Saturday, October 15, 2016

A Week Of Minor Setbacks

Earlier in the week on Tuesday evening Mike T. was at the airport watching his mechanic perform an annual on his airplane and we got to talking about things left to do prior to a first flight and conditioning the brakes was one of the items still left to do. After Mike’s mechanic decided to call it quits for the evening to resume the following morning, Mike gave me a hand temporarily installing the upper forward fuselage skin with a few screws.

It was getting late (almost dusk) and we felt it was a good time to make Banzai taxi runs up and down the taxiway because the likelihood of having other taxing aircraft to contend with would be slim to none at that hour.  The goal for the evening was to condition the RV-12’s brakes as suggested in the Matco brake manual. The DOG Aviation RV-12 was rolled out of the hangar and started. After letting the oil temperature warm up, two fast taxi runs were performed along the long taxiway adjacent to the hangers while dragging the brakes the whole way in an effort to heat them up as suggested in the Matco manual.

After the high speed taxi/brake conditioning was completed, the airplane is to sit for at least 15 minutes to let the brakes cool. By the time the brakes cooled it was, for the most part, getting dark so decided to roll the RV-12 back into the hangar. After hooking up the tow bar and about to push the RV-12 back into the hangar, I noticed the S-1207 bushing was missing from the nose cone. This is the bushing that the pitot tube pokes through on the tip of the spinner …. what the heck? !!! .

Yep, the bushing was flat out missing. The bushing is glued in place using blue Locktite 242 which, at the time I thought was odd, but that is what Van’s calls for in the plans … guessing to make the bushing easily replaceable. Thus far, I have not heard of any RV-12’s losing the S-1207 bushing, so guess this is unique to me. I know I followed the directions precisely and roughed up the mating surfaces with coarse sandpaper as instructed, and even cleaned the mating surfaces with both Acetone and Isopropyl alcohol prior to assembly.

Of course, by now it was totally dark outside and while Mike used his golf cart with lights on to run up and down the taxi area, I was walking around with a flashlight. At one point, I also had a car following me with its brights on and we just could not locate the bushing. So I decided I would call Van’s in the following morning and have a couple of bushings overnighted … so if it happens again, I will have a spare (they are inexpensive $6 each). So prior to heading to the hangar the following morning, a call was placed to Van’s and the two bushings were ordered for overnight delivery.

As luck would have it, the next morning Mike rolled his airplane outside to warm it up for a compression test and his mechanic noticed this strange looking round object on the asphalt and said to Mike “look at this strange looking thing I just found here on the asphalt”. Mike told him it was the bushing from my airplane that we were looking for the previous evening.
The recovered S-1207 bushing that came out of the RV-12’s spinner. Amazingly, it does not look as though it suffered any damage whatsoever. Even so, I will replace it with a new bushings.

I have decided to NOT use Loctite 242 to secure the replacement bushing onto the spinner. I figure the bushing will not come out on its own if I use a glue that is a bit more tenacious.  Silicone was considered briefly, but if the spinner is to be painted, the silicone will certainly guarantee a problem getting the paint to stick in that area. Finally decided to use fuel tank sealant. Granted, it will make replacing the bushing much more of a challenge if it ever needs to be replaced … but I don’t care. The main thing is it will not be parting company with the spinner on its own accord anytime soon … theoretically at least. After scuffing up the bushing with coarse sandpaper, I mixed up a small batch of fuel tank sealant.

I did not get crazy with the fuel tank sealant, just placed a very thin film on the bushing and under the lip on the bushing. Also placed a very thin film of the tank sealant on the inside of the hole in the spinner (this may have been a bad idea from the standpoint of easy removal). After pressing the S-1207 bushing into the tip of the spinner, the tank sealant was spread along the base of the inside of the spinner and then up onto the side of the bushing … theoretically, this should prevent the S-1207 bushing from backing out unless the tank sealant is cut away from the sides of the bushing.
We have been having some cold nights here at DOG Aviation so brought the spinner home so the fuel tank sealant can cure where it is warmer. The S-1207 bushing set on the S-1201 spinner in a thin bed of fuel tank sealant.
The inside of the S-1201 spinner with fuel tank sealant spread around the base of the hole in the spinner and up onto the side of the bushing to keep it in place.

The other setback, which was totally my fault, was breaking one of the vacuum gauges used for balancing the carburetors on the Rotax engine. Yep, dropped it Wednesday while going to a different length of mounting screw and really hosed it up bigtime. Had it sitting on my leg while sizing a screw and it slid off onto the hangar floor and broke the glass cover, along with displacing the movement internally so badly, the gauge is unusable. Fortunately, I was able to find a supplier that had the gauge in stock and had it shipped to me and received it yesterday … so it should not hold up progress. I do want to give the fuel tank sealant two full days to cure, so will not attempt starting the engine until Sunday at the earliest … but Sunday is forecasted to be a rainy day, so may have a little weather delay thrown into the mix as well.

The only shining light of the week … the Dynon 470 ADS-B unit was received back from Dynon late yesterday evening. Dynon gave me an exchange unit under the warranty rather than having me wait for the one I sent in to get repaired. So the project for later today is to install the ADS-B unit and hope it works like it should.