Transition to Multiengine  Airplanes Chapter 12 This chapter is devoted to the factors associated with the  operation of small multiengine airplanes. For the purpose  of this handbook, a “small” multiengine airplane is a  reciprocating or turbopropeller-powered airplane with a  maximum certificated takeoff weight of 12,500 pounds or  less. This discussion assumes a conventional design with two  engines—one mounted on each wing. Reciprocating engines  are assumed unless otherwise noted. The term “light-twin,”  although not formally defined in the regulations, is used  herein as a small multiengine airplane with a maximum  certificated takeoff weight of 6,000 pounds or less. There are several unique characteristics of multiengine  airplanes that make them worthy of a separate class rating.  Knowledge of these factors and proficient flight skills are a key  to safe flight in these airplanes. This chapter deals extensively  with the numerous aspects of one engine inoperative (OEI)  flight. However, pilots are strongly cautioned not to place  undue emphasis on mastery of OEI flight as the sole key to  flying multiengine airplanes safely. The inoperative engine  information that follows is extensive only because this chapter  emphasizes the differences between flying multiengine  airplanes as contrasted to single-engine airplanes. Introduction