation into Australian maintenance programs.\n\n**Implementation risks, trade-offs and compliance burden**\n\n- Trade-offs: the measure trades regular inspection and possible downtime/costs for reduced risk of an in-flight thrust reverser deployment incident. Operators face opportunity costs: maintenance man-hours, possible ripple effects on aircraft utilisation, and parts/repair costs if failures are found.\n\n- Compliance burden: amending the maintenance program, training staff to perform the specific sync-lock test, keeping records of recurring inspections, and implementing MEL conditions if used. The directive cross-references FAA AD text and Boeing service messaging, which creates modest administrative complexity for maintenance organisations to ensure they are using the correct, current test procedure (Requirement 1; Note 1; Note 3).\n\n- Bureaucratic discretion: CASA enforces the AD; the AD requires incorporation of a Boeing service bulletin and compliance with FAA-specified test intent, so the operator’s discretion is limited to how fast to repair versus using MEL allowances (Requirement 1–2; Compliance).\n\n**Concrete measurements and pass/fail criteria**\n\n- The test contains specific numeric tolerances: neither reverser sleeve may move aft more than 0.08 inches; both sleeves must move aft at least 0.15 inches but not more than 1.25 inches (Requirement 1 amendments to FAA AD paragraphs B.(2) and B.(4)).\n\n**Net effect on market/operations**\n\n- The AD imposes a recurring maintenance obligation on a defined subset of Boeing 737s and prescribes specific acceptance criteria. It increases operating cost and scheduled maintenance time for affected operators but does not alter ownership, competition rules, pricing regulation, or contract freedom. It centralises the technical compliance standard on FAA and Boeing test content, reducing technical discretion for operators but increasing uniformity of inspection criteria.\n\n**Where to look in the AD for specifics**\n\n- Applicability, required test wording and numeric criteria: \"Requirement\" paragraphs 1 and 2. Timing and repeat interval: \"Compliance\" paragraph. Background and rationale: \"Background\". Notes reference FAA ADs and Boeing operator message.\n\n\n"},"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-b737-82-amdt-2-thrust-reverser-sync-lock-system-test","history":"/api/acts/ad-b737-82-amdt-2-thrust-reverser-sync-lock-system-test/history","analysis":"/api/acts/ad-b737-82-amdt-2-thrust-reverser-sync-lock-system-test/analysis","conflicts":"/api/acts/ad-b737-82-amdt-2-thrust-reverser-sync-lock-system-test/conflicts","importantCases":"/api/acts/ad-b737-82-amdt-2-thrust-reverser-sync-lock-system-test/important-cases","documents":"/api/acts/ad-b737-82-amdt-2-thrust-reverser-sync-lock-system-test/documents"}}