---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Fri 08/28/15: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:05 AM - Re: Sticky valve? (JL2A) 2. 01:55 PM - Re: Re: Sticky valve? (Bitterlich, Mark G CIV NAVAIR, WD) 3. 10:00 PM - Re: Re: Sticky valve? (Walter Lannon) ________________________________ Message 1 _____________________________________ Time: 04:05:03 AM PST US Subject: Yak-List: Re: Sticky valve? From: "JL2A" Mmm ok, so Aeroshell 100 then? In the manual it specifies castor oil OR type 8 aviation oil, what ever that is (or type x I can't remember) Do we think that it is probably a mineral oil? Has anyone got a way to find out? I am done with castor oil! The book calls for a colossal amount (something like 30mL into each end if I recall correctly?) and around the front rudder pedals and all that area is a sticky mess. There's a very well preserved CJ under it all which is a plus I guess. I think I read here that others were using machine oil and it was fine - the thought did cross my mind about seal compatibility but one of those wanting to believe situations I guess. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=446468#446468 ________________________________ Message 2 _____________________________________ Time: 01:55:25 PM PST US From: "Bitterlich, Mark G CIV NAVAIR, WD" Subject: RE: Yak-List: Re: Sticky valve? I was talked into putting pneumatic tool oil into my pneumatic system back around 2001 or so, on the original version of the YAK LIST. I had just purchased my YAK-50 and had no idea how old the landing gear actuator seals were, but they were working fine at the time. I injected the oil and several flights later, the seals in the landing gear actuators started coming apart. What I noticed was air leaking out the gear handle when the gear was down and locked. Luckily I figured out that if the actuator had internal leakage, you would hear that at the gear handle. When I took the actuators apart, the chevron seals were pretty much like soft putty. Granted, these were probably original Russian seals. Granted, they were probably hardened and in very poor shape. However, the oil caused them to just fall apart. To each his or her own, but after that little experience I have never injected a DARN thing into my air system. NADA ZERO ZIPPO. I did rebuild the actuators, and honestly it is about time to do them again and personally... I believe that rebuilding the actuators, and taking apart and looking at pneumatic components every so often is a very good idea, especially the areas where there is known corrosion issues and doing that is much more important than injecting ANYTHING into that system. As I said, I own a YAK-50, so my experience may not be applicable to 52's or CJ's. However, I'd be very cautious of what I inject into the air system and would not ad hoc it under any circumstance, or make guesses. Also of note is that my brake system is no longer pneumatic, it is now toe brakes and hydraulic. So my pneumatic system is just for landing gear and starting. There is long term impact with this decision, so caution is the order of the day (so to speak). Best of luck, Mark -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of JL2A Sent: Friday, August 28, 2015 7:02 AM Subject: Yak-List: Re: Sticky valve? Mmm ok, so Aeroshell 100 then? In the manual it specifies castor oil OR type 8 aviation oil, what ever that is (or type x I can't remember) Do we think that it is probably a mineral oil? Has anyone got a way to find out? I am done with castor oil! The book calls for a colossal amount (something like 30mL into each end if I recall correctly?) and around the front rudder pedals and all that area is a sticky mess. There's a very well preserved CJ under it all which is a plus I guess. I think I read here that others were using machine oil and it was fine - the thought did cross my mind about seal compatibility but one of those wanting to believe situations I guess. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=446468#446468 ________________________________ Message 3 _____________________________________ Time: 10:00:39 PM PST US From: "Walter Lannon" Subject: Re: Yak-List: Re: Sticky valve? Mark, et al. Been meaning to join this discussion for a while but due to old age, inertia, laziness (or a combination of all three) have failed to do so. But you have given me a kick in the butt so here we go. Back in the day of PT19s, PT22s, PT26s, early T6s etc. aircraft hydraulic fluid (Mil spec. 3586 if I remember correctly) was blue in color and was a vegetable based oil, perfectly compatible with the natural rubber seals of that era. With the introduction of mineral oil based fluids (eg. Mil 5606) all seals had to be replaced with synthetic rubber equivalents (nitrile, neoprene, etc.) Natural rubber exposed to mineral based oils was (and is) a disaster. Nitrile seals are perfectly OK in vegetable fluids (castor oil, etc.) but the reverse is not true. As a result over the past 20 years whenever I overhaul a Nanchang oleo or actuator I first immerse the new seals in MIL 5606 for a period of 48 hours prior to installation. Not surprisingly some have to be rejected due to swelling. There appears to be both natural and nitrile seals from China though as I indicated both would be acceptable in castor oil. Air tool oil (which I use) is a petroleum based fluid with a moisture retaining additive (though seems impossible to get a definitive breakdown of ingredients) which will certainly destroy natural rubber seals. Cheers; Walt -----Original Message----- From: Bitterlich, Mark G CIV NAVAIR, WD Sent: Friday, August 28, 2015 1:51 PM Subject: RE: Yak-List: Re: Sticky valve? I was talked into putting pneumatic tool oil into my pneumatic system back around 2001 or so, on the original version of the YAK LIST. I had just purchased my YAK-50 and had no idea how old the landing gear actuator seals were, but they were working fine at the time. I injected the oil and several flights later, the seals in the landing gear actuators started coming apart. What I noticed was air leaking out the gear handle when the gear was down and locked. Luckily I figured out that if the actuator had internal leakage, you would hear that at the gear handle. When I took the actuators apart, the chevron seals were pretty much like soft putty. Granted, these were probably original Russian seals. Granted, they were probably hardened and in very poor shape. However, the oil caused them to just fall apart. To each his or her own, but after that little experience I have never injected a DARN thing into my air system. NADA ZERO ZIPPO. I did rebuild the actuators, and honestly it is about time to do them again and personally... I believe that rebuilding the actuators, and taking apart and looking at pneumatic components every so often is a very good idea, especially the areas where there is known corrosion issues and doing that is much more important than injecting ANYTHING into that system. As I said, I own a YAK-50, so my experience may not be applicable to 52's or CJ's. However, I'd be very cautious of what I inject into the air system and would not ad hoc it under any circumstance, or make guesses. Also of note is that my brake system is no longer pneumatic, it is now toe brakes and hydraulic. So my pneumatic system is just for landing gear and starting. There is long term impact with this decision, so caution is the order of the day (so to speak). Best of luck, Mark -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of JL2A Sent: Friday, August 28, 2015 7:02 AM Subject: Yak-List: Re: Sticky valve? Mmm ok, so Aeroshell 100 then? In the manual it specifies castor oil OR type 8 aviation oil, what ever that is (or type x I can't remember) Do we think that it is probably a mineral oil? Has anyone got a way to find out? I am done with castor oil! The book calls for a colossal amount (something like 30mL into each end if I recall correctly?) and around the front rudder pedals and all that area is a sticky mess. There's a very well preserved CJ under it all which is a plus I guess. I think I read here that others were using machine oil and it was fine - the thought did cross my mind about seal compatibility but one of those wanting to believe situations I guess. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=446468#446468 ------------------------------------------------------------------------------------- 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.