what about repairing the holes in a wooden fire door?
Covering the holes with a section of solid wood or using wood plugs to fill in the holes is not acceptable. The door has to be Underwriter's Lab (UL) certified as a unit and any modification other than putting on or replacing firestop metal strips on the door will void that rating. Since the solid wood or wood plugs wouldn’t be fire-rated, they would burn quickly during a fire, allowing flames and smoke to pass through the barrier. So when repairing holes in a fire door, always contact the door and frame manufacturer to guarantee that your solution is acceptable.