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

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The 553 was superseded by the DEFA 554, which incorporates a number of detail improvements.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 a


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 same ammunition.

The DEFA 550 series has given way to the GIAT 30 series used on the Dassault Rafale, although it is likely to remain in widespread use for many years.