---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Tue 10/15/13: 15 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:33 AM - Re: Re: looking for help with "mushy" brakes on CJ (Gary Gabbard) 2. 07:02 AM - Re: Staking a Housai exhaust valve (or M-14) (Bitterlich, Mark G CIV NAVAIR, WD) 3. 08:59 AM - Re: Staking a Housai exhaust valve (or M-14) (Mark Davis) 4. 10:18 AM - Re: Staking a Housai exhaust valve (or M-14) (keithmckinley) 5. 10:49 AM - Re: Re: looking for help with "mushy" brakes on CJ (jblake207@comcast.net) 6. 01:32 PM - Re: Re: Staking a Housai exhaust valve (or M-14) (Mark Davis) 7. 02:15 PM - Air Compressor (?) Issue (Jill Gernetzke) 8. 03:23 PM - Re: Air Compressor (?) Issue (Jay Land) 9. 05:41 PM - Re: Air Compressor (?) Issue (Frank Stelwagon) 10. 07:18 PM - Re: Air Compressor (?) Issue (Roger Kemp M.D.) 11. 07:39 PM - Re: Air Compressor (?) Issue (keithmckinley) 12. 07:48 PM - Re: Staking a Housai exhaust valve (or M-14) (keithmckinley) 13. 08:35 PM - Re: Re: Staking a Housai exhaust valve (or M-14) (Roger Kemp M.D.) 14. 08:54 PM - Re: Air Compressor (?) Issue (Vic) 15. 11:42 PM - Re: Air Compressor (?) Issue (Jan Mevis) ________________________________ Message 1 _____________________________________ Time: 05:33:04 AM PST US Subject: Re: Yak-List: Re: looking for help with "mushy" brakes on CJ From: Gary Gabbard Guys on my cable the strands of the cable had worn so much inside the outer h ousing that several of the strands were broken and only one strand was actua ting the brakes. A few more applications of the brakes and I would have had n o brakes. They were broken inside the housing where you can not see to cable . Don't screw around with it, CHANGE THE CABLE!!!! CJ N 22YK. Gary G. Sent from my iPad > On Oct 14, 2013, at 9:54, doug sapp wrote: > > Guy's, cable stretch to the degree that it would effect your brakes is a " wives tale". The cable is not stretching, your swedge might be slipping or t he gob/ball of solder (on the stock cable) might be giving way, but the cabl e is not stretching. I would estimate that 75% of the guys who adjusted the ir cables because of "stretch" had the cable break soon after the adjustment .. > > > > >> On Mon, Oct 14, 2013 at 5:43 AM, keithmckinley wrote : >> >> Hi Sam and Doc, >> >> It is my feeling that the differential and proportioner are in good shape . The cable is no doubt an original Chinese cable that I believe has stretch ed some. Good news is I do have SS cable from Doug in stock. >> >> I may try the adjustment the retaining nut, but there is not much left on it >> >> Keith >> >> -------- >> Keith McKinley >> 700HS >> X26 Sebastian, FL >> >> >> >> >> Read this topic online here: >> >> http://forums.matronics.com/viewtopic.php?p=410488#410488 >> >> >> >> >> >> >> >> ========== >> rget="_blank">http://www.matronics.com/Navigator?Yak-List >> ========== >> http://forums.matronics.com >> ========== >> le, List Admin. >> ="_blank">http://www.matronics.com/contribution >> ========== > > > 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > ________________________________ Message 2 _____________________________________ Time: 07:02:58 AM PST US From: "Bitterlich, Mark G CIV NAVAIR, WD" Subject: RE: Yak-List: Staking a Housai exhaust valve (or M-14) Not trying to shoot you Gary, but I would like to know what you consider a "reliable source" to be. I have used both multi-weight and single weight oils. I found the single weight to be a real pain in the tail, especially in anything less than HOT weather. 50 weight just did not want to drain out of the intake drain kit, and with a tail dragger (YAK-50) that is a serious problem as oil left in the intakes can get "gulped in" and that is bad ju-ju. Some folks using their airplanes (primarily) for really hard aerobatics switch to single weight in an attempt to cut down on consumption, etc. The concept being that thicker oil is less likely to creep past piston rings in the short term. Probably has some basis in fact because the Russian piston rings leak like crazy when they are cold anyway, but I doubt there has been any real study done on how effective that might be for contributing to valves sticking. That said, after that experience I have used Phillips Multi Weight Radial Engine Oil (20-60W) with great success for many hundreds of hours. During that time, I have had to pull just one cylinder for a sticking exhaust valve and that was soon after I purchased the aircraft. Just FYI, sticking exhaust valves are typically caused by lead deposits and not oil. That was true in my case, and was in my opinion caused by me running the engine at 60-70% and letting it get too cool resulting in lead precipitation onto the valve. My M-14 does not have shutters by the way, so running it that low caused it to have cylinder head temps down in the "yellow" range. Increasing the normal operating RPM to get cylinder head temps up, and adding MMO to the fuel ended the sticking exhaust valve issue. Over the next 700 hours following that, I have had to stake one valve, and that procedure worked. I am writing all of this because I want folks to be very cautious considering things to do to their airplane that come from a "reliable source". Many things have been recommended in the same fashion over the years, one of the best known being squirting air tool oil into the pneumatic system. Something in my ignorance I actually went ahead and tried, followed shortly there-after by total failure of both landing gear actuator chevron seals. Luckily I avoided a gear up landing. Making a decision on whether to run a single or multi