Cracked Cylinders

Cracked Cylinders

Cracked Cylinders

 

During a routine inspection, a cracked cylinder was found requiring replacement.
This was the latest AOG event related to a long series of cylinder problems.

What previously was a smooth, aerodynamic engine cowl is now laying on the hangar’s concrete floor with various parts never intended for public viewing being exposed in all their tangled awkwardness for any passerby to see. Within this jumble of tubes, wires and other objects mounted on various odd-shaped brackets, there is a small spark plug opening, and next to that a half-inch black line from which there extends an ominous blue stain. The stain results from the fact that 100LL fuel has mixed with it a blue dye, and when it leaks out through a crack in a cylinder head, it leaves a trail of blue pigment running uncomfortably close to the nearby Mexhaust stack.

To make matters worse, Paul the mechanic says the No.1 cylinder on the opposite (right) engine also has low compression, but he has not (yet) been able to find a crack. The involved cylinders, of course, are located on the far back side of the engines and almost impossible to see unless gifted with extraordinary eyesight, a very bright light, plus a huge dental mirror, and unmatched mechanical ability. Nevertheless, in spite of this difficulty, Paul an airplane mechanic of great aptitude, had just managed to find at least the one crack during a routine exhaust inspection and oil change on my Cessna 340.

Given the possibility that there may be some carbon deposit within the cylinder on the right side that is interfering with compression, what he now wants me to do is fly the airplane for 30 minutes or so, running the right engine through peak EGT a couple of times, to see if it can be burned off. That sounds OK, until he also says I should not operate the left engine with the visibly cracked cylinder and leaking fuel at anything but very reduced power.

Luckily, a lightly loaded RSTOL C340 is quite a performer. After carefully making sure all the cowls are back in place, I taxi out for the required maintenance flight. Getting on the runway, I mentally brief myself on single-engine procedures, then gradually push the right engines throttle to the stop, while holding the left engine no more than 30 inches of MP. A bit of fiddling is needed with the rudder pedals to keep the airplane on the white line with the differential power setting, but otherwise the airplane accelerates just fine, and I shortly find myself at 5,500 feet out over the Cascades cycling the right engine, while the left is kept down to not much more than idle power.

Upon my return the compression on the right engine has miraculously returned to normal. So, now the only problem is just the cracked cylinder on the left side.

In spite of this relative good news, it always seems the timing for this kind of thing is very inopportune. In three days, we were scheduled to fly to Ashland, Oregon, the town also known as the Shakespeare capital of the United States to attend a play. Once you have hotel reservations, rental cars arranged, friends invited and tickets purchased, this kind of airplane news is never welcome. Paul knows it, having apologized several times for having found the problem. But then, given events over the past several years with this particular set of RAM VII engines with ECI cylinders, Paul and his fellow mechanics have learned to be very, very careful when it comes to assessing cylinder health.

The RAM Upgrade That Wasn’t

About four years ago, the RAM VI engines on my Cessna 340A arrived at TBO having been flown using the same technique by the same professional pilot crew for 1,500 hours, all without really much maintenance fanfare. With the engines having worked well through that period, and being pretty happy with the service from RAM, I decided to take the airplane to Waco, Texas and have RAM change the installation to a VII conversion, the turbochargers coolers for which are quite larger.

When it was finished, I airlined back down, had lunch in the Tex-Mex restaurant the RAM sales guys like to take customers to, then flew the airplane from Waco to Seattle. Almost right away, I could see that the RAM VII conversion did what was advertised. The CHTs were cooler, and the TAS at 220 knots at FL200 with an 18.5 gph fuel flow on the rich side of peak EGT, which was five to 10 knots faster than the prior engines with the same fuel burn. I also thought they ran a little smoother and quieter with the new Scimitar propellers. Although it was somewhat more expensive than having the existing VI series engines overhauled, I was quite happy with my decision.

For about a year those engines ran perfectly. Then the problems began. It was almost like a contagious disease. Starting at about 200 hours, the right engine developing a cracked cylinder with the typical blue stain from leaking fuel. Then over 50 to 100 hours, this malady gradually spread to a random assortment of other cylinders, including those on the opposite engine. All this was going on while the airplane was being regularly flown by myself and the same three professional pilots who had managed to get 1,500 hours out of the previous engine set without any such problems.

We were also in the middle of a Northwest winter, with short days, low IFR conditions, and trips that inevitably took us across mountainous terrain with high MEAs, and a lot of ice. A Cessna 340 flies just fine on one engine, but it will not maintain adequate cabin pressure, nor the MEA required over a lot of the western United States with one engine out. We also noticed that the effected cylinders were all made by ECI. This coincided with an active public discussion about the need for an AD on the problem. All this made us pilots feel very ill at ease, and look for reasons to fly a different airplane.

