In preparing this paper it was obvious to the writer, from a perusal of the titles of the other papers arranged for this meeting, that some of the subjects discussed will have been dealt with in some measure by previous speakers, as this paper also deals with the Westland-Sikorsky S-51 helicopter. Where such repetition occurs the writer tenders his apologies.

The Westland Sikorsky helicopter is well known in this country through its commercial activities over the past three years, and more recently its application to the Navy and R.A.F., whilst its American opposite, the Sikorsky S-51, has accumulated many thousands of flying hours to its credit, proving that the design has dependability and adaptability for the many roles of operation it has to meet. A close liaison between the American and British makers ensures the best possible service to all its operators.

The Westland-Sikorsky S-51 inherits to a large degree the same qualities as the American model, and in discussing its maintenance many of the practices used are common to both models.