"Conventional racks for avionics are made from metal. Most of the avionics fielded today offer a monolithic architecture in form closed box packed with electronics and lots of connectors at the front or the back with corresponding heavy cable harness. More recent developments go for modular avionics, packing electronics with standard dimensions and connectors that assure physical interchangeability.The proper housing protects the electronics against the environment, ensures EMC and supports the thermal management. In order to reach higher power density and lower costs the optimisation of the housing is a must.The amount of electronically controlled tasks in modern aircraft is increasing steadily and also the contribution of racks for avionics to the overall weight of an aircraft has reached a magnitude that requires an analysis to obtain mass reduction.Modern structures built in composite technology are able to provide important mass savings with respect to conventional designs. The advantages of high performance composites are many, including lighter weight, the ability to tailor lay-ups for optimum strength and stiffness, improved fatigue life, corrosion resistance and, with good design practice, reduced assembly costs due to fewer detail parts and fasteners.Composite enclosures can be made significantly lighter than machined aluminium enclosures and may be produced at an affordable cost provided a modular approach is followed while possessing equal or better mechanical and thermal performance.The objective of the present work is the development of a lightweight “open box” ARINC housing (ARINC standards) which withstands vibration levels C/C1 according to RTCO-DO160.A lightweight and modular composite solution is proposed. Using advanced fibre-reinforced composite materials, a 40 % of weight reduction in the housing is estimated."