Collection: FAR 91.411/413 Certifications

All transponder-equipped aircraft, both VFR and IFR, must have their transponder tested and certified every two years (see FAR 91.413). Aircraft operating under IFR must also have their altimeter(s), encoder and static system tested and certified every two years (see FAR 91.411).

In addition, FAR 91.217 requires that all transponder-equipped aircraft have their altimeter and encoder checked for data correspondence after initial installation or following any subsequent modification or maintenance.

Note: Part 91 of the Federal Aviation Regulations also apply to Experimental Aircraft.

VFR Certification

For VFR operations, the FAA requires all transponder-equipped aircraft to be inspected to verify the proper operation of the transponder.

Transponders systems that don't meet minimum requirements and/or are out-of-alignment can cause significant problems with ATC radar systems, including incorrect altitude readout, duplicate targets or no target at all.

FAR 43, APPENDIX F, describes the transponder inspection requirements. The tests are fairly simple and can be performed on the ramp in about 15-30 minutes using our automated test equipment.

IFR Certification

In addition to the transponder tests required for VFR, IFR aircraft are required to have each altimeter, encoder and static system inspected and certified.

These tests are more involved and usually requires the removal of the altimeter and altitude encoder for bench testing and adjustment. In some cases, testing can be done in the aircraft.

• The altimeter is subjected to a series of tests to insure it meets the minimum requirements for accuracy and repeatability.
• The altitude encoder is checked against the primary altimeter and adjusted as required to insure data correspondence.
• After the equipment has been inspected and reinstalled in the aircraft, a static system leak check is performed. Leaks in the static system can cause significant errors in the altitude reporting equipment (and airspeed) and are sometimes difficult to locate.

FAR 43, APPENDIX E, describes the altimeter system inspection requirements. Usually, the altimeter is removed and checked on the bench along with the altitude reporting encoder to insure data correspondance. Testing usually takes 2-3 hours, depending on the type of equipment and aircraft.Pitot Static Systems