The ornamental design for a helicopterhook, as shown and described.
FIG. 1 is a right side elevational view of a helicopter hook showing our new design, the left side elevational view being a mirror image of the right side elevational view;
FIG. 2 is a front elevational view of the helicopter hook showing our new design;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side perspective view thereof;
FIG. 5 is a right side perspective view thereof;
FIG. 6 is top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The contrast in shading techniques represents a contrast in appearance; no particular color, material or texture attribute is claimed. The broken line showing of the attachment stud forms no part of the claimed design.