{"id":"F2006B05761","name":"AD/PA-31/57 - Elevator Balance Weights - Inspection","slug":"ad-pa-31-57-elevator-balance-weights-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":135620,"registerId":"commonwealth-F2006B05761-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-31/57 - Elevator Balance Weights - Inspection","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 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Piper PA-31 Series Aeroplanes\n\n \n\nAD/PA-31/57 Elevator Balance Weights - Inspection 9/77\n\nApplicability: All model PA-31 and PA-31-300 with wing luggage lockers per nayak STC. SA 986 SW.\n\n \n\nRequirement: 1. Inspect the elevator balance weights fitted in the nose channel of the elevator for security of attachment (“Rivnut” pull-up) and check elevator unbalance (96.4 inch lbs. tail heavy maximum); or\n\n \n\n2. FAA AD 77-12-02 amdt. 39-2915.\n\n \n\nCompliance: Within 25 hours time in service after 19 August 1977.\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\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of ensuring elevator balance weight security in the affected Piper models."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined technical terms requiring explanation (Rivnut, inch-pounds)","Simple binary compliance path (inspect per CASA requirements OR follow FAA alternative)","Single applicability criterion (specific aircraft models with specific modification)","No cross-references to other legislation beyond optional FAA AD reference","Clear, unambiguous deadline (25 hours time in service after fixed date)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain **Piper PA-31 series aeroplanes** (including the PA-31 and PA-31-300 models) to inspect the **elevator balance weights** — small counterweights fitted inside the front part of the elevator (the moveable surface on the tail that controls up and down movement). The inspection must check:\n- That the weights are securely attached (specifically checking the \"Rivnut\" fasteners haven't pulled loose)\n- That the elevator isn't unbalanced beyond safe limits (no more than 96.4 inch-pounds \"tail heavy\")\n\nAlternatively, operators can comply by following a similar American directive (FAA AD 77-12-02).\n\n**Who it affects:**\n- Owners and operators of Piper PA-31 and PA-31-300 aircraft that have **wing luggage lockers** installed under a specific modification certificate (Nayak STC SA 986 SW)\n\n**Why it matters:**\nIf elevator balance weights come loose or the elevator is improperly balanced, the pilot could lose control of the aircraft's pitch (nose up/down movement), potentially leading to a crash. This directive was issued to prevent accidents caused by weight detachment or improper balance.\n\n**Compliance deadline:**\nThe inspection had to be completed within **25 hours of flying time** after 19 August 1977."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive sets its scope explicitly: it applies only to \"All model PA-31 and PA-31-300 with wing luggage lockers per nayak STC. SA 986 SW.\" (Applicability). No material change of scope from that statement is indicated within the text of the instrument."},"complexity_factors":["Narrow and specific applicability (particular PA-31 models with a named STC) (Applicability)","Single, short-term technical action required (inspection of rivnut pull-up and balance measurement) (Requirement 1)","Concrete numeric performance limit to check against (96.4 inch‑lbs tail heavy) (Requirement 1)","One clear alternative compliance path provided (FAA AD 77-12-02) (Requirement 2)","Short fixed compliance window (25 hours TIS after 19 August 1977) (Compliance)","Lack of ancillary administrative detail (no records, no repeated intervals, no enforcement procedure stated) increases reliance on external maintenance practice"],"plain_english_summary":"This directive requires a short safety inspection of elevator balance weights inside the elevator nose channel on certain Piper PA‑31/PA‑31‑300 aeroplanes: verify rivnut pull‑up security and measure elevator unbalance (limit 96.4 inch‑lbs tail‑heavy). Compliance (or following FAA AD 77‑12‑02 instead) was required within 25 hours TIS after 19 Aug 1977.\n\nIt affects aircraft owners/operators or their maintenance organisations, who must arrange, pay for, and remedy any insecure fittings or excessive unbalance to protect elevator behaviour."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-31-57-elevator-balance-weights-inspection","history":"/api/acts/ad-pa-31-57-elevator-balance-weights-inspection/history","analysis":"/api/acts/ad-pa-31-57-elevator-balance-weights-inspection/analysis","conflicts":"/api/acts/ad-pa-31-57-elevator-balance-weights-inspection/conflicts","importantCases":"/api/acts/ad-pa-31-57-elevator-balance-weights-inspection/important-cases","documents":"/api/acts/ad-pa-31-57-elevator-balance-weights-inspection/documents"}}