Finally, following one particularly bad nighttime IFR trip from Seattle to Spokane and back, two additional cylinders on opposite engines were discovered to be cracked, and on further investigation the cam shafts were also found to be spauled. This being the fifth and sixth cracked cylinders discovered within a 50-hour period, a conference between the Gary the shop supervisor and longstanding lead mechanics Paul and Danny led to the conclusion that even if the two newly cracked cylinders were replaced, these 200-hour RAM VII engines with ECI cylinders were simply not airworthy. So, they grounded the airplane. The other pilots were relieved, the owner (me), not so much.

New Engines, New Problems

Anytime this sort of thing happens, pilot technique is the first item brought up when discussing causation. And so, we went through the routine of defending how (we) the pilots operated the engines with RAM many times. With the airplane now grounded (AOG), something needed to be done. Their solution was to offer to sell us at a discount two newly overhauled engines they had on the shelf. But first before shipping, I needed to send a $100,000 cash deposit directly into RAM’s bank account. Given the airplane with relatively new engines from RAM was grounded, this seemed like an odd way to handle a repeat customer known for paying his bills. But they insisted this was just standard company policy.

A tell-tail black line and blue staining in an otherwise brand-new looking cylinder revealed an unfortunate conclusion: a crack in the cylinder head.

It also seemed odd that given all the difficulty being described publicly, RAM had not already switched to a brand of cylinder not plagued with this
issue. The way they saw it, the ECI cracking problem was no better or worse than cylinders from other sources. So, the new engines they planned to send up also all had ECI cylinders, albeit a new version wherein the “problem” (not admitted being present in the first place) had been fixed.

A couple of days later, two newly overhauled engines in RAM crates were delivered to the maintenance shop. While this had been going on, the shop crew had sent out both propellers to be flushed just as a precaution. The new engines were promptly mounted and the left one performed perfectly. The engine on the right however immediately drove the propeller into feather, a position from which it refused to budge. Finally, after doing a long checklist of mechanical tests, it was decided there must actually be something wrong with this newly overhauled engine itself, probably the oil separation ring on the front of the crank shaft.

By now the AOG period had extended to a month. RAM sent yet another engine, which was installed within a few days, and ran without problem.

The procedures for breaking in a new cylinder are detailed and requires the
full attention
of the pilot.

We thought with the “new” and improved ECI cylinders, our problems were over, but now two years later as I was looking at the mess of parts and cowling resting on the hangar floor, with the Ashland personal trip now just three days away, I realized with restrained irritation that it was just not so. We again called our friendly RAM customer service guy, who said the engines still had some warranty coverage, but they (finally) were no longer using ECI products, and therefore he could not send us up a replacement cylinder of the same brand. They would however send up a newly overhauled one from Continental, at a prorated discount given the warranty. The cylinder was shipped to arrive the next morning, and was then promptly installed, now just a day before our scheduled Ashland trip.

I have learned to never take passengers, fly IFR or at night on a first flight after major maintenance, so I still needed to test fly the airplane. At 5 p.m. on the day before our departure, I showed up at the airport and received a “new cylinder” break-in briefing from mechanic Paul, plus a yellow and red checklist from RAM outlining what specifically needed to be done. I noticed the single most repeated line on the list was “FULL POWER SHOULD ALWAYS BE USED AS REQUIRED IN THE EVENT OF AN EMERGENCY” in all caps, something that seemed obvious to me as a pilot. Taking care to avoid any “EMERGENCY” I completed the break-in process, which basically involved cycling the power over a certain range for about an hour or so without any difficulty.

The next morning, all log entries completed, we departed in low IFR conditions to Oregon. There was a low-pressure system off the coast, producing a line of weather that extended offshore from Vancouver Island to northern California, and was working its way inland across the entire area. The left engine with its new Continental cylinder performed just fine, and we made an ILS into Medford, with a breakoff to fly VFR down the valley the few miles to the small airport at Ashland without any problem. The next day the return trip also went without a single hitch, with a nice tailwind and on top of an extensive cloud layer at FL220.

But, I am still feeling somewhat ill at ease about the remaining 11 ECI cylinders on my airplane. Just in case this happens again, I bought a spare one made by Continental.

Kevin Ware’s Cessna 340 parked in the maintenance hangar as it awaits a replacement cylinder.

Cracked cylinders and blue fuel stains next to hot exhaust are never a good thing.

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