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How is a hydraulic lock removed from an aircraft engine?
Remove a spark plug from the locked cylinder and drain all of the oil out. Clean the spark plug and replace it.
What is a low tension ignition system?
It is an ignition system using a magneto with a brush-type distributor and a coil that has no secondary wiring. Low voltage is directed from the magneto to a transformer mounted on the cylinder head. Here the low voltage is boosted to a high voltage and is directed through a very short high-tension lead to a spark plug. There is one transformer for each spark plug.
What is a floating cam ring on a large radial engine?
It is a cam ring that rides on a shelf-type bearing with a large amount of clearance between the bearing and the ring. When adjusting the valves on an aircraft engine with a floating cam ring, the pressure of the valve springs on the opposite side of the engine must be removed so the cam ring will be tight against the bearing for the valves being adjusted.
Why is valve clearance adjusted on radial engines, but not on most horizontally opposed engines?
Most horizontally opposed engines have hydraulic valve lifters that keep all of the clearance out of the valve train. Radial engines have solid lifters.
Why are both the hot and cold valve clearances given for most radial engines?
The hot clearance is given for valve timing purposes. The timing is adjusted with the valves in cylinder no. 1, set with the hot clearance. When the timing is set, all of the valves are adjusted to their cold clearance.
In what position should the crankshaft be when a magneto is being timed to the engine?
The piston in cylinder 1 should be in the correct position for ignition to occur. This is normally about 30° before top dead center on the compression stroke.
What is the purpose of a cold cylinder check?
A cold cylinder check determines which cylinder is not firing. Run the engine for a few minutes at the speed, and on the magneto, at which it runs roughest. Shut it down and feel the exhaust stack near the cylinder head. The cylinder with the stack that is not as hot as the others is the cylinder that has not been firing.
What is checked on engine runup to determine the operational condition of the engine?
Idling RPM and manifold pressure, engine acceleration, maximum static RPM and manifold pressure, magneto drop, ignition switch safety check, propeller pitch change, propeller feathering, oil pressure, fuel pressure, and fuel flow.
How can you determine the firing order of an 18-cylinder radial engine?
Begin with cylinder 1, add 11, and subtract 7, whichever will keep the numbers between 1 and 18. 1-12-5-16-9-2-13-6-17-10-3-14-7-18-11-4-15-8.
What are two main causes of a cylinder having low compression?
Piston rings not seating or broken, and valves not seating or burned.
What is a hydraulic lock in an aircraft engine?
Oil has drained past the piston rings and filled the combustion chamber of cylinders that are below the center line of the engine. If the crankshaft is turned over with this oil in the cylinder it will lock, and there is a probability that the piston, cylinder, or connecting rod will be damaged.
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