The DEFA cannon (Direction des Études et Fabrications d'Armement) is a family of widely-used French-made aircraft revolver cannon firing 30 mm caliber NATO standard rounds. Design history The initial DEFA 551 was developed in the late 1940s. It is based on the German Mauser MG 213C, an experimental revolver cannon developed for the Luftwaffe. The MG 213 never reached production, but inspired the DEFA, the very similar British ADEN cannon, and the smaller American M39 cannon. As the DEFA 552 it entered production in 1954. In 1968 an upgraded version, Canon 550-F3, was developed, entering production in 1971 as the DEFA 553. The new version provided a new feed system, nitro-chrome plated steel barrel, forged drum casing, and improved electrical reliability. Overview The DEFA 553 is a gas-operated five-chamber revolver cannon using pyrotechnic cocking and electrical ignition. It fires a range of 30 mm ammunition of various types, and is capable of continuous fire or 0.5-second or 1-second bursts. The 553 was superseded by the DEFA 554, which incorporates a number of detail improvements. The DEFA 554 uses three, rather than two, of the chambers for reloading, increasing the rate of fire. Barrel life and mechanical reliability are improved, and an electrical control unit allows the pilot to select two rates of fire: 1,800 rounds per minute for air-to-air use or 1,200 rounds per minute for air-to-ground attacks. The 554 also provides three Pyrotechnic cocking charges rather than one, allowing the pilot to cock the weapon after take-off and have two cartridges to re-cock the weapon if necessary in flight. Service use The DEFA 550 series was the standard cannon armament of all gun-armed French fighters from 1954 until the advent of the Dassault Rafale in the 1980s. A pair of these weapons, with 125–135 rounds per gun, is standard fit on the Brazilian ground-attack aircraft AMX International AMX, the French Dassault MD 450 Ouragan, Dassault Mystere, Mirage III/V, Dassault Étendard IV and Dassault Super Étendard, Sud Aviation Vautour, Mirage F1, SEPECAT Jaguar, and the Mirage 2000 series. It was also used on Israeli Douglas A-4E/F/H/N Skyhawks, IAI Nesher, IAI Kfir, and IAI Lavi, the Italian Fiat G.91Y and Aermacchi MB-326K, the Indonesian A-4, and the South African Atlas Cheetah and Impala Mk.II. Various gun pod installations are available from CASA, Dassault Aviation, and Matra. The DEFA 550 is very similar to the British ADEN cannon, and can use the