weight oil is based on many factors, but I would consider the least of them to be "preventing valves sticking". And the reliable source in this particular case is myself. :-=) Mark Bitterlich -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Gary Gabbard Sent: Monday, October 14, 2013 15:03 Subject: Re: Yak-List: Staking a Housai exhaust valve (or M-14) This is some info I was supplied with from a reliable source. What type of oil are you using? It has been observed that there is a valve sticking problem with multi grade oils. Not sure what brand. It has been a couple of years since I got the info. But the suggestion that straight grade oils have not been having the problem. I know there will be people with different personal opinions. I am just the messenger. Don't try to shoot me. Won't do any good. Gary G. CJ. N22YK Sent from my iPhone On Oct 14, 2013, at 10:49, Robin Hou wrote: I had a sticky valve in #5 that staking did not help. Filling the cylinder head with MMO for a few nights cured it. It has been about 20 hours since the MMO treatment and it is still running well. Last conditional inspection a month ago #5 read in the mid-70's, so I was pleased. ________________________________ From: keithmckinley To: yak-list@matronics.com Sent: Monday, October 14, 2013 6:56 AM Subject: Yak-List: Staking a Housai exhaust valve (or M-14) Anyone that has done this... can you share your "gotchas" Keith -------- Keith McKinley 700HS X26 Sebastian, FL Read this topic online here: http://forums.matronics.com/viewtosp; ======================= D============================================ ist"">http://www.matronics.com/Navigator?Yak-List D============================================ //forums.matronics.com D============================================ ot;">http://www.matronics.com/contribution D============================================ ________________________________ Message 3 _____________________________________ Time: 08:59:26 AM PST US From: "Mark Davis" Subject: Re: Yak-List: Staking a Housai exhaust valve (or M-14) Mark, I've had the same experience with sticking valves, two of which wouldn't stake and required the jugs being replaced with spares I had. Both happened while running X/C 25W60, with MMO and either Decalin or TCP in the fuel. I had been adding MMO to the oil only immediately prior to an oil change, flying it for 30 minutes to warm it up and draining the oil while hot. I don't run an oil filter, but never run the oil past 25 hours. Since my last cylinder replacement 18 months ago, I've been running MMO per Jill's recommendation in the oil continuously and haven't had a problem since....knock on wood. I run half the recommended amount in hot summer months and a full dose in winter months. I occasionally fly in very cold temps in the winter time, which may have aggravated the lead accumulation as you suggested. Sometimes running with the gills full closed at cruise is necessary to keep the cylinders warm enough to scavenge a little heat for my cold blooded wife in the back seat! I mix the MMO in with the new Phillips in the 2.5 gallon jug so I don't have to do the higher level math to add the right amount every time I add oil. My engine is approaching 900 hrs and I believe it may be using just a bit more oil due to the thinning by the MMO, but it's cheaper than replacing cylinders. As they say, YMMV. Mark Davis N44YK ----- Original Message ----- From: "Bitterlich, Mark G CIV NAVAIR, WD" Sent: Tuesday, October 15, 2013 7:58 AM Subject: RE: Yak-List: Staking a Housai exhaust valve (or M-14) > > > Not trying to shoot you Gary, but I would like to know what you consider a > "reliable source" to be. > > I have used both multi-weight and single weight oils. I found the single > weight to be a real pain in the tail, especially in anything less than HOT > weather. 50 weight just did not want to drain out of the intake drain > kit, and with a tail dragger (YAK-50) that is a serious problem as oil > left in the intakes can get "gulped in" and that is bad ju-ju. Some folks > using their airplanes (primarily) for really hard aerobatics switch to > single weight in an attempt to cut down on consumption, etc. The concept > being that thicker oil is less likely to creep past piston rings in the > short term. Probably has some basis in fact because the Russian piston > rings leak like crazy when they are cold anyway, but I doubt there has > been any real study done on how effective that might be for contributing > to valves sticking. > > That said, after that experience I have used Phillips Multi Weight Radial > Engine Oil (20-60W) with great success for many hundreds of hours. During > that time, I have had to pull just one cylinder for a sticking exhaust > valve and that was soon after I purchased the aircraft. > > Just FYI, sticking exhaust valves are typically caused by lead deposits > and not oil. That was true in my case, and was in my opinion caused by me > running the engine at 60-70% and letting it get too cool resulting in lead > precipitation onto the valve. My M-14 does not have shutters by the way, > so running it that low caused it to have cylinder head temps down in the > "yellow" range. Increasing the normal operating RPM to get cylinder head > temps up, and adding MMO to the fuel ended the sticking exhaust valve > issue. > > Over the next 700 hours following that, I have had to stake one valve, and > that procedure worked. > > I am writing all of this because I want folks to be very cautious > considering things to do to their airplane that come from a "reliable > source". Many things have been