Firewall Forward

I don’t know about you, but I consider any aircraft that has a prop to be only a marginal glider. OK let’s exclude motor gliders, since they can fly quite nicely with their mill stopped. I often hear that aircraft engines are reliable, and can go almost forever with a proper maintenance regime in place. Ah, here is the catch phrase, “proper maintenance.” Since my Colt is an old boy, and even though the engine looks and sounds great, I need some more reassurance than the nice and steady growl. I simply need to know what is going on up front there. I briefly considered one of those fancy all-in-one engine monitors, but decided to do it with about half the money, and go with a set of discrete gages. I still wanted a high-tech setup, so I opted for Electronics International Inc. These guys are terrific. They respond to your every question in a timely manner, and there is always a live person on the other end of the wire.

As with all electronic installations, there is a lot of wiring to consider, but with the engine instruments, we must add another wrinkle – probes of all sorts. EGT probes, CHT, probes, OAT probes, fuel flow probes – getting the drift? Let’s have a look what is involved.

Exhaust Gas Temperature Probe

Installed EGT probe

To install the EGT probes, Don carefully drilled small holes to the exhaust piping, and installed the probes using supplied clamps. This was a relatively simple task, at least for Don.

Cylinder Head Temperature Probe

Installed CHT Probe

My engine did not have the cavities for the cylinder head temperature probes, so we had to install the type that goes under the spark plug. Here was a good example of how EI works with their customers. I ordered the instruments from Aircraft Spruce, but they arrived with the wrong CHT probe. One quick call to EI, and a couple of days later, I had the correct probes.

Fuel Flow Sensor

Fuel Flow Sensor Installed on the fuel line

Don tells me that the installation of the fuel flow sensor, while somewhat more involved, went smoothly. Frankly, I expected this one to be more of a challenge.

As with the above probes, all the rest of the installations went smoothly. Here is a note of caution. I ordered the V/A gage with the internal shunt. I thought I was smart, because I was going to save on installation time, and $35 for the external shunt.  Wrong. Can you imagine bringing two wires the size of your little finger to the gage? Maybe this could work in some installation, but definitely not behind my already tight panel. Once again, EI came to rescue. I now have an instrument with an external shunt which is nicely tucked away far up front on the firewall. Here is the new engine instruments cluster.

Engine Instrument Cluster

Section of the panel showing the engine instruments

In my next post I will discuss new accessories that replaced some of the old equipment.

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