Awqward Posted January 29, 2015 Report Posted January 29, 2015 With my airplane grounded still waiting for a new spinner aft bulkhead that Hartzell haven't managed to slot into their manufacturing program yet, it has been three months already and I'm looking at another six weeks minimum before I can even run the engine....I am very worried that my cylinders and cam lobes and crankshaft are now coated with a film of corrosion!....someone recently sent me an email with a homemade dehumidifier based on a fish tank air pump and a soda bottle full of silica gel which pumps dried air in through the oil filler and takes the return air from the oil breather.... Just how bad can my engine have gotten in these three months? I mean it is not unusual for an engine to not run for three months especially at this time of year....What views? Anthony Quote
John Pleisse Posted January 29, 2015 Report Posted January 29, 2015 Not...unlikely. Some people think they can actually see corrosion growing or maybe they can hear it actually being destructive... Please...get a full night's sleep tonight. Quote
Trailboss Posted January 29, 2015 Report Posted January 29, 2015 In the same vein of thought... What about desert/arid climate, sitting 8 months? Let's assume corrosion is present, how would one go about finding it on a PPI? Would it require pulling a cylinder, or is there a way to examine the internals w/o that? Quote
N201MKTurbo Posted January 30, 2015 Report Posted January 30, 2015 You could leave an engine here for a hundred years and it wouldn't get corroded. That's why the Air Force bone yard is here, well a hundred miles south of here where it gets a lot more rain. 75 deg and rainy! winter $%^&$... Getting all our football and golf fans wet... Quote
orionflt Posted January 30, 2015 Report Posted January 30, 2015 Anthony, A dehumidifier is easy and inexpensive to make, i built mine for under $20. look in my gallery and there are some pic. it's pretty much what you described. I use it during the winter when my plane is sitting for several weeks at a time. Brian Quote
Awqward Posted January 30, 2015 Author Report Posted January 30, 2015 Thanks Brian...as others have pointed out such a device is very cheap....whether it is essential or not... I will be building one this weekend... To answer TBA's question; I understand that if the RH is less than 50% there will never be any corrosion....but most places have more than this most of the time...where I am it usually runs around 60-80% Quote
carusoam Posted January 30, 2015 Report Posted January 30, 2015 keep in mind the RH 50% is a guideline... Sounds like there may be some confusion of when to use or when not to use dry air... the word 'never' is really too strong for this statement. RH changes with temperature. If you have 50% RH during the day, you may have something higher as the IAT cools overnight. a real night and day difference. Cams are sensitive to moisture, not just condensed moisture, all moisture... if you can't run it to keep oil spread all over it. Use dry air... the other thing to be aware of is the location of the cam. The Lyc IO360 has a tendency to have the oil run off the cam because of the engine design. So I have been told... -a- Quote
Awqward Posted January 31, 2015 Author Report Posted January 31, 2015 Ok for simplicity and expediency I am making an open circuit "dry air injector " system to pump dehumidified air into the oil filler....maybe I will rig up a return line from the oil breather at some point in the future....one question though: what about the exhaust and intake manifolds? Should they be sealed / stoppered? Quote
DonMuncy Posted January 31, 2015 Report Posted January 31, 2015 I run my dryer into the breather and vent out the filler (with a check valve). It is nice, after a flight, to see the moist air being pumped out the filler opening. Quote
Awqward Posted February 1, 2015 Author Report Posted February 1, 2015 Is there any advantage / disadvantage to using Calcium Chloride compound vs Silica Gel crystals? Quote
Awqward Posted February 25, 2015 Author Report Posted February 25, 2015 To answer my own question, I inderstand Calcium Chloride is corrosive if in direct contact with metal....how it performs with air being forced through it I don't know... Maybe the air would carry some of the CaCl into the engine...I don't know... Quote
David Mazer Posted February 25, 2015 Report Posted February 25, 2015 Anthony, I can tell you I had to major overhaul my engine after 8 weeks idle time at Venice airport in Florida. Now, Venice is right on the Gulf of Mexico and the salt is very real. So is the humidity. The dehumidifier is cheap insurance. I also advise against the open circuit as the air gets drier each pass in a closed circuit (or uses up your descant more slowly) and only gets so dry on an open circuit. Quote
