MOTOR FUEL: AVGAS 100 L (Hansard, 6 March 1980)

§ Lord WHADDON
My Lords, I beg leave to ask the Question which stands in my name on the Order Paper.

§ Lord TREFGARNE
My Lords, may I apologise briefly for the length and complexity of this Answer, but it is an important matter, so I hope your Lordships will bear with me. Avgas 100 L differs from four-star motor fuel by virtue, inter alia, of its octane characteristics, its vapour pressure, its sulphur content, its aromatic content and its comparative freedom from gum formation. Furthermore, Avgas is manufactured to more stringent specifications, particularly with regard to impurities. The use of four-star motor fuel in light aircraft engines not so approved will lead to shortenened engine life, and increase the risk of engine failure, both because of vapour locks in the fuel system and for other reasons. It also prevents the engine delivering full power at take-off, thus invalidating take-off performance data.
I wish to emphasise that the use of unapproved fuels in any aircraft invalidates the manufacturer's guarantees, the insurance cover and the certificate of airworthiness. Operators use them, therefore, at grave risk to their aircraft, their passengers and themselves.

§ Lord WHADDON
My Lords, does the noble Lord appreciate that, if he insists that there are sound technical reasons for using exclusively 100 L, there is a concomitant duty on the Government to try to ensure adequate supplies? Is he aware of the chronic shortages which have plagued the industry in the last year or two, and that the overall quantity of fuel is negligible to the oil companies but absolutely vital to the vast majority of aircraft on the British register? What action do the 396 Government propose to ensure greater security of supplies in the future?

§ Lord TREFGARNE
My Lords, we do recognise that there is a world problem, certainly a European problem, and an acute problem indeed in some parts of the world, regarding this particular product. The oil companies are urgently considering whether they can adjust the manufacture of motor spirit in such a way that it could be used safely in small aircraft engines.

§ Lord WYNNE-JONES
My Lords, can the noble Lord tell the House what are the vapour pressures of Avgas 100 L and of ordinary four-star fuel? Can he also tell us what are their relative octane numbers? These are both important parts —in fact, they seem to me to be vital parts —of his Answer.

§ Lord TREFGARNE
My Lords, I can give the noble Lord the answer on the octane numbers. Four-star motor spirit has an octane rating of not less than 97 research octane number, whereas 100 L Avgas has a rating of not less than 100 octane performance octane number weak mixture, and not less than 130 performance octane number rich mixture. I am afraid I have not got the vapour figures in front of me.

§ Lord WYNNE-JONES
My Lords, will the noble Lord not agree that when he talks about vapour lock in the system, it depends entirely upon the relative vapour pressures of the two, and therefore his answer is, if he will forgive me for saying so, unsatisfactory.

§ Lord TREFGARNE
My Lords, I do apologise to the noble Lord.

§ Lord GISBOROUGH
My Lords, will the noble Lord accept that the price of Avgas in the United States is only 50p compared with, I think, four times more here, and that as a result of that and other factors the cost of becoming an airline pilot is something like £30,000 here compared to 6,000 dollars in the United States, in addition to which VAT is payable on learning to fly here, unlike any other instructional course? Does not this militate very much against British flying, and can the Government look into this?

§ Lord TREFGARNE
My Lords, while there is a significant difference between the prices of gasoline here and in the United States, those are not the only causes for the difference in the costs of learning to fly. A commercial pilot achieving his licence in this country is required to undertake, I believe, at least twice the number of flying hours of his American counterpart.