BitterlichMG(at)cherrypoi
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 Posted: Thu Feb 23, 2006 4:05 pm Post subject: Technical Thoughts; No Flight Suits Required |
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Any YAK or CJ aircraft equipped with the air compressor has a pressure relief valve. This pop-off valve pressure is adjusted by a cap that tightens a spring, thus controlling the point where the valve will open and vent excess pressure.
Over time, the pop-off valve seal will wear which will result in a constant leak, and the systems inability to told pressure.
In the YAK-50, closing the main air valve stops this leak and you will keep whatever happens to be left in the tank for later use. In the YAK-52, this is NOT the case, and the air will leak until it is completely gone... regardless of whether the main air valve is off or on.
Doug Sapp sells replacement pop-off valves for the CJ-6. The internal parts of this valve assembly will interchange with the slightly different external valve assemblies used on the YAK-50, 52, and 55, along with the Sukhoi 26,29, 31 series. The YAK-52W and TW use a different POP-OFF valve and are not interchangeable with any other model listed above.
There is a very slick alternative to the above made by Circle Seal Controls. A suitable part number would be something like:
M5132T2M(L)711 Check out their Web Site.
This American made pop-off valve can be ordered with a pull up manual pressure relief control ring to allow bleeding of the air system, and is totally rebuildable, and has a much better controlled set pressure. Price is around $430 or so. Not cheap by any means, but a totally reliable product. Of course, some American pipe thread to Russian 37 degree flare fitting adaptation will be required.
On this note, the AN6 female flare >| fits the Russian air and smoke fittings dead on. You can take a fitting such as an AN6, remove the B nut, and put on the metric Russian B nut, and it will work perfectly.
Sergei Boriak showed me an idea he had where a piece of steel was machined to give an AN6 female flare and on the other end was a male AN4 with threads. Using this adapter, one simply slides on the Metric Russian B nut to the AN6 side, and you have an instant converter going from Russian Air or Smoke line to an AN4 male flare. With two of these a person can replace most lines in the CJ-6 or YAK series of aircraft with an American made AN-4 hose line in seconds. I have made several of these in Stainless and in hard Aluminum, and carry two of them with me at all times for emergency purposes. (Doug Sapp, are you listening buddy?) I am throwing this idea out to the public at large, even though a smart person would order a whole bunch of these and sell them to people reading this list. You can have an American AN-4 line made just about anywhere, any shape, any size, any length. With converters such as the ones I have described here, you have an "out" when you have a Russian line or hose fail on a cross country flight. Two of these need to be in every flight bag out there. (Go for it Doug)
Another neat idea is the idea of the "compressor unloader". The most simple method here is to simply run a telex type cable from the cockpit to the engine compartment and mount it to an arm that you attach to the snot valve "knob". Pulling on the control cable from the cockpit opens the snot valve, and thus unloads the compressor. This not only increases the life of the compressor, but it also gives you some horsepower back from what it took to drive it. Don't laugh, it takes a few horses to turn this little jewel.
A REALLY slick method of accomplishing the above is to go to the snot valve and unscrew the copper line that attaches to the bottom of it. Make a new fitting with a line that then goes over to an electrically controlled 28 volt valve. Now you can open your snot valve // unload the compressor ELECTRICALLY. Any number of electrically controlled 28 volt DC valves that can handle 750-800 PSI are available surplus or new. Your choice. The only trick is hooking to the bottom of the snot valve. Some folks have taken the snot valve and retapped the bottom threads for this reason.
Another slick trick I have seen is to replace the standard three gage device in our aircraft (oil temp/Fuel Pressure/Oil Pressure) with an American made instrument that fits in the same hole and gives not only the original three, but also manifold pressure. The Russian sensors have to be replaced, but it opens a hole in a tight instrument panel if you need it.
Speaking of engine instruments, the TACH GENERATOR on the M-14 engine can in many cases be a pain. If the Tachometer in the aircraft starts rotating backwards, or is way out of place from where it is supposed to be, ALWAYS go to the Tach Generator cannon plug and check for broken wires first. 9 times out of 10, you will find your problem right here. However... keep in mind that if you have more than one broken wire, reversing these wires will cause the Tach to read in any number of ways. For the savvy electronic types, this is a synchro hookup. Treat it accordingly. Also make sure... DARN SURE... that you have the shield ground hooked up on this baby, or else stand by for some HUGE whining noises in your radio. Lastly, unless the Tach Generator itself is kept tightly snugged up to the engine, it can come loose and then ruin the drive shaft. All this ends up being kind of a pain. The Horizon Instruments P-1000 Electronic Tach is a SUPER replacement for the above problem. You can install this tach and remove the existing Russian Tach Generator and replace it with a cover plate. Abandon the wiring or cut it out. The P-1000 attaches to the "P" leads on your MAG CONTROL SWITCH and not only gives you RPM, but gives you TWO RPM sensors.... one for each MAG! This instrument will warn you if there is a difference between rotational speeds of either MAG thus warning you instantly of a total failure of either MAG in flight. It also automatically records engine time, and maximum recorded RPM. The operator can also select either MAG to output RPM, etc., etc. No, I do not have stock in this product, but I wish I did. It is a marvelous replacement for the Russian Tach, and in the end... cheaper.
Mark Bitterlich
N50YK
p.s. Sadly, I must inform everyone that only people that fly in shorts and sneakers can apply these ideas.
Just kidding.... good ideas, like good training, should always be shared without rancor or requirement.
And yes Ernie, in this case I very much indeed was trying to get in the last word.... but I AM smiling.
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