recommended in the same fashion over the > years, one of the best known being squirting air tool oil into the > pneumatic system. Something in my ignorance I actually went ahead and > tried, followed shortly there-after by total failure of both landing gear > actuator chevron seals. Luckily I avoided a gear up landing. > > Making a decision on whether to run a single or multi weight oil is based > on many factors, but I would consider the least of them to be "preventing > valves sticking". > > And the reliable source in this particular case is myself. :-=) > > Mark Bitterlich > > > -----Original Message----- > From: owner-yak-list-server@matronics.com > [mailto:owner-yak-list-server@matronics.com] On Behalf Of Gary Gabbard > Sent: Monday, October 14, 2013 15:03 > To: yak-list@matronics.com > Subject: Re: Yak-List: Staking a Housai exhaust valve (or M-14) > > This is some info I was supplied with from a reliable source. What type of > oil are you using? It has been observed that there is a valve sticking > problem with multi grade oils. Not sure what brand. It has been a couple > of years since I got the info. But the suggestion that straight grade oils > have not been having the problem. I know there will be people with > different personal opinions. I am just the messenger. Don't try to shoot > me. Won't do any good. Gary G. CJ. N22YK > > Sent from my iPhone > > On Oct 14, 2013, at 10:49, Robin Hou wrote: > > > I had a sticky valve in #5 that staking did not help. Filling the cylinder > head with MMO for a few nights cured it. It has been about 20 hours since > the MMO treatment and it is still running well. Last conditional > inspection a month ago #5 read in the mid-70's, so I was pleased. > > ________________________________ > > From: keithmckinley > To: yak-list@matronics.com > Sent: Monday, October 14, 2013 6:56 AM > Subject: Yak-List: Staking a Housai exhaust valve (or M-14) > > > > Anyone that has done this... can you share your "gotchas" > > Keith > > -------- > Keith McKinley > 700HS > X26 Sebastian, FL > > > Read this topic online here: > > http://forums.matronics.com/viewtosp; ======================= > > > D============================================ > ist"">http://www.matronics.com/Navigator?Yak-List > D============================================ > //forums.matronics.com > D============================================ > ot;">http://www.matronics.com/contribution > D============================================ > > > ________________________________ Message 4 _____________________________________ Time: 10:18:01 AM PST US Subject: Yak-List: Re: Staking a Housai exhaust valve (or M-14) From: "keithmckinley" I religiously use 2 oz/ 5 gal in my fuel but have never put it in the oil. DO you use the same dilution ratio? K -------- Keith McKinley 700HS X26 Sebastian, FL Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410628#410628 ________________________________ Message 5 _____________________________________ Time: 10:49:17 AM PST US From: jblake207@comcast.net Subject: Re: Yak-List: Re: looking for help with "mushy" brakes on CJ I would strongly suggest that you replace the old =C2-brake cable and hou sing.=C2- It is the single point of failure in the brake =C2-system... it fails and you're SOL.=C2- My cable broke while I was taxing and I inst antly realized that the only option I had, since no one was in the back sea t, was to kill the mags and hope for the best.=C2- Fortunately, the airpl ane rolled to a stop a few feet from another airplane.=C2- I went to a lo cal motorcycle shop and bought a new cable and housing (I think it was actu ally a throttle cable for an ATV) that fit perfectly.=C2- I now squirt a little oil in it each year and so far no signs of wear or stretch.=C2- Mu ch better solution than trying to swag an end to a new cable and =C2-then trying to route that through the old housing.=C2- Or maybe Doug has the perfect replacement. Jon Blake jblake207@comcast.net ----- Original Message ----- From: "Gary Gabbard" Sent: Monday, October 14, 2013 9:47:53 AM Subject: Re: Yak-List: Re: looking for help with "mushy" brakes on CJ Several years ago I had the same brake problem found the old cable was comi ng apart inside of the outer covering. Don't mess with adjustment. Install the replacement cable. Or you might get a nasty surprise. =C2-Made a new inside cable =C2- I think that was before anyone was selling replacement parts. =C2-Gary G. =C2-CJ. N22YK Sent from my iPhone > On Oct 14, 2013, at 5:43, "keithmckinley" wrote: > > > Hi Sam and Doc, > > It is my feeling that the differential and proportioner are in good shape . The cable is no doubt an original Chinese cable that I believe has stretc hed some. Good news is I do have SS cable from Doug in stock. > > I may try the adjustment the retaining nut, but there is not much left on it > > Keith > > -------- > Keith McKinley > 700HS > X26 Sebastian, FL > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=410488#410488 > > > > > > > > > > =========== =========== MS - =========== e - =C2- =C2- =C2- =C2- =C2--Matt Dralle, List Admin. =========== ________________________________ Message 6 _____________________________________ Time: 01:32:44 PM PST US From: "Mark Davis" Subject: Re: Yak-List: Re: Staking a Housai exhaust valve (or M-14) Keith, I add it at the rate recommended on the label in the cold months and cut it in half in the summer. Just my personal choice to not dilute the oil so much in high temps when I know the oil temp may be nudging the red arc. Mark ----- Original Message ----- From: "keithmckinley" Sent: Tuesday, October 15, 