{"id":"F2006B05802","name":"AD/PA-31/97 Amdt 2 - Horizontal Stabiliser and Elevator Outboard Hinge","slug":"ad-pa-31-97-amdt-2-horizontal-stabiliser-and-elevator-outboard-hinge","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":135727,"registerId":"commonwealth-F2006B05802-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-31/97 Amdt 2 - Horizontal Stabiliser and Elevator Outboard Hinge","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPiper PA-31 Series Aeroplanes\n\nAD/PA-31/97\n\nAmdt 2\n\n  \nHorizontal Stabiliser and Elevator Outboard Hinge 13/99\n\nApplicability: Models PA-31, PA-31-300, PA-31-325, PA-31-350, PA-31-350 T1020, and PA-31P-\n\n350, with serial numbers listed in Piper Mandatory Service Bulletin (MSB) 1007.\n\nRequirement: 1. With the elevator fully deflected up and down and using a 10x magnifying glass, perform a detailed visual inspection of the elevator outboard hinge, the horizontal stabiliser rear spar at the elevator outboard hinge attachment and the spar radius forward of the hinge for cracks.\n\n    2. If no cracks are found as a result of the above inspection, continue to inspect in accordance with Requirement 1.\n\n    3. If cracks are found in the horizontal stabiliser as a result of the Requirement 1 inspection, modify the horizontal stabiliser rear spar in accordance with Requirement 4.\n\n    4. Modify the horizontal stabiliser rear spar by incorporating Piper Kit No. 766-646, in accordance with the Instructions contained in Piper Kit No. 766-646, which is referenced in Piper MSB 1007.\n\nCompliance with requirement 4 constitutes terminating action for this AD.\n\nNote: FAA AD 99-06-01 Amdt 39-11065 refers.\n\nCompliance: 1. Within 100 hours time in service after 30 December 1999, unless Requirement 4 is accomplished.\n\n    2. At intervals not to exceed 100 hours time in service, until accomplishment of Requirement 4.\n\n    3. Before further flight.\n\n    4. Upon the accumulation of 500 hours time in service after 30 December 1999, or when cracks are found, whichever occurs first.\n\nThis Amendment becomes effective on 30 December 1999.\n\nBackground: Cracks were found in the horizontal stabiliser rear spar at the elevator hinge attachment point. Piper Service Bulletin 687 was introduced to inspect the rear spar and install modified hinges. Amendment 1 extended on-going repetitive inspections to aircraft with modified elevator hinge attachments as a result of local reports of cracked modified hinges.\n\nAmendment 2 is issued as a result of a new FAA AD which requires installation of the Stabiliser Rear Spar Modification and Outboard Hinge Replacement Kit, in order to prevent possible failure of the horizontal stabiliser rear spar, which could result in loss of control of the aircraft.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nAmendment 1 of this Airworthiness Directive became effective on 17 August 1995. The original issue of this Airworthiness Directive became effective on 31 May 1981.","sortOrder":0}],"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":true,"description":"The legislation has evolved significantly from its original 1981 intent. Originally, the directive likely addressed initial crack findings with inspections and hinge modifications. Amendment 1 (1995) expanded scope to include aircraft that had already received modified hinges due to new reports of cracks in those 'fixed' components. Amendment 2 (1999) shifted the approach again from ongoing repetitive inspections to a mandatory permanent structural modification (the rear spar kit), effectively changing the end-state from 'inspect indefinitely' to 'modify and terminate'."},"complexity_factors":["Multiple numbered requirements with interdependent conditions (Requirements 1-4 reference each other)","Layered compliance deadlines (100 hours, 500 hours, 'before further flight', and 'whichever occurs first' triggers)","External document references requiring cross-checking (Piper MSB 1007, Piper Kit No. 766-646, FAA AD 99-06-01)","Technical aviation terminology requiring domain knowledge (elevator deflection, rear spar, time in service)","Amendment history tracking (original 1981, Amendment 1 1995, Amendment 2 1999) indicating evolving regulatory response"],"plain_english_summary":"This safety order applies to certain Piper PA‑31 (Navajo/Chieftain) aircraft with serials listed in the manufacturer bulletin. It requires regular visual inspections of the horizontal stabiliser rear spar/elevator hinge area (every 100 flight hours if no cracks), immediate grounding and installation of Piper Kit No. 766‑646 if cracks are found, and mandatory permanent modification by the earlier of 500 flight hours after Dec 1999 or immediately upon finding a crack."},"flash_summary":{"complexity_score":7,"scope_assessment":{"changed":true,"description":"Yes. Earlier versions focused on repetitive inspections and hinge changes; Amendment 2 requires installation of the stabiliser rear spar modification and outboard hinge replacement kit (Piper Kit No. 766‑646) as a terminating action. The change responds to a new FAA AD and shifts from inspection‑only measures to a mandated modification pathway (Background; Requirement 4; Compliance)."},"complexity_factors":["Applicability limited to specific PA‑31 models and serial numbers referenced in Piper MSB 1007 (Applicability).","Prescribed detailed visual inspection technique requiring elevator fully deflected and a 10× magnifying glass (Requirement 1).","Repetitive inspection cadence with a 100‑hour interval until modification is completed (Compliance 2).","Conditional mandatory modification when cracks are found, with a before‑further‑flight requirement if cracks are discovered (Requirement 3; Compliance 3).","Terminating action achieved only by installing Piper Kit No. 766‑646 per kit instructions and Piper MSB 1007 (Requirement 4; Compliance 4).","Multiple and staggered compliance triggers: within 100 hours after 30 Dec 1999, every 100 hours until mod, before further flight if cracks, or at 500 hours (Compliance 1–4).","Dependence on external documents and manufacturer instructions (Piper MSB 1007 and Kit No. 766‑646) and reference to FAA AD 99‑06‑01 (Note; Background).","Safety‑critical context (risk of spar failure and potential loss of control) increases compliance urgency and operational impact (Background)."],"plain_english_summary":"This directive requires detailed visual inspections (with a 10× magnifying glass) of the elevator outboard hinge and adjacent horizontal stabiliser spar on listed Piper PA‑31 models at 100‑hour intervals and before further flight where defects are suspected. If cracks are found, or upon accumulating 500 hours, operators must install Piper Kit No. 766‑646 in accordance with Piper MSB 1007; aircraft owners/operators pay for inspections and the kit. Installing the kit stops the repeating inspections (terminating action)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-31-97-amdt-2-horizontal-stabiliser-and-elevator-outboard-hinge","history":"/api/acts/ad-pa-31-97-amdt-2-horizontal-stabiliser-and-elevator-outboard-hinge/history","analysis":"/api/acts/ad-pa-31-97-amdt-2-horizontal-stabiliser-and-elevator-outboard-hinge/analysis","conflicts":"/api/acts/ad-pa-31-97-amdt-2-horizontal-stabiliser-and-elevator-outboard-hinge/conflicts","importantCases":"/api/acts/ad-pa-31-97-amdt-2-horizontal-stabiliser-and-elevator-outboard-hinge/important-cases","documents":"/api/acts/ad-pa-31-97-amdt-2-horizontal-stabiliser-and-elevator-outboard-hinge/documents"}}