Exhaust Gas Temperature Gauge (EGT)
Mountain Flying was a topic for the last several posts but I forgot the importance of performance enhancing steps that are safety related to all types of flying.
In the mountains a six probe EGT gauge helps you adjust your planes air/fuel mixture for top performance.
Test each cylinder, one at a time, for its peak EGT by carefully leaning the mixture for that cylinder. After the maximum reading back off 50 degrees.
Note each cylinders temperature. Select the cylinder with the highest temperature and back off 50 degrees. now you know, for sure that none of your cylinders are operating at a "too lean" mixture that may cause valve warp. (think expensive labor and parts cost)
You can back off just 25 degrees to lean for greatest fuel economy but you run the risk of engine overheating problems and possible damage. ( no free lunch)
On take offs at high altitude airports, if you are a flatlander, don't forget to lean out the engine for peak performance before you begin your takeoff and climb to altitude.
Open cowl flaps, while climbing to altitude, keep the engine cool. Once on the step close the cowl flaps.
When the mixture is adjusted for sea level and you take a trip out West you may experience a fouled plug or two on your coolest running cylinders.
Cylinder Head Temperature Gauge
A major expense that faces a high performance single engine aircraft owner is finding the fouled of flawed spark plug when there are 12 plugs that a A&E needs to remove to see which one needs replacement. Thats a large labor bill.
You know what you must do before you takeoff, even in smaller power-plants in lower performance planes. Why do you run up an engine and switch from both magnetos to left magneto and back to both and then switch to right magneto before returning back to both?
You are looking to see if all the plugs are working properly. In an aircraft engine the left magneto supplies a spark to the left cylinders upper plugs and the right cylinders lower plugs. Just the reverse for the right magneto. When the both position for the electrical preference is selected both the upper and lower plugs are firing on each cylinder bank.
The reason for two plugs for each cylinder is safety. The RPMs will drop a slight bit if one set of plugs stops firing. Performance, of course, will suffer.
With the CHT gauge, six probe, on a high performance plane it is possible to tell an A&E mechanic the exact plug(s) to remove when you experience a "rough" engine periodically.
In flight, you can check both banks. Set the EGT and CHT to cylinder head #1. Switch from Both Magnetos to Left Magneto. When the left magneto is running alone it supplies electricity to the upper plug. If there is no drop in temperature with the left magneto running alone it means the left upper plug is okay. If you switch to the right magneto and check the EGT and CHT for cylinder head #1 and you see a discernible drop in EGT and CHT it may mean the lower plug on the cylinder #1 is fouled, flawed or cracked.
You can continue to test each cylinder in this manner. If you detect a change in EGT and CHT for another cylinder note which plug isn't operating properly and report those plugs to your mechanic.
Net effect is vastly lower cost and your peace of mind.
