{"id":"F2006B10319","name":"AD/GROB 115/12 Amdt 1 - Elevator Trim Tab","slug":"ad-grob-115-12-amdt-1-elevator-trim-tab","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56070,"registerId":"commonwealth-F2006B10319-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/GROB 115/12 Amdt 1 - Elevator Trim Tab","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)  \n![](image.002.png)  \nGrob G115 Series Aeroplanes\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/GROB 115/12 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nAD/GROB 115/12\n\nAmdt 1\n\n  \nElevator Trim Tab 6/2000\n\nApplicability: All Grob 115 aircraft which have not been modified in accordance with a scheme approved by the Authority.\n\nNote 1: Aeronautical Engineers Australia Engineering Order EO4796/1 is an approved scheme for the purposes of this Directive.\n\nRequirement: Clean the area around the Elevator Trim Tab Hinges including in the space between the Tab and Elevator.\n\nInspect using a x 10 magnifying glass around all Elevator Trim Tab hinges for cracking or debonding between the hinge tabs and the resin (See Figure 1). Not only the upper surface of the tab is to be examined, but close attention is to be paid to the junction between the sides/lower surface of the hinge flap and the forward edge of the elevator trim tab.\n\n![](image.003.png)  \n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nThis AD may be carried out by a pilot. A copy of the AD is to be kept in the Flight Manual.\n\nNote 2: The flap segment of the hinge attached to the trim tab runs under the upper surface of the tab.\n\nNote 3: The debonding of the hinges appears as ‘cracking’ along the line joining the resin and hinge tabs. The growth rate of any cracking will be extremely fast.\n\nFurther, the crack progression will not be uniform nor similar to fatigue cracking. Therefore, any cracking found is indicative that the entire hinge has debonded.\n\nNote 4: This inspection may be carried out by the pilot provided that a copy of this AD is available to him and a LAME has provided him with full instruction on where, what and how to look for any cracking. The pilot should also be aware of the possible consequences of partial or total separation of the elevator trim tab.\n\nCompliance: Before the first flight of every day.\n\nIf operations of the aircraft are such that more than 5 hours are flown during the day, the inspection is to be carried out every 5 hours flight time until the end of flying for that day.\n\nThis Amendment becomes effective on 15 June 2000.\n\nBackground: On return from a flight a trim tab was found nearly departed from an aircraft.\n\nInvestigations found that the cause was bond failure between the hinges and the attaching resin. A further 6 tabs have since been found debonded, with one of the tabs having little more than 50 hrs TTIS. A loose trim tab can lead to flutter of the control surface. The manufacturer has been advised, and the initial issue of this AD was an interim solution pending development of a permanent solution.\n\nService experience with tabs which have been repaired/modified in accordance with the above scheme shows that it is effective in preventing this type of failure. This amendment excepts modified tabs from the requirement.\n\nThe initial issue of this Airworthiness Directive became effective on 6 May 1998.\n\n![](image.004.png)  \n\nBernard Malcolm Hole\n\nDelegate of the Civil Aviation Safety Authority 5 May 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 17 May 2000.","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":2,"scope_assessment":{"changed":false,"description":"This amendment narrows the scope slightly by exempting modified aircraft, but remains tightly focused on its original purpose: preventing elevator trim tab failures on Grob G115 aircraft. The scope has not expanded beyond this specific safety issue."},"complexity_factors":["Single, specific aircraft type (Grob G115 series)","Straightforward applicability test (modified vs unmodified aircraft)","Simple two-step requirement: clean then inspect","Clear compliance schedule (daily + every 5 hours)","Minimal defined terms (only standard aviation acronyms like LAME, TTIS)","No nested exceptions or complex conditional logic","Background section provides clear rationale without legal cross-references","Single exception for modified aircraft clearly stated in Note 1 and Background"],"plain_english_summary":"This AD requires owners/operators of Grob G115 aircraft (unless modified under EO4796/1) to regularly clean and inspect elevator trim-tab hinges for cracking or debonding — a failure that can cause severe flutter and loss of control. Pilots may perform the checks (LAMEs must train them); inspections are before first flight each day and every 5 flight hours if flying more than 5 hours that day. The amendment exempts aircraft already modified under the approved repair scheme."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"This amendment narrows the ongoing scope of the original interim directive by explicitly excepting Grob 115 aircraft that have been modified under an Authority-approved scheme (Aeronautical Engineers Australia Engineering Order EO4796/1 is named). The original AD was an interim measure applying to the whole fleet pending a permanent fix; this amendment formally recognises and exempts aircraft that have received the approved modification, and it also clarifies that pilots may perform the inspection following LAME instruction. The net effect is a reduced recurring inspection population (those with approved modifications are no longer subject to the daily/5-hour inspections) and an explicit operational pathway (pilot inspection after training) that changes who performs compliance work."},"complexity_factors":["Short single-subject Airworthiness Directive focused on one component (elevator trim tab hinge).","One clear applicability clause with a single, stated exception (approved modification schemes; EO4796/1 named).","A single prescriptive requirement (clean and inspect with x10 magnifier) rather than multiple corrective options.","One conditional compliance rule (daily before first flight, and repeat every 5 flight hours if >5 hours flown that day).","Minor procedural complexity from allowing pilot-performed inspections after LAME instruction (Note 4).","Technical detail on non-uniform/rapid crack growth that raises practical detection risk but does not add legal conditionality."],"plain_english_summary":"**What this instrument does (mechanical changes)\n\n- Revokes the earlier AD/GROB 115/12 and replaces it with AD/GROB 115/12 Amdt 1. (See \"Requirement\" and \"Applicability\".)