T&B -- props could well be your dad's downfall. When visiting New Zealand in 2001 I was invited to an aircrew reunion at which no participant was under 77 and many were deaf. The latter were ex-Catalina pilots who explained they had spent hundreds of hours only a few feet below the prop tips -- plus the pair of Twin Wasps which drove them. The reunion chit-chat was almost as noisy despite their hearing aids ... I felt privileged to meet such a wonderful bunch of people.