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In the past, the engine break-in period was very important to the overall life and durability of the engine. The break-in period required has changed over the years with improved piston ring materials and designs. In reference to small engines, the break-in period now (5–10 hours) is short in comparison with that of engines of the past.
First, the lubricating oil in the engine will not adhere properly to the smooth surface, and in the absence of an oil film the resulting friction is increased. Secondly, while breaking in newly installed piston rings, a minute amount of wear must occur between rings and cylinder wall in order to seat the rings properly, and ensure a gas-tight seal.
Technical Service Bulletins (TSBs) are document recommended procedures for repairing vehicles issued by a vehicle manufacturer when there are several occurrences of an unanticipated problem. [1] TSBs can range from vehicle-specific to covering entire product lines and break down the specified repair into a step-by-step process.
A motor vehicle service or tune-up is a series of maintenance procedures carried out at a set time interval or after the vehicle has traveled a certain distance. The service intervals are specified by the vehicle manufacturer in a service schedule and some modern cars display the due date for the next service electronically on the instrument panel.
This procedure was applied to V9977 shortly before its fatal flight. One of the nuts on the engine had not been properly tightened and came loose in flight. The valve began to work its way loose and eventually broke off. This allowed the fuel-air mixture entering the engine to flow into the area under the rocker cover and catch on fire.
The valve seat is a critical component of an engine in that if it is improperly positioned, oriented, or formed during manufacture, valve leakage will occur which will adversely affect the engine compression ratio and therefore the engine efficiency, performance (engine power and engine torque), exhaust emissions, and engine life.
Engine braking is a generally accepted practice and can help save wear on friction brakes. It is even used in some motor sports to reduce the risk of the friction brakes overheating. Additionally, fuel injection engines generally do not use fuel while engine braking. This is known as deceleration fuel cut-off (DFCO).
The tests require engine manufacturers to carry out at least two tests of the engine, to make sure that the engine can survive a compressor or fan blade breaking off within the engine and a turbine blade breaking off within the engine, without fragments being thrown through the outside enclosure of the engine, creating a contained engine failure.