{"id":"F2006B07401","name":"AD/TFE 731/18 - Digital Electronic Engine Control","slug":"ad-tfe-731-18-digital-electronic-engine-control","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49611,"registerId":"commonwealth-F2006B07401-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TFE 731/18 - Digital Electronic Engine Control","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series\n\n \n\nAD/TFE731/18 Digital Electronic Engine Control 2/90\n\nApplicability: TFE 731-2, -5, -5AR, -5R series engines as listed in Garrett SB TFE 731-76-3049.\n\n \n\nRequirement: Replace suspect digital electronic engine controls (DEEC) as listed by serial number in Garrett SB TFE 731-76-3049.\n\n \n\nNote: FAA AD 89-22-16 refers.\n\n \n\nCompliance: Prior to 31 March 1990.\n\n \n\nBackground: This Directive reflects advice from the manufacturer of a possibility that uncommanded thrust increase or decrease may occur due to a defect in certain electronic engine controls.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive with a single specific purpose. It has not expanded beyond its original intent of addressing a known hardware defect in specific engine control units."},"complexity_factors":["Very short document (approximately 150 words)","Only 4 defined engine model variants in applicability section","Single, unambiguous compliance action (replace specific parts)","No nested exceptions or conditional logic","One cross-reference to manufacturer service bulletin and one FAA AD reference","Clear, fixed compliance date with no alternative methods stated"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance action on aircraft engines.\n\n**What it does:**\n- **Targets:** TFE 731-2, -5, -5AR, and -5R series turbine engines (made by AlliedSignal, formerly Garrett/AiResearch)\n- **Requires:** Replacement of specific \"digital electronic engine controls\" (DEECs) — the computer systems that manage engine power — identified by serial number in a manufacturer service bulletin\n- **Why:** Some DEEC units have a defect that could cause the engine thrust to suddenly increase or decrease without the pilot commanding it (\"uncommanded thrust change\")\n\n**Who it affects:**\n- Aircraft operators using these specific engine models\n- Maintenance organisations servicing these engines\n\n**Why it matters:** Uncommanded thrust changes during flight are extremely dangerous — they could cause loss of control, runway excursions, or inability to maintain altitude. This directive forces replacement of faulty components before a deadline to prevent accidents.\n\n**Key deadline:** All replacements had to be completed before 31 March 1990."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope, as stated in this text, aligns with the manufacturer’s advice: it targets specific DEEC units (by serial number) on specified TFE 731 engine models and requires their replacement to address a reported risk of uncommanded thrust change (Background; Applicability; Requirement). There is no indication in the provided text that the AD expands beyond that stated safety concern or that it changes the set of aircraft or components addressed by the manufacturer’s service bulletin."},"complexity_factors":["Serial-number-specific applicability requires cross-referencing to Garrett SB TFE 731-76-3049 (Requirement; Applicability).","Safety-critical nature of the component increases procedural and documentation requirements (Background; Requirement).","Firm compliance deadline creates logistical planning for operators and maintenance providers (Compliance).","The AD mandates replacement rather than describing conditional inspections or alternatives in this extract (Requirement).","Reference to another authority (FAA AD 89-22-16) may require operators to consult multiple documents for fuller context (Note)."],"plain_english_summary":"The AD requires owners/operators of specified TFE 731-2/‑5/‑5AR/‑5R engines to remove and replace particular digital electronic engine controls (DEECs) identified by serial number in Garrett SB TFE 731‑76‑3049 by 31 March 1990. It responds to manufacturer advice of a defect that could cause uncommanded thrust changes; operators bear the cost, must check the SB to determine applicability, and comply by the deadline."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tfe-731-18-digital-electronic-engine-control","history":"/api/acts/ad-tfe-731-18-digital-electronic-engine-control/history","analysis":"/api/acts/ad-tfe-731-18-digital-electronic-engine-control/analysis","conflicts":"/api/acts/ad-tfe-731-18-digital-electronic-engine-control/conflicts","importantCases":"/api/acts/ad-tfe-731-18-digital-electronic-engine-control/important-cases","documents":"/api/acts/ad-tfe-731-18-digital-electronic-engine-control/documents"}}