{"id":"F2009L03005","name":"AD/JBK 117/32 Amdt 1 - Tail Rotor Gearbox Bevel Gear","slug":"ad-jbk-117-32-amdt-1-tail-rotor-gearbox-bevel-gear","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":80540,"registerId":"commonwealth-F2009L03005-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Kawasaki BK 117 Series Helicopters","sectionType":"division","heading":"Kawasaki BK 117 Series Helicopters","content":"### Kawasaki BK 117 Series Helicopters\n\n| AD/JBK 117/32 Amdt 1 | Tail Rotor Gearbox Bevel Gear | 10/2009 DM |\n| -------------------- | ----------------------------- | ---------- |\n\n| Applicability: | Kawasaki BK117 C-2 helicopters. |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Determine the serial number (S/N) of the bevel gear part number (P/N)4639 310 065 installed in the Intermediate Gear Box (IGB) in accordance with Kawasaki Service Bulletin No. KSB-117-307A (hereinafter referred to as the SB).2. If, as a result of the inspection detailed in Requirement 1 of this AD, no bevel gear with one of the S/Ns listed in Table 1 of the SB is installed, no further action is required by this AD.3. If, as a result of the inspection detailed in Requirement 1 of this AD, a bevel gear with one of the S/Ns listed in Table 1 of the SB is installed, the associated reduced life limit must be entered into the list of life-limited parts and in the log card of the IGB in accordance with the instructions of the SB.4. If, as a result of the inspection detailed in Requirement 1 of this AD, a bevel gear which has already exceeded its reduced life limit is found, the bevel gear must be replaced with a serviceable one in accordance with the instructions of the SB.The use of later JCAB approved revisions of the referenced SB is acceptable for compliance with the requirements of this AD.Note: JCAB AD TCD 7494-1-2009 refers. |\n| Compliance: | For Requirements 1 and 4 - Before further flight after the effective date of this AD, unless previously accomplished.For Requirement 3 - From the effective date of this AD. |\n| | This Amendment becomes effective on 27 August 2009. |\n| Background: | During a recent review of the production documents for the bevel gears of the IGB for the ECD MBB BK117 C-2 helicopter, it was discovered that certain production batch numbers have tooth foot fillets below the required minimum values that would ensure the approved life limits for this part. |\n\n| | The Kawasaki BK117 C-2 helicopter uses the same gear P/N from the same S/N batch as the MBB BK 117 C-2 helicopter.This condition, if not corrected, could lead to a significant reduction of the lifetime of IGB bevel gears, potentially resulting in failure of the IGB and consequent loss of control of the helicopter. This AD requires a one-time inspection to determine if one of the affected bevel gears is installed. If an affected bevel gear is installed, this AD also requires the revision of the life limit in the aircraft maintenance program, in accordance with Kawasaki Service Bulletin No. KSB-117-307A.This amendment mandates Rev A of the referenced SB. The revision adds additional serial numbers to the list of affected bevel gears.The original issue of this AD becomes effective on 27 August 2009. |\n| --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n30 July 2009","sortOrder":0},{"sectionNumber":"AD/JBK 117/32 Amdt 1","sectionType":"part","heading":"AD/JBK 117/32 Amdt 1","content":"## AD/JBK 117/32 Amdt 1","sortOrder":1},{"sectionNumber":"Tail Rotor Gearbox Bevel Gear","sectionType":"part","heading":"Tail Rotor Gearbox Bevel Gear","content":"## Tail Rotor Gearbox Bevel Gear","sortOrder":2},{"sectionNumber":"10/2009 DM","sectionType":"part","heading":"10/2009 DM","content":"## 10/2009 DM","sortOrder":3}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: addressing the specific manufacturing defect in bevel gears for the BK117 C-2 helicopter. The amendment simply expands the list of affected serial numbers based on additional data — it does not broaden the scope to other aircraft, other parts, or other types of maintenance actions. The original intent was to identify and mitigate the risk of premature gear failure; this amendment continues that exact purpose with additional affected units identified."},"complexity_factors":["Single, discrete mechanical issue (one part, one helicopter model)","Clear conditional logic (if/then structure in Requirements 1-4)","Only 4 substantive requirements with straightforward compliance paths","References external technical document (Service Bulletin) but provides clear cross-reference","Limited defined terms (only 'SB' and standard aviation abbreviations like P/N, S/N, IGB)","No nested exceptions or complex temporal conditions beyond standard 'before further flight' aviation language"],"plain_english_summary":"Operators of Kawasaki BK117 C-2 helicopters must check whether the Intermediate Gear Box bevel gear (P/N 4639 310 065) installed on their aircraft is on the affected serial-number list in Kawasaki Service Bulletin KSB-117-307A. Certain gears were manufactured with under‑thick tooth fillets, risking early failure, IGB loss and possible loss of control. If listed, record the reduced life limit and replace any gear that has exceeded it before next flight. This amended AD expands the affected serial numbers."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"The amendment expands the set of affected bevel-gear serial numbers by mandating Revision A of Kawasaki Service Bulletin KSB-117-307A, thereby broadening which gears must have reduced life limits entered or be replaced. The core requirement (inspection, record update, replacement if life exceeded) remains, but the population of affected parts is increased."},"complexity_factors":["Technical specificity: exact part number (P/N 4639 310 065) and serial-number matching required (Requirement 1; SB Table 1).","Dependence on an external document: compliance tied to Kawasaki Service Bulletin KSB-117-307A Rev A (Requirement 1 and note).","Timing constraints: inspection and any required replacement must be completed before further flight in certain cases (Compliance).","Record-keeping: mandatory entry of a reduced life limit into the list of life-limited parts and IGB log card (Requirement 3).","Decision rule clarity: replacement is mandatory if a bevel gear has exceeded its reduced life limit (Requirement 4).","Regulatory layering: acceptance of later JCAB-approved SB revisions and cross-reference to JCAB AD TCD 7494-1-2009 introduces multi-jurisdictional reference points (Note)."],"plain_english_summary":"This airworthiness directive requires operators of Kawasaki BK117 C-2 helicopters to inspect the tail-rotor gearbox intermediate bevel gear (P/N 4639 310 065) for listed serial numbers and, if present, record a reduced life limit or replace the gear if that reduced life has been exceeded. Compliance inspections and replacements must be done before further flight where specified and maintenance-program/log-card changes take effect from the AD's effective date. The amendment adds serial numbers and mandates Kawasaki Service Bulletin KSB-117-307A Rev A as the compliance method; operators pay inspection, recordkeeping and replacement costs."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jbk-117-32-amdt-1-tail-rotor-gearbox-bevel-gear","history":"/api/acts/ad-jbk-117-32-amdt-1-tail-rotor-gearbox-bevel-gear/history","analysis":"/api/acts/ad-jbk-117-32-amdt-1-tail-rotor-gearbox-bevel-gear/analysis","conflicts":"/api/acts/ad-jbk-117-32-amdt-1-tail-rotor-gearbox-bevel-gear/conflicts","importantCases":"/api/acts/ad-jbk-117-32-amdt-1-tail-rotor-gearbox-bevel-gear/important-cases","documents":"/api/acts/ad-jbk-117-32-amdt-1-tail-rotor-gearbox-bevel-gear/documents"}}