2013 11:13 AM Subject: Yak-List: Re: Staking a Housai exhaust valve (or M-14) > > I religiously use 2 oz/ 5 gal in my fuel but have never put it in the oil. > DO you use the same dilution ratio? > > K > > -------- > Keith McKinley > 700HS > X26 Sebastian, FL > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=410628#410628 > > > ________________________________ Message 7 _____________________________________ Time: 02:15:22 PM PST US From: "Jill Gernetzke" Subject: Yak-List: Air Compressor (?) Issue Group, We have met up with a head scratcher. I am throwing it out to the group to chew on: The Yak 52 owner purchased his aircraft on an insurance sale. The aircraft had been totaled because of an engine fire. Attempts to talk to the original owners and learn more about the aircraft's history have been unsuccessful. Originally, we were contacted because the air system was not building pressure. A photo sent by the owner, elicited a remark by me that there seemed to be a lot of oil in the banjo/outlet valve fitting. The compressor itself was very dirty. The owner cleaned the outlet valve with no appreciable change in output. He then bought a "NOS" comp from a private party, installed it and it failed in 2.5 hours. This compressor had actually been overhauled by us in 2006. The nuts stripped off of the 4 studs on the bottom end of the compressor (green case), allowing the top end off the compressor to hammer up and down. Oil was all over the back end of the engine. The customer then sent his original compressor for overhaul and run on our test bench. He installed this overhauled compressor and it failed after 40 minutes in flight. This time the 4 studs sheared off of the bottom end of the compressor. He sent us both failed compressors, the drive and drive gear, shear coupling, the FT-1 "snot" valve and the pressure relief tee setup. We built one compressor out of the two failed units. The 4 stripped studs were replaced with new studs and installed with Loctite. The compressor was test run and produced 925 psi. The pressure relief valve tee setup was tested - it relieved normally - rebuilt with a new piston, new seals in the one way checkvalves and the pressure set to 50 atm. (The pressure relief valve had a Teflon seal which was in very poor condition.) The snot valve was tested, flushed and retested. The compressor, gaskets and drive unit were secured to one another in the proper alignment for the reinstall. The air compressor was returned to the customer and it was reinstalled without attaching the steel air line. Everything was normal for about 1.5 hours of ground runs. A flight was completed with the steel coiled air line still not attached. The flight was normal. The steel line was reattached and 90 minutes of ground run time. He noticed that pressure was not building as it should and opened the cowling to find one of the 4 hold-down nuts backing off. He also reported that the other 3 nuts were not tight. The owner drilled and safety wired the nuts. (Note: There is a CRITICAL clearance that is set between the bottom of the Stage I piston and the top of the Stage II cylinder. Over-tightening these nuts will cause the top of the piston to hit the top of the Stage II cylinder. Too much clearance and it bottoms out on the other end.) We received the compressor and installed new studs and steel locknuts with Loctite. The compressor has been returned but not run, yet. Here is what we know: 1. The FT-1 Snot valve is was flushed and functioning properly. 2. The pressure relief valve tee and checkvalves were all tested and the system functioned normally on a bench test, with the pressure relief valve popping off at 750 psi. 3. A new steel line was provided to the customer, but I do not know if this was installed. 4. On the 4th installation of the compressor, we returned the compressor, shear coupling, drive pad and gear tie-wrapped as a unit for correct clocking. We received photo verification that the compressor drive was installed correctly. 5. The compressor operated normally on the last run until the steel line was attached to it. Then, 1 nut backed off and the other 3 were reported loose. Hence, we replaced the hex nuts/lockwashers with steel locknuts in case the lockwashers had failed and that was the only problem on the last run. 6. The force to shear the compressor studs is in excess of 22,000 lbs. 7. The shear coupling appears to be a factory unit. A new one was sent to the customer, but returned back to me. 8. The oil return holes in the accessory case are large and not plugged. In the 20+ years that we have been overhauling air compressors, we have never encountered this problem. Please use this problem as your own theoretical and reasoning challenge to put forth real possibilities -grasping at unicorns, rainbows or butterflies not allowed. : ) Jill M-14P, Inc. ________________________________ Message 8 _____________________________________ Time: 03:23:41 PM PST US From: Jay Land Subject: Re: Yak-List: Air Compressor (?) Issue It needs some MMO.........;) On 10/15/13 5:09 PM, "Jill Gernetzke" wrote: Group, We have met up with a head scratcher. I am throwing it out to the group to chew on: The Yak 52 owner purchased his aircraft on an insurance sale. The aircraft had been totaled because of an engine fire. Attempts to talk to the origi nal owners and learn more about the aircraft's history have been unsuccessf ul. Originally, we were contacted because the air system was not building pressure. A photo sent by the owner, elicited a remark by me that there se emed to be a lot of oil in the banjo/outlet valve