97 Octane Super Unleaded Since the replacement of regular E5 Mogas at the pumps by E10, for the time being at least, Mogas users have an alternative option in the form of 97 RON Super Unleaded fuels. 97 RON Super Unleaded fuel supplied by garage forecourts is NOT necessarily ethanol-free, but its ethanol content will be capped at a maximum of 5%. 97 RON E5 Super Unleaded fuel can be used under the LAA process for E5 Mogas, as before. There’s currently no legal requirement for ethanol to be present in super unleaded petrol and in fact, quite a few members have reported that their tests have shown Super Unleaded fuel to be ethanol-free in their areas. Esso reports that “Synergy Supreme+ 99 is actually ethanol free (except, due to technical supply reasons, in Devon, Cornwall, North Wales, North England and Scotland). Legislation requires us to place E5 labels on pumps that dispense unleaded petrol with ‘up to 5% ethanol’, including those that contain no ethanol, which is why we display them on our Synergy Supreme+ 99 pumps”. Shell, BP, Tesco and other fuel suppliers don’t commit to such detail, merely stating their fuels “may contain up to 5% ethanol”. Of course, many LAA members have been using Mogas of one sort or another for many years. For many airstrip users, the prospect of having to go to an airfield to fill up with Avgas would seem at best very off-putting, and at worst totally impractical for their style of operation. Hopefully Super Unleaded will continue to be an option using the LAA’s E5 procedure. Where 97 octane E5 super unleaded can be found that’s ethanol-free, it can be used in the broader range of LAA aircraft with engines eligible for use with E0 unleaded fuel. But it is important that Mogas users take on board the fact that unlike with aviation fuels, automotive fuel specifications generally only describe the properties of the fuel blend, in terms of octane rating and other characteristics, they don’t specify the chemical make-up of the fuel. Apart from specifying broad maxima and minima for those components that the powers-that-be wish to either encourage or discourage, the specifications leave to the fuel supplier the choice of how to blend the fuel to achieve the described properties. In some cases it’s the relatively small amounts of additives that cause compatibility issues, rather than the main components of the fuel that cause the problems – and the mix of additives may vary from one batch to the next. With Mogas of any type, what you get from the pump one week may be different to what you get the week after, or got the week before. The fact that your fuel system pump diaphragms, seals, composite tanks and so on might have been unaffected by Mogas up till now does not guarantee that they will be OK with the blend that the next tanker-load brings to your garage forecourt. Unfortunately there is no simple answer to this, and the only way to mitigate this problem is by constant vigilance, and thoughtful adaption of your maintenance schedule to check for signs of problems developing before they create a safety issue – more frequent checking of filters, changing of fuel lines etc. Signs to watch out for are swelling of rubber components like diaphragms, fuel valve seals and O rings, fuel pipes hardening or developing surface cracks, fuel tank sealants wrinkling or detaching from the internal surfaces of fuel tanks. Varnishes on cork floats may go gummy, or plastic carburettor floats absorb fuel and lose buoyancy, causing a rich mixture and rough running. Watch out for discolouration of the fuel you take out as fuel samples, which may imply something dissolving somewhere in the system, and for corrosion in the bases of your carb float bowls and gascolator. Avoid letting Mogas go stale in your fuel system – drain it out before a long period of disuse. Don’t leave the tanks empty for a long period – better to fill them with Avgas which will reduce condensation, and also, particularly with plastic tanks, prevent the tank’s internals drying out which can cause problems with shrinkage, and in extreme cases, the tanks splitting open. O rings and other rubber parts are best kept submerged in fuel continuously. We’ve seen cases where composite aircraft skins have rippled apparently due to exposure to the vapours created by the break-down products in stale Mogas, after being left unattended over a single winter. Mogas is blended with the expectation that in a car it will be used within a few weeks of being supplied, so it doesn’t need to be as stable over a long period of time as an aviation fuel. If a composite or plastic fuel tank is built into your aircraft, consider carefully whether you want to run the risk of having to replace it should the tank deteriorate with Mogas exposure, with all that that implies. With an integral tank in a wet-wing Jabiru aircraft, the answer should be certainly not – but even with the embedded polyethylene fuel tank in a Europa’s fuselage, changing the fuel tank is not an operation for the faint-hearted, involving cutting out quite large parts of the fibreglass cockpit module to release the tank, and then scarfing them back again afterwards in-situ. The Europa kit was first produced in the era of four-star Mogas, a very different blend to what we find at the pumps today. Ethanol-proof rubber hoses are available. In particular SAE J30/R9 or the European equivalent DIN 7339 D3 are automotive hose standards that are widely available from auto factors, and should be used in preference to the older SAEJ30/R6 standard hose which is more permeable to fuel vapour and will more quickly harden and crack, particularly using fuel containing ethanol. The SAE spec J30/R14 is a lower pressure, more pliable version for carburettor systems. Watch out for cheap imitations – the real McCoy should come from a reputable manufacturer, be marked with the SAE number along its length and will likely cost at least £10 a metre. What can we do to help the situation ? It may be that off-the-shelf drop-in-the-tank additives can be used to mitigate some of the problems with mogas fuel, in particular, stabilisers and anti-corrosion products, just as they are routinely in the marine and race-car world. Not knowing what’s in them, we recommending steering clear of any additives that claim to boost the fuel’s octane. Definitely avoid additives that claim to actively enhance an engine’s power or fuel economy, other than just to restore proper performance by giving the carburettor jets and orifices an occasional clean-up. For most aircraft engines UL91 Avgas remains the ideal fuel, in that it is a tightly-controlled aviation-grade fuel of a guaranteed composition, blended for long-term stability and optimal volatility for aviation use. As it is in effect the familiar 100LL Avgas but supplied without its tetraethyl lead, any fuel system designed for 100LL Avgas will be unaffected by using UL91 fuel, or, if circumstances demand, by a mix of 100LL and UL91. Despite a pervasive mis-conception, UL91 fuel is NOT Mogas and suffers from none of the issues associated with Mogas use in aircraft. A list of engines suitable for use with UL91 fuel can be downloaded from the ‘operating and maintaining an LAA Aircraft’ page of the LAA’s new website. Moves are afoot to increase the number of airfields supplying UL91 fuel, with full LAA backing.

