The International Cessna 170 Association

Mark Harwood wrote:Miles, Are you doing your aggressive leaning with the help of gauges or are you using the the by ear method? When I questioned my engine builder on this topic, he said to use only 100 LL and lean it on the ground and in the air as you are. Can you detail your " aggressive" leaning techniques. Do you have the original mixture control? Thanks, Mark

I've only had CHT/EGT instrumentation for about 6 months. I still lean by ear, then cross-check and fine-tune with EGT. On the ground I lean to the point that adding throttle causes the engine to stumble. With the low throttle settings used to taxi, I usually see somewhere around 1000 degF EGT, but I don't use it to set the mixture. I set the mixture just rich enough for smooth running.

I had a vernier mixture control installed 3 or 4 years ago after my original cable broke. The vernier control makes it a bit easier to make small changes, especially in rough air.

For the initial cut at leaning for cruise, I push the button to disengage the vernier feature and pull the mixture until I detect a little roughness, then use the vernier feature to richen to just smooth, or a little more for max RPM, depending on whether I'm going for best economy or best power, respectively. For slightly better economy, I can reference the EGT to lean until the first cylinder (almost always #5 on my engine) peaks, usually around 1450 degF, then richen to around 1425 or so.

The vernier mixture and CHT/EGT instrumentation on this low-thyroid carbureted engine are probably suit clothes on a hog, but I like them anyway.

Miles

I have a split EGT gauge. One probe is mounted in the aft end of the exhaust on either side. When I calibrated the gauges, I followed the instructions - which resulted in climbing to 9500 and at full throttle leaning to peak and setting the needles. I lean by ear and RPM indications. I don't trust the EGT gauge enough to lean solely with it. I use it as an indicator of lean condition during descents. I find the needle locations at peak wander from day to day - perhaps the result of atmospheric conidtions. I am of the mind that I could live just fine without the EGT gauge.

I got my Stabil bottle today (32 oz)...... Huge improvement!!! Thanks for the suggestion!

Robert Eilers wrote:I have a split EGT gauge. One probe is mounted in the aft end of the exhaust on either side. When I calibrated the gauges, I followed the instructions - which resulted in climbing to 9500 and at full throttle leaning to peak and setting the needles. I lean by ear and RPM indications. I don't trust the EGT gauge enough to lean solely with it. I use it as an indicator of lean condition during descents. I find the needle locations at peak wander from day to day - perhaps the result of atmospheric conidtions. I am of the mind that I could live just fine without the EGT gauge.

Bob,

Your EGT is probably a direct-reading type, with no compensation. In these types of temp gauges, the voltage generated by the thermocouple drives the meter movement directly. Those types will vary with OAT (or more correctly, with the temperature of the point at which the thermocouple wires terminate), as there is a secondary thermocouple where the thermocouple wires connect to the meter. There IS a reason why the scales don't have numbers. They are still useful in finding a peak during leaning, although you'll never quite know what the actual temperature is.

Miles

gahorn wrote:I carry it in a heavy-duty, freezer zip-lock bag. But first I loosen the main cap, then squeeze out excess air, and tighten the cap so that the bottle is slightly collapsed, to make room for expansion while airborne. I also store it so that it will be right-side up and be less likely to spill even if those measures should fail.

I was pretty concerned about the consequences of a TCP spill in the bagage compartment of my plane, so I found this solution. I keep a 5 gallon bucket in the baggage compartment with a few quarts of oil and my stabil bottle of TCP. I also keep anything else that might soil the baggage compartment but would not cause problems if it came in contact with Tcp or engine oil. I make a point not to put my windshield/window cleaning rags in the same bucket as I doubt TCP residue/fumes would do the plexiglass much good.

The bucket also comes in handy to turn upside down and stand on if there is not a ladder at a fuel pump some where.

Bruce

Great idea, Bruce! I've been thinking of some way to mount a metal storage box on the firewall to store spare oil, etc. in. But your idea is so much simpler and more useful.
Thinking about this reminded me of a time when I wanted to long-term preserve some amm... er...some stuff... in a 50-cal ammo can. I took it up to 12K feet and vented, then closed the can. (They've got a neoprene seal on the lid.)
10 years later I thought I was going to have to drill a vent hole in the can to get it open.

Where are you guys getting your Sta-bil and larger cans of TCP. I looked on the Spruce website to find only the small plastic bottle of TCP. No Sta-bil. Also the last squeeze bottle of TCP I got from Spruce did not work properly.

Your explanation of the EGT was very useful Miles - clarified things well. I appreciate it.l

Curtis Brown wrote:Where are you guys getting your Sta-bil and larger cans of TCP. I looked on the Spruce website to find only the small plastic bottle of TCP. No Sta-bil. Also the last squeeze bottle of TCP I got from Spruce did not work properly.

TCP can be purchased in gallon cans from some (not all) suppliers if they are picked up in person or shipped bulk with hazmat fees.

Stabil bottles (32 oz) can be purchased at department, auto, and variety stores.

I ordered my Stabil bottle on-line. Shipping I think was 6 bucks, but it saved me a trip to the store.
http://www1.acehardwareoutlet.com/(3xo3 ... ?SKU=86164&

Here is the accident report involving TCP....

http://www.ntsb.gov/ntsb/GenPDF.asp?id= ... 139&rpt=fa

Pretty scary, especially the part about static being able to ignite the fumes..... I still don't like the idea of carrying TCP around in a plastic bottle in the plane, possibly because that accident report reads like my worst nightmare. I have been using my Stabil bottle in the hanger.

Another reason to use MOGAS!

You wont need TCP!

If you felt you had to carry TCP in the plane, maybe an army surplus ammo box would keep it safely sealed up. Just thinking out loud....

Unless I am missing something, I can't see where TCP came into action on the NTSB report that John was so good to forward to all of us. What I read was the autopisy report said that there was no touleen in the lungs of either people. this seames to be the only low flash point product in TCP, and should have been ingested pryer to the fire (just my thoughts) Like I said maby I'm missing something there's many more inteligent people out there than myself (many more) Please throw in your ideas!!!
brad

SMOKING AND FLYING DON'T MIX...GARY