Piston Engines - General: DGCA Technical General questions

Question 1

Excessive blue smoke from the exhaust of an engine that has been warmed up to normal operating temperature may indicate that:

Accepted Answer

The piston rings are worn or stuck in their grooves

Answer

The mixture is too rich

Answer

The oil pressure relief valve has stuck in the open position

Answer

The oil pressure is too low

Question 2

In a divergent duct:

Accepted Answer

The temperature and pressure increase, the velocity decreases

Answer

The velocity and temperature increase, the pressure decreases

Answer

The temperature and pressure decrease, the velocity increases

Answer

The velocity and temperature decrease, the pressure increases

Question 3

The inlet valve opens before TDC in the exhaust stroke to:

Accepted Answer

Induce a greater amount of mixture into the cylinder

Answer

Increase the pressure in the cylinder on completion of the induction stroke.

Answer

Reduce engine vibration

Answer

Allow the incoming mixture to mix with a certain proportion of the exhaust gases

Question 4

Tappet clearance is provided in a piston engine to:

Accepted Answer

Allow for expansion of the valve gear as the engine warms up

Answer

Adjust the valve timing

Answer

Allow for manufacturing tolerances

Answer

Prevent valve bounce

Question 5

In a convergent duct:

Accepted Answer

The pressure and temperature decrease, the velocity increases

Answer

The pressure and velocity increase, the temperature decreases

Answer

The temperature and velocity increase, the pressure decreases

Answer

The pressure and velocity remain constant, the temperature decreases

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