What must be inspected every 24 months for IFR flying?

The requirement for inspection every 24 months for IFR flying specifically pertains to VOR (VHF Omnidirectional Range) receivers. Under FAA regulations, VOR equipment must be checked for accuracy and functionality at least every 30 days when used for navigation, but it requires a more thorough inspection and testing every 24 months. This ensures that pilots are using reliable navigation aids, which is critical for maintaining safety in instrument flight rules (IFR) conditions.

Other equipment, such as transponders, emergency locator transmitters (ELTs), and altimeters, have their own specific maintenance and testing requirements. For instance, transponders must be tested every 24 months, but that is distinct from the VOR requirements. Altimeter tests are required every 24 months for IFR operations, but the primary focus in this context is on the VORs, which require more frequent navigational checks in live flight scenarios. Therefore, the VOR inspection stands out as the clear requirement for IFR flying.