oil change and general inspection, 1000 hrs

[A2022]

some photos. the oil filter drain works well, no mess. carb heat mechanism looks good at 1000 hrs, pristine actually, all original. I cleaned the air filter in place and did not remove it. this is a simple machine. no complicated electronics.

[A2022]

the airbox brace failed at 1000 hrs. I have the original thin airbox plate, so I originally braced it with alum 3/8-inch OD tube smashed on the ends. this is not an ideal mechanical design but rather quick and dirty. I was surprised it lasted so long. I decided to stay with the design and changed to SS tube and 1/2-inch OD. SS is a lot better for fatigue, so I believe this one will go to 3000 hrs. it only took 1 hr to fab since I had the original, so not too bad. what you want is the brace to be a nested fit with no stress (deflection) of the top plate when installed. in this way the assembled fit is in a stress-free condition. I believe the primary stress on this part occurs when you remove and install the cowl. this is the first structural part I have needed to replace. while not the optimum mechanical design (smashed and bent tube) it is compact, smooth, really stiffens the airbox and should allow for 3000 flt hrs.

[bullojm1]

This is my solution and it seems to be holding up for about 500 hours now.

[A2022]

the weird thing for me, I was hearing some unknown buzzing or unusual wind noise for the past 5 flights, something. could it have been the airbox brace had failed 5 flights before? maybe... after the brace replacement the unusual noise was gone. Mike's brace is easier to fit in a stress-free condition by drilling in place and then riveting, but mine is shiny-er.