Engine Gauges and More Systems

Question 1

What does the manifold pressure gauge indicate, and what are its limits?

Answer 1

The manifold pressure gauge measures the air pressure entering the engine, directly correlating with engine power. Its limits in the R22 are: Yellow arc: 19.6–24.1 in. Hg, Red line: 24.1 in. Hg.

Question 2

What are the normal operating ranges for the oil pressure and oil temperature gauges?

Answer 2

Oil Pressure: Idle minimum: 25 psi, Flight: 55–95 psi, Maximum during start/warm-up: 115 psi. Oil Temperature: Green arc: 75°F–245°F, Red line: 245°F.

Question 3

What does the cylinder head temperature (CHT) gauge measure, and what are its limits?

Answer 3

The CHT gauge measures the temperature of one of the cylinder heads in an air-cooled engine. Its limits are: Green arc: 200–500°F, Red line: 500°F.

Question 4

What is the significance of the carburetor temperature gauge?

Answer 4

The carburetor temperature gauge monitors air temperature in the carburetor to prevent icing. Yellow arc: -15°C to +5°C (potential icing range). Aim for 10°C–15°C above the yellow arc to avoid carb ice.

Question 5

What does the oil pressure warning light indicate, and how should you respond?

Answer 5

It signals dangerously low oil pressure. If illuminated: Check the oil pressure gauge, Verify loss of power on the engine tachometer. If confirmed, land immediately.

Question 6

What does the starter warning light signify?

Answer 6

The starter warning light illuminates if the starter remains engaged after the ignition key is released. If it stays on, shut down the engine immediately by pulling the mixture and turn off the battery.

Question 7

What does the governor off light indicate?

Answer 7

It signals that the governor is not managing throttle input. This requires manual throttle adjustments during flight or is used during training for governor-off operations.

Question 8

What is the function of the governor and correlator in RPM management?

Answer 8

Governor: When turned on, it automatically adjusts throttle to maintain engine RPM at 104%. Correlator: Mechanically adjusts throttle with collective movements to assist in maintaining RPM.

Question 9

How does the mixture control work in the R22?

Answer 9

The mixture control adjusts the air-to-fuel ratio. Typically set to full rich for optimal performance and cooling. At higher altitudes, air density decreases, making the mixture naturally richer.

Question 10

How does the carburetor heat system function?

Answer 10

It pulls air into the carb heat scoop where it gets warmed within the exhaust shroud then pumped into the carburetor, preventing icing by raising the air temperature.

Question 11

Why is carburetor icing more likely at low power settings?

Answer 11

At low manifold pressure (throttle closed), the air velocity through the carburetor venturi increases, causing greater cooling, which promotes ice formation, especially in humid conditions.

Question 12

How is carb heat used to prevent carb ice?

Answer 12

When conditions are susceptible to carb icing (-4° to 30°C and dew point spread less than 15°), pull carb heat during run up, take off, climb, cruise, and during descent.

Question 13

Why are we more susceptible to ice at low power settings?

Answer 13

Due to an increased Cooling Effect– when the throttle is partially closed, the air passing through the carburetor venturi experiences a greater pressure drop, causing significant cooling.

Question 14

What effects does carb heat have on engine performance?

Answer 14

It decreases engine performance and can lower hover ceilings by up to 2000’.

Question 15

What is the function of the exhaust system in the R22?

Answer 15

The R22’s exhaust system uses straight pipes (no muffler) for noise reduction.

Question 16

How can carbon monoxide poisoning occur in helicopters?

Answer 16

Cracked exhaust pipes or leaks in the cabin heat system can allow carbon monoxide to enter the cabin, leading to hypoxia, dizziness, or even death.

Question 17

What should you do if you experience symptoms of CO poisoning?

Answer 17

Shut off the heater and open nose and door vents; if hovering, land or transition into forward flight. If symptoms occur, land immediately.

Question 18

How does the oil cooler system function in the R22?

Answer 18

The oil cooler system routes engine oil through an external cooler where air from the squirrel cage fan dissipates heat.

Question 19

How is cold oil directed away from the oil cooler?

Answer 19

A vernatherm valve regulates oil viscosity/flow to the oil cooler based on the oil temperature.

Question 20

What is the purpose of the oil filter in the R22?

Answer 20

The oil filter removes contaminants from engine oil. A bypass valve ensures oil flow to the engine even if the filter is clogged.

Question 21

Why does evaporation cause cooling?

Answer 21

During evaporation, liquid molecules absorb heat to transform into gas, removing heat from the surrounding area.

Question 22

How is the engine and relevant components cooled?

Answer 22

Approximately 50% of heat is released through the exhaust; the squirrel cage blower sends cooling air to various components.

Question 23

What is the grounding strap?

Answer 23

It is a white braided metal strap that ensures the engine is connected to the negative side of the battery and therefore grounded.

Question 24

What is electrical grounding in a helicopter?

Answer 24

Electrical grounding connects the helicopter’s electrical system to its metal frame, ensuring proper operation of electrical components.

Question 25

Why is electrical grounding important in a helicopter?

Answer 25

Grounding ensures the electrical system operates safely and reliably by providing a return path for electricity.