fitting. The compressor itself was very dirty. The owner cleaned the outlet valve with no appreciable change in output. He then bought a "NOS" comp from a private party, installed it and it fail ed in 2.5 hours. This compressor had actually been overhauled by us in 200 6. The nuts stripped off of the 4 studs on the bottom end of the compresso r (green case), allowing the top end off the compressor to hammer up and do wn. Oil was all over the back end of the engine. The customer then sent his original compressor for overhaul and run on our test bench. He installed this overhauled compressor and it failed after 40 minutes in flight. This time the 4 studs sheared off of the bottom end of the compressor. He sent us both failed compressors, the drive and drive gear, shear couplin g, the FT-1 "snot" valve and the pressure relief tee setup. We built one compressor out of the two failed units. The 4 stripped studs were replaced with new studs and installed with Loctite. The compressor was test run an d produced 925 psi. The pressure relief valve tee setup was tested - it re lieved normally - rebuilt with a new piston, new seals in the one way chec kvalves and the pressure set to 50 atm. (The pressure relief valve had a Te flon seal which was in very poor condition.) The snot valve was tested, flu shed and retested. The compressor, gaskets and drive unit were secured to one another in the proper alignment for the reinstall. The air compressor was returned to the customer and it was reinstalled with out attaching the steel air line. Everything was normal for about 1.5 hours of ground runs. A flight was completed with the steel coiled air line still not attached. The flight was normal. The steel line was reattached and 90 minutes of ground run time. He notice d that pressure was not building as it should and opened the cowling to fi nd one of the 4 hold-down nuts backing off. He also reported that the other 3 nuts were not tight. The owner drilled and safety wired the nuts. (Note: There is a CRITICAL clearance that is set between the bottom of the Stage I piston and the top of the Stage II cylinder. Over-tightening thes e nuts will cause the top of the piston to hit the top of the Stage II cyli nder. Too much clearance and it bottoms out on the other end.) We received the compressor and installed new studs and steel locknuts with Loctite. The compressor has been returned but not run, yet. Here is what we know: 1. The FT-1 Snot valve is was flushed and functioning properly. 2. The pressure relief valve tee and checkvalves were all tested and the system functioned normally on a bench test, with the pressure relief va lve popping off at 750 psi. 3. A new steel line was provided to the customer, but I do not know i f this was installed. 4. On the 4th installation of the compressor, we returned the compres sor, shear coupling, drive pad and gear tie-wrapped as a unit for correct c locking. We received photo verification that the compressor drive was inst alled correctly. 5. The compressor operated normally on the last run until the steel l ine was attached to it. Then, 1 nut backed off and the other 3 were report ed loose. Hence, we replaced the hex nuts/lockwashers with steel locknuts in case the lockwashers had failed and that was the only problem on the las t run. 6. The force to shear the compressor studs is in excess of 22,000 lbs .. 7. The shear coupling appears to be a factory unit. A new one was se nt to the customer, but returned back to me. 8. The oil return holes in the accessory case are large and not plugg ed. In the 20+ years that we have been overhauling air compressors, we have nev er encountered this problem. Please use this problem as your own theoretic al and reasoning challenge to put forth real possibilities -grasping at uni corns, rainbows or butterflies not allowed. : ) Jill M-14P, Inc. ________________________________ Message 9 _____________________________________ Time: 05:41:02 PM PST US From: "Frank Stelwagon" Subject: Re: Yak-List: Air Compressor (?) Issue If you think about it, every time the steel line is connected the compressor fails. That seems to say that there is a blockage between the compressor and the pressure relief valve. Since compression is not being built up in the aircraft the compressor output is blocked before the pop off valve. Not much there the steel line the water catch bottle and the line from there to the tee. One other question is the compressor sensitive to the gasket thickness between the engine and the compressor? Why not disconnect the compressor line and connect it to a dive bottle and see if pressure builds up in the aircraft. Just thinking! Frank ----- Original Message ----- From: Jill Gernetzke To: yak-list@matronics.com Sent: Tuesday, October 15, 2013 2:09 PM Subject: Yak-List: Air Compressor (?) Issue Group, We have met up with a head scratcher. I am throwing it out to the group to chew on: The Yak 52 owner purchased his aircraft on an insurance sale. The aircraft had been totaled because of an engine fire. Attempts to talk to the original owners and learn more about the aircraft's history have been unsuccessful. Originally, we were contacted because the air system was not building pressure. A photo sent by the owner, elicited a remark by me that there seemed to be a lot of oil in the banjo/outlet valve fitting. The compressor itself was very dirty. The owner cleaned the outlet valve with no appreciable change in output. He then bought a "NOS" comp from a private party, installed it and it failed in 2.5 hours. This compressor had actually been overhauled by