Awqward Posted February 25, 2015 Author Report Posted February 25, 2015 Thanks David, did you use silica gel or calcium chloride compound? Quote
Marauder Posted February 25, 2015 Report Posted February 25, 2015 On 2/25/2015 at 12:29 AM, Awqward said: Thanks David, did you use silica gel or calcium chloride compound? Use this: https://www.aircraftspruce.com/catalog/eppages/tempest-silica-blue.php?clickkey=4159 1 Quote
Danb Posted February 25, 2015 Report Posted February 25, 2015 Chris if want to duplicate the tempest system slip over my hanger and use it as a prototype..it looks easy to duplicate. 1 Quote
Marauder Posted February 25, 2015 Report Posted February 25, 2015 On 2/25/2015 at 7:00 PM, Danb said: Chris if want to duplicate the tempest system slip over my hanger and use it as a prototype..it looks easy to duplicate. May take you up on that Dan. I bought all the fixings to make one, but it is a bit clunky of a design. What do you expect, I'm a Cheap Bast$&d and damn proud of it! Quote
David Mazer Posted February 26, 2015 Report Posted February 26, 2015 On 2/25/2015 at 12:29 AM, Awqward said: Thanks David, did you use silica gel or calcium chloride compound? Silica. Easy to use and reuse by drying in the oven at low temperatures overnight. Attached are the directions for the unit I used. Engine_Dryer_Sport_Avi.pdf 1 Quote
DonMuncy Posted February 26, 2015 Report Posted February 26, 2015 As I have posted here before, I built my dryer, and have a photo in my gallery. I overbuilt mine, but will gladly share any details. Quote
mike28w Posted February 26, 2015 Report Posted February 26, 2015 I'm unsure just how effective any of these systems really are. Has anyone measured relative humidity of the air before it goes through the desiccant and compared the humidity after it has left the desiccant. Should be easy to do....what are the before and after numbers ?? mike Quote
Awqward Posted March 1, 2015 Author Report Posted March 1, 2015 On 2/25/2015 at 12:25 AM, David Mazer said: Anthony, I can tell you I had to major overhaul my engine after 8 weeks idle time at Venice airport in Florida. Now, Venice is right on the Gulf of Mexico and the salt is very real. So is the humidity. The dehumidifier is cheap insurance. I also advise against the open circuit as the air gets drier each pass in a closed circuit (or uses up your descant more slowly) and only gets so dry on an open circuit. I am not a metallurgist (although I am an engineer), but normal corrosion is oxidation...meaning it is not just the moisture level (RH), but the O2 in that moisture that is the problem. There are two opposing effects with temperature: colder water can hold more O2, and; warmer water facilitates diffusion of O2....the net effect of these two factors is that there is a slight increase in corrosion rate with increasing temperature....I read that the rate doubles with a 30degC temperature increase...up to 80degC where it drops off because the O2 becomes very low....(even Az doesn't get that hot!)... That is for normal oxidation. For pitting of Stainless Steel the chloride content of the water along with temperature work in the same direction... So being in hot marine environment like Venice is probably a recipe for increasing both types of corrosion...where I live the temperatures have been more like 0-10degC overt the last few months and the airport is a few miles inland with a prevailing wind from inland (>85% of the time)....nonetheless I have now rigged up an open circuit silica gel dehumidifier pumping dried air into the oil filler... Next week I will finally get my spinner part from Hartzell and be able to run the engine...so fingers crossed that it doesn't start making lots of metal! Quote
Guest Posted March 1, 2015 Report Posted March 1, 2015 I'd bet you that Hartzell would have built you a whole new Top Prop conversion faster than your spinner parts. They're not know for great customer support in my experience. Clarence Quote
Awqward Posted March 1, 2015 Author Report Posted March 1, 2015 You're absolutely right Clarence....it was one of those problems that just kept dragging out....until, wow it's 4 months!.....if I had known I maybe would have gone with a new prop....I did get P&A on a 3 blade MT prop early on...but couldn't justify it financially....but if it has caused corrosion damage to my engine it may have been the cheaper alternative! Quote
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