Jur's RV7 Aircraft Factory
3497 hours and counting

Today I worked on the Dynon EGT "exhaust gas temperature" sensor.

These need to be installed by drilling a #30 hole in the exhaust tube and inserting the probe in the hole. The probe is held in place by a hardware clamp. You get the point looking at the image below.
Drilling into an exhaust is a bit scary at first but it is actually quite straightforward and easy. For each hole, I measured carefully, the with a punch marked the location on the tube and drilled a pilot hole with a very fine dril.
From there updrilled it #40, then #31 and finally reamed it with a #30 reamer.

Key is to make a nice round hole and have the probe just inserted in there without too much margin. This is an exhaust tube, co2 gasses are bursting out of these things and you don't want any leaks through this hole.

A hardware clamp delived with the probe is installed around the tube and then secured with double safety wire.

It is crucial for accurate reading that all probes are installed at exactly the same distance from the exhaust flange on the cylinder head. 

There are many articles and discussions on the location of the probes on the exhaust pipe. Dynon refers to the engine manual where in case of Lycoming they indicate 6 inch.
However, with bending pipes and curves everywhere, this is practically difficult to measure accuratly and most of the time one of the pipes has this distance in the middle of a bend.

Vetterman himself mentions 1.5 to 2 inch but I read somewhere that less than 2 inch significantly reduces the lifetime of the probes.

I checked all of my exhaust tubes, especially the ones with a bend near 2 inch and tried with a regular hardware clamp around the tube whether it would fit nicely on the exhaust pipe without nicking.

In my case, 2 inch was a good spot and I continued with that measurement on all pipes.
In the image below, you see where the 2 inch probe would end up and how the clamp still fits nicely  on the tube despite the curve starting just below it.

 The probe itself has a fixed position on the hardware clamp. When you position the location for drilling the hole keep in mind and check :

- the orientation of the probe itself. The probe is quite long so check the end wiring doesn't hit the bottom cowl.

- ensure that you can still access the nuts for thightning the exhaust flanges in front and behind

- ensure you can get to the spark plug. the clamp body is quite wide. (in the image the spark plug location is where I put the sillica plugs)

In my case, the best orientation for the probe was pointing out at a 45° angle backwards with the probe itself in the direction of the firewall.

 Then I measure with a metal ruler from the top of the exhaust flange down 2 inch. and marked the sweet spot. I started here at cylinder #4 (pilot side rear)

 Using the procedure of drilling described in the beginning of the article I soon had a nice round hole which I deburred and sanded smooth.

I remeasured each hole after it was drilled.As you see 2 inch right down the middle. Perfect !

With cylinder #2 also done, I installed the probes I thightened them down.

Dynon writes in it's manual : "Place sensor in exhaust manifold and secure it by tightening the clamp with a flathead screwdriver. Make sure the clamp is tight and provides a secure fit, but do not over-tighten such that visible stress is put on the pipe."

Now that's the kind of instructions I truly hate. Just give us a number for Christ's sake. I'm anal and I know it, I need a value. I don't have the same experience of Airplane mechanics who "feel" what thight enough is.

After some research I found that the Garmin G3X manual has same clamp type and states that the max torque value for their sensors is 35 in/lbs

Thank God !

I torqued mine all to 30 in/lbs

 Moving on to the passenger side cylinder #1 and #3
On this side , the sensors probes are oriented 45° forward towards the prop.

 Again did all the check of accessibility and maked the sweet spot at 2 inch. Then drilled the hole and reverified. Spot on !

 This is the exhaust on cylinder #3, the bend here is little too high already but with the hardware clamp very lightly rotated it clamps on well.

 Then moved on to cylinder #1. I already made the little punch mark for drilling in the left picture. Drilled at 2 inch in the right picture.

 Both probes installed.

Next step is to safety wire the clamp. I cut back all the excess hardware clamp ends and safety wired the clamp screw and the tail. 

The safety wire on the tail is hooked into the tail and twisted up to the probe and then additionaly twisted behind the probe.

The safety wire at the vise goes through the bottom opening in the clamp body, around the body and lays in the screw head notch.

EGT sensors done. All that is left to do is connect the wiring up to the Dynon EMS220 engine monitoring module.

Getting into some more systems installations. Today I installed the "sniffle valve".

The sniffle valve is a small, spring-loaded one-way drain valve installed at the lowest point of the induction manifold on the Superior IO-360 engine. When the engine is shut down, it opens to allow any accumulated fuel, oil, or condensation to drain from the intake plenum. As soon as the engine starts and manifold vacuum is created, the valve closes, preventing unfiltered air from entering the induction system. By removing excess liquid from the intake manifold, the sniffle valve helps prevent difficult starts, rough engine operation, induction backfires, and in extreme cases, the possibility of hydraulic lock caused by liquid entering a cylinder.

The location to install this valve is at the lowest point of the induction chamber. In my engine, the two plugs on the top here are entries to the induction chamber. This contains cold air that entered through the throttle/fuel servo.
The fuel could accumulate there after an engine shutdown and cause backfire that kills your airfilter and possible the entire induction system.Installing this simple valve gets rid of this fuel as soon as the engine stops and the vacuum in the induction chamber dissappears. The excess fuel is carried away through a aluminum tube the exist between the exhaust pipe exists.

