14 CFR § 107.9 - Accident reporting.
No later than 10 calendar days after an operation that meets the criteria of either paragraph (a) or (b) of this section, a remote pilot in command must report to the FAA, in a manner acceptable to the Administrator, any operation of the small unmanned aircraft involving at least:
(a) Serious injury to any person or any loss of consciousness; or
(b) Damage to any property, other than the small unmanned aircraft, unless one of the following conditions is satisfied:
(1) The cost of repair (including materials and labor) does not exceed $500; or
(2) The fair market value of the property does not exceed $500 in the event of total loss.