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E10 Mogas From 1st September 2021, the government mandated that all regular grade unleaded petrol must contain up to 10% ethanol, rather than up to 5% as previously. In the autumn of 2021, most filling stations around the UK re-marked their E5 petrol pumps to show that they now supply E10 specification fuel, and started receiving tanker-loads blended with up to 10 percent ethanol content. For the automotive world this means reduced carbon dioxide emissions, which is better for the environment, and, arguably in terms of eco-desirability, a small further reduction in the reliance on fossil fuel. The automotive industry had been preparing for this change, and people with road vehicles registered after 2002 should be able to switch to E10 without noticing any difference. Unfortunately, the additional ethanol content is bad news for aviation users if we were to ignore the change and start putting E10 in our aircraft regardless. Ethanol is a powerful chemical solvent which can attack components including rubberised gaskets and fuel pipes, older lacquered carburettor floats and composite or plastic components in some newer fuel systems. The doubling of the concentration of ethanol in E10 compared to E5 makes it much more likely that problems will be experienced if these parts are not designed to be ethanol-proof. Ethanol also has an affinity for absorbing water, which over time can then become acidic, attacking metal components in the fuel system and engine. Even if there was a practical way to do so in the volumes of fuel we use in our aircraft, we cannot safely remove the ethanol content from the fuel because the ethanol acts as an octane enhancer, so the washed-out fuel would be left with a reduced octane value, likely to cause detonation problems. Another issue is that ethanol-blended fuel has a lower energy density than petrol, so to develop full power from our engines using an E10 fuel, we may need to richen the fuel/air mixture, for example using a bigger carburettor jet size. Owners of Rotax and Jabiru engines are probably already aware that many of these engines are supplied as being able to use E10 fuel – though with Jabiru engines, in particular, it’s far from straightforward because some of the earlier engines require cylinder head modifications and reduced compression ratio if they are to avoid detonation issues when using any form of Mogas. Jabiru also say that Mogas of any type should not be used in commercial flight schools and only at the owners own risk. Even with a supposedly E10-compatable engine, the chemical compatibility problems with fuel system components are such that the LAA does not at present approve the use of E10 Mogas in any LAA amateur-built or vintage aircraft. For factory-built microlights and factory-built gyroplanes, where LAA is not the approving authority but only renews the CAA’s Permits to Fly, owners need to refer to the TADS for the types for details of the approved fuel types, and monitor the service bulletins from the approved manufacturers for news of any updates. Where we need to be particularly careful in reading-across from (hopefully) a trouble-free transition to E10 in automotive use is the big difference between our petrol cars and the way our aircraft engines are configured. Our cars generally have submerged fuel pumps in their petrol tanks and a sealed fuel system. In our aircraft we have an open-vented tank and usually a fuel pump several feet away, often mounted in a hot area of the engine bay near to the engine exhaust, dragging the fuel through a fairly convoluted pipework system, a filter and fuel selector – all features encouraging a vapour lock - and then to make matters worse we want to climb up to altitude and operate in reduced atmospheric pressure. Modern petrol cars have a fuel injection systems rather than carburettors, a circulating fuel system designed to purge any vapour forming in the fuel line, and an ECU that monitors the engine’s parameters constantly and adjusts the fuel mixture strength and ignition timing to prevent damage to the engine – and if all else fails and the engine should ‘pink’, we can hear it from the driver’s seat and drop a gear to lighten the load. Because of the much higher background noise level in our aircraft, detonation cannot be heard and the pilot’s first indication of a problem may be when the first piston crown disintegrates, or a valve head departs its stem. In conclusion - E10 is presently not approved for use in any LAA aircraft. ‘Hoping for the best’ and using E10 fuel in your aircraft regardless could risk ruining the fuel system components, fibreglass tanks falling to bits, engine failure through contamination of the fuel or ruptured fuel pump diaphragms etc, or more serious engine damage. For most of our engines, UL91 Avgas is the best choice, but 97 octane E5 Super Unleaded remains an alternative to the now-obsolete E5 spec Mogas.

Continuing Airworthiness Information One of the key strengths of the LAA's system is that we can monitor the fleet centrally and keep track of airworthiness incidents from around the world. Where necessary, we can then let our owners know, to help them keep flying safely. A full listing of Airworthiness Alerts, Technical Service Bulletins and Mandatory Technical Directives can be found below: ALERTS, TECHNICAL SERVICE BULLETINS & MANDATORY TECHNICAL DIRECTIVES

< Back LAA Alert for some models of Rotax Engines 1 Mar 2025 LAA Alert A-02-2025 has been published on the LAA website (and is also attached), highlighting a recent service bulletin published by Rotax regarding the inspection and/or replacement of the crankcase and/or gearbox housing on affected engines. Rotax has identified a potential manufacturing issue affecting the hardness values of the crankcase and/or gearbox housing materials in certain engines. These components may not meet the required specifications for material hardness, which could lead to reduced component durability and/or potential oil leakage. Rotax regards this bulletin as mandatory. A-02-2025 - Rotax Crankcase .pdf Download PDF • 220KB Next Previous