The fuel will flow back and accumulate at the lowest point For aa 7A, you would choose the front port. Since I have a RV7 taildragger, my lowest point on the ground is on the second port circled in blue in the image below.

As said, a short flex hose followed by an aluminum tube carries the excess fuel to the cowling opening behind the firewall in between the exhaust tubes.
The aluminum tube is held with a single adel cushion clamp in the flange of the firewall. I located the hole so one of the nutplate ears is at the dead center of the lower firewall flange.
The hole of that ear is an existing rivet hole which i drilled out and used as reference for drilling the large center hole for the fastner and the other nutplate ear.
I could not just open the hole for a #12 screw as the existing hole was already dimpled. 

Drilling into the flange is always a bit critical so once I removed the existing center rivet. I made a template in a thick aluminum plate and clamped that to the bottom of the fuselage with one rivet inserted in the hole of hte nutplate ear.

 Drilled the #12 hole and other nutplate ear #40. It's never fun having to deburr holes when there is no access. The lower engine mount bar is seriously in the way of the lower flange and there is no way you can get a drill or deburr tool in there to clean the edges of the inside. So I had to use sandpaper to clean the edges here. Not easy with steel plate but it works.

Ok next problem... dimpling the new nutplate ear. A squeezer doesn't fit here and even the pop dimpler set couldn't get in there. Fortunatly I still have this #40 vise grip dimpler which just fit underneath.

Dimple done... not perfect but it will work fine. Dimpling multiple layers including steel after they have been assembled required a lot of force. I pushed the vise grip as hard as I could here.

 Rivetted the nutplate on. Ready to attach the sniffler valve tube.

 Then I started bending the aluminum line from the port to the firewall. and test fitted it with a clamp to the new nutplate. It's still too long here, it will be shortened in a bit.

 Here is how the line looks on the inside with the lower cowl on.Plenty of space. No risk of rubbing or touching.

 I temporarily taped the flex host to the port to get an indication of height below the port. The flex hose is attached to the tube and later on to the valve with hardware clamps.

 Finally I shortened the exist and bend it down a bit just behind the adel clamp.

 Finally I tried to install the valve in the engine. This is where the nightmare starts again. 
There was just no way I could get this plug removed from the engine. It's probably put in with locktite and even after heating the induction block and trying to remove it, I simply couldn't get any movement in it.
I had the impression my allen key started to get more play in plug hole. That is in principle difficult as the plug is steel and the engine case is aluminum. 
I think it's just the allen key wear out by the excessive force. But I'm not willing to take a risk here and will let Patrick at PMM wingservice remove this for me once the engine goes back for a test run.

Another perfect example how a job that sounds easy ends up in another uncompleted job and frustration.

A big day again in my project. Nothing substantially done but I have hung the propellor on the engine prop hub for the first time.
I kind of wanted an idea how everything would fit together and what is delivered by Catto with the propellor, spinner and saber extention.

I have a 4 inch Saber extention, spool type. This is required for the Sam James cowling installation.
It took a couple of tries to find the way to do this but it's pretty self explanatory once you understand things. The spinner is predrilled and cut and the holes in the spinner plate are also made with nutplates installed. This makes it pretty simple.

Short bolts hang the spool to the prop hub behind the starter flywheel. You bolt these in in a star pattern. I am just doing this temporarily so there is no torqueing involved yet. This will come of a zillion of times. The long bolts holding the propellor and everything forward of the spool extentions are very long. The threads also extend quite far through the extension. This is probably for having enough space if an additional weight plate has to be added up front.

Here is a view with the prop bolted on. This is pretty damned cool seeing this a first time.

Front picture.

Milestone day ! 
This is one of those days that you know mark the timeline of building your airplane. The moment you hang the engine in the engine mount.
After many days of thinking about missing any things on the firewall, I came to the conclusion that this is the right moment to hang the engine and move on to the firewall forward work. There are some more things I need to do on the firewall, but it's not possible to be sure about the exact location to drill large holes in the firewall until I can actually evaluate the position with the engine in place. i'm thinking of the mixture and throttle cable and alternate air cable. Other than those, I'm pretty sure everything on the firewall is in place.

The same thinking goes for the rear of the engine case. Make sure the 45° restrictor fitting for the oil pressure is mounted in the engine case prior to hanging the engine. It's almost impossible to install this once the engine is on the engine mount. Mine was already installed by PMM during engine assembly. While you are at it, also install the other oil cooler fittings in the engine case (in and out). These can also be done later but it's easier now.

First step was to remove the safety straps that held the engine to the wood pallet that was used for transport. I want to keep track of how this was done as this engine is a brand new engine that has not yet been on the test bench. When all is ready, I will need to unhook the engine and bring it to PMM Wingservice to have it running on the test bench for a first time. This has the disadvantage of extra work on removing the engine and all connections again and having to do it again after it has been run. On the other hand, the major advantage is that I do not have to worry about corrosion and idle time of the engine as it has not yet been running. The cylinders are as if they would be in a stock location on a bench waiting for an engine. There has been no movement of the cylinder heads on the cylinder walls and everything has an oil film on it as delivered from Superior Air Parts. Whether building takes me another 3 years or just 1, it won't matter. I'm gladly willing to take that extra work knowing there is no pressure.

