Sunday, June 20, 2021

It Flies!!

Edit:  Here is a link to the video I compiled from all the cameras.

 This is just a quick post to let everybody know that N88DA has taken to the skies!  On Saturday morning the 19th of June, 2021 at about 10AM the airplane broke ground for the first time.  She flew beautifully with no trim changes, no heavy wing, and nothing less than a smooth climb.  As expected I did get some high CHT values but with a slight reduction in power and RPM I was able to limit the highest to 421 and even then only 3 of the 6 cylinders broke 400 degrees.  As soon as I leveled out all temps dropped nicely and I had no more issues with temps.  The oil temps never got above 185 during the entire flight and that's with prop and throttle at max.  I'm happy with how the engine is cooling so far.  Airspeed and altimeter tested out perfectly against Harry's chase plane.  The fuel flow is off considerably but that's to be expected and is an easy correction on my next fuel up.

The airplane is a dream to fly but its definitely on the heavy side for controls compared to all the other RV models I have flown.  You actually have to push the stick instead of just thinking about it.  :-)

I had one surprise during the flight, and that was the huge amount of aft stick needed to land.  My approach was over the dump and that always has a bit of updraft followed by a significant down draft on short final.  My approach was on target but I found that was almost unable to arrest the decent in time because the control stick was full aft and bumping into my belly!  The landing was actually pretty good but it was very close to being a bouncer.

I have a few squawks (issues) that need addressing.  One was discovered on flight three today.  The prop control cycles just fine on the ground but in flight there is enough wind pressure on the cowling that it pushes it aft enough to block the governor control movement such that I can't bring the prop down below 2350 RPM.  I should have that one taken care of in time for the next flight.

I also had some oil door issues.  Most people have their oil door pop open on the first flight, and I knew that, so I reinforced the door so the latch would not flex.  However, I did not reinforce the corners opposite the hinge and as a result those corners were bulging up due to the extreme air pressure in the cowling.  Nothing that a little duct tape couldn't cure for flights two and three.  :-)

I'm still chasing a couple of minor oil leaks and one grease leak from the starter.  Otherwise the engine seems to be in good condition.

Oh, I should mention that on the runup for the first flight my coil (MAG) check failed on the right side (bottom plugs).  This required a taxi back to the hangar where a simple cleaning of the plugs resolved the issue.  Too much very rich run time on the ground.  However, I mention this not only as a warning to others but also to let you know that I had great plans for lots of video of the first flight.  Well, I did get good video but not from inside the airplane.  In fact I had a 360 camera set up on the VS top as well as a GoPro camera installed in the cockpit.  The 360 camera only caught the initial taxi out to the runup and the interior camera I forgot to turn on until I was already airborne and doing my initial circuits of the airport.  Oh well, I had a few people there and still got some video so hopefully I will have a video to share in the near future.

A big thanks to the ground and flight crew for the day!  

  • Harry, chase plane pilot
  • Ben, the ground crew and videographer
  • Randy the flight photographer and note taker
  • Bob the ground crew car driver

Ok, on to a few pictures of the day.

Monday, June 14, 2021

The last N88DA build phase (planned) update

As the title says I expect this to be the last update on the build phase for N88DA.  This past week I have managed (with lots of help) to get all of the build phase tasks complete.  That list includes things like resolving the leak on the oil filter adapter.  That leak turned out to be an interesting one...the oil filter housing itself had a microscopic crack near the upper outboard bolt hole.  The only way to see it was to watch it very closely with a light and a mirror when oil pressure came up.  Then you could see it seep out of what looked like a tiny line about 1/8" long and very thin.  After replacing the oil filter adapter the oil leak was gone!

In addition I was able to finish up the wing tips, wire up the landing, position, strobe lights and get all of the required bulkheads and fairings installed.  Last Sunday I took her out to the runway (first time moving on her own power!) and did a brake burn in.  That was a bit challenging because I did not want the CHT's to exceed 350 degrees.  I sure wish I had recorded the run because that 540 really sounds amazing and is soooo smooth.  Can't wait to run it up for the first flight.

So, if all goes as planned this is it....its on to phase 1 and flight testing.  That's certainly not the end of the build process though...there are hundreds of hours of finish work ahead so stay tuned.  Besides...I'm already planning my next build.... ;-)

I will leave you with this photo...its N88DA as she sits waiting for first flight!

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.