Check your Heater Muff fasteners - Added locking hardware due to lost fasteners

[scottrsellers]

During engine inspection at a recent oil change we noticed a missing rivet on the pilot's side and a missing screw on the co-pilot's side per the below heater muff pics. Presumably this is due to vibration however our engine seems to run smoothly per the dynamic balance report in the Engine Talk section viewtopic.php?t=73. Due to lack of access(couldn't get rivet gun into place) we used machine a screw with locking nut on pilot's side and added flat & split washers to all screws on co-pilot's side to repair. Here's another good example of why close engine inspection at 25hr oil changes matters.
1st four pics are the co-pilot's side. Last shot is the pilot's side.