Noun
tail boom (plural tail booms)
On an airplane or helicopter, a spar that connects tail surfaces to a fuselage.
The longer tail boom incorporated a wider chord vertical fin on the tail rotor pylon and larger synchronized elevators. Source: Internet
The main structure consists of two longitudinal main beams that run under the passenger cabin to the nose and back to the tail boom attachment point. Source: Internet
The semi-monocoque tail boom attaches to the fuselage with four bolts. Source: Internet