BGS all
The conditions to be met to activate a shunt generator are:
1. Presence of a permanent field; 4. Minimum rotation speed.
On a normally aspirated engine, the manifold pressure gauge always indicates:
A lower value than atmospheric pressure when the engine is running.
In the stator of a turbine, the gas velocity V and static pressure p vary as follows:
A turbine stator is a convergent duct. Pressure will decrease, velocity will increase.
An EGT (Exhaust Gas Temperature) indicator for a piston engine is used to:
Assist the pilot to set the correct mixture.
Exhaust gas temperature sensing is usually taken:
Between the gas generator turbine and the free power turbine.
At constant RPM with a normally aspirated engine and a fixed pitch propeller, as altitude increases, if the mixture is not leaned:
Both the density of air entering the carburettor and the fuel flow decrease.
On an aeroplane equipped with a constant speed propeller, the RPM indicator enables:
Control of the propeller regulator and the display of propeller RPM.
The purpose of the contact breaker is to:
Control the primary circuit of the magneto
The by-pass air in a turbo fan engine has the effect of a lower specific fuel consumption by causing an overall:
Decrease in average exhaust gas flow velocity and a higher mass flow.
The primary reason for a limitation being imposed on the temperature of gas flow in a gas turbine is to:
Ensure that the maximum acceptable temperature at the turbine blades is not exceeded.
If an engine fails to stop with the magneto switch in OFF position, the cause may be:
Excessive carbon formation in cylinder head.
Pulling the fire shutoff handle causes a number of devices to disconnect. In respect of the AC generator it can be said that the:
Exciter control relay and the generator breaker open.
The conditions which can cause detonation are:
High manifold pressure and low revolutions per minute.
Dual ignition provides a factor of reliability and:
Improves combustion efficiency.
The power output of a piston engine without supercharging increases with increasing altitude in standard atmosphere at constant Manifold Air Pressure (MAP) and RPM because of the:
Increase of the air density behind the throttle valve.
The function of a feed box in the fuel tank is to:
Increase the fuel level at the boost pump location
During a climb in a standard atmosphere with constant MAP and RPM indications and at a constant mixture setting, the power output of a piston engine:
Increases.
When changing power on engines equipped with a constant speed propeller, engine overboost is avoided by:
Increasing the RPM before increasing the manifold pressure.
In a free turbine engine, the energy delivered by the free turbine stages:
Is dependent on the rotational speed of the gas generator.
An abortive (hung) start is the term used to describe an attempt to start in which the engine:
Lights up, but fails to accelerate sufficiently.
The rotor blades of an axial compressor of a gas turbine engine are often mounted on a disk or drum using a 'loose fit' because this:
Limits damage to the blades due to vibration.
Engine ignition in continuous mode provides:
Low power ignition when there is a risk of flameout.
The primary input signals for a hydro-mechanical gas turbine engine fuel control system include:
N2, compressor discharge pressure, compressor inlet temp, fuel shut-off, thrust lever angle
The frequency of an AC generator is dependent on the:
Number of pairs of poles and the speed of the moving part. Frequency (Hz) = RPM x Number of pole pairs/60
Concerning a constant speed propeller of a twin engine aeroplane controlled by a single-acting pitch control unit:
Oil pressure turns the propeller blades towards a smaller pitch angle.
In flight, if the temperature of the constant speed drive (CSD) indicator is in the red arc the:
Pilot must disconnect it, and the generator is not available for the rest of flight.
The diffuser in a centrifugal compressor is a device in which the:
Pressure rises and velocity falls.
An impulse coupling is installed on a magneto of a piston engine to:
Provide a strong spark at top dead centre for engine starting.
Engine auxiliary gearboxes:
Provide the drives for a wide variety of services and may even provide for the support of the engine in the airframe.
In a gas turbine combustion chamber:
Secondary air is required for cooling of the inner casing.
The purpose of a distributor in an ignition system of a piston engine is to distribute:
Secondary current to the sparking plugs.
The type of windings commonly used in DC starter motors are:
Series wound.
Equation for thrust
T = m(Vj -Vv ) + A(pj - p0). m (vj - vv): the thrust caused by the acceleration of the air mass flow. A (pj -p0): the thrust caused by the pressure difference at the exhaust.
The function of a constant speed drive (CSD) is to ensure:
That the generator produces a constant frequency.
On landing and prior to shut down, a gas turbine engine should be run at "GROUND IDLE" for a short period. This allows:
The core temperature to diminish.
When applying carburettor heating:
The mixture becomes richer.
Pre-ignition refers to the condition that may arise when:
The mixture is ignited by abnormal conditions within the cylinder before** the spark occurs at the plug
One of the advantages of annular combustion chamber over a multiple can is that:
The thermal load distribution on the HP turbine is more favourable.
The purpose of gas turbine engine trending is:
To enhance maintenance planning and detect anomalies.
In the event of an engine failure during flight, the blades of a constant speed propeller in a single engine aeroplane not fitted with a feathering system tend to move:
Towards the smallest blade angle by centrifugal twisting moment and/or spring force.
In a gas turbine engine the creep phenomenon is the most severe in the:
Turbine rotors.
Engine temperature limitations of a gas turbine engine are usually imposed due to temperature limitations on the:
Turbine section.
The replenishment of an onboard oxygen bottle must be done:
With the engine(s) off.
An axial compressor, compared to a centrifugal compressor:
has a higher pressure ratio and the ability to compress a high mass of air.
