Pedals2Paddles
Cleared for Takeoff
Reading a log book, it say "Cylinders nu-chromed by ACA" as part of the last major overhaul in 1991. What can ya'all tell me about nu-chrome?
To expound on what FORANE says, when your cylinders are worked they can be honed or even bored oversize to a point. If it is sufficiently warn you have to plate new metal on the interior surface. This is "chroming" because the alloys involved typically have a lot of chrome in them.
There are a number of brand name chroming processes such as Cermicrome, NU-Chrome,
etc... that add silicon-carbide additives to the process. This helps solve some problems straight chroming has. Good article here: http://www.avweb.com/news/reviews/182885-1.html?redirected=1
So it sounds like this may be favorable if the engine spends or had spent a long time sitting without regular use since it can't rust. But of course does nothing to prevent the crank and camshaft from rusting...
Wearing the iron rings out on a hard chrome cylinder is actually the better option IMO than wearing the cylinder out with the chrome ring; pop of the jug, re-ring, reseat the new rings. Lots cheaper that way anyway. The problem I always saw was due to being bored to thin, not the surface.
So it sounds like this may be favorable if the engine spends or had spent a long time sitting without regular use since it can't rust. But of course does nothing to prevent the crank and camshaft from rusting...
I get the impression Tom does not like chromed cylinders. As someone who owns a plane that came with chromed cylinders, I agree with him. My O-320 with them is approaching 900 hours. I replaced one cylinder after it lost compression over WV. We put a new steel cylinder on. Oil consumption has remained high since new. Oil consumption got as high as 1 qt every 2 hour prior to the cylinder replacement. It currently uses about 1 qt every 6 hours. Given the choice I would not use chromed cylinders again.The big problem with chrome is the cylinders are old. old cylinders crack. Old cylinders that are chromed were at one time worn out, bored, then plated back to standard, to try to get one more run out of them. seldom happens with out problems.
In many cases the cylinder will not stop burning oil, we then pull it to see why, and fine the new rings worn out, several cycles thru this process maybe the cylinder will wear smooth and the rings will stop the oil usage. or not.
You never use a chrome compression rings in a chrome cylinder. the chrome to chrome wear will tear off the plating of both the ring and cylinder, and embed it into the bearing set, which will ruin the crank, and many of the gears in the engine.
You never use a stone in a chrome cylinder to smooth the chrome, it simply removes it. Take a hone stone to your bumper see what happens.
Try to imagine the cost of removing the cylinders and basically doing a top overhaul every 40-50 hours until you give up and buy new cylinders.
Correct me if I'm wrong. The cylinder being old is what causes the failure.