Fly by the seat of one's pants is the present tense of flew by the seat of one's pants.
The third-person singular simple present indicative form of fly by the seat of one's pants is flies by the seat of one's pants.
The present participle of fly by the seat of one's pants is flying by the seat of one's pants.
The past participle of fly by the seat of one's pants is flown by the seat of one's pants.
