The engine mount agony! This started with the first
mount I obtained with my reduction drive. This is the one
shown below. This one was perfect in principle, but did not allow me
to install the radiator inside the cowling. I needed a mount that
puts the engine at least 2" more forward. So, I asked Dave to
make another one for me.
I received a second mount that was similar to the first one in design
and allowed me to install the radiator behind the engine. However,
there were some problems with that mount.... the trust line was not what I
wanted (pitch up 3 degrees-if I remember). While it is within
specifications (0 degree +- 5 degrees as per the plans), I did not like
the look at all. So, I showed it to some local
"experts". They said that the design is not appropriate...
an aircraft engine mount usually has 1 post supported by three tubes, 1
post supported by two tubes and two by only one tube (see T. Bingelis,
Firewall Forward, p. 78). So, I gave the "go" to modify it
so it is like that! See below...
On the day I thought Zulu Golf Quebec was ready for first flight (June
13, 2004), I discovered a problem. I was looking at my gascolator
and saw that my right side exhaust pipe touched the firewall
fairing! I put an entry in the Journey and the Airframe logs saying
"... This aircraft is not serviceable." NOT
The engine mount modification that I had done was wrong! Sh.t! As
you see it above, the upper arms are going down at a steep angle.
What happens is that as force is applied, these arms can flex up and down
easily. We quickly pin-pointed the issue to the engine
mount.... The original design was the right one! :(
Imagine... more than 375 hours to rebuild and install that engine... and I
may have to remove it...
I called someone who does a lot of stuff for homebuilders including
design and repair, assistance and also does welding for a kit
manufacturer. He looked at this and found a way to fix it without
removing the engine and engine mount. He modified the design (again)
so that the upper arms will attach directly to the reduction drive instead
of to the cylinder heads. Several friends have that arrangement and
it works fine.
So, after he machined some attachment blocs, we spent a day at the
airport to make the modification. (see below). One evening
later, on June 24th at 1H37am, C-GZGQ was again "serviceable".
The installation is now nice looking (better than it was). I'm
more confident in this type of engine mount and as of June 24, 2004, I
can't wait to see this plane flying!