Roger Lee Posted July 20, 2010 Report Share Posted July 20, 2010 Hi Guys, Someone ask me why we can't turn our props clockwise? Well the plane will explode, ok maybe not :unsure:, but it will cause damage. You are allowed if necessary to turn the prop clockwise one turn. If you don't have to do this then don't. Turning it clockwise more than once will induce air into the oil system. It will cause the lifters to malfunction which will cause damage to the rods and valves. You will also loose lubrication. The lifters need the oil pressure to function properly, the system can't pump air. This is why when we break open the oil system beyond what is allowed then we have to do an oil purge. So bottom line is don't let anyone rotate your prop clockwise. If an untrained mechanic does this or breaks open your oil system trying to drain more oil out then don't start it until an oil purge has been done. You can watch this demonstrated on the R.O.A.N. website. Link to comment Share on other sites More sharing options...
Mike Posted July 20, 2010 Report Share Posted July 20, 2010 Another quick thing i found by accident over the weekend is ...if you have plugs out of the engine you cant burp/gurgle the engine to get the oil level right in the tank you can turn the prop as much as you like oil doesn't go back to the tank must be something to do with back pressure with plugs in .. Mike Link to comment Share on other sites More sharing options...
Roger Lee Posted July 20, 2010 Author Report Share Posted July 20, 2010 Hi Mike, Oil is circulated in our engines by crankcase pressure. So without the plugs no pressure. Link to comment Share on other sites More sharing options...
coppercity Posted July 20, 2010 Report Share Posted July 20, 2010 Good info Roger, thanks.. My new students sometimes get confused which way to rotate for preflight if needed, so I have shown them not only the leading edge of the prop but if you look at the Neuform decal, the "O" in Neuform is made with an arrow in the direction of rotation, that usually keeps the confusion down until they learn clockwise vs counterclockwise... Link to comment Share on other sites More sharing options...
chanik Posted July 23, 2010 Report Share Posted July 23, 2010 Wait a second; can't you just purge any entrained air by burping the rotax really well if the prop has been counter-rotated? Maybe 30 turns the right way? Link to comment Share on other sites More sharing options...
Roger Lee Posted July 23, 2010 Author Report Share Posted July 23, 2010 Hi Chanik, Once the system has had air introduced by draining or breaking it open you need to do a purge. Rotating the prop will not work or Rotax would let you do it that way and not be so adamant that it be fully purged.The only exception is if you drain the oil and put on a new filter. You should always pre-fill the filter with part of the 3 qts. of oil you will pour in the tank. Then the prop needs to be rotated 20 times. If the filter is not pre-filled then it should be rotated 30 times. Never ever turn the prop after the oil has been drained or the filter removed or you will be doing a purge. Link to comment Share on other sites More sharing options...
sandpiper Posted July 23, 2010 Report Share Posted July 23, 2010 At oil change, after doing the 20 rotations, I then briefly motor the starter with no choke, cold engine only, for a few seconds. That usually gets me 45 - 50 psi. Then I start it. This won't work with a warm engine as it will start even with no choke. Probably overkill. Link to comment Share on other sites More sharing options...
airhound Posted November 8, 2012 Report Share Posted November 8, 2012 Roger, is 20-30 turns for a burp a sign of air in the system? Perhaps overtime, oil changes, tank cleaning, etc enough air can be introduced? I just remember burping happening in less props. The ROTAX oil purge procedure looks interesting,how about the Aircraft Spuce purge kit? Any experience or comments as far a ease of use. Link to comment Share on other sites More sharing options...
Roger Lee Posted November 8, 2012 Author Report Share Posted November 8, 2012 Hi Doug, I haven't seen the Spruce purge kit, but I bet it is the same as the CPS one since they are one in the same company and in the same building. As far as prop turns for a gurgle. All our planes have some oil left in the bottom of the crank. Some of our planes actually leak back some oil from the return line back to the bottom of the crankcase depending on the oil tank reservoir location. So what the main determining factor is for the number of prop turns is how much oil is in the bottom of the crankcase. Yes it can change over time. I have seen people turn the prop 1-2 times and it gurgles. I have seen some that never seem to gurgle after 30 times because I have seen as much a a quart drain back and that would take forever to return back to the tank with a slow turning hand propping. So bottom line if it doesn't gurgle after a few turns don't loose any sleep over it. Link to comment Share on other sites More sharing options...
airhound Posted November 9, 2012 Report Share Posted November 9, 2012 I haven't seen the Spruce purge kit, but I bet it is the same as the CPS one since they are one in the same company and in the same building. Roger any opinion on the CPS kit which is what I was refering to..Thanks! Doug Link to comment Share on other sites More sharing options...
Roger Lee Posted November 9, 2012 Author Report Share Posted November 9, 2012 Hi Doug, It is a small air regulator, a cap for the oil tank fitting and a small piece of hose and an air hose fitting. I bought one many years ago and still use it. Link to comment Share on other sites More sharing options...
sandpiper Posted November 9, 2012 Report Share Posted November 9, 2012 I'm not sure the CPS/Spruce kit is worth the money. Certainly it works and has good instructions. I bought one but only use the cap for the oil tank fitting. I regulate the pressure using the regulator on my compressor and I blew air into the tank using the tank vent tube. On the plus side if you only have minimal tools, clamps, fittings and no regulator floating around your shop then this kit has it all in one small package. Link to comment Share on other sites More sharing options...
airhound Posted November 9, 2012 Report Share Posted November 9, 2012 Roger/Sandpiper, I'm ELSA RANS S-19, and I have a Air Compressor with regulator (0-150). So, do I fix a short hose with a nipple on it to the oil tank vent tube and pressurize to what pds? The what? How would a void escape? What is the cap used for?? And will a Ace Hardware End Nut, probably metric, work, if ther is such a thing??? I do not have a water separator or filter to take the moisture out of the IL air. How can someone mess things up. Seems simple but what to look out for? Thanks Doug in IL Link to comment Share on other sites More sharing options...
Roger Lee Posted November 9, 2012 Author Report Share Posted November 9, 2012 Hi Doug, You don't really need the kit just an understanding of how to do it. Your air compressors is fine so long as you can dial it down to 5-15 psi. I usually use 10. Then you only need a hose that will fit on the oil tank vent tube or a fitting to connect to your existing vent tube hose. Now you only need to block off the intake fitting on the oil tank. You can use a cap or even a rubber cork. Do not use a real cork as it can break off chunks. The only issue with the rubber cork is that it needs to be held in place so it doesn't pop out. Someone's finger can easily hold it in place. Or you could put a piece of hose over the intake and use a hose clamp to hold it and block off the other end of the hose so oil and air don't come out. Piece of cake. Link to comment Share on other sites More sharing options...
airhound Posted November 10, 2012 Report Share Posted November 10, 2012 Great! Thank you Roger!! After I rig it up and apply 10 pds of pressure what next? Turn the Prop or ? How does any air/void escape....sorry for being high maintenance with all the questions :unsure: Link to comment Share on other sites More sharing options...
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