The 822nd Lecture to be read before the Royal Aeronautical Society, “Progress Towards Hydraulic Serviceability,” was given by R. H. Bound, F.R.Ae.S., and H. G. Conway, F.R.Ae.S., on 15th March 1951 at the Institution of Civil Engineers, Great George Street, S.W.I. Major G. P. Bulman, C.B.E., F.R.Ae.S., President of the Society, presided at the meeting and introduced the lecturers, Mr. R. H. Bound, Technical Director of Dowty Equipment Ltd., and Mr. H. G. Conway, Technical Director of British Messier Ltd.

To be asked to prepare a paper for delivery to the Royal Aeronautical Society on the subject of the serviceability of a product with whose design the authors are closely associated, offers an excellent opportunity for a critical survey of the field, uninfluenced by commercial considerations and with the realisation that the admission of faults, where present, is essential for constructive consideration of the whole problem.

The hydraulic installation of an aircraft is now such an important and integral item of equipment that any steps which may be taken towards improved performance in serviceability would contribute notably to the operational success of transport and military aircraft. The degree of complexity required in modern aircraft hydraulic systems is such as to make impossible a completely fool-proof system. But consideration of factors which keep trouble within very small bounds is of vital importance.