The CANT Z.506 Airone (Italian: Heron) was a triple-engine floatplane produced by CANT from 1935. It served as a transport and postal aircraft with the Italian airline "Ala Littoria". It established 10 world records in 1936 and another 10 in 1937.During World War II it was used as a reconnaissance aircraft, bomber and air-sea rescue plane, by the Italian Regia Aeronautica and Regia Marina, Aeronautica Cobelligerante del Sud, Aeronautica Nazionale Repubblicana and the Luftwaffe. The military version revealed itself to be one of the best floatplanes ever built. Despite its wooden structure it was able to operate in very rough seas A number of Z.506S air-sea rescue aircraft remained in service until 1959
The CANT Z.506 was designed as a 12 to 14-seat transport twin-float seaplane, powered by three 455 kW (610 hp) Piaggio Stella IX radial engines. It was derived from the larger and heavier Z.505 seaplane. The Z.506 entered production in 1936 as the Z.506A, powered by more powerful 560 kW (750 hp) Alfa Romeo 126 RC.34 nine cylinder radial engines, giving a maximum output of 780 hp on take off and 750 hp at 3,400 meters. The fuselage had a wooden structure covered in tulipier wooden lamellas. The wings were built with a structure of three box-type spars linked by wooden wing-ribs covered by plywood. The floats were made of duraluminium, covered in chitonal and were 12.50 meters long. The armament consisted of a 12.7  Breda-SAFAT machine guns in the dorsal position and three 7.7 mm  machine guns, one in the ventral position and two on the sides of the fuselage. The CANT Z.506 had a crew of five.
It was produced at the "Cantieri Riuniti dell 'Adriatico" and "Cantiere Navale Triestino" (CRDA CANT) factories in Monfalcone and Finale Ligure respectively. The aeroplanes were in such demand that the Piaggio company also produced CANT Z. 506s under licence. The Z.506A entered service with the Ala Littoria air company flying around the Mediterranean.
While flown mostly by Mario Stoppani, the Z.506A set a number of altitude, speed and distance records for its class between 1936 and 1938, including speeds of 308.25 km/h over 5000 km and 319.78 km/h over 2000 km, and 322.06 km/h over 1000 km. It subsequently flew 5383.6 km in a closed circuit. It carried a load of 2000 kg to 7810 m. and 5000 kg to 6917 m.
A military version appeared after 15 civil aeroplanes had entered service with Ala Littoria It was developed as the Z.506B. This military version was powered by three 560 kW (750 hp) Alfa Romeo 127 RC 55 engines and entered service in 1939. This version was also a record breaker. A larger version of the Z.506A was built in 1937 as the Z.509. The last CANT Z.506B was built by Piaggio in January 1943. Total production was more than 320 aircraft.

The Airone saw more than 20 years of service. The Z.506B was first used as a reconnaissance aircraft and torpedo bomber in the Spanish Civil War. When Italy entered the war, on 10 June 1940, 97 aircraft were operational with two Stormi da Bombardamento Marittimo (sea bombing units) and some Squadriglia da Ricognizione Marittima. 31°Stormo B.M. "autonomo" with 22 planes was based at Cagliari-Elmas airport, in Sardinia; 35° Stormo B.M., with 25 Z.506 in Brindisi, Puglia. It was used extensively in 1940-41 in France and Greece. On the outbreak of World War II, four Squadriglie for air-sea rescue missions were formed in Orbetello. These were the 612a in Stagnoni, with aircraft marked DAMB, GORO, BUIE, CANT (the prototype) and POLA, and the 614a in Benghazi, with DUCO, ALA, DODO and DAIM. The two other sections with two aircraft each were based in Torre del Lago and in the Aegean Sea at Leros. The latter was later transferred to Rhodes.
The Z.506 had its baptism of fire on 17 June 1940, the day after some French bombers had attacked Elmas base, killing 21 airmen and destroying some Cant. Z.501s. On the evening of 17 June, four 506Bs from 31° Stormo attacked targets in Northern French Africa, each dropping two 250 kg and three 100 kg bombs. The type also took part in the Battle of Calabria. In the war against Greece it was used against coastal targets and the Corinth canal. It played an important part in the conquest of many Greek islands, including Corfu, Cephalonia and Zante. Due to its vulnerability against fighters, it was restricted to use by 'recce' units (Squadriglie da Ricognizione). Later in the war, it was used in maritime patrol and air-sea rescue missions. The 506 was often forced to land in Spain, due to engine failure, combat damage or a lack of fuel. A special air-sea rescue version, the Z.506S Soccorso, was produced; it was used in small numbers by the Luftwaffe.
The air-sea rescue Z.506s suffered severe losses as many Allied pilots did not stop attacking them, even after they had spotted the red crosses. For instance, on 12 June 1942, off Malta, a Hawker Hurricane from 46 Squadron shot down a Z.506, then shot another one down which had been sent to rescue the crew of the first. Sergeant Etchells, in 249 at Malta recalled:
"I shot down a Cant Z506 near Sicily, painted white, which had red crosses on its wings, and was apparently an air-rescue aircraft. Sqn Ldr Barton disapproved but the AOC approved. I did not see the red crosses on its wings at the time and do not know if it would have made any difference had I done so."
A Cant 506 became famous, among the Allies, because it was the only plane hijacked by prisoners of war on the Western Front (it was then used by the RAF from Malta).
When Italy surrendered to Allied, on 8 September 1943, about 70 Cant 506s were still in service with Italian Air Force. About 30 surviving Z.506S were assimilated into Allied forces and served with the Italian Co-Belligerent Air Force. The Germans soon captured the 506 and started using them in Italy, Germany, France, Yugoslavia and even on Greek islands and in Poland. The Cant of 171a Squadriglia kept on operating air/sea rescue and patrol missions from the military port of Toulon, with mixed Italian/German crews. Some 506s captured by Germans, flown by Italian volunteer crews, operated in 1944 on the Baltic sea, patrolling the area around Peenemunde.] Some examples survived in postwar service until 1959.
Variants
Z.506Prototype, one built.Z.506ACivil version Z.506BMilitary version, 324 built.Z.506S Air-sea rescue version Z.506 Landplane One aircraft was converted to a landplane for an attempt by Mario Stoppani on an endurance record. It did not take place to due bad weather.Z.509A larger and heavier version of the Z.506B, three built.

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