Archive for March, 2010

Primer, Manifold Pressure, Adel Clamps

My new-style ECI O-200 pistons have primer ports on each cylinder. I decided to go ahead and prime at the cylinder rather than just north of the carburetor in the intake spider. Updraft carbs are somewhat notorious for the possibility of an engine fire due to over-priming. I think it’s a little less likely when the prime is going directly to the cylinder. I’m going to prime 2 cylinders and then use another primer port for a line to my manifold pressure transducer.

Rather than cluttering up my firewall, I decided to mount my manifold pressure transducer using an Adel clamp on my engine mount. I’ve used Adel clams for a few things here and there in the past and have always cussed how hard it is to get them lined up and the bolts installed. Trying to get two clamps lined up is darned near impossible. I purchased this special modified vice grip tool specifically designed for Adel clamps. It comes with an awl that you use to get the holes aligned. Once the awl is in place, you use the vice grip tool with its forked jaws to squeeze everything together and hold it in place while you remove the awl and replace it with a bolt. It works VERY well and is worth the ~$30 it cost me!

This is an overhead shot of my primer lines running from a T-fitting to 2 cylinders. The other copper line you see at the lower left of the picture is a manifold pressure input to my manifold pressure transducer. I haven’t run the primer input line to the T at this point.

I started working with my firewall pass-throughs today. The firewall has a few extra holes in it from the original builder. I’ll do my best to make use of existing holes with the idea that I’ll cover them once all my pass-throughs are complete.

I received my Aircraft Spruce order containing the steel fittings for my fuel flow transducer. JPI spec’d steel fittings so who am I to question the experts. They cited a concern for galling problems with aluminum AN fittings. It’s hard to tell in this picture, but I managed to break the glue bond on my transducer bracket where it is [supposed] to be attached to the oil tank. The failure mode was interesting in that it basically sheared between layers of paint. The good news is that once I installed the hoses, the bracket is pretty much held in the same place as if it were glued. I’m going to re-glue it using a fresh batch of JB Weld. I’m kind of wondering if my original attempt was hampered by an old, less-effective, tube of JB Weld.

Aircraft Spruce Order Arrives

No pictures today, but I’m happy to say that when I arrived back in town from flying a 3-day trip, I found a good-sized Aircraft Spruce order waiting for me. Woo, hoo!

I’ve now got plenty of things to keep me busy for a few days of hangar work. Unfortunately, I’ve got 4 days until I have to go fly another trip and 2 of those 4 days are filled with recurrent ground school down in Denver. Bummer. This working for a living is really getting in the way of progress!

The ACS order contained my carb heat cable, parking brake cable and mixture cable. I also ordered a bunch of those firewall eyeball-style pass-through fittings. Boy, those things sure are expensive. At $30-something apiece, I’ve got $250+ invested in pass-throughs. I guess if I ever have an engine fire I’ll appreciate spending a few extra bucks.

I also received a bunch of different fittings to allow me to plumb my primer system and my manifold pressure line to the manifold pressure transducer. It should be fun trying to solder that 1/8″ copper tubing. Everybody says it isn’t too difficult, but I ordered extras of everything assuming I’ll screw up at least a little bit.

I’m going out to the airport tomorrow (Monday) for most of the day. I won’t be out there much at all on Tuesday and Wednesday because of ground school. I should be able to get in a pretty full day on Thursday before going back to work on Friday. I have a similar schedule next week, with the 2 days of recurrent ground school replaced by 2 days of Proficiency Training in the simulator. I go out of town again on Friday of that week.

The great news is that I worked my 1 week vacation in April such that I am completely off work between April 5th and April 22nd. I’m hoping to make some serious progress and maybe even get the engine started during that period. I think I’m getting close.

I should have pictures tomorrow! I’ve been up since 2:30am Colorado time this morning so even though it’s only 9:30pm, I’m headed to bed. Talk to you all tomorrow.

Firewall Forward Electrical

I installed the battery box today. I purchased the battery box from a place down in Denver called Portable Power Systems. I can’t believe I’ve had it for about 2-1/2 years. It seems like just yesterday… In any case, it’s a standard Odyssey 680 battery box, but I’ve modified it by adding all the lightening holes.

I used a Greenlee punch to make the holes. I then painted what was left of the box with yellow engine paint and baked it in my oven… because that’s where single guys bake their airplane parts! I installed the box against the firewall using a total of 6 floating nutplates. It turned out to be very accessible and shouldn’t get in the way of the day-to-day maintenance like an oil change. FYI, the battery in the picture is actually “borrowed” from my motorcycle. It’s the same size as an Odyssey 680, but it’s not exactly the same battery.