\n- Requires cleaning and a close visual inspection (using a x10 magnifying glass) of the elevator trim tab hinges on Grob G115 series aeroplanes for signs of cracking or separation (debonding) between the metal hinge tabs and the surrounding resin. The inspection must include the spaces between the tab and elevator and attention to the junctions on sides and lower surfaces. (Requirement; Notes 2–3.)\n- Allows the inspection to be carried out by a pilot provided the pilot has a copy of the AD and has been instructed by a Licensed Aircraft Maintenance Engineer (LAME) on what and how to inspect. A copy of the AD must be carried in the aircraft Flight Manual. (Note 4; Requirement.)\n- Sets the inspection frequency: before the first flight of each day, and, if more than 5 hours are flown during the day, repeat every 5 flight hours until flying for that day ends. (Compliance.)\n- Exempts aircraft that have been modified under an Authority-approved scheme from the inspection requirement. Aeronautical Engineers Australia Engineering Order EO4796/1 is named as an approved modification scheme. (Applicability; Note 1.)\n\n**Who this affects\n\n- Owners and operators of Grob G115 series aeroplanes that have not been modified in accordance with an Authority-approved modification scheme (see Exception/Note 1). (Applicability.)\n- Pilots who will be expected to perform the daily inspections if the operator relies on pilot inspection rather than a maintenance technician. (Note 4.)\n- Maintenance organisations and LAMEs who must instruct pilots on how to inspect and who will perform repairs or approved modification work. (Note 4; Background.)\n\n**Why it matters (stated purpose and safety mechanism)\n\n- The AD is issued because bond failure was found between the trim tab hinges and the attaching resin, and at least one trim tab nearly departed in service. A loose or separated trim tab can cause control-surface flutter and a sudden failure. The AD’s stated purpose is to detect hinge debonding early and prevent in-flight loss of the trim tab. (Background; Requirement; Notes 2–3.)\n\n**Practical effects, costs, incentives and risks (analytical note)\n\n- Direct compliance cost and time: Operators must perform a short but close inspection before the first flight every day. If the same aircraft flies more than 5 hours in a day, inspections must be repeated every 5 flight hours until flying for that day ends. That creates recurring labour/time cost for each aircraft day flown. (Compliance.)\n- Equipment and training: Compliance requires a x10 magnifying glass and LAME instruction to any pilot who will carry out inspections. Licence-holding maintenance personnel may perform inspections instead, but the AD explicitly permits pilots to do them after instruction. (Requirement; Note 4.)\n- Repair or modification costs: Finding cracking/debonding will require grounding for repair or replacement; the AD points to an approved modification (EO4796/1) that, once carried out, removes the need for the recurring inspection. That creates a clear incentive for operators to pay the up-front cost of modification to avoid ongoing inspection burden. (Applicability; Background.)\n- Reliability and detection risk: The AD notes that debonding appears as a fast-growing crack and that crack growth is not uniform (meaning a defect can progress rapidly and unpredictably). Allowing pilot inspections reduces maintenance labour costs but shifts detection reliability to non-specialists; the AD tries to mitigate that by requiring LAME instruction. (Notes 3–4.)\n- Distribution of burden: Costs are concentrated on operators of unmodified Grob G115s and on pilots/maintenance staff who must carry out inspections and repairs. Benefits (reduced risk of trim-tab separation) are diffuse (passenger and third-party safety). The named approved modification concentrates benefit to operators who pay once and remove recurring cost. (Applicability; Background.)\n- Implementation risk and substitution effects: If operators delay modification, they will incur the ongoing inspection cost and the operational risk associated with possible missed defects. If pilots perform inspections without adequate instruction or discipline, there is an elevated risk of missed cracking given the AD’s statement about rapid crack growth. (Notes 3–4.)\n\n**What decisions are being made and who pays\n\n- Who decides: The regulator (CASA delegate) requires the inspections and approves modification schemes; LAMEs decide whether to instruct pilots and perform repairs; aircraft owners/operators decide whether to keep performing inspections or to adopt the approved modification. (Requirement; Note 1; Note 4.)\n- Who pays: Owners/operators pay for inspections (time), LAME instruction, and any repairs or modifications. If a crack is found, repair or modification costs (and any downtime) fall on the owner/operator. (Background; Applicability.)\n\n**Key references inside the AD**\n- Applicability: scope and exception for modified tabs (Note 1).\n- Requirement: cleaning and x10 inspection instructions and where to look (including Figures as referenced).\n- Compliance: inspection timing rules (daily before first flight; every 5 flight hours if >5 hours flown per day).\n- Notes 2–4: detail on hinge construction, how debonding appears, and permission for pilot-conducted inspection following LAME instruction.\n- Background: incident history and reason for urgent interim action and incentive to adopt approved modification.\n\n(Sections cited above are taken from the AD’s Applicability, Requirement, Notes, Compliance and Background text.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-grob-115-12-amdt-1-elevator-trim-tab","history":"/api/acts/ad-grob-115-12-amdt-1-elevator-trim-tab/history","analysis":"/api/acts/ad-grob-115-12-amdt-1-elevator-trim-tab/analysis","conflicts":"/api/acts/ad-grob-115-12-amdt-1-elevator-trim-tab/conflicts","importantCases":"/api/acts/ad-grob-115-12-amdt-1-elevator-trim-tab/important-cases","documents":"/api/acts/ad-grob-115-12-amdt-1-elevator-trim-tab/documents"}}