Aircraft Induction, Cooling, and Turbocharging Systems Study Guide

Vocabulary flashcards covering reciprocating engine induction principles, carburetor icing mechanisms and indications, manifold pressure behavior, and turbocharger control systems.

Carburetor Icing Prevention (Intake Air)

The most common method of preventing carburetor icing, achieved by preheating the intake air before it enters the carburetor.

Critical Carburetor Icing Range

The ambient condition under which carburetor ice forms most severely, occurring at air temperatures between $30^\natural$ and $40^\natural\text{F}$ ($30^\text{--}40^\natural\text{F}$) when relative humidity is high.

Deicing Alcohol Spray Ring

A ring located at the air inlet of the carburetor that injects deicing alcohol into the airstream ahead of the carburetor to eliminate impact ice.

Carburetor Icing Indication (Constant-Speed Propeller)

A detectable drop in engine manifold pressure while engine RPM remains constant, caused by ice restricting airflow into the induction system.

Carburetor Susceptibility to Icing

The characteristic of the carburetor being the first component on an aircraft to accumulate ice in flight, caused by fuel vaporization causing a temperature drop even without visible moisture present in the air.

Carburetor Ice Elimination Methods

The dual operational methods of heating the induction air (routed around exhaust or picked up from a warm nacelle area) and applying an alcohol spray to prevent impact ice.

Alternate Air System (Fuel Injection)

A system on fuel-injected engines—which require no carburetor air heater—that admits warm air from the engine compartment into the induction system if the inlet air filter is blocked by ice.

Manifold Pressure Rise Upon Carburetor Heat Application

An engine instrument response indicating that carburetor ice had previously formed inside the carburetor and was melted by the applied heat.

Carburetor Air Scoop Pressure

The location in an unsupercharged float-type carburetor engine operating at full power where the highest pressure exists, maintaining a pressure higher than ambient while the venturi and intake manifold are below ambient.

Unnecessary Carburetor Heat Consequences

A decrease in engine power due to an excessively rich fuel/air mixture, accompanied by a heightened risk of engine detonation from excessive cylinder charge temperatures.

Manifold Pressure

The measure of absolute air pressure inside a reciprocating engine's induction system; as it increases, the density of the air charge entering the cylinder increases proportionally.

Volumetric Efficiency

The ratio of the fuel/air charge drawn into a cylinder relative to the charge that cylinder would hold at normal atmospheric pressure, which can exceed $100\%$ through proper supercharging.

Bootstrapping

A transient increase in engine power that causes the turbocharger to speed up and induce further engine power output, indicated by a continual drift in manifold pressure.

Carburetor Heat Valve Linkage Maladjustment

An improper mechanical linkage adjustment that admits excessively low-density heated air with insufficient oxygen, preventing an engine from developing full power at takeoff.

Closed Waste Gate

The operational state of a turbosupercharger where the bypass is shut, forcing all engine exhaust gases directly through the turbine.

Boost Manifold Pressure

Any manifold pressure exceeding existing ambient pressure, generally defined as an absolute pressure greater than $30\text{ "Hg}$.

Density Controller

A turbocharger system controller that regulates bleed oil only at full throttle to limit maximum manifold pressure below the turbocharger's critical altitude.

Rate-of-Change Controller

A turbocharger control unit that regulates the rate at which compressor discharge pressure increases.

Turbocharger Waste Gate

The regulating unit that directly controls turbocharger rotational speed by varying the volume of exhaust gas directed across the turbine.

Small Aircraft Turbocharger System

An induction system component designed to compress ambient intake air, automatically maintaining a constant manifold pressure from sea level up to the engine's critical altitude.

Sea-Level Boosted Turbocharger Regulating Components

The three primary regulating units of a sea-level boosted turbocharger system: the exhaust bypass assembly, the density controller, and the differential pressure controller.