query: What types of helicopters are there?
passage: Helicopter
The mast is a cylindrical metal shaft that extends upwards from the transmission. At the top of the mast is the attachment point for the rotor blades called the hub. The rotor blades are attached to the hub. Main rotor systems are classified according to how the rotor blades are attached and move relative to the hub. There are three basic types: hingeless, fully articulated, and teetering; although some modern rotor systems use a combination of these.
passage: Yugoslav Air Force
Helicopter units of JRV were equipped with about 190 home-made Gazelle helicopters in utility, attack, rescue and scout versions, 90 Soviet-made Mil Mi-8T Hip-C cargo helicopters and 12 Soviet anti-submarine helicopters. Each Corps of AF and AD had a Special Helicopter Squad ("Specijalno Helikoptersko Odeljenje" - SHO) equipped with four Mi-8 helicopters unless the Special Helicopter Squad of the First Corps of AF and AD, which was equipped with two Aérospatiale Alouette III light utility helicopters and two Mi-8 transport helicopters. In the 138th Transport Aviation Brigade which was separate unit under direct command of JRViPVO HQ there was one transport helicopter squadron, 890.TRHE equipped with Mi-8 and Gazelle helicopters. The First Corps of AF and AD had the 107th Helicopter Regiment from Mostar (BiH), which consisted of two squadrons, 782.HE equipped with Gazelle helicopters in SA.341 and SA.342 Gama versions and Mi-8, and 783.HE equipped with Gazelle helicopters. Squadrons of the 107th Helicopter Regiment were used by the Marshal Tito Air Force Military Academy. Also there were three helicopter squadrons of the 97th Aviation Brigade at Divulje; 676.PPAE equipped with Gazelle helicopters and CL-215 firefighting aircraft, 784.PPHE equipped with 12 Mi-14, Ka-25 and Ka-28 anti-sub helicopters and 790.TRHE equipped with Mi-8 cargo helicopters. In the Third Corps of AF and AD there were three helicopter squadrons in 119. Aviation Brigade; 712.POHE equipped with Gazelle Gama attack helicopters, 714.POHE also equipped with Gazelle Gama helicopters and 787.TRHE equipped with Mi-8 transport helicopters. In Fifth Corps of AF and AD there were also three helicopter squadrons; 711.POHE equipped with Gazelle Gama, 713.POHE also equipped with Gazelle Gama attack helicopters and 780.TRHE equipped with Mi-8 cargo helicopters. There was also one mixed-aviation squadron, 333.AE from 105.LBAP which had few Gazelle helicopters used for training by the Marshal Tito Air Force Military Academy. The Army command regions also had their helicopter squadrons equipped with Gazelle Hera scout helicopters. EIV of 1st Army region was at Batajnica Airbase, EIV of 2nd Army region was at Skopski Petrovac, EIV of 3rd Army region at Pleso and EIV of Navy region was at Divulje.