Helicopter Transmission Lubricants,
IMPERIAL COLL OF SCIENCE AND TECHNOLOGY LONDON (ENGLAND) DEPT OF MECHANICAL ENGINEERING
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This paper outlines problems associated with the lubrication of helicopter transmissions and then discusses how helicopter lubricants are likely to change over the next decade. For many years, helicopter transmission reliability has suffered both in the UK and the USA from the requirement that the oil be common to both the transmission and the gas turbine. In practice, certainly in the UK, most helicopters do not, in fact, use a common oil. The UK helicopter industry is in sympathy with the logistic advantages of minimizing the number of oils stocked but feels that this could be more successfully achieved by adopting a single transmission oil for all NATO helicopters. It now appears that this is now being considered as a practical alternative on both sides of the Atlantic. In the UK, the Ministry of Defense has funded the successful development of a helicopter transmission oil in anticipation of such a move. The USA, after many years of being antagonistic towards separate gearbox and engine lubricants, is about to embark on a relevant oil development program. Another likely change is the move towards a higher temperature transmission oil, as the amount of external cooling is progressively removed. The British helicopter industry is engaged in developing new oils to meet this requirement.