jsharkey
Well Known Member
During my last pre-flight walk around I noticed some missing rivet heads on the inboard end of one of the lower cowl hinges. Knowing that this is a weak area I removed the lower cowl with the intention of replacing the rivets and making some kind of a link that more effectively secures the exhaust outlet area of the cowl to the fire wall or engine frame.
Further investigation uncovered broken hinge loops on the other side of the aircraft, but sound rivets, and some local scorching of the inner surface of the cowl under the exhaust on the LHS where it passes close to the corner between the main cowl and the carb scoop.
I sanded off the scorched material and reinforced the area with a wet layup of glass fiber and epoxy resin before covering it with aluminum foil tape in the hope of adding some heat resistance. When I did a trial fit of the cowl I noticed that the tail pipes seemed very flexible and realized that the screws that join tail pipe supports to the engine sump were missing on both sides allowing the exhaust to drop slightly. I had initially assumed that this was due to overall engine drop as the AV mounts bedded in. Never assume.
Anyone else experienced this? And how did you better secure the supports to the sump? Wired drilled head bolts?
Also any ideas for better securing the lower cowl? I am thinking about fitting Adel clamps around the lower transverse engine mount tube (will they fit?) and then using these to connect to angle stock links that screw to the vertical cheek of the exhaust outlet of the cowl.
PS - Interesting how one fault discovered on a walk around lead to finding more which goes to show that you shouldn't ignore anything.
Jim Sharkey
RV-6 TT60hr
Further investigation uncovered broken hinge loops on the other side of the aircraft, but sound rivets, and some local scorching of the inner surface of the cowl under the exhaust on the LHS where it passes close to the corner between the main cowl and the carb scoop.
I sanded off the scorched material and reinforced the area with a wet layup of glass fiber and epoxy resin before covering it with aluminum foil tape in the hope of adding some heat resistance. When I did a trial fit of the cowl I noticed that the tail pipes seemed very flexible and realized that the screws that join tail pipe supports to the engine sump were missing on both sides allowing the exhaust to drop slightly. I had initially assumed that this was due to overall engine drop as the AV mounts bedded in. Never assume.
Anyone else experienced this? And how did you better secure the supports to the sump? Wired drilled head bolts?
Also any ideas for better securing the lower cowl? I am thinking about fitting Adel clamps around the lower transverse engine mount tube (will they fit?) and then using these to connect to angle stock links that screw to the vertical cheek of the exhaust outlet of the cowl.
PS - Interesting how one fault discovered on a walk around lead to finding more which goes to show that you shouldn't ignore anything.
Jim Sharkey
RV-6 TT60hr