Wednesday, June 9, 2021

Not quite there ....

I've got a surprising number of people reaching out to me to see if I have flown the 10 yet....and unfortunately I'm still working on a few issues that I want resolved before it flies.  From a readiness perspective I am just about there.  Last Tuesday N88DA became an official airplane through the blessing of Charlie Cotton (and 4 of his closest FAA friends).  AKA... I got my air worthiness certificate.  

As I mentioned in my last blog update I ran the engine for the first time and during that run we detected the oil leak at the oil filter adapter.  Well, it turns out that the two small dings in the mounting pad were not the source of the leak.  We tried several different methods of sealing the leak (about 5 gaskets worth!)  In the end I asked Harry to hop in the airplane and start it while I was looking at the exact spot where the oil leak was occurring.  What I saw was a bit of a surprise...there was oil coming out of a very small, almost invisible, crack in the oil filter adapter housing.  It was near the upper outboard bolt hole and when the engine was running you could see oil seeping out of the crack.  A new adapter should be arriving in the next couple of days and that will hopefully be the last of the issues to resolve before first flight.

In the past week I have fixed a number of small issues that came up after completing the assembly process.  One of those issues was related to the LRU's (Garmin Line replaceable units) that I installed in the tail cone.  The Magnetometer, Pitch AP servo, and the Yaw servo were showing up on the EFIS as 100% data failure on the CAN bus.  I then started trouble shooting one device at a time starting with the Magnetometer at one end of the bus and working my way to the other end of the bus (Roll AP Servo). What I found was a bit frustrating!!!  I had forgot to install the termination jumper on the Roll AP the exact opposite end of the bus!  Once I installed that jumper everything came online as it was supposed to.  

I also found a couple of wires swapped on the tail light that was a simple fix.  I will say that I am glad that today's electronics are so well protected from installer stupidity!

Finally, during my air worthiness inspection Charlie mentioned that the elevator trim did not look like it was operating to full extents.  The issue was that I had what appeared to be full nose up trim but the trim tabs only moved up to being in trail for full nose down trim.  I spent a significant amount of time troubleshooting and researching, including a call to Vans support, only to find that I had installed the wrong Servo.  A couple of years ago I had purchased an extra trim servo to use as a rudder trim servo.  In the mean time I had decided to try something different for rudder trim and didn't use the servo.  Come time to install the elevator trim mechanisms I had two servo's and the instructions don't tell you which one is correct so 50/50/90 I chose the wrong one.  After installing the correct servo (a huge project) I now have full elevator trim movement.

The next step is to prepare the weakest part of the project....the test pilot.  Time to get my pilot brain back to full fitness and then its time.....

Charlie (left) going over my operating instructions with me.  The guy on the left is one of the 4 other FAA guys that came along to observe the EAB certification process.

See the servo (black box) T2-7A?  That's the wrong servo for the elevator trim.  This picture is taken by reaching down into the tail from the far aft end.  Its almost impossible to see unless you crawl down the tail and that is a painful process.  But this picture combined with the one below is how I discovered I had the wrong servo installed.

In this picture you see the servo in its full extension mode.  If you look closely you will see that the servo cable that is visible is not in the position required for full extension.  That bolt attachment should actually be below the level of the mount plate.  This tells me that the servo was not extending far enough.  The T2-7A servo has about 3/4" of travel where as the T3 servo that is the correct servo has about 1.25" of travel.