Part 11 details the general requirements for the performance, operating characteristics, design, reliability and maintainability of gas turbine aero engines and associated jet pipes for use in UK military aeroplanes and rotorcraft. It also includes the demonstrations, tests, reports and other work required to be completed satisfactorily prior to prototype flight clearance and subsequent Design Certification of the engine.

Guidelines on the content and format of individual Engine Model Specifications are given in clause 1.6.