Cylinder Glazing, C172 0-320
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Ah yes Ernie, the H model! To try to solve the cam wear problems on one of our customers aircraft we fitted a pre lube system{hand operated pump} he finished up in the trees in bad weather {walked away from it} so we never did find out if it helped, any one have any experience with such a system?
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Lycoming publish enough info for a satisfactory break-in, operation & continued airworthiness - is it being read, understood & acted upon by ALL concerned? 6 cylinders a month is a costly way of finding out its not!
Chief instructor is an ex military C-47 pilot and insists that 2,300 to 2,400rpm is too high and won't take any further arguement on the subject.
Get a new chief instructor.
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Lycoming publish enough info for a satisfactory break-in, operation & continued airworthiness - is it being read, understood & acted upon by ALL concerned? 6 cylinders a month is a costly way of finding out its not!
The CFI and I used to be on good terms until my recent poking around on this issue , I don't work for the company but I do a lot of business with them including leasing them cargo aircraft and buying their surplus parts and aircraft. I'm trying to help them out but it means a lot of them will 'lose face' with the owner
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It's not being read and probably hasn't been read for years
Perhaps time to get the latest data translated and offer it as a refresher training course notes to avoid loss of face? That thought wouldnt go amiss anywhere after reading some of Pprunes' threads & general sweeping statements of "knowledge"
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So what is glazing then ?
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Something that doesn't take place at idle...........
If glaze of the cylinder isn't caused by combustion product and at low RPM you need to state what it is - or become irrelevant.
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Glazing, as has been thoroughly discussed, involves two forms of improper wearing-in of an engine. If the cross-hatching in the engine is filled in with oil and other products during the break-in process, the piston rings won't properly wear. Improper break-in also results in burnishing of the crosshatch ridges, as well as filling in of the groves in the cross-hatching of the cylinder, also resulting in a failure of the rings and cylinder sleeve or barrel to mate and wear together.
Oil baked into the valleys of the cross hatching occurs due to combustion, and low power settings do fail to cause a proper gas seal during the break-in process.
HOWEVER, as has been pointed out by lycoming publications already cited in this thread, power settings as low as 65% are sufficient, and the issues regarding low power apply to the break-in period.
Operating an aircraft engine at idle at any time after the break-in period does not glaze cylinders. This returns us to the original assertion, that in lieu of better information, the symptoms as described (while lacking in adequate information) point to an improper break-in.
Operation at lower power settings in flight, and idle operation, do not result in glazed cylinders. Several posters attempted to show otherwise, citing lycoming publications, as well as attempting to cite mineral vs. AD oil usage...but failed to read the material they linked. The issues with break-in with respect to power settings apply ONLY during the break-in period.
Oil baked into the valleys of the cross hatching occurs due to combustion, and low power settings do fail to cause a proper gas seal during the break-in process.
HOWEVER, as has been pointed out by lycoming publications already cited in this thread, power settings as low as 65% are sufficient, and the issues regarding low power apply to the break-in period.
Operating an aircraft engine at idle at any time after the break-in period does not glaze cylinders. This returns us to the original assertion, that in lieu of better information, the symptoms as described (while lacking in adequate information) point to an improper break-in.
Operation at lower power settings in flight, and idle operation, do not result in glazed cylinders. Several posters attempted to show otherwise, citing lycoming publications, as well as attempting to cite mineral vs. AD oil usage...but failed to read the material they linked. The issues with break-in with respect to power settings apply ONLY during the break-in period.
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Operation at lower power settings in flight, and idle operation, do not result in glazed cylinders. Several posters attempted to show otherwise
BH