The engine was protected well on the front and rear crankcase and supported in the front under the front with some wood block supports. I'll have to keep all this in stock so that I can re use it in the same way when I bring the engine back to PMM.

Using the engine hoist, we pulled it up, removed the pallet and moved it over to the front of the airplane. Alain helped me on this task to keep the engine in position. It's best having some extra hands around when you do this as the engine is heavy and the bolts are not always willing to go in as easy as you think it would. 

The last part of the moving is the most critical as you don't want your magneto's or fuel pump to bump into the engine mount. Having one person moving and another one guiding the engine is no luxury.

Also notice I leveled the airplane in flight mode. This is much easier to position the engine than if it would be sitting on all tyres which would require you to position the engine at an angle. This leveled way makes it much easier.

I found some documentation online from someone who did this before and described the process. I studied this carefully and upfront, had a close look at the barry mounts and dyna bolt set. You can read it following this link https://www.myrv14.com/buildlog/20150917/Engine_Hanging.pdf. Vans Aircraft also has some drawings available which are not part of the standard plan set that you receive with the kit. 

Study the plans carefully, the barry mounts have to be positioned so that the engine rests on the compression side in the bottom and the compression side in the back on the top mounts. The compression barry mounts are the ones that have a step in the rubber. The non compression ones don't have the ribble on it and look like plain rubber. If I remember well, the non compression ones also are a little larger. Also take care that the washers are in the correct locations. The barry mounts come with one big washer in the box. It's good to assemble the order of all this before starting to move the engine and have thing prepared well. I colored the position of the large washer red in the picture above.

There are 2 lengths in the dyna bolt kit. 2 x AN7-43A and 2 x AN7-44A. The longer ones go on the bottom side, the shorter ones go on the top. The difference is not much more than the length of one of the washers.

Start with the 2 top bolts. The first one is very easy... tighten the bolt but don't torque it yet, you'll probably have to loosen them again working on the bottom bolts.
You do need to tighten the first so that the barry mounts compress allowing the other hole to come in line with the engine case. Remember this is a dynafocal mount, the bolts point inwards. If the bolt is not tightened enough on one side, it's impossible to insert the second one. As you tighten the bolts, the barry mounts compress and also position themselves in the engine mount. That's important.

What I found very annoying is that you can't put a socket on the bolt head as the engine mount is in the way.  I used an extension on the wrench but that didn't make it easier.

The engine sometimes needs a bit of persuasion to get it in position :) Although I don't think this did much. Found out later it's more important to tigthen the other side and use the engine hoist to lower or lift the engine a bit in order to get a bolt in.

The large washer goes between the compression mount and the crankcase as a spacer for the bottom mounts. On the top mounts, I have put that washer on the compression mounts under the bolt head as you can see in the image below. The image has both top bolts in place and tightened.

From there on, things went less smooth and it took about an hour or 2 before I got the last bolt in so I did not take any more pictures until it was done.

I'll try to describe the further process I took.

As both top bolts were tightened, I lifted the engine a bit using the engine hoist. This allowed me to slip the barry mounts between the case and the engine mount. Don't forget the large washer between the barry cookie and the engine case. Don't forget the compression side of the barry mounts is against the engine for the bottom mounts. Then I lowered the engine again and after some wiggling I was able to put the 3rd bolt in. I did have to loosen the top bolts a bit though. 

The fourth bolt is the most difficult one. Looking with a mirror through the hole there was no way the bolt would go in. After a lot of moving up and down, I finally discovered my problem : the washer between the barry mount and the engine case was not aligned and the pressure on it is high enough that it makes it hard to move it. After lifting the engine a bit and tapping on it, I could get it more or less into place. 
A second trick I used was to take an old bolt which was smaller in size and grind down into a guide pin. Once I could slide that smaller bolt in, I was able to wiggle it around in order to get that washer and the engine hole into alignment. I put some grease on the final bolt shank and finally was able to put it in with only very light tapping of a rubber hammer.

I was feeling relieved as I bolted the final nut on that fourth bolt.

As final step, I torqued the bolts. These are AN7 which take 450 - 500 inch/lbs. I used the middle value of 480 inch/lbs. The engine will still need to come off as mentioned earlier but the position of the engine is very important when installing the cowling so I torqued it to the final value.

Took some pictures of the plane with the engine in place. This surely is a big milestone and is a "feel good" moment during the build.

Happy camper...

As I had some time left, I took out the fuel throttle body. This comes with a plastic spacer.

The orientation of the throttle body was a bit of a mystery at first but soon figured out what side was the throttle lever and which side the mixture. 
In the image below I installed it on the forward horizontal induction air intake at the cold sump of the engine. In the image below, the throttle lever is the gold colored arm.

Finally I covered the intake with some paper and masking tape in order not to get foreign objects entering the engine.

End of a productive day was off course celebrated with Alain with a good strong Belgian HQ beer.