The Sikorsky S-65/H-53 Sea Stallion was designed to meet a USMC requirement for a heavy-lift troop transport helicopter. The twin-engined CH-53D has been in service since 1968 and currently equips four heavylift units. The CH-53D can carry 37 troops or 3.6 -5.4 t of cargo.
The three-engined CH-53E Super Stallion equips six USMC units and can transport 55 troops or 16 tons of cargo internally; it can can carry the 11 794-kg Light Armored Vehicle externally. It is armed with two 7.62-mm machine-guns for self-defense, and can be refuelled in flight from a KC-130. The CH-53E is expected to remain in service until 2025, the USMC plans a two-phase service-life extension programme that will comprise an airframe overhaul followed by an avionics upgrade with new cockpit systems compatible for night operations.
The US Navy operates a derivative of in the mine countermeasures (MCM) role. The three-engined MH-53E Sea Dragons tows a variety of MCM and side-scan sonars and equips two joint active/reserve HM squadrons, plus an HC squadron in the vertical onboard delivery role.
The USAF has operated a variety of twin-engined MH-53 variants in the combat search and rescue and special operations roles. The current MH-53J Pave Low III variant is comprehensively equipped for low-level night/all-weather insertion of special forces troops in a hostile air defense environment.
The major non-US S-65 operator is the Heeresflieger (German army) with around 96 license-built CH-53Gs. These are receiving three major upgrades: new missile warning and self-protection systems; provision for two external fuel tanks allowing range to be increased to 1 800 km when carrying 36 armed soldiers or a 5 500-kg payload; and addition of an night vision goggles-compatible cockpit for night low-level flying capabilities. All CH-53Gs had been upgraded by Eurocopter Germany by early 2001.
Other lesser operators are Israeli air force which has two squadrons of upgraded CH-53D Yasur-2000 transports and the Iranian navy which operates five former MCM-tasked RH-53Ds as logistical transports.