14 CFR 61.427: How do I reinstate my flight instructor privileges if I fail to establish recent experience for my flight instructor certificate with a sport pilot rating?

If you fail to establish recent experience for your flight instructor certificate with a sport pilot rating, you must reinstate your flight instructor privileges by satisfactorily completing one of the following reinstatement requirements:

(a) If 3 calendar months or less have passed since the last month of your recent experience period, you must successfully complete an approved flight instructor refresher course consisting of ground training or flight training, or a combination of both, or satisfy the requirements specified in paragraph (b) of this section.

(b) If more than 3 calendar months have passed since the last month of the flight instructor's recent experience period, you must pass a practical test as prescribed in § 61.405(b) or § 61.183(h) for one of the ratings listed on your flight instructor certificate with a sport pilot rating. The FAA will reinstate any privilege authorized by that flight instructor certificate with a sport pilot rating.