Reciprocating Induction and Engine Cooling Systems Oral

"Where is the heat taken from that is used to heat the induction air in a reciprocating engine?"

"From a muff that is installed around some part of the exhaust system."

"Where does the alternate air come from that is used with a pressure carburetor or a fuel injection ­system?"

"From inside the engine cowling."

"Where does carburetor ice normally form in a carburetor?"

"In the throat of the carburetor

"Does the application of carburetor heat cause the air-fuel mixture to become richer or to become leaner?"

"Heated air causes the air-fuel mixture to become richer."

"What is used to drive most of the external superchargers used on modern reciprocating engines?"

"Exhaust gases."

"What controls the speed of a turbocharger com­pressor?"

"The amount of exhaust gas that is forced to flow through the turbine. This is controlled by the position of the waste gate."

"What is the danger of operating an aircraft reciprocating engine with too high a carburetor air temperature?"

"Too high a carburetor air inlet temperature can cause the air-fuel mixture to reach its critical temperature and detonate."

"What is usually installed in a large reciprocating engine between the turbosupercharger and the carburetor?"

"An intercooler. This is an air-to-air heat exchanger."

"In what position should the carburetor heat control be placed when starting a reciprocating engine?"

"In the COLD position."

"How does an engine air inlet vortex destroyer help prevent foreign object damage to the engine?"

"A high-velocity stream of compressor bleed air is blown out in front of the engine to break up the vortices that form in front of the engine when it is operating at high power on the ground."

"What is meant by pressure cooling of an aircraft engine?"

"Air cooling in which air is forced to flow through baffles and cylinder fins by a pressure differential across the engine."

"What is the purpose of an augmentor tube in the cooling system of an aircraft reciprocating engine?"

"The augmentor tube uses the velocity of the exhaust gases to produce a low pressure on one side of the engine that helps pull cooling air through it."

"Where is the highest temperature located in a turbine engine?"

"At the inlet to the high-pressure turbine."

"How are the turbine inlet guide vanes and the first-stage turbine blades in some turbine engines cooled?"

"High-pressure compressor bleed air flows through the hollow guide vanes and hollow turbine blades."

"Which side of an air-cooled engine cylinder has the greatest amount of cooling fins?"

"The side of the cylinder in which the exhaust valve is located."

"What should be done to repair a bent cooling fin in a cast aluminum cylinder head?"

"It is normally best to leave a bent cast fin alone if it does not restrict the flow of air. Cast fins are brittle and could break off."

"What is used in a helicopter to increase the amount of cooling air that flows over the engine cylinders?"

"A belt-driven fan."

"What should be the position of the cowl flaps on a reciprocating engine when it is run on the ground?"

"They should be wide open when operating the engine on the ground."

"What is the function of the majority of the air that passes through a turbine engine?"

"Most of the air is used for cooling."

"How does metallic sodium in an exhaust valve aid in transferring heat?"

"The sodium melts when the engine is running

"How is the structure around a turbine engine protected from excessive heat from the engine?"

"An insulating blanket protects the structure from excessive heat."

"What is the function of blast tubes that are installed in a pressure cooling system of a reciprocating engine?"

"These blast tubes direct cooling air to the magnetos and the generator."

"Of what material is the insulation blanket made that is used to protect the aircraft structure from the heat produced by a turbine engine?"

"Fiberglass sandwiched between sheets of metal foil."