That is right, today was the first day I could work with the overhead door open in the shop. There have been other days with the temperature high enough, but I was either gone, or it was too windy. Man is it nice to ‘be outside’ while working. 🙂
Just after opening up the garage door, brown santa arrived…. You know, the UPS Guy with my Earl’s Performoflex hoses and fittings. These were the recommended new technology over the aeroquip fabric/rubber hoses. Boy am I glad that I changed. These hoses are a joy to work with, much easier to assemble than the aeroquip.
The process to fabricate a hose is very similar to the aeroquip process, but easier as things fit better. Also, there is no need for an assembly mandrel as it is pretty much incorporated into the fittings. I used the former aeroquip oil cooler line to cut a new section of Earl’s hose to the right length. The same method, tape the outside before cutting, applies to prevent the stainless braid from fraying. Note that in this photo you can see the fire sleeve installed as well to protect the oil line in the event of an engine fire. As James told me, the pilot can cut off the fuel, but not the oil, so protect the lines.
I forgot to take photos of each of the steps of adding the fittings to the ends of the hose. It was so simple and quick. It required a LOT less force than getting the aeroquip hose together. Big thing to remember is to mark the hose to be sure it doesn’t back out of the fitting during assembly. I also used a set of feeler gauges to ensure that the nipple and the fitting were tightened down to the spec of .060″.
Then I had to secure the fire sleeve to the hose. Many, many years ago, I bought a “wire clamp” tool at Oshkosh. This was back in the days when I knew I wanted to be a builder, but didn’t have much money to spend. It was about the only tool I could afford, and of course you need to take a souvenir home from Oshkosh. Securing the fire sleeve was the perfect opportunity to use it.
The directions go through how to use it. Basically you loop safety wire around the fire sleeve twice, routing the loose ends through the loop of safety wire. If you are careful and take time with the routing, you can get the wires to lay down nice and parallel.
Secure the wires on the tool pegs, and twist them together. Then twist the wing nut to tighten. As you are doing that, pay attention to how the wires are laying down. You can manipulate them to make them look nice.
Once the wire clamp is sufficiently tight, then bend the tool over to the opposite side to lock the clamp. Remove the tool, and trim the ends. Take a pliers and fold the cut ends over and place them in towards the fire sleeve to prevent from catching a sharp edge when you are working near the hose. I think they look pretty nice.
I am very happy with the way the hose turned out and the way the Earl’s Performoflex system assembles. I have more hoses to fabricate, but need to take the engine off again to get access to the area so I can measure hose lengths.
I moved on to the throttle and mixture cables again. My original plan proved ill advised, so I came up with a new one. The cables are going to be routed out of the firewall and then around the back side of the fuel injection servo, actuating forward. The throttle arm will be on the left side of the servo and the mixture on the right. To do this, I need to fabricate brackets to hold the cable housings.
For the throttle, the most obvious place to secure the cable is off the oil cooler. There needs to be about 8 inches between the bracket and the throttle control arm on the fuel servo when the throttle is in its middle position. I got this from the manufacturer’s specs for the cable. The oil cooler is about this distance away from the throttle control arm and fairly rigid to the engine. So, the oil cooler and this the throttle cable should vibrate with the engine without relative motion, which is what we are looking for. Any vibration between the airframe and the engine will be taken up by flex in the throttle cable.
To build the bracket to hold the cable housing, i located the two holes on the lower forward flange of the oil cooler on a piece of aluminum plate.
The plate is a piece of scrap, and is clearly over sized. In fact, it certainly won’t fit in the cowl. So I translated a straight line from the throttle control arm to the plate to locate the ideal location for the cable to penetrate. Then I cut away a bunch of the excess.
That was about as far as I got today with only a few hours in the shop today. I did put the cowl up after I got the excess cut away and the mounting bracket is still too big. I will probably have to move the cable penetration in the bracket, and angle the cable to accommodate this. The cable can flex unto 15 degrees off center, but having the cable perpendicular at mid travel is ideal. So we will see how close I can get to that tomorrow.