Transponder and Encoder Inspection
This includes a performance and accuracy assessment of:
Transponder System.
Altitude Encoder System (Mode C)
Altimeter - Encoder coincidence
Usually this inspection is carried out every 2 years coinciding with other avionics inspections (Comm & Altimeter)
The cost will vary depending on the style of static system installed. This inspection is almost always carried out alongside the altimeter inspection for efficiency and economics.
A typical VFR aircraft will take about 2 - 3 hours for both the transponder system and altimeter inspection