N521SM is reserved. Fee-paid reservation held by Michael Christian — if it isn't renewed, the FAA releases it on Mar 19, 2027 (in about 9 months).
Reserved by an individual or company for $10 per year.
Reservations lapse more often than you'd think. Check back around Mar 19, 2027 — if the holder doesn't renew, it becomes available. See everything scheduled to free up in March 2027.
N521SM has been worn before. Past registrations from FAA deregistration records:
Tails one nudge away from N521SM that aren't assigned or reserved: