The AI/AH and DI/TC instruments are operated by which method?

The AI (Artificial Horizon/Aircraft Attitude Indicator) and AH (Altimeter) utilize the vacuum/suction method for their operation. These instruments rely on atmospheric pressure changes and directional gyroscopes, which are supported by a vacuum system in most general aviation aircraft like the PA-28A. The vacuum is created by a vacuum pump which pulls air out of the system, allowing the gyroscope to spin freely and maintain its orientation. This enables the AI to display the aircraft's attitude by indicating whether the wings are level or if the aircraft is climbing or descending.

When considering the other methods listed, static pressure is primarily used for altimeters and airspeed indicators, but it does not directly apply to the operation of the AI. Electric power is used for various electronic flight instruments but is not relevant for the traditional operation of these particular instruments in the PA-28A, as they are generally powered by the vacuum system. The Pitot tube is specifically utilized for measuring airspeed, but it does not play a role in the functioning of the AI and AH. Therefore, the vacuum/suction method is essential for the correct operation of these specific instruments.