What makes Avgas 100LL so special and how should it be handled? Philip Whiteman asked an industry expert, Gulf Aviation’s Ops and Technical Manager, Sam Crooks.

Thanks to a huge cut in the price of crude oil, fuel prices have been falling – and this is good news to aircraft operators. However, Avgas 100LL continues to be sold at a premium over motor fuel and many people continue to ask why there is such a difference in price.

So what is it that differentiates avgas from mogas – and why is Avgas 100LL so costly? Pilot put this, and other questions to aviation industry expert Sam Crooks, who has almost forty years’ experience in the industry and is Operations and Technical Manager at Gulf Aviation, a part of Certas Energy.

‘Avgas 100LL is highly refined, with specific octane ratings to make it resistant to detonation. Mogas is less refined, with a lower octane rating meaning it has a higher volatility, a lower ignition and flashpoint temperature. More prone to vapour lock in fuel lines compared to avgas, the motor fuel also restricts pilots to a maximum flying altitude.’

Sam has reservations about the use of mogas in aircraft. ‘There has been a long raging debate on the use of mogas over Avgas 100LL within the general aviation industry. Designed for use in automotive vehicles, mogas being used as fuel for aircraft is a contentious issue, as the two fuels are refined and supplied in very different ways.

‘The difference in cost between the two is down to the fact that Avgas 100LL is produced to higher specification and with far greater quality control than mogas. Another contributing factor to the higher cost of 100LL is that it is manufactured in smaller quantities and is not produced in the UK, so has to be imported.

‘Regulatory standards are designed to ensure all aviation fuel is fit for purpose, meeting the aviation industry’s expectation of good clean fuel reaching the aircraft engines. Contamination within the fuel supply chain is a very real threat, making it essential for all processes to be adhered to in order to ensure the products are free of contamination. Choosing the right fuel for your aircraft and being confident that it has passed the correct quality control procedures is essential to maintaining flight performance as well as safety.’

Sam is keen to ensure pilots are aware of the safety implications of poor fuel management at all levels of the fuelling process: ‘Poor maintenance of aircraft, pilot experience and weather conditions are perhaps more obvious factors, but poor fuel management can cause huge issues for pilots. The regulations state that everyone involved in the process must take responsibility for fuel’s quality. For their part, the major fuel suppliers offer training courses for anyone involved in 
the handling.

‘Pilots should also take measures themselves to check fuel quality by sampling fuel tanks during preflight checks. In the remote chance fuel has been improperly managed, this is the last point at which any possible contamination can be discovered.’

What about the issue of storage? The throughput of airfield tanks and pumps can be very low at times?especially the winter months?and aviation fuel can sit around for extended periods. ‘There has been much discussion on how to handle avgas that has been stored for longer than six months. The product should be re-tested in a laboratory every six months to ensure it still meets specification; particular attention is given to its vapour levels.’

Finally, is there any prospect for reducing the cost of aviation fuel? ‘While crude oil prices are falling, there is a delay to this impacting on the price of refined products such as Avgas 100LL. In addition to this, most refined products are bought on lagged pricing which also explains why there are delays in it feeding through to the end user. Avgas 100LL also contains the component tetraethyl lead which is not linked to crude oil prices.’

‘There is also a fixed duty element of 37.7 pence per litre and VAT at twenty per cent, which limits the potential to reduce the price. However, it is falling and looks likely to continue to do so in the first quarter of 2015.’

Will the present trend continue? ‘Although predicting the prices of fuel is a risky business, the current supply and demand differentials don’t indicate that there will be any significant rises in 2015. That said, geopolitical risks in oil producing regions remain and these have the potential to significantly impact 
the market.’


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