INSPECTIONS OF PISTON ENGINES Unit I INSPECTIONS OF PISTON ENGINES

INSPECTIONS OF PISTON ENGINES Inspection and maintenance and trouble shooting. Inspection of all engine components- Daily and routine checks Overhaul procedures Compression testing of cylinders –Special inspection schedules Engine fuel, control and exhaust systems – Engine mount and super charger Checks and inspection procedures

Starting reciprocating engines The starting of engine can be relatively simple matter or it can be a very complex and critical operation depending upon the size and type of the Engine. No attempt should be made to use the methods presented here for actually starting the engine.

Engine starting precautions The aircraft should acquire the following safety habits. Treat all the propellers as though the ignition switches were on. Chock airplane or test stand wheels before working around the engine. After an engine run and before the engine is shut down ,perform an ignition switch test to detect a faulty ignition circuit.

Before the moving a propeller or connecting an external power source to an aircraft be sure that the aircraft is chocked, the ignition switch is off position , throttle is closed , the mixture is in idle cutoff position. Ground clearance Only authorized person can start the engine. Safety measures are taken into account.

Ground engine fire If an engine fires occurs while engine is started move the fuel shutoff lever to off position. Co2 can be discharged into the inlet duct . Do not discharge co2 directly into the engine exhaust because it may damage the engine. If the fire is on ground under the engine overboard drain, discharge the Co2 on the ground rather than on the engine

Engine operating conditions Leaning the mixture With the mixture full rich position a predetermined mixture of fuel and air is used . For takeoff a mixture is setting of full rich is used. This setting ensures the best combination of power and cooling.

As an aircraft climbs the air becomes dense . On full rich setting the carburetor is putting out the same amount of fuel, but there is less air to mix with it, so the mixture gets richer . If the aircraft climbs high enough the F/A ratio becomes too great for smooth operation.not only the engine run roughly ,but also fuel will be wasted. Two types of fuel metering float carburetor and fuel injection.

Problems caused by spark plug lead fouling Many aircraft engines designed to operate on 80/87 –octane avgas are forced to use 100ll (low lead) avgas because of the reduction in the availability of 80/87 avgas. Although the engines are approved to operate on 100ll avgas ,this presents the problems of spark plug fouling because 100ll avgas contains four times of TEL(tetraethyl Lead) . This sparkplug fouling leads many operational problems and can increase the need for spark plug cleaning.

Reciprocating engine operations in winter Winterization procedures-(precautions and preparations ) Draining sumps-(important during changes in temperature, particularly near freezing ) Anti-icing additives-anti-icing agents ISOPROPYL ALCHOLOL or EGME Engine preheating

ENGINE PREHEATING PRECAUTIONS Preheat the aircraft by storing in a heat hanger, if possible. Use only heater that are in good conditionand do not refuel the heater while it is operating During the heating process, do not leave the aircraft unattended and keep a fire extinguisher handy.

Inspection and maintenance Engine section-(visual excessive fuel or hydraulic leaks) Studs and nuts-(for improper torquing and defects) Internal engine-(for cylinder compression and metal particles) Engine mount-(cranks .looseness of mount and looseness to mount) Flexible vibration dampers-(for poor condition and deterioration) Engine controls-(for defects ,improper travel and improper safetying) Lines ,hoses and clamps-(for leaks ,improper condition ) Exhaust stacks- (for leaks ,defects and improper attachment) Accessories-(for apparent defects in security of Mounting) All systems-(for improper installation ,poor general condition, defects and insecure attachment) Cowling-(for cracks and defects)

Opening and cleaning FAR 43 Appendix D ,begins by starting Each person performing an annual or 100- h inspection shall before that inspection ,remove all necessary inspection plates access doors and cowling. He shall thoroughly clean the aircraft and aircraft engines

INSPECTION Group A-PROPELLOR GROUP Group B-ENGINE GROUP

COMPRESSION TESTING OF AIRCRAFT ENGINE CYLINDERS The purpose of testing the cylinder compression is to determine the internal condition of the combustion chamber by ascertaining any leakage is occurring

Types of compression testers There are two basic types DIRECT COMPRESSION TESTER DIFFERENTIAL –PRESSURE TESTER Common practice to use only differential type ,ideally one would utilize both types in checking the compression of aircraft cylinders. So direct –compression method is used first and the findings substantiated with the differential pressure method

Procedures When the spark plug is removed identity the cylinders which they belong to. Review the operating and maintenance records of the engine. Precautions should be taken to prevent the accidental starting of the engine. The tester should be cleaned and checked foe accuracy.