Inspections

14 CFR 91.411 requires inspection every 24 months for the altimeter and static system if an aircraft is to be flown under IFR.

14 CFR 91.413 requires inspections every 24 months for the transponder if the aircraft is to be flown in A, B, or C airspace, or above 10,000 feet (if more than 2,500 above the ground), or in any Mode C veil.

The altimeter and static system are tested with a Barfield DPS-1000 test set that is calibrated annually to assure accurate measurements. The DPS-1000 is attached to the static system and reduces pressure in the system to simulate various altitudes while the altimeter and encoder are compared against the calibrated altitude. The altimeter must be within certain limits depending upon the selected altitude, and the encoder must be within a certain limit regardless of the altitude.

The transponder is tested with an IFR-6000 test set that evaluates the RF output at the transponder antenna either by coupling to the antenna or by reading the RF signal remotely. There are numerous parameters considered and the transponder is issued a Pass or Fail result.

Transponders with ADS-B capability have 19 separate test pages while non-ADS-B transponders have 5. Operation of the IFR-6000 is automated, and like the Barfield-1000, it is calibrated annually to assure accurate results.

ONLY A CERTIFIED REPAIR STATION OR MANUFACTURER IS AUTHORIZED TO CONDUCT THESE TESTS.

Twin City Avionics, LLC is an authorized FAA Certified Repair Station #8WTR984C.