May 2nd

Fresh Air Matters... with Capt. Yaw

I have been often quoted as saying ‘Chocolate is go-juice for pilots!’ which I hold to as ‘personal fuel’ preference.  The ‘go-juice’ we put in our engines is critical for the functioning of our engines, as is the ‘go-juice’ we put into our bodies.

At Techiman, in Brong Ahafo, a few weeks ago I was privileged to share the concepts of the four-stroke engine, in relation to the human body.  Our bodies have millions of internal combustion engines.  The cells in our bodies are blessed with a miniature engine called the mitochondria.  We consume suitable fuels, or go-juice, and then it is carried in our blood along with oxygen along our ‘intake manifold’ or arteries before reaching the cells.  After the cell has literally ‘burnt’ the fuel with the oxygen from the air we took through the ‘air-filter’ we call lungs, it expels the waste gas of carbon dioxide into the exhaust manifold or veins, which route back to our lungs which switch roles to an exhaust muffler as we pump our carbon emissions into the atmosphere.  Feed our bodies the right ‘go-juice’ and the engines run fine, feed them some ‘junk-food’ and they soon start misfiring and eventually result in the need for an additional service interval at the ‘body-mechanic’, sometimes called ‘the doctor’.

The engines in our cars have the same challenge.  Put the wrong go-juice in your car and it may not even make it out of the filling station!  How much more important is it with our aircraft engines!

Aircraft engines run on a variety of ‘go-juices’.  Jet A1 or Aviation Kerosene is used in the jets, turbines and some ‘so-called-diesel’ engines.  Jet A1 is a very carefully controlled go-juice, for obvious reasons.  It is also not always available in every country in West Africa, and although normally available at the international airports in each country in our sub-continent, it is rarely available at the other airports.  Airliners and most helicopters use this ‘go-juice’ in their gas-guzzlers – for their engines really are quite thirsty!  Few helicopters have standard range tanks able to reach from Kotoka International Airport in Accra to the North and back without taking another draught of their favourite hydrocarbon soup.

Traditionally, piston engines in aircraft drink 100LL or AvGas, a sweet smelling lead laced juice that is essential for the smooth sustenance of thrust.  International pressure has led to the imminent demise of this source of combustible juice inside the cylinders of the high compression power-plants.

Fortunately, there are many aircraft engines on the market that are able to run on car petrol, often called Motor Car Gasoline or MoGas.  Now, if it were only that simple!

I have friends in Ghana who can run for months, without a misfire, on a diet of kenkey, fufu, banku, goat soup and other local delicacies.  ‘Go-juice for Ghanaians’ – and it is a high impact diet of energy that will continue tastefully and successfully for many more tradition cycles to come.  Most visitors to Ghana are not able to run on that ‘octane’ of fuel – they may accept one or two tank fills, but they have been groomed to run on a different group of ‘go-juice concepts’.

Likewise, internal combustion engines come with a variety of tastes.  We classify these tastes broadly as ‘octane’.  There are even three different ‘standards’ for calculating the ‘octane’ or compressibility level of the different fuels.  Commonly we use RON to recognise the octane, for example, 91, 95, 98 and 100 octane.  The higher the number the more you can compress the fuel in the cylinder without the engine blowing a hole out through its own cylinder head!  Many engines have been seen to self-destruct through the inappropriate use of a low-octane fuel in an engine designed for something more compressible.  In the same way as different foods contain energy in different ways, and some foods make some people sick, the same goes for the fuels we feed our car and light aircraft engines.  And it goes further than that.

Fuels have additives – just the same as foods do!  Worldwide we add iodine to salt for the health of our children.  In the same way, there are certain additives to our fuel that are common the world over.  In some countries they add fluoride to the piped water to boost the strength of children’s teeth, and in others they do not.   So, when you buy one brand of the same octane fuel from one petrol station or the other, the additives – positive ones and, perhaps for your engine, negative ones too are in there.  In the same way, you can purchase the ‘same meal’ from two different restaurants – and one will have more pepper in it than the other – the same meal may be tasty in one place, and unpalatable in another – to your ‘octane testing tongue’.  This is the primary reason it is recommended to select a fuel provider for your car and stick with them.  Fuels and oils are blended by their relevant brand owners based on their target audience.  In our country there are now competing ‘plus’ fuels, those with a higher octane and claimed cleaner burning with ‘secret blends of additives’.  If you are running a more modern engine in your car, it is important to feed it the right ‘go-juice’ – or it could cost you far more than simply a tank-full of the wrong stuff!

In aircraft the issues are far more critical.  Having done many aircraft engine installations, services and maintenance operations, I have seen the issues.  Some fuels leave nasty sticky remains, and stain the receptacle in which they are stored.  Others burn cleanly, leaving the fuel tanks, lines, carburettors, manifolds, etc. in pristine condition.  Interestingly, there is a trend towards the more expensive fuel being the better fuel – but that is also the case in the world of ‘human go-juice’…

Worldwide there are arguments for adding ethanol to fuel – this is a red-herring.  Experts in engines agree that ethanol has many disadvantages, and the claimed ‘green’ benefits are terribly arguable!  Imagine growing maize or soya for fermenting to ethanol instead of feeding the people?  Yet, that is what is going on in many countries, thankfully, West Africa is still remaining sensible and focused in this regard, so far.  Interestingly many of the fuel lines and systems in the older cars get damaged by ethanol in the fuel – and so such an introduction in our ‘working museum of motor-vehicles’ would have catastrophic consequences.  Likewise, many aircraft engines cannot accept ethanol in their fuel, it can result in serious consequences.  Even if the engine can cope, fuel lines, fuel tanks and other systems may not be ethanol resistant.

My recent visit to AERO Friedrichshafen in Germany, where the worlds aircraft industry joined hands in a festival of wings, fuel was a top topic.  The vast majority of the show heralded two-seat aircraft, and the vast majority of them ran the Rotax engine.  Why?  It is proven to run with both 100LL and car fuels, and has an excellent reliability record.  It was a pleasure to hear the quote being given about this ubiquitous engine ‘and it is used in Ghana where they build aircraft that are used in mission critical, hostile terrain applications’.  It made me more than proud at the reception given to the worlds leading Female Rotax Aircraft Engine expert, from Ghana, Patricia Mawuli Nyekodzi, who spoke confidently with manufacturers, pilots and engineers.  Thank you Patricia, you have made Ghana and West Africa proud.  Make sure that you keep on feeding those engines, and yourself, the right ‘go-juice’.

Capt. Yaw is Chief Flying Instructor and Chief Engineer at WAASPS, and lead Pilot with Medicine on the Move, Humanitarian Aviation Logistics (http://www.waasps.com/   http://www.medicineonthemove.org/ e-mail capt.yaw@waasps.com)