Permit me a war story: During the summer months, the air around New Braunfels, Texas is as thick as concrete. At the airport, the ramp temperatures begin to soar at first light and pitchers of iced tea are downed for breakfast.
Id flown there on a warranty trip put together in a hurry. Inadvertently, the wrong ring set was installed in all 12 cylinders attached to a very nice, but older Cessna 310. While it was in for maintenance, the cylinders were to be pulled and the rings replaced before anyone got wise to the error.
The job took about eight hours longer than normal because the heat slowed everything down to a crawl. During one of the many iced tea breaks, a wiry man with an oil-stained ball cap walked over with a cylinder barrel cupped in one hand. It was 1989 and our first introduction to Engine Components Inc. Cermicrome-coated cylinder barrel.
We were told that the new coating would revolutionize the chroming business. Hard as a brick-bat, tough as nails and able to be re-used over and over, the new Cermicrome barrel was supposed to render everything else obsolete. Just you wait. We did. But like many, we didnt wait long enough.
Almost immediately, we learned that in some installations, the Cermicrome process failed to survive in even the least demanding of engine applications, the Lycoming-powered Mooney line and the Cessna singles.
Sagging compressions, just-okay oil consumption and blowing breather oil were but a few of the complaints. Some found the new barrel would wear prematurely, primarily due to the loss of the oil-wetted silica impregnated into the chrome wall, the very process that was supposed to make a Cermicrome cylinder the product of the future.
Some engine installations held up fine for a while. But after several years of use, many engines exhibited a slow but noticeable slide into marginal compressions, erratic oil consumption and fouled spark plugs. Cylinder replacement and warranty claims increased from a trickle to a fat stream.
Cermicrome not only proved to be less than advertised, it became very much less than desirable. It proved a hard step down for ECI, which continued to beat the marketing drum until the failing process proved too expensive to support.
The company maintained that the problem with Cermicrome was not the process itself but the type of piston rings used with Cermicrome cylinders. But the damage was done. Morale at ECI sagged and Cermicrome eventually became the bastard child that no one wanted to touch, regardless of price.
Citing EPA concerns in 1997, ECI ceased production of all chrome plating procedures, including Cermicrome. The decision came after several years of trial and error with a new plating process developed in Europe by M&T Chemicals and Blasberg Oberflachentednik for exotic car engines, such as the air-cooled Porsche 911.
In Europe, the plating of cylinder barrels with a nickel and silica matrix had been in place for many years. The results were generally considered good, but the process was more complex and slightly more expensive than chrome plating. But it was environmentally more friendly.
Nonetheless, as Cermicrome was being shelved, ECIs version of Europes Nikisil, the CermiNil cylinder, was gaining market share. CermiNil struggled through a slow start because owners and shops previously burned by Cermicrome were hesitant to try yet another revolutionary process.
Whats more, early reports from users of the new barrel were less than complimentary. Poor ring seating and complaints of cylinder barrel scoring created some initial panic. But ECI had faith in the process and work continued, in spite of the fact that cheap prices on factory-new cylinders made fooling with any aftermarket treatment less appealing.
We routinely check with overhaulers and maintenance shops around the country, asking about their experiences with various produces and services. A.E.R.O. Aviation (800-362-3044) reports that early use of CermiNil cylinders proved problematic.
Chrome and cast-iron piston rings were wearing out at an alarming rate and while CermiNil-treated Continental cylinders seemed to seat fine during the break-in process, Lycoming engines didnt do as well with the new process.
After much research and study, the problem was solved by using a plasma-coated top compression ring and cast-iron piston rings for the second and third ring lands. The plasma-coated ring uses a layer of chrome molybdenum on the ring face, which apparently provides a better wear surface than does the straight cast-iron ring.
Continental provided a similar type of ring in their steel cylinder kits, but rather than coating the top compression ring with chrome moly, TCM made the entire ring out of the harder material. Both styles are resistant to heat distress and both provide exceptional wear characteristics.
Once the piston-ring dilemma was resolved, CermiNil performance seemed to improve, as did market acceptance. A.E.R.O. Aviation recommends using only ECIs piston rings when assembling plated Lycoming barrels but stops short of that for Continental cylinders.
Experience seems to show that either the Continental or Superior rings work fine for all Continental barrels.
As far as rings go, G&N Aircraft, Inc. (800-348-6504) and Zephyr Aircraft Engines, Inc. (800-204-0735) use only ECIs rings. Like many shops, theyre not interested in experimenting with other ring types and paying for mistakes with warranty claims.
One of the chief complaints about Cermicrome had been the inability to successfully field dress the barrel in preparation for a new set of rings. The barrel was hard and the silica could not be replaced without sending the cylinder back to ECI for re-chroming.
That didnt keep shops from trying, however. Many mechanics tried to roughen the surface enough to get a new set of rings to seat properly. Most failed miserably.
CermiNil-coated cylinders suffer from some of the same concerns, but nickel is not quite as hard as chrome and because the silica is an integral part of the CermiNil coating, wiping and inadvertent removal isnt a problem.