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< 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

Night IFR PROCESS SUMMARY LIST OF TYPES PERMIT IFR FEES NIGHT IFR INSPECTORS FAQs POH LITE TEMPLATE (PowerPoint File) NIGHT IFR PILOTS ACCEPTED INSTRUMENTS TL 2.27 - PROCEDURE FOR APPROVAL & TL 2.28 - ASSESSMENT OF AIRCRAFT LAA/MOD15 APPLICATION FORM

Inspector Zone The Inspector Zone is designed for use by LAA Inspectors (though is available to all) and is intended to provide a focal point for LAA Inspectors to source important airworthiness and other useful information. LAA Inspector Updates are provided via email. Inspectors should check the contact information shown in the Inspector Map held on this website, and let the Head of Continuing Airworthiness & Inspection (Chief Inspector) know of any changes needed. Inspectors are encouraged to submit items of news they think might be suitable for inclusion in future Inspector Updates to the Head of Continuing Airworthiness & Inspection (Chief Inspector) , Lucy Wootton at [email protected] . This email address may also be used by Inspectors with queries directly relating to their role as an LAA Inspector. AIRWORTHINESS INFORMATION SPARS (COMING SOON...) INSPECTOR APPROVAL INFORMATION BECOME AN INSPECTOR FIND AN INSPECTOR INSPECTOR TRAINING SEMINARS

Preliminary Design Preliminary Design is the stage where the design is sized and developed in outline, leading to a three view drawing, performance and weight predictions. To help with this, LAA has developed a number of spreadsheets. Spreadsheet 1 is used to develop the basic geometry of the proposed aircraft, size the wing, fuselage and tail surfaces and work out some of the key parameters used later. Spreadsheet 2 is used to estimate the performance of the aircraft based on the geometry, initial weight estimates, engine power and guestimates of the drag coefficient and prop efficiency, allowing you to see how the performance is affected by changing each parameter in turn. Spreadsheet 3 is used to work out the critical structural speeds, develop the flight envelope and predict the aerodynamic loads on the main surfaces which can be used to size the structure, and as the basis for a load test program. The weight and balance spreadsheet elsewhere on our website allows the designer to quickly evaluate the implications on weight and cg of different positions for the crew, fuel tanks and baggage bay, and work out what empty aircraft weight and cg he must aim for. Thanks to the simplicity of these programs it takes only minutes to study the implications of changing the aircraft’s specification, for example the effect of changing the wing aspect-ratio, the trade-off between extra weight and cleaning up the airframe drag, extra power etc. Downloadable Spreadsheets Worked Spreadsheet Examples Design Tutorials

Light Aviation Magazine 2015 Click on the links below to open each issue of Light Aviation Magazine from 2015 January 2015 April 2015 July 2015 October 2015 February 2015 May 2015 August 2015 November 2015 March 2015 June 2015 September 2015 December 2015

Lycoming Lycoming engines in certain specific airframe types have been approved by the CAA for the use of unleaded Mogas, using the process described in CAP747 , See Section 2, Part 4, General Concession 5. This involves purchasing an STC (Supplemental Type Certificate) from either the EAA or Petersen Aviation in the USA and carrying out the actions called for by the STC. The procedures stated in CAP747 may be followed for LAA aircraft but only for aircraft with the exact same engine/airframe combinations quoted on in CAP747.. An LAA inspector must check that the aircraft operator has obtained a copy of CAP747, Section 2, Part 4, GC5 and of the appropriate STC and complied with the actions called for therein, and signed off a suitable logbook entry accordingly before the aircraft may be flown with unleaded 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 Engineering updates in July 7 Aug 2025 The following documents have been issued/updated in the Engineering 'Info Library' during July. Continuing airworthiness information : Mandatory Technical Directive MTD-05-2024 issue 2 - Jabiru distributor caps Mandatory Technical Directive MTD-03-2025 - Marquart Charger aileron slave strut Alert A-05-2024 issue 2 - Rotax engine oil spray nozzle Alert A-07-2025 - Glastar aileron servo-tab pushrod cracking Alert A-08-2025 - Gen 4 Jabiru engine crankshafts Technical leaflets : TL 2.00 - Revalidating your aircraft's Permit to Fly TL 2.19 - The LAA Generic Maintenance Schedule TL 2.33 - Insepctor categories for type TADS : 274 - Europa 315 - Eurostar 324 - Supermarine Spitfire mk26 Propeller type lists PTL/1 : Kitfox mk1/mk2/mk3 Forms : LAA/AR-REF (FB GYROPLANE) - Airworthiness review reference guide (crib sheet) LAA/AR-REF (HOMEBUILT GYROPLANE) - Airworthiness review reference guide (crib sheet) LAA/AR-REF (FIXED WING) - Airworthiness review reference guide (crib sheet) LAA/CFS-1 (GYRO) - Check flight schedule LAA/CFS-1 (FIXED WING) - Check flight schedule LAA/FBG-SUPP - Supplement to factory-built gyroplane revalidaton form LAA/PFRC-1 - Permit Flight Release Certificate LAA/FT-NEW - Flight test schedule, new builds, transfers, modifications and repairs LAA/FT-ENG - Flight test schedule, engine modifications Next Previous

LAA Member Discounts

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.