Aircraft skin is extremely thin. You only need it to be there and be strong enough to not be destroyed by airflow. Any more than that is undesirable excess mass

Aircraft skin is extremely thin. You only need it to be there and be strong enough to not be destroyed by airflow. Any more than that is undesirable excess mass. Typically it's only a bit more than a millimeter thick. A hammer with a light swing would almost certainly puncture it. Contrary to the and movies, helicopters can move fairly fast. You average news helicopter has a top forward speed of around 160 mph. Drones, being mostly made of what would otherwise be considered in the aircraft world to be fairly durable material, would have no issues passing through the thin aluminum skin of a helicopter at 120+ mph. The pictures of the damage shows it on the leading edge of the horizontal stabilizer, indicitive of a strike when the helicopter was in nose down, forward motion (they lean in the direction they're moving).