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