Airworthiness Directive DCA/RAD/35B Transponder Inspection

Airworthiness Directive DCA/RAD/35B Transponder Inspection

This AD is applicable to almost all transponder equipped aircraft.  Also note that it is a repetitive AD, it needs to be carried out every 2 years.  The easiest way to achieve this is to combine it with your 2 yearly Part 43 transponder, altimeter and radio inspection.

In simple terms, it checks for the following 2 failure conditions:

1. Incorrect Mode C (Altitude) reports at certain specified altitudes (1000, 4100, 15700 and 31000 ft).  This applies to all aircraft except those using serial data wiring between the encoder and transponder.
2. incorrect operation of the mode C comparator.  This only applies a aircraft with 2 transponder systems and a comparator.

Call us to discuss applicability to your aircraft.

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