What is the voltage supply for the pitot heat heating elements in a TH-73?

• A. 26 VAC
• B. 115 VAC
• C. 28 VDC
• D. 60 Hz

Answer: (C)

The correct voltage supply for the pitot heat heating elements in a TH-73 is 28 VDC. This supply voltage is significant as it is necessary for providing adequate heating to the pitot tube. The pitot heat is crucial for preventing ice from forming on the pitot and static ports, which ensures accurate airspeed and altitude readings during flight. Using a direct current (DC) voltage of 28 volts allows for effective power delivery, which is necessary in aviation applications where reliability and safety are paramount.

In contrast, the other voltage options, such as 26 VAC and 115 VAC, would not be appropriate for this application as they are alternating current (AC) voltages and do not match the pitot heating element's requirements. The option of 60 Hz refers to frequency rather than voltage, and thus does not pertain to the heating element’s voltage supply. Understanding these specifications is vital for proper aircraft maintenance and operation.