Regarding titanium helicopter tail rotor parts that are peened: Is there reason to suspect that with exposure to cyclic stress the peen is somehow becoming ineffective? The reason I ask is Sikorsky has a requirement (albeit a very old requirement) to re-peen every 2000 flight hours. These are the load-bearing parts of the tail rotor head (hub, blade grips, etc), mostly exposed to varying magnitudes of tensile and bending stress. I could understand if there was exposure to high temperatures, but in this case there is not. Is there any guidance on the subject?
