Today's modern airplanes are powered by turbofan engines. These engines are quite reliable, providing years of trouble- free service. However, because of the rarity of turbofan engine malfunctions, and the limitations of simulating those malfunctions, many flight crews have felt unprepared to diagnose engine malfunctions that have occurred.turbo machinery in the engine uses energy stored chemically as fuel. The basic principle of the airplane turbine engine is identical to any and all engines that extract energy from chemical fuel. The basic 4 steps for any internal combustion engine are:
) Intake of air (and possibly fuel).
) Compression of the air (and possibly fuel).
) Combustion, where fuel is injected (if it was not drawn in with the intake air) and burned to convert the stored energy.
) Expansion and exhaust, where the converted energy is put to use.can be found some damages of the aircraft engine caused by overheating, birds strike, or other reasons.
Damages Caused by Overheating in Engines
·When the engine reaches just above 220 degrees, combustion of the gasoline can occur in areas other than just in the combustion chamber; this is known as detonation. This detonation creates painful blows to the piston and can damage the piston, piston rings and even the connecting rod bearings. Detonation can damage spark plugs and create enough heat to actually melt down the ground strap of the spark plug.
·If the engine reaches 250 degrees, all the rubber and plastic parts of the engine will begin to soften, which can pose a serious risk to engines with plastic intake manifolds, because they can crack or distort, losing their shape and creating vacuum leaks even after the engine has cooled. Hot spots will begin to develop inside the combustion chamber, causing pre-ignition, which can be so damaging it can even burn holes through the top of the piston and crack the ceramic insulator of any spark plug.
265 degrees and up
·At 265 degrees and above, the metal components of the engine, aluminum and cast iron will begin to soften and distort. When this type of distortion happens, the cylinder head will expand and can crush the head gaskets, creating an instantaneous mixture of engine oil and coolant. Even after the engine has cooled the cylinder heads will remain warped and will need to be replaced. The stress from this heat can cause any metal component of the engine to crack or become damaged beyond repair. The engine valves and pistons can begin to swell and scrap inside of their bores. In most cases of this type of extreme heating, the engine itself will generally seize and need to be replaced.
Effects of Extreme Heat on Coolant
·A 50/50 mixture of ethylene-glycol antifreeze and water can withstand temperatures of up to 265 degrees in a sealed system before it will boil. When engine coolant becomes this hot it can potentially produce holes and leaks in old coolant hoses. An aged radiator can burst and spew hot coolant in any and all directions. If coolant gets this hot and manages to work its way into the crank case, all of the bearings and seals for the crankshaft will be ruined.
Aircraft Damages Caused by Birds
Most of the bird strikes do not lead to any serious consequences and do not cause any significant damage to the aircraft itself. However in a small number of strikes engine or planner parts can be damaged, and in particular cases the strikes become an acute problem with a catastrophy character. to the data registered for the civil aviation aircrafts belonging to Russian air companies in 2002-05 the percentage of strikes in regard to different parts of the plane is the following.
One strike can involve up to several dozens of birds, which can cause damage to more than one part of the aircraft.
Figure 9. The impeller blade damages
10. Birds strike
maintenance of an engine requires a very proper exploration. The vibration in the engine must be checked.the visual inspection of the aircraft engines we did not notice any damages. But if this inspection was more precise I think this damage could have been found.
.3 Damages of a wing
wing is a principal structural unit of an airplane. Its function is to lift and to support the airplane during the flight.maintain its all-important aerodynamic shape, a wing must be designed and built to hold its shape even under extreme stress. Basically, the wing is a framework composed chiefly of spars, ribs, and (possibly) stringers (see figure 1-5). Spars are the main members of the wing. They extend lengthwise of the wing (crosswise of the fuselage). All the load carried by the wing is ultimately taken by the spars. In flight, the force of the air acts against the skin. From the skin, this force is transmitted to the ribs and then to the spars.wing structures have two spars, the front spar and the rear spar. The front spar is found near the leading edge while the rear spar is about two-thirds the distance to the trailing edge. Depending on the design of the flight loads, some of the all-metal wings have as many as five spars. In addition to the main spars, there is a short structural member which is called an aileron spar.ribs are the parts of a wing which support the covering and provide the airfoil shape. These ribs are called forming ribs and their primary purpose is to provide shape. Some may have an additional purpose of bearing flight stress, and these are called compression ribs.damages of a wing are different: damaged ribs or bulkheads, broken fastening, broken parts of trailing (or leading) edge.
Figure 11. The rear of the slate is de-laminating Figure
. Broken leading edge
In our hangar there were some airplanes with broken parts of wings. Particularly, there were troubles with the skin on the wings. Some of airplanes even did not have a skin cover at all.
.4 Damages of a tail unit