Learjet 55 incorporates successful elements of former Learjets, while adding a few design modifications of its own like a larger cabin.
The cabin typically accommodates six or seven passengers in a Club configuration: 4 armchair with a side-facing bench and an additional aft seat.
The seats can move 30 cm fore and aft. The lavatory is more sophisticated and better equipped than its predecessors – the room is more spacious and moved to the aft, separating it from the cabin. The small kitchen area has also been upgraded and, in addition to the minibars, has been adapted for preparing hot drinks and has a microwave.