Mark has a unique way of doing removals. He leaves the intake manifold assembly in the airframe. This procedure helps expedite both the removal and installation of the engine. A last minute cavity inspection is prudent. Be careful not to pinch any of the harnesses.
Notice that the push rod tubes can be installed after the head is torqued. They have doughnut seals on both ends and they compress in the middle. The seals should be placed in the appropriate recesses wet with black RTV. The tubes should be immediately installed and not moved until the sealant cures.
Do not forget the two ground wires from the engine block to the head. Valves are set and ready to have the rocker covers installed. Do not over tighten the two bolts that hold these covers, they will crack if over torqued. Engine is now ready to be installed into the airframe.
Next step is to re-install all the push rods and rocker arms. It is advantageous to set the lash at this time. Remove one spark plug from each cylinder to allow for easier engine rotation. Follow the RWI instruction manual.
Installing the heads is pretty straight forward. We used black RTV on all joints. Note the sheet in Doug's hand is the torques and the tightening sequence. Everything is Aluminum so this is very important to preclude warping the head. Cleanliness is also very important throughout the assembly evolution.
The bolts holding the cylinders on are through bolts. We used pal nuts on one end to facilitate installing the 12 point nuts on the opposite side. Do not force the cylinders over the rings. We used a narrow band type ring compressor. Also we were able to do one piston at a time and then slowly rotate the crank enough for the other piston to be inserted.
During assembly it is prudent to liberally apply STP to all moving parts. This allows the oil system time to pump adequate supplies of lubricant to the engine. Also make sure that the ring gaps are not lined up. Be advised that on initial startup the engine will smoke due to the STP, do not panic, it will do it only briefly.
Here the engine is clean and ready for rings and cylinder’s to be installed. It is easier to assemble the engine in a vertical position. The table has a hole in it similar to the airframe engine mount. Note the ratchet strap which ensures rigidity.
This is the damaged cylinder pair. Note the right hand cylinder lip. Toward the center the sleeve cracked at the lip and allowed the entire sleeve to slide down. This allowed water to enter the case and a total loss of compression in that cylinder.
The piston were reusable. There was some minor damage on the bad cylinder piston. I, again, burnished the nicks. All four pistons had some carbon film which was chemically and mechanically removed. We opted to replace both cylinders, port and starboard. Time on this engine was only twenty hours.
This picture shows how much the left cylinder sleeve slid as compared to the undamaged sleeve on the right. Current cylinder pairs from RWI have an internal champhered edge which engineering hopes will prevent this type of failure on current production units. Time will tell!!
Every job has a starting point. Removing the engine and securing it to an appropriate stand is the first step. Vertical is the best way to do almost any task on the Rotorway engine. Note the strap which insures a stable attachment to the stand.
The first disassembly task is to remove the rocker arms and push rods. A storage rack is very handy. The rack keeps all the removed item in the proper order as removed from the head.
Mark Peterson's rack is ideal for this purpose.
Removal of the heads is the next step toward cylinder removal. With aluminum heads it is good practice to relieve the head bolt torques sequentially. During disassembly you should inspect items as removed. Note bolt length and threads for damage. Prying the head off is never a good idea! Take a look at the valves for color and carbon build up. Check valve seating. Sometimes around the exhaust valve edge there is burned away metal, this requires a valve replacement.
As with everything concerning an aircraft engine cleanliness is vital. Clean and inspect as you progress through the disassembly. Defective items can be ordered sooner and be available for the re-assembly without any major work delays
This engine had only about 20 hours since new at the time of failure. This is a 2003 kit and evidently there was a production run of cylinder assemblies that had this failure potential. The black crud is common with all engines and is a combination of carbon and lead. Solvents and elbow grease will clean these deposits.
Notice where the sleeve was severed from the rim of the water jacket casting. RWI does not re-sleeve their cylinder sets. They say it is not cost effective and they have had poor results when previously attempted. Cylinder assemblies cost @$1068 each in 2010.
Currently there are improved cylinders available from Rotorway. The new units use studs to attach the head to cylinders instead of the previous head bolts. The head bolts had fine thread and were never a good idea when installed in Aluminum. They frequently "pulled" the threads when over torqued. Other improvements were also incorporated to increase the life expectancy of the cylinder assemblies.
Hooking up the intake manifold is somewhat difficult. Some of the bolts are hard to get started. Grinding a little off the bolt heads facilitates installation. Don't get carried away with over grinding. Trial fit frequently to save as much head as possible. Do not forget to torque. Everything is Aluminum and torqueing is very important to prevent stripping threads.
Finally, hook up all the plumbing and wiring. Secure the harness and maintain a safe distance from the exhaust manifolds
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By the way while you have your exhaust off the engine, it would be a great time to re-coat with the silicon heat paint to fresh up the protection as well as the cosmetics. Verify all connections prior to first start. Expect smoke and be ready to shut down if necessary.
The tail needs to be supported before un-hooking the braces. Note that only the upper end needs to be detached. Two people make this operation both safer and quicker. Easy does it, not a good time to rush! Do not forget the belts, this is easier to do than one would think! Line up the upper clevis and ease up into position. On a re-installation shimming or adjust usually is not necessary.