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

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< Back Rally Entrance Tickets, Airside Passes and Camping Permits on Sale!! 18 Jul 2025 Entry Tickets and Airside Passes now on sale via the LAA Shop . Landing slots will be available soon. We have a special offer for non members - £50 for all 3 days including Airside. Available for purchase until 31st July 2025 Next Previous

Info Library Navigate the folders below for any document that you require, like you would on your computer. To search for a particular document, use the 'magnifying glass' symbol below on the right.

< Back New LAA Inspector - Clive Sutton 28 Mar 2024 The LAA is pleased to welcome Clive Sutton as a new LAA Inspector. Clive came to an Assessment Day at LAA HQ at the start of March. Clive is ex-RAF, a Chartered Engineer and a BMAA Inspector. He prefers composite & metal airframes and Rotax 4-stroke engines (especially the Europa type). He has little experience with 2-strokes of Continentals/Lycomings or wood and fabric aircraft. He is ready to travel a maximum of an hour; Wellesbourne, Bidford and Coventry are within easy reach for him. Next Previous

Membership Full Plus Category is for members who own, operate or are currently building an aircraft and gives access to LAA Engineering services. (For Group Owned aircraft, at least one member of the group must have Full Plus membership.) Full Category is for everyone else and includes a monthly copy of Light Aviation Magazine and a discount at the annual LAA Fly-In. JOIN THE LAA Member Full - £75 Full Plus - £117 Member Joint Full - £85 Full Plus - £139 Joint members are members who are the partner of a full member or any children under the age of 18 and living at the family house. Under 30 Member Full - £31 Full Plus - £139 Please forward proof of DOB i.e. copy of passport, driving licence or pilots licence. Overseas Member Full - £91 Full Plus - £139 Overseas includes Ireland. Payment Methods ONLINE Via the Member Area / Renew my Membership DIRECT DEBIT You are now able to set up your direct debit online. Please see your renewal or joining page for details. BY CALLING HQ 01280 846 786 with card details NOTE: Permit Revalidation payments are taken ONLINE only through the Permit Revalidation online system BY INTERNET BANKING Please ensure you pay the correct fees for 2026 Account No : 26225220 Sort Code : 60-30-03 Please note, for membership payments, you MUST quote your membership number and your surname or your payment will not be credited to the correct record. For Permit revalidation & engineering fees, you MUST quote your aircraft registration. If paying from abroad, SWIFT code is : NWBKGB2L IBAN code is : GB81 NWBK 6030 0326225220 Important Links RENEW MY MEMBERSHIP MY AIRCRAFT DETAILS MEMBER AREA ADDRESS CHANGE

< Back Mandatory Technical Directive issued for Supermarine Spitfire mk26 and mk26a 16 Feb 2024 It has been found that there is potential for the fin of the Supermarine Spitfire Mk26 and 26B to be misaligned during build, due to a build-up of tolerances in the fin and its attachment, possibly leading to a mis-rigging of the rudder and failure to achieve the desired range of rudder travel. This could possibly result in degraded controllability in flight and on take-off and landing. In the interests of safety MTD 01-2024 calls for mandatory checks to be made on the fin alignment and rudder range of movement. Next Previous

< Back New LAA Inspector - Keith Troughton 4 Sept 2025 We are pleased to welcome Keith Troughton as a new LAA Inspector, having attended an LAA Inspector Assessment Day at Turweston recently. With an active aviation interest from a very young age, he has been involved in certified, homebuilt, and microlight aircraft for over 40 years. He is currently operating within a C.A.O. General Aviation Facility as a Licensed Aircraft Engineer (L.A.E.). He is a CAA-approved maintenance manager within an approved Aircraft Maintenance Facility, with access to most of the necessary tooling for standard aircraft maintenance support, including facilities to weigh aircraft, if required. Next Previous

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