---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Sat 08/25/12: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:26 PM - Re: Re: Can not turn over prop (Damien) 2. 07:44 PM - Re: Re: Can not turn over prop (rparigor@suffolk.lib.ny.us) 3. 08:53 PM - Re: Re: Can not turn over prop (FLYaDIVE) ________________________________ Message 1 _____________________________________ Time: 06:26:24 PM PST US From: "Damien" Subject: Re: RotaxEngines-List: Re: Can not turn over prop The problem seems to be crankcase fretting, as Roger had suspected. I am flying the plane again, carefully, but obviously I need to have this corrected. I am going to contact LEAF and see what they suggest. Roger, my mechanic and I would still be floundering around if you had not jumped in to help. Thanks. Regards, Damien Graham N48TK ----- Original Message ----- From: "Roger Lee" Sent: Monday, August 20, 2012 6:14 PM Subject: RotaxEngines-List: Re: Can not turn over prop > > I talked with them today and think they have found the problem. I don't > have absolute confirmation yet, but should have when they do a test I gave > them. The cylinders and everything else was clean. The gearbox too. > > -------- > Roger Lee > Tucson, Az. > Light Sport Repairman - Maintenance Rated > Rotax Repair Center - Heavy Maint. Rated > Home 520-574-1080 TRY HOME FIRST > Cell 520-349-7056 > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=381411#381411 > > > ________________________________ Message 2 _____________________________________ Time: 07:44:50 PM PST US Subject: Re: RotaxEngines-List: Re: Can not turn over prop From: rparigor@suffolk.lib.ny.us Hi Damien "The problem seems to be crankcase fretting, as Roger had suspected." Do you mind explaining exactly what crankcase fretting is and why it prevented you from turning over your prop. Thx. Ron Parigoris ________________________________ Message 3 _____________________________________ Time: 08:53:53 PM PST US Subject: Re: RotaxEngines-List: Re: Can not turn over prop From: FLYaDIVE Ron: Fretting wear is the repeated cyclical rubbing between two surfaces, which is known as fretting, over a period of time which will remove material from one or both surfaces in contact. It occurs typically in bearings, although most bearings have their surfaces hardened to resist the problem. Another problem occurs when cracks in either surface are created, known as fretting fatigue. It is the more serious of the two phenomena because it can lead to catastrophic failure of the bearing. An associated problem occurs when the small particles removed by wear are oxidised in air. The oxides are usually harder than the underlying metal, so wear accelerates as the harder particles abrade the metal surfaces further. Fretting corrosion acts in the same way, especially when water is present. *Fretting* refers to wear and sometimes corrosion damage at the asperities of contact surfaces. This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration. The ASM Handbook on Fatigue and Fracture defines fretting as: "*A special wear process that occurs at the contact area between two materials under load and subject to minute relative motion by vibration or some other force.*" The amplitude of the relative sliding motion is often in the order from micrometers to millimeters, but can be as low as 3 to 4 nanometers .[1] The contact movement causes mechanical wear and material transfer at the surface, often followed by oxidation of both the metallic debris and the freshly exposed metallic surfaces. Because the oxidized debris is usually much harder than the surfaces from which it came, it often acts as an abrasive agent that increases the rate of both fretting and a mechanical wear called false brinelling .. False brinelling gets it's name from the Brinell Scale of Hardness. Not to be confused with the Mohs Scale of Hardness. Now the questions are: What caused it? Was it poor preventative maintenance? Such as way, way over due oil changes? Poor quality of oil? Too many short runs with not enough heat generated to drive out the condensed moisture in the oil? Improper matching of mating materials? Poor tolerances on rotating surfaces? Poor tolerances and excessive lateral movement on the rotating surfaces? Leaking of the cooling system into the crankcase? Barry On Sat, Aug 25, 2012 at 10:44 PM, wrote: > Hi Damien > > "The problem seems to be crankcase fretting, as Roger had suspected." > > Do you mind explaining exactly what crankcase fretting is and why it > prevented you from turning over your prop. > > Thx. > > Ron Parigoris > > * > > * > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-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/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-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.