Subject P - Engine cooling systems Flashcards
What is the most common means of regulating the cooling air flow through a reciprocating systems?
By the use of cowl flaps.
What is the purpose of the fins on engine cylinders?
To increase the surface area of the cylinder for cooling.
What other engine characteristics are designed to aid in engine cooling besides cooling fins?
The engine cowling and baffles are designed to force air through the cylinder cooling fins.
Why is the “open and close” adjustment during installation of cowl flaps important?
For each engine installation the cowl flaps are set for a tolerance that will permit them to open and close in the correct amount to keep the cylinder head temperature within allowable limits.
What should be done to cylinders when to much of the cooling fin area is broken off?
The cylinder should be replaced because it cannot cool properly and hotspots will develop.
When should cowl flaps be kept in the fully open position?
Normally during all ground run operations.
What Publication should be referred to before re-profiling cylinder cooling fins?
The Manufacturers service or overhaul manual should be used to obtain the allowable limits.
What power sources are used to operate the Cowl flaps?
Cowl flaps can be operated by electrical power, hydraulic power or manually.
What is the purpose of blast tubes?
To direct jets of cooling air to accessories of the engine that have high heat concentrations such as a generator.
On a radial engine they duct air onto the rear spark plug elbows of each cylinder to prevent overheating of the ignition leads.
What are the main reasons that excessive heat in a reciprocating engine is undesirable?
Excessive heat shortens the life of the engine parts, impairs lubrication, and affects combustion.
Describe the augmentar system.
The augmentor system is used to help keep the temperature of the air cooled engines down by using exhaust gas energy to draw cool air to over the engine.
What is the source of air directed to engine bearings for cooling?
Bleed air from the compressor section of the engine.
What is the purpose of insulation on the exhaust duct of a turbine engine?
To reduce temperature of the structures in the vicinity of the exhaust duct or afterburner, and to eliminate the possibility of fuel or oil coming in contact with the hot parts of the engine.
What types of materials are used to make insulation blankets for turbine engines?
They are made of stainless steel, layers of aluminum foil, fiberglass, and silver foil.
What areas of a turbine engine are cooled by the secondary air passing through the engine?
The combustion chamber and the turbines.
