This book is aimed at future pilots willing to study Airframe (021) within the framework of ATPL Theoretical Certificates. It complies with EASA’s Learning Objectives for the 021 Certificate. The chapters are all illustrated to facilitate the reader’s comprehension. At the end of each chapter, the reader will find key-points highlighting the most important notions. Laurence Morin is engineer and head of pilot theoretical training at the ENAC. She teaches Airframe, Systems and Electricity to future pilots and engineers at the ENAC. Mélanie O’Quigley is a former student pilot of the ENAC.