us in 2006. The nuts stripped off of the 4 studs on the bottom end of the compressor (green case), allowing the top end off the compressor to hammer up and down. Oil was all over the back end of the engine. The customer then sent his original compressor for overhaul and run on our test bench. He installed this overhauled compressor and it failed after 40 minutes in flight. This time the 4 studs sheared off of the bottom end of the compressor. He sent us both failed compressors, the drive and drive gear, shear coupling, the FT-1 "snot" valve and the pressure relief tee setup. We built one compressor out of the two failed units. The 4 stripped studs were replaced with new studs and installed with Loctite. The compressor was test run and produced 925 psi. The pressure relief valve tee setup was tested - it relieved normally - rebuilt with a new piston, new seals in the one way checkvalves and the pressure set to 50 atm. (The pressure relief valve had a Teflon seal which was in very poor condition.) The snot valve was tested, flushed and retested. The compressor, gaskets and drive unit were secured to one another in the proper alignment for the reinstall. The air compressor was returned to the customer and it was reinstalled without attaching the steel air line. Everything was normal for about 1.5 hours of ground runs. A flight was completed with the steel coiled air line still not attached. The flight was normal. The steel line was reattached and 90 minutes of ground run time. He noticed that pressure was not building as it should and opened the cowling to find one of the 4 hold-down nuts backing off. He also reported that the other 3 nuts were not tight. The owner drilled and safety wired the nuts. (Note: There is a CRITICAL clearance that is set between the bottom of the Stage I piston and the top of the Stage II cylinder. Over-tightening these nuts will cause the top of the piston to hit the top of the Stage II cylinder. Too much clearance and it bottoms out on the other end.) We received the compressor and installed new studs and steel locknuts with Loctite. The compressor has been returned but not run, yet. Here is what we know: 1. The FT-1 Snot valve is was flushed and functioning properly. 2. The pressure relief valve tee and checkvalves were all tested and the system functioned normally on a bench test, with the pressure relief valve popping off at 750 psi. 3. A new steel line was provided to the customer, but I do not know if this was installed. 4. On the 4th installation of the compressor, we returned the compressor, shear coupling, drive pad and gear tie-wrapped as a unit for correct clocking. We received photo verification that the compressor drive was installed correctly. 5. The compressor operated normally on the last run until the steel line was attached to it. Then, 1 nut backed off and the other 3 were reported loose. Hence, we replaced the hex nuts/lockwashers with steel locknuts in case the lockwashers had failed and that was the only problem on the last run. 6. The force to shear the compressor studs is in excess of 22,000 lbs. 7. The shear coupling appears to be a factory unit. A new one was sent to the customer, but returned back to me. 8. The oil return holes in the accessory case are large and not plugged. In the 20+ years that we have been overhauling air compressors, we have never encountered this problem. Please use this problem as your own theoretical and reasoning challenge to put forth real possibilities -grasping at unicorns, rainbows or butterflies not allowed. : ) Jill M-14P, Inc. ________________________________ Message 10 ____________________________________ Time: 07:18:29 PM PST US Subject: Re: Yak-List: Air Compressor (?) Issue From: "Roger Kemp M.D." One thought, since there was a fire that involved the firewall were the chec k valves at the pop off valve rebuilt or replaced. Is it possible that the l ower check valve between the snot bottle and the pop off valve and the filte r are reversed. Instead of the one way valve arrow on the check valve pointi ng to the filter and theophylline off valve could it be pointing at the snot bottle. Did y'all re-assemble the H or was it done in the field? Is the fil ter patent or is it clogged up from carbon deposited? I saw your #2 in the summary list that referred to testing the H setup. Was i t disassemble after ya'll shipped it. As you know the check valve direction w ill have a big impact on air flow. Just a though. Doc Sent from my iPad On Oct 15, 2013, at 4:09 PM, "Jill Gernetzke" wrote: > Group, > > We have met up with a head scratcher. I am throwing it out to the group t o chew on: > > The Yak 52 owner purchased his aircraft on an insurance sale. The aircraf t had been totaled because of an engine fire. Attempts to talk to the origi nal owners and learn more about the aircraft=99s history have been uns uccessful. Originally, we were contacted because the air system was not bui lding pressure. A photo sent by the owner, elicited a remark by me that the re seemed to be a lot of oil in the banjo/outlet valve fitting. The compres sor itself was very dirty. > The owner cleaned the outlet valve with no appreciable change in output. > He then bought a "NOS" comp from a private party, installed it and it fai led in 2.5 hours. This compressor had actually been overhauled by us in 200 6. The nuts stripped off of the 4 studs on the bottom end of the compressor (green case), allowing the top end off the compressor to hammer up and down . Oil was all over the back end of the engine. > > The customer then sent his original compressor for