{"id":"F2006B07436","name":"AD/TPE 331/27 - FCU Drive Check","slug":"ad-tpe-331-27-fcu-drive-check","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49724,"registerId":"commonwealth-F2006B07436-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/27 - FCU Drive Check","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAlliedSignal (Garrett/AiResearch) Turbine Engines \\- TPE 331 Series\n\nAD/TPE 331/27 FCU Drive Check 3/86\n\nApplicability: All TPE331 series engines fitted with P/N 3101726-1 torque sensors.\n\nRequirement: 1. Check backlash in accordance with AiResearch SB TPE331-72-0095, paragraph 2C, or\n\n    2. Inspect the security of the torque sensor arm and drive gear in accordance with an alternative inspection procedure approved by the Secretary. One such inspection is Stillwell Aviation Engineering Relrease No. 80093, or\n\n    3. AD/AIR-T/36A.\n\nCompliance: (a) For \\-3 Series Engines: Within 125 hours time in service after 30 November 1980 and thereafter at intervals not exceeding 125 hours time in service until P/N 3101726-2 torquementer body is fitted.\n\n(b) For All Other Series Engines: At each hot section inspection completed after 30 November 1980 until P/N 3101726-2 torquemeter body is fitted.\n\nBackground: This Directive is raised in issue to reflect an alteration of the inspection method and an increase of inspection period for \\-3U Series engines. The inspection period for all other models is reduced. Rework in accordance with AiResearch SB 72-0095 was also deleted from the requirement since the torque on the retaining bolt may be ineffective due to bottoming. Thus, only the backlash check part of SB 72-0095 is retained in this requirement.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":3198},"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"This directive revises previous requirements by altering inspection methods and changing inspection intervals—increasing the period for -3U Series engines while reducing it for all other models. It also removes the previously permitted 'rework' option (tightening the retaining bolt) from compliance options, narrowing the scope to inspection-only after discovering the rework was ineffective due to bottoming."},"complexity_factors":["Technical aviation terminology (e.g., 'backlash', 'hot section inspection', 'torquemeter') requiring specialized engineering knowledge","Three alternative compliance pathways with cross-references to external technical documents (Service Bulletins and Engineering Releases)","Different compliance schedules based on specific engine sub-series (-3 Series vs. others)","Precise part number applicability (P/N 3101726-1) requiring hardware verification against maintenance records","Reference to 'alternative inspection procedure approved by the Secretary' creating delegated discretionary authority without defined criteria"],"plain_english_summary":"This is a CASA safety directive requiring owners/operators of AlliedSignal (Garrett/AiResearch) TPE331 turboprop engines with torque-sensor P/N 3101726-1 to inspect the torque-sensor drive mechanism. You must follow one of three approved inspection procedures to check backlash or security of the sensor arm/drive.\n\nIt prevents sensor failure and incorrect power readings. The directive revised inspection intervals for different models and removes reworking/tightening as an acceptable fix; affected engines must be inspected until the part is upgraded."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-27-fcu-drive-check","history":"/api/acts/ad-tpe-331-27-fcu-drive-check/history","analysis":"/api/acts/ad-tpe-331-27-fcu-drive-check/analysis","conflicts":"/api/acts/ad-tpe-331-27-fcu-drive-check/conflicts","importantCases":"/api/acts/ad-tpe-331-27-fcu-drive-check/important-cases","documents":"/api/acts/ad-tpe-331-27-fcu-drive-check/documents"}}