I just kept going today after I finished with the battery box. I installed 4 more floating nutplates to mount the master solenoid and the starter solenoid. I can’t claim to know much about solenoids so I asked a friend a few questions and then tested the units with my multimeter and a spare battery. I discovered that the master solenoid is triggered with a ground lead while the starter solenoid is triggered by 12 volts, positive. Bummer… because I planned my wire runs assuming both were triggered by a ground wire. Hmm.

Luckily, I had a 12 volt lead running to the instrument panel switches that I had planned to use for a boost pump. I ended up abandoning the idea of the boost pump so I used its 12 volt lead as power to the switch instead of the ground lead I had originally planned to attach to the switch. It actually turned out to be a pretty easy swap.

I’m a pretty big fan of trying things out as I go along. It’s probably a waste of time, but I’m actually pretty motivated by seeing things work! I first connected test leads to the solenoids and tried out the master switch and starter button logic. Everything checked out so I lit up the rest of the airplane. It was pretty cool to see the GPS, fuel totalizer, Comm radio and compass light come on.

I even tried out the red/green nav lights and strobe. Everything worked as I had hoped. My nav lights are turned on with a button on my control stick and the strobes have a switch on the panel. The instrument panel lighting and backlight for my comm radio come on with the position lights. These position lights are LED and draw almost no power.

This is a view of what’s lurking under my seat pan. I’ve got a bus bar under there that distributes power and ground to things that are in the aft part of the airframe. I used a DB connector for my multifunction stick grip.

Here’s a close up of the connections under the seat. The little black box is a reverser relay sold by the Ray Allen Company, the same folks who sell the little electric servo I’m using for my elevator trim.

Firewall Forward Electrical Connections

Dave Cook loaned me this “spoon” tool. It works great to thread an additional wire into a harness that’s already been tied together. It seems like there’s always room for another wire with this little baby. Good thing, because I failed to include a wire to power my manifold pressure transducer. I really dreaded the process of adding a single 22 gauge wire to my completed harness, but once I got started it wasn’t bad at all. I think it only took me about 10 minutes.

I’m trying to make everything I’m doing easy to work on in the future. I want to be able to troubleshoot and replace components without tearing everything apart. To this end, I used crimp-on DB connector pins to join the wires for my manifold pressure transducer. This way, if the transducer ever needs to be replaced, I can just remove the shrink wrap and unplug the sensor. These little babies are cool, but not cheap. They are the solid, very high quality variety and require a special tool to make the crimp. They’re also a tad expensive at 25 cents per piece.

Here are the DB connectors joined. I’ll add shrink wrap over the connections when I do the final installation and button-up.

Breakfast in Grandby

Dave Cook is a friend of mine who’s built a total of 3 RV’s so far. His most recent creation is an RV-7A. He still owns his RV-6. It’s probably for sale so if anyone is looking for an RV-6, let me know and I’ll put you in contact with Dave.

Dave grew up in Grandby and still owns a house and a little bit of land up there. He flies over the hill almost every Tuesday morning for breakfast with his flying buddies. This week, he invited me to tag along. [He won’t be able to avoid having me along once my Midget Mustang is flying!]

This is the whole gang posing for a picture at the Grand River Inn restaurant along the shore of Grandby Lake. They move around to different restaurants each week as the mood strikes them. This particular restaurant isn’t too far from Dave’s house so we stopped by and picked up a few things before we headed back to the airport for the 25 minute flight home.

This is the view from Dave’s driveway. He looks out over 5400 acres that his family used to own. The new owner sold a conservation easement on 900 acres closest to Dave’s house, so most of what you see in this picture will never be developed in any way. Not too shabby.

Routing all the Firewall Forward Stuff

Honestly, I just didn’t know where to start on the firewall forward. So I just started! I decided that the control cables were probably the least flexible of all the things I’ll need to install so I started with them thinking that the wiring can work around the cables. I’m using wax string for now just to tie things in place for fitting. I’ll use Adel clamps for the final installation.

I used the old throttle cable to determine placement for the new throttle cable. I’m not wild about the angle from the cable mounting point to the throttle linkage, but this is the way it’s done on every O-200 installation I could find so I decided to just go with it. The problem is that the oil tank sits directly aft of the throttle linkage so it’s pretty much impossible to get a straight shot at the linkage.

The mixture control is set up to be lean when the linkage is pulled to the right and rich when it is pushed to the left. As a result the mixture cable had to take a circuitous route to the linkage. I’ve just tied it in place for now to get an approximate location and routing. Since I only have one cable to use for fitting purposes, I used a length of aluminum tubing to verify that the throttle cable won’t interfere with the mixture cable as they cross. In fact, I’ll probably tie the two cables together where they cross. It should stiffen up the whole installation.