The Gavilán 358 was designed to comply with the airworthiness requirements of the Federal Aviation Agency of the USA contained in Parts 23 (amendment 46) and 36 ( amendment 20) . There are few aircraft that meet these regulations given the fact that they were certified when the regulations were much less strict.
The structure of the fuselage is a truss made up of 4130 steel tubes. The attachments for the landing gear, wings and tail form an integral part of this structure. This means that the fuselage is very rugged and is well adapted for operations from rough runways. This method of construction is also very easy to repair.
The firewall is made from stainless steel and protects the cockpit from fire.
The fuselage is covered in aluminum 2024-T3 sheet and the thickness of the skins varies from 0.025" to 0.032". This skin is not part of the structure of the fuselage.
The windshield and windows are made from flat sheets of plexiglass. This means that they are inexpensive to replace.
The pilot and the front passenger each have a door. There is a large double cargo door on the left side of the fuselage through which the aft passengers and cargo are loaded. This door permits the loading of awkward items such as stretchers, drums and construction material. It is possible to carry a standard sheet of plywood (4x8 feet) flat on the floor.