overhaul and run on our test bench. He installed this overhauled compressor and it failed after 40 minutes in flight. This time the 4 studs sheared off of the bottom end of t he compressor. > > He sent us both failed compressors, the drive and drive gear, shear coupli ng, the FT-1 =9Csnot=9D valve and the pressure relief tee setup . We built one compressor out of the two failed units. The 4 stripped stud s were replaced with new studs and installed with Loctite. The compressor w as test run and produced 925 psi. The pressure relief valve tee setup was t ested =93 it relieved normally - rebuilt with a new piston, new seals in the one way checkvalves and the pressure set to 50 atm. (The pressure re lief valve had a Teflon seal which was in very poor condition.) The snot val ve was tested, flushed and retested. The compressor, gaskets and drive unit were secured to one another in the proper alignment for the reinstall. > > The air compressor was returned to the customer and it was reinstalled wit hout attaching the steel air line. Everything was normal for about 1.5 hours of ground runs. > > A flight was completed with the steel coiled air line still not attached. The flight was normal. > > The steel line was reattached and 90 minutes of ground run time. He notic ed that pressure was not building as it should and opened the cowling to fi nd one of the 4 hold-down nuts backing off. He also reported that the other 3 nuts were not tight. The owner drilled and safety wired the nuts. > > (Note: There is a CRITICAL clearance that is set between the bottom of th e Stage I piston and the top of the Stage II cylinder. Over-tightening thes e nuts will cause the top of the piston to hit the top of the Stage II cylin der. Too much clearance and it bottoms out on the other end.) > > We received the compressor and installed new studs and steel locknuts with Loctite. The compressor has been returned but not run, yet. > > Here is what we know: > 1. The FT-1 Snot valve is was flushed and functioning properly. > 2. The pressure relief valve tee and checkvalves were all tested and the system functioned normally on a bench test, with the pressure relief va lve popping off at 750 psi. > 3. A new steel line was provided to the customer, but I do not know i f this was installed. > 4. On the 4th installation of the compressor, we returned the compre ssor, shear coupling, drive pad and gear tie-wrapped as a unit for correct c locking. We received photo verification that the compressor drive was insta lled correctly. > 5. The compressor operated normally on the last run until the steel l ine was attached to it. Then, 1 nut backed off and the other 3 were reporte d loose. Hence, we replaced the hex nuts/lockwashers with steel locknuts in case the lockwashers had failed and that was the only problem on the last r un. > 6. The force to shear the compressor studs is in excess of 22,000 lb s. > 7. The shear coupling appears to be a factory unit. A new one was s ent to the customer, but returned back to me. > 8. The oil return holes in the accessory case are large and not plug ged. > > In the 20+ years that we have been overhauling air compressors, we have ne ver encountered this problem. Please use this problem as your own theoretic al and reasoning challenge to put forth real possibilities =93grasping at unicorns, rainbows or butterflies not allowed. : ) > > Jill > M-14P, Inc. > > > > > ========================== ========= ========================== ========= ========================== ========= ========================== ========= > ________________________________ Message 11 ____________________________________ Time: 07:39:16 PM PST US Subject: Yak-List: Re: Air Compressor (?) Issue From: "keithmckinley" If this plane came from the east coast I know it well. I flew A LOT with the owner who had before the ins company sold it and don't ever remember hearing about a compressor issue. ever. I would guess there are some big time metallurgy issues after watching it burn. -------- Keith McKinley 700HS X26 Sebastian, FL Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410668#410668 ________________________________ Message 12 ____________________________________ Time: 07:48:40 PM PST US Subject: Yak-List: Re: Staking a Housai exhaust valve (or M-14) From: "keithmckinley" I know just about everyone on this list is saying "for the love of GOD not again" so I'll stop it right here and get back to the staking question at the heart of this post and not MMO..... ....but thanks! [Wink] -------- Keith McKinley 700HS X26 Sebastian, FL Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410670#410670 ________________________________ Message 13 ____________________________________ Time: 08:35:19 PM PST US Subject: Re: Yak-List: Re: Staking a Housai exhaust valve (or M-14) From: "Roger Kemp M.D." But the real question we want to know Was it the lack of MMO That precipitated your situation Doc Sent from my iPad On Oct 15, 2013, at 9:42 PM, "keithmckinley" wrote: > > I know just about everyone on this list is saying "for the love of GOD not again" so I'll stop it right here and get back to the staking question at the heart of this post and not MMO..... > > > ....but thanks! > > > [Wink] > > -------- > Keith McKinley > 700HS > X26 Sebastian, FL > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=410670#410670 > > > > > > > > > > ________________________________ Message 14 ____________________________________ Time: 08:54:28 PM PST US Subject: Yak-List: Re: Air Compressor (?) Issue From: "Vic" Hello Jill, I wonder why the shear pins did not snap before the