Transponder "Calibration Date"

[Way2Broke]

I have a plane that was signed off for its Transponder/Mode C check in 7-05, so its due for another check 7-07. Heres the catch, on the paperwork it says "Calibration date 3-05" and "Due Calibration Date 3-06". What does "Due Calibration Date" mean and why wouldn't they have calibrated it when they did the transponder check. Thanks.

 

[erj-145mech]

I have a plane that was signed off for its Transponder/Mode C check in 7-05, so its due for another check 7-07. Heres the catch, on the paperwork it says "Calibration date 3-05" and "Due Calibration Date 3-06". What does "Due Calibration Date" mean and why wouldn't they have calibrated it when they did the transponder check. Thanks.

Most likely the encoder was tested and certified in March, and sat on the shelf until July. It wasn't a fresh calibration when installed or the rest of the system was tested/certified.

Just a guess, but it's most probably accurate.

 

[Way2Broke]

So does that mean that I need a new Mode C/Transponder check, or is it good until 7/07? All I was ever taught is that I must have the transponder tested ever 24 calender months. I have never heard of a calibration date before.

 

[Way2Broke]

I got to the bottom of it. The calibration date and calibration due date refer to tests required for the machine that is used to do the test.

 

[Gatorman]

It is like having a shelf life.
Engine fire bottle cartridges have a manufacture date and has an expiration date, but if they are installed before the expiration date (shelf life) they are still good until the chapter 5 requires them to be replaced.
It is kind of odd in a wrong way, but it actually extends the life of the cartridge