Powerplant

Compression To prevent loss of power, all openings to the cylinder must close and seal completely on the compression and power strokes. In this respect, there are three items in the proper operation of the cylinder that must be operating correctly for maximum efficiency. First, the piston rings must be in good condition to provide … Read more

Combustion Process Normal combustion occurs when the fuel/air mixture ignites in the cylinder and burns progressively at a fairly uniform rate across the combustion chamber. When ignition is properly timed, maximum pressure is built up just after the piston has passed top dead center at the end of the compression stroke. The flame fronts start … Read more

The operation of the powerplant is controlled from the cockpit or flight deck. Some installations have numerous control handles and levers connected to the engine by rods, cables, bellcranks, pulleys, etc. In most cases, the control handles are conveniently mounted on quadrants in the flight deck. Placards, or markings, are placed on the quadrant to … Read more

Engine Testing of Reciprocating Engines The procedures and equipment used in determining that an engine is ready for airworthy service and is in excellent mechanical condition, normally requires the use of a test stand, or test cell, although the aircraft can be used. [Figure 1] The method of engine testing or run-in that takes place … Read more

The dimensional inspection is used to assure that the engine’s component parts and clearances meet the manufacturer’s specifications. These specs are listed in a table of limits, which lists serviceable limits and the manufacturer’s new part maximum and minimum dimensions. Many measuring tools are used to perform the dimensional inspection of the engine. Some examples … Read more

After visually inspecting engine recesses for deposits of metal particles, it is important to clean all engine parts thoroughly to facilitate further inspection. Two processes for cleaning engine parts are: Degreasing to remove dirt and sludge (soft carbon). The removal of hard carbon deposits by decarbonizing, brushing or scraping, and grit-blasting. Degreasing Degreasing can be … Read more

Visual inspection should precede all other inspection procedures. Parts should not be cleaned before a preliminary visual inspection, since indications of a failure may often be detected from the residual deposits of metallic particles in some recesses in the engine. Several terms are used to describe defects detected in engine parts during inspection. Some of … Read more

Both maintenance and complete engine overhauls are performed normally at specified intervals. This interval is usually governed by the number of hours the powerplant has been in operation. The actual overhaul period for a specific engine is generally determined by the manufacturer’s recommendations. Each engine manufacturer sets a total time in service when the engine … Read more