Monday, May 2, 2016

Lower Cowling Half Sanded & Test Fitted

With the aid of friend Bernie, the lower cowling was held up against the firewall and it was determined that if the aft edges of the cowling were sanded down to the scribe marks, the fit of the cowling should be in the ball park. Prior to test fitting the lower cowling, the spinner back plate was mounted with temporary hardware so a visual could be obtained to check for both centering of the cowling and clearances between the  spinner back plate and the cowling.
The spinner backing plate is temporarily installed with temporary hardware for the test fitting.

Between rain showers, the afternoon was spent hand sanding the last 1/8" of fiberglass down to the edge of the scribe marks on the fiberglass. Of course, there are places where the scribe line is very difficult to see and there was one area on the right side that there appeared to be multiple markings for “the line” so only sanded to the first marks.

After spending the afternoon sanding and sanding, Bernie helped me position the lower cowling half on the RV-12. For the test fitting, the hinge pieces are installed and secured with the hinge pins and the lower cowling section is set in place so the “tab” on the cowling sits flat on the fuselage side skin and the aft portion of the cowling butts up against the firewall and follows the curve of the fuselage. Once in position the lower cowling is secured to the upper hinges with clamps.
The lower cowling is held in place with the C clamp my finger is pointing towards … there is one clamp on either side holding the cowling. The overall fit looks quite good, although there are a couple of places on each side that need a swipe or two of sandpaper to improve the fit. There needs to be at least 1/8" of clearance between the back plate and the cowling. This is a bad camera angle but it appeared that is approximately where it is at.

Just for the heck of it and to check how close the scribe marks were to being correct, the upper cowling was set in place. Even though it was touching the clamps and not fully in position it was possible to discern that if trimmed to about the trim line the overall fit would be seemingly OK.
Bernie giving me a hand in positioning the upper cowling so the scribe marks were approximately at the edge of the fuselage skin. Overall the fit looks great.