Light Aviation Magazine 2023 Click on the links below to open each issue of Light Aviation Magazine from 2023 January 2023 April 2023 July 2023 October 2023 February 2023 May 2023 August 2023 November 2023 March 2023 June 2023 September 2023 December 2023

Light Aviation Magazine 2016 Click on the links below to open each issue of Light Aviation Magazine from 2016 January 2016 April 2016 July 2016 October 2016 February 2016 May 2016 August 2016 November 2016 March 2016 June 2016 September 2016 December 2016

< Back New LAA Course dates released 6 Oct 2023 Dates have now been published for upcoming LAA Courses for the rest of this year. To find out about specific courses and their dates, click here . Please note, the next 'Caring for your Gipsy Major' course is on the 11th November, not 7th November, as published in the latest edition of Light Aviation magazine. Next Previous

Light Aviation Magazine 2020 Click on the links below to open each issue of Light Aviation Magazine from 2020 January 2020 April 2020 July 2020 October 2020 February 2020 May 2020 August 2020 November 2020 March 2020 June 2020 September 2020 December 2020

< Back New LAA Inspector - Phil Hebdon 27 Nov 2025 We are pleased to welcome Phil Hebdon as a new LAA Inspector, having attended an LAA Inspector Assessment Day at Turweston recently. Phil previously worked as a commercial pilot, before moving into aircraft maintenance. Phil has been an LAA aircraft owner for many years – including a Taylor Monoplane, Pitts Special and a Miles Gemini. Phil has been maintaining his own aircraft, as well as those of others, and has significant experience maintaining and rebuilding gliders, specialising in wood repairs and fabric work. Next Previous

< Back MTD-06-2025 published - Europa Tailplane Torque Tube Mod Failure 16 Dec 2025 Ref: LAA Mandatory Technical Directive MTD-06-2025 – Europa Tailplane Torque Tube Clamp Mod A recent inspection of a Europa fitted with the tailplane torque tube clamp modification, LAA MOD 10623, revealed both halves of the clamp had broken and fallen apart. These clamps are intended to prevent relative movement between the tailplane torque tube, the tailplane drive plates and the central drive horn, on which the mass balance arm is mounted. Failure of these clamps could allow free play to develop, potentially leading to taper pin hole damage, tailplane flutter, or jamming of the pitch control mechanism. An inspection must be carried out within the next 5 flying hours to determine whether MOD 10623 is fitted. If MOD 10623 clamps are fitted, making use of a light source and mirror as necessary, inspect the alloy clamp blocks for any signs of cracking (in particular along the sharp corner between the bolt flanges and main body), for any signs of looseness or relative movement between the parts and for any other abnormalities. If any of these are detected, the aircraft must not be flown and LAA Engineering must be contacted. This must be repeated at intervals not exceeding 25 flight-hours or the next Permit revalidation inspection, whichever occurs first, for as long as MOD 10623 remains fitted. Please refer to the below Mandatory Technical Directive for full details, compliance times, and certification requirements. This MTD can be found HERE and is also available below. MTD-06-2025 - Europa Tailplane Torque Tube Mod Failure .pdf Download PDF • 259KB Next Previous

Weight & Balance The subject of Weight and Balance covers at least four distinct procedures: weighing an aircraft, calculating its empty weight and centre of gravity (CG), establishing the worst forward and aft CG loading cases according to an appropriate design code and calculating weights and centres of gravity for an actual flight. This section includes guidance notes on each of these aspects, forms and worked examples (imperial or metric) for recording and calculating empty weight and CG, as well as worst forward and aft CG cases and an Excel based spreadsheet that makes the weight and CG calculations for you. The table on the spreadsheet is set out in the same layout as the Loading Examples tables. This spreadsheet can, of course, also be used for carrying out calculations for an actual flight. Simply input the actual weights of the items to be loaded rather than the standard occupant or maximum fuel and baggage weights. Remember, it is important to check that the CG remains within limits with no usable fuel as well as with the loaded fuel in the tanks, even though it will not be your intention of running the tank dry. The calculator generates two sets of weight and CG values for this purpose. Weight & Balance arrangements for gyroplanes are different to those of aeroplanes and a special type of report is used, unless the manufacturers concerned provides their own special schedule in which case this should be used instead. Before accessing the documents below, please ensure you have read Technical Leaflet 3.16 - Weight and Balance Guidance Notes . Technical Leaflet 3.16 Other useful documentation is as follows: Weight & Balance Forms Weight and Balance Example Forms Weight and Balance Excel Calculators

< Back Engineering updates in December 2 Jan 2025 The following documents have been issued/updated in the Engineering 'Info Library' during December. Continuing airworthiness information: Mandatory Technical Directive 07-2024 - Eurofox trim cables Alert 03-2024 - Eurostar trim cables Alert 04-2024 - Loose Rotax engines Alert 05-2024 - Rotax 900 series engines - blocked oil spray nozzle Technical Leaflets: TL 2.22 'non-type specific MPDs' TADS : Sling 4 TSi Wishing all our members a very Happy New Year. Next Previous