According to USC, the air carrier can use the good faith clause, but this must happen before the person enters revenue service, except for the 90 day non-scheduled exception that applies to light aircraft. The key is most likely showing that the company made the good faith request, which means documentation. It's expected that the requesting company will make a reasonable attempt, such as sending the written request to the last mail address or company that took possession of the assets, calling, etc. I'd recommend do a 3-strikes if possible and document it, like mail, email, phone. Then you have your own paper trail to show it was done.