ON FURTHER USES OF SHOT PEENING IN THE AIRCRAFT REPAIR AND OVERHAUL FIELD

It is more than likely that a fair percentage of aircraft components are used within an environment that were not designed for it at the first place, consequently some defects may appear long before the expiry of the time between overhauls. Aircraft users may develop special repair and maintenance techniques suitable for their own particular environment. Reliability, effectiveness and airworthiness should not be affected by the adopted repair techniques. A successful exercise in this field may lead to important design aspects for the designers to bear in mind for this particular environ-ment. Another important issue in the A/C repair/overhaul business is the compulsory use of alternatives instead of the original item/material either because of availability problems or economical reasons. When the technical specifications of an alternative does not meet the genuine item/material specification endeavors should not be spared to promote the reliability of the alternative bearing in mind all the side effects of the techniques used in the course of doing that.
Along the lines of case No. 1 this paper will discuss the suceptibility to fretting corrosion of the oscillating races of helicopter hub bearings operating in a reactive environment; and how shot peening was used to decrease the suceptibility to fretting corrosion (false brinelling). For case No. 2 this paper will discuss the use of special shot peening technique to promote the bonding strength of the blade pockets to the helicopter blade spar when using an alternative bonding procedure and material.