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Aviation History
1964
1964 - 0182.PDF
•JGHT International, 23 January 1964 123 Kerosine v JP.4 IN the USA the CAB has now recommended that theFAA should ban the use of JP.4 in civil aircraft. IATA's ambivalent attitude on this matter was discussed in these pages for January 9, page 50; and a controversy in the pages of the New York Herald Tribune has drawn this response—not published in the newspaper as this issue went to press—from Mr J. W. Rickard:— "Your recent articles concerning the accident to the PanAm 707 at Elkton on December 8 have aroused considerable interest in this country where the jet fuel issue has been stated and restated many times over the past 12 years. Interest over here reached its peak in November 1960 following a television demonstration carried out by Lord Brabazon and myself of the relative flammabilities of kerosine and JP.4. "First, a general note about the two fuels. Kerosine is and always has been the world's standard civil jet fuel, and this is because of its greater safety. No fuel is safe under all circumstances but kerosine offers by far the highest standard of safety from an overall standpoint. JP.4, on the other hand, has become the standard military jet fuel on account of the fact that a barrel of crude oil will yield more JP.4 than kerosine, and this could be an important factor in the event of global war when oil resources might be strained to the utmost. But it is worth noting that British and American Naval Air Forces do not use JP.4: it is not permitted on board carriers. "Whatever the USAF's reasons for forbidding fuel mixing, and it is not difficult to think of several, they could have nothing to do with flammability. JP.4 is by itself explosive overa widerangeof day to day flight conditions, whereas kerosine vapour/air mixtures are usually too weak (except in the tropics). Gasoline, on the other hand, is often too rich for explosion. The effect of adding kerosine to JP.4 would be to produce a mixture of intermediate vapour pressure dependent on the percentage mix. This in turn could have the effect of weakening an over rich fuel/air mixture into the explosive range, or of weakening an already explosive mixture out of the explosive range. As you say, there is no ready formula for predicting when a blend of the two is hazardous. But one thing remains certain: in the circumstances of the Elkton accident, kerosine alone could not have produced an explosive mixture. The fuel temperature must have been much too low. Incidentally, has it been established that all of the 707's tanks had kerosine added to them at Baltimore ? "It is not correct to refer to the lightning hazard as a new threat. Almost all of the articles written on the jet fuel issue, on both sides of the Atlantic, have contained a reference to the danger of flight explosion although, of course, much greater prominence has been given to the crash fire aspect. Nor is it correct to state that there has been no previous case of an airliner having been destroyed by lightning strike, for it is believed that the TWA Constellation lost near Milan in 1959 suffered an explosion due to this cause in an almost empty tank. "The ease of ignition of JP.4 vapour/air mixtures has many times been manifested by explosions in aircraft on the ground, and in ground storage installations, a spectacular case of the latter having occurred at a Malton, Ontario, depot in February 1961. Here two airport trucks exploded separately, but on the same evening, while being loaded with JP.4. No doubt the mixture strength was near stoichiometric in view of the winter temperature. "In flight there have been a number of cases of tip tanks of JP.4 on military aircraft being exploded by lightning, and it was therefore only a matter of time before a strike was to occur in such a manner as to destroy an aircraft. This has now happened. It may have hap- pened before, for the sudden disappearance of a KLM DC-8 off Lisbon has never been explained. It was reported at the time (over two years ago) in Aviation Week that the aircraft may have been carrying JP.4. "The dangers of explosion have long been appreciated by your own Lightning and Transients Research people, by Esso Export (Mr A. R. Ogeton) and by the FAA. Some five or six years ago I several times visited the FAA in Los Angeles, and I gained the impression that prior to certification of the 707 there was a Special Condition calling for some form of tank inerting system to be fitted in the event of JP.4 being used. This condition must eventually have been waived. I cannot offer any explanation as to why no Air Force aircraft has been destroyed by lightning. This one must be left to the statisticians who will need to make very careful com- parisons between military and civil operating techniques. "When the regular JP.4 burning airlines claim that there is a widespread shortage of kerosine where they operate, this claim is usually a guise to divert public attention away from their cut-price fuel activities. All the world's airlines which operate turbine powered aircraft (with one exception) started the jet age using kerosine. Those few which, at a later date, started to use JP.4 in addition to kerosine, did so for one reason only, namely that in some places JP.4 was becoming cheaper. This trend was openly admitted by IATA at their thirteenth annual technical conference (Lucerne, May 1960) when Mr Knut Hagrup of SAS said: ". . . the finance people want us to tank the aircraft with kerosine in one place and JP.4 in another. "PanAm started to pick up JP.4 at London around October 1960, This virtually windowless DC-8 is an all-"F" version, one of three of these 46-ton pay load freighters ordered last March by United and due to be delivered before the end of the month
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