studs let go - unless you did not really check this ? I suspect an insufficient oil supply to the compressor and seized pistons. After the pins snapped the whole shear coupling may have seized again and consequently leading to breaking the studs. Did you look inside the compressor cylinders to check them for seizure ? With poor oil supply to the compressor drive I can imagine a snapped shear coupling will seize again in little time causing more damage. Please keep us posted with your findings. Cheers Vic Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410678#410678 ________________________________ Message 15 ____________________________________ Time: 11:42:34 PM PST US Subject: Re: Yak-List: Air Compressor (?) Issue From: Jan Mevis Probably a stupid remark, but are you sure that the shear coupling was OK? I've seen shear couplings that were repaired with STEEL from nails. Jan From: "jill@m-14p.com" Subject: Yak-List: Air Compressor (?) Issue Group, We have met up with a head scratcher. I am throwing it out to the group to chew on: The Yak 52 owner purchased his aircraft on an insurance sale. The aircraft had been totaled because of an engine fire. Attempts to talk to the original owners and learn more about the aircraft=B9s history have been unsuccessful. Originally, we were contacted because the air system was not building pressure. A photo sent by the owner, elicited a remark by me that there seemed to be a lot of oil in the banjo/outlet valve fitting. The compressor itself was very dirty. The owner cleaned the outlet valve with no appreciable change in output. He then bought a "NOS" comp from a private party, installed it and it failed in 2.5 hours. This compressor had actually been overhauled by us in 2006. The nuts stripped off of the 4 studs on the bottom end of the compressor (green case), allowing the top end off the compressor to hammer up and down. Oil was all over the back end of the engine. The customer then sent his original compressor for overhaul and run on our test bench. He installed this overhauled compressor and it failed after 40 minutes in flight. This time the 4 studs sheared off of the bottom end of the compressor. He sent us both failed compressors, the drive and drive gear, shear coupling, the FT-1 =B3snot=B2 valve and the pressure relief tee setup. We built one compressor out of the two failed units. The 4 stripped studs wer e replaced with new studs and installed with Loctite. The compressor was tes t run and produced 925 psi. The pressure relief valve tee setup was tested =AD it relieved normally - rebuilt with a new piston, new seals in the one way checkvalves and the pressure set to 50 atm. (The pressure relief valve had a Teflon seal which was in very poor condition.) The snot valve was tested, flushed and retested. The compressor, gaskets and drive unit were secured to one another in the proper alignment for the reinstall. The air compressor was returned to the customer and it was reinstalled without attaching the steel air line. Everything was normal for about 1.5 hours of ground runs. A flight was completed with the steel coiled air line still not attached. The flight was normal. The steel line was reattached and 90 minutes of ground run time. He notice d that pressure was not building as it should and opened the cowling to find one of the 4 hold-down nuts backing off. He also reported that the other 3 nuts were not tight. The owner drilled and safety wired the nuts. (Note: There is a CRITICAL clearance that is set between the bottom of the Stage I piston and the top of the Stage II cylinder. Over-tightening these nuts will cause the top of the piston to hit the top of the Stage II cylinder. Too much clearance and it bottoms out on the other end.) We received the compressor and installed new studs and steel locknuts with Loctite. The compressor has been returned but not run, yet. Here is what we know: 1. The FT-1 Snot valve is was flushed and functioning properly. 2. The pressure relief valve tee and checkvalves were all tested and the system functioned normally on a bench test, with the pressure relief valve popping off at 750 psi. 3. A new steel line was provided to the customer, but I do not know i f this was installed. 4. On the 4th installation of the compressor, we returned the compressor, shear coupling, drive pad and gear tie-wrapped as a unit for correct clocking. We received photo verification that the compressor drive was installed correctly. 5. The compressor operated normally on the last run until the steel line was attached to it. Then, 1 nut backed off and the other 3 were reported loose. Hence, we replaced the hex nuts/lockwashers with steel locknuts in case the lockwashers had failed and that was the only problem o n the last run. 6. The force to shear the compressor studs is in excess of 22,000 lbs .. 7. The shear coupling appears to be a factory unit. A new one was sent to the customer, but returned back to me. 8. The oil return holes in the accessory case are large and not plugged. In the 20+ years that we have been overhauling air compressors, we have never encountered this problem. Please use this problem as your own theoretical and reasoning challenge to put forth real possibilities =ADgrasping at unicorns, rainbows or butterflies not allowed. : ) Jill M-14P, Inc. ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message yak-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Yak-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/yak-list Browse Digests http://www.matronics.com/digest/yak-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.