ECI recommends the use of a stick hone wrapped with emery cloth to provide a field finish to the barrel. Others use a bristle or carbide ball hone to scratch the barrel surface.
Everyone maintains that a generous flood of solvent should be used with the finish hone procedure and that whatever hone is used, it should be dedicated to CermiNil barrels only. Any chrome particulate found in the typical shop hone will score the CermiNil barrel, leaving future ring seating to chance.
ECI began production of the CermiNil process in March 1993. Since then, by their own reports, some 100,000 nickel-treated barrels have been pushed through the new plating process. Unlike Cermicrome, the CermiNil process is made up of a nickel plating in which the silica carbide is part and parcel of the entire plated thickness.
This is a big departure from the 0.0015-0.002-inch deep layer of silica ground into the Cermicrome barrels. As a result, wiping away of the silica to an under-lubricated layer beneath is virtually impossible. Whats more, nickel is a far better oil-wetting agent than chrome and performs much like steel from the standpoint of ring seating, oil consumption and cylinder compression.
Of those overhaulers offering CermiNil-processed cylinders, including Western Skyways (970-249-0232) and those mentioned previously, none tell us that CermiNil has been a warranty problem, at least not from the standpoint of ring-to-barrel integrity.
ECI claims that of the 100,000 jugs produced, none have come back. None. That seems difficult to believe, but rebuilders say that statistically, if there were going to be a problem, it would have surfaced by now. In other words, so far, so good.
While ECI maintains that the new CermiNil process will work on any engine and any engine model, theres enough feedback in the field to support the idea that the coating is not recommended in Mooney aircraft, particularly the Lycoming-powered versions. But that has proven true for Mooneys with any chrome process, not just ECIs.
With the exception of ECI, most shops weve talked to agree that Mooneys should be topped only with steel barrels. Some also recommend that owners of the Piper Saratoga and Navajo should also avoid using CermiNil. The jury is still out on this, however, because not all agree that these engines are problematic.
What we do know is that the turbocharged Lycoming TIO-540-J and -S engines are hard on barrel surfaces. Theyre highly-stressed, high-heat engines that dont respond well to careless rework or ham-fisted pilots. If the CermiNil works long-term in these engines, it will work in anything made-except Mooneys, of course.
Treating of cylinder barrels with any kind of plating procedure is a salvage process designed to rejuvenate a worn out barrel. The intention is, and always has been, to provide an economical alternative to purchasing new cylinders. But the cylinder overhaul process has fundamentally changed since the factories got into the engine business a decade ago.
Ten years ago, when an owner overhauled an engine, using reconditioned cylinders was usually a given. New ones were simply too expensive to consider. Now that new cylinder prices are more competitive, the reverse is true. For a couple of grand extra, a rebuilder can offer factory new jugs, which probably adds real value to an engine overhaul, both in terms of durability and resale value.
In that context, ECI will only sell the CermiNil process for those cylinders in which head welding and re-machining (along with the heat-treat IFR process) has been done. They prefer to sell you a complete cylinder assembly, but are willing to provide minimal rework for owners or shops who want to install their own guides and seats.
As a price comparison, a standard, ready-to-install Lycoming O-360 parallel-valve CermiNil cylinder sells for $750. A factory-new cylinder kit for the same engine costs about $1200.
For the average four-cylinder Lycoming engine, a reduction in price of a top overhaul by $1800 is significant. Setting aside the durability issue for a moment, will the upfront savings come home to roost later when you try to sell an airplane with reworked cylinders? Maybe, maybe not. Its impossible to predict.
On the other hand, if just one of those heat-treated, nickel-plated, plasma-ringed cylinders lunches in 300 or 400 hours, youll easily eat into any savings and it wont take much to go seriously in the red. Mordecai Kutz, a Professor of Economics at Stanford, once said of stocks, There is only one truth and many opinions. Therefore, most people are wrong most of the time.
The same kind of logic seems to apply to CermiNil cylinders. Given the unsavory history of Cermicrome, were inclined to be somewhat skeptical. But based on our interviews with shops and owners, the good news is that CermiNil is holding up quite well at a point in its operational history when its progenitor, Cermicrome, was stumbling badly.
If youre considering CermiNil jugs for a top overhaul or an economy major, we think its a reasonable bet that the favorable trend will continue. It thus becomes a pure bottom line consideration on whether spending an extra $1800 to $2700 for new cylinders is worth it.
Its a close call, in our view, depending on the aircraft itself and how its used. It doesnt make sense to put new cylinders in a beater trainer but it might for your pride-and-joy Bonanza. In that sense, we think CermiNil is worth considering.
Contact- Engine Components, Inc., P.O. Box 17099, 9503 Middlex, San Antonio, TX 78217; 800-324-2359; www.eci2fly.com.
Also With This Article
Click here to view “CermiNil at a Glance.”
by Paul Brevard
Paul Brevard is editor of Aviation Consumers sister publication, Light Plane Maintenance.