{"id":"F2006B07455","name":"AD/TPE 331/44 - Pitch Control Gasket","slug":"ad-tpe-331-44-pitch-control-gasket","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49799,"registerId":"commonwealth-F2006B07455-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/44 - Pitch Control Gasket","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 331/44 Pitch Control Gasket 2/93 TX\n\nApplicability: TPE 331-1, \\-2, \\-3, \\-5, \\-6, \\-8, \\-10, \\-11, \\-12, \\-14, \\-25, \\-43, \\-47A, \\-55B and \\-61A engines\n\nthat have had the propeller pitch control gasket replaced after 10 May 1992.\n\nRequirement: Action in accordance with Garrett (Allied-Signals) Service Bulletin TPE331-A72- 7092 or TPE331-A72-0857, as applicable.\n\nNote: FAA Priority Letter Airworthiness Directive 92-26-07 refers.\n\nCompliance: A. For installed engines. Within the next 10 hours time in service from 21 December 1992.\n\nB. For uninstalled engines. Prior to installation in an aircraft.\n\nBackground: Several failures of the propeller pitch control gasket have been reported. Failure of the gasket resulted in a sudden loss of engine oil and propeller control. In one incident the failure occurred during the landing run when reverse pitch was applied.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific mechanical failure mode. It has not expanded beyond its original purpose of mandating gasket inspection/replacement."},"complexity_factors":["Single, specific mechanical component targeted (propeller pitch control gasket)","Clear applicability criteria based on engine model numbers and date of prior maintenance","Straightforward binary compliance structure (installed vs uninstalled engines)","Only two cross-references (to manufacturer service bulletins and one FAA directive)","No defined terms section, no nested exceptions, no conditional logic beyond the applicability date","Total length: approximately 200 words"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance action on certain aircraft engines.\n\n**What it does:**\nOrders owners and operators of specific AlliedSignal (formerly Garrett/AiResearch) TPE 331 turbine engines to inspect or replace the **propeller pitch control gasket** — a seal that helps control the angle of the propeller blades and keeps engine oil contained.\n\n**Who it affects:**\nAnyone operating or maintaining TPE 331 engines (models -1, -2, -3, -5, -6, -8, -10, -11, -12, -14, -25, -43, -47A, -55B, and -61A) **IF** the gasket was replaced after 10 May 1992.\n\n**Why it matters:**\nThe gasket has been failing unexpectedly. When it fails, two dangerous things happen simultaneously:\n- **Sudden loss of engine oil** — risking engine seizure or fire\n- **Loss of propeller control** — meaning the pilot can't adjust blade pitch, including reverse thrust for braking on landing\n\nOne failure already occurred during landing when reverse pitch was applied — a critical phase of flight.\n\n**What must be done:**\n- **Engines currently installed in aircraft:** Fix within the next 10 flight hours after 21 December 1992\n- **Engines not currently installed:** Fix before putting the engine into any aircraft\n\nThe work must follow specific manufacturer service bulletins (TPE331-A72-7092 or TPE331-A72-0857, depending on the engine)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope is narrowly defined and remains targeted to those TPE331 engine models where the propeller pitch control gasket was replaced after 10 May 1992. It differentiates between installed and uninstalled engines for timing of compliance and prescribes the manufacturer’s service bulletins as the remedy. There is no indication in the instrument text that the scope has been broadened or narrowed from an earlier stated intent; the AD as published applies only to the engines and replacement-date cohort specified (Applicability; Requirement; Compliance)."},"complexity_factors":["Narrow technical scope limited to specific TPE331 engine models and to gaskets replaced after a particular date (10 May 1992) (Applicability)","Mandates compliance by following external technical documents (Garrett service bulletins), so operators must obtain and apply manufacturer procedures rather than relying solely on the AD text (Requirement)","Time-sensitive compliance window for installed engines (10 hours TIS from a specified date) increases operational urgency and scheduling pressure (Compliance)","Different compliance triggers for installed versus uninstalled engines (installed within 10 hours; uninstalled before installation) require administrative tracking of installation status (Compliance)","Technical repair work requires certified maintenance capability and parts, creating logistical and cost considerations for operators and maintainers (Requirement; Compliance)"],"plain_english_summary":"Owners/operators of specified AlliedSignal TPE331 engines that had the propeller pitch control gasket replaced after 10 May 1992 must carry out the corrective work in Garrett Service Bulletin TPE331‑A72‑7092/0857. For engines installed in aircraft the work is required within 10 hours TIS from 21 December 1992; uninstalled engines must be corrected before installation. The AD shifts repair cost and downtime to operators to address reported gasket failures that can cause oil loss and loss of propeller control."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-44-pitch-control-gasket","history":"/api/acts/ad-tpe-331-44-pitch-control-gasket/history","analysis":"/api/acts/ad-tpe-331-44-pitch-control-gasket/analysis","conflicts":"/api/acts/ad-tpe-331-44-pitch-control-gasket/conflicts","importantCases":"/api/acts/ad-tpe-331-44-pitch-control-gasket/important-cases","documents":"/api/acts/ad-tpe-331-44-pitch-control-gasket/documents"}}