02/28/2015. Remarks by Johan Visschedijk: "Appearing in 1928, this multi-purpose aircraft for the German Navy was a further improvement of the H.E.5 and was further improved in the course of production. The H.E.9 was partly flown as a two-seater, partly as a three-seater, in Germany the aircraft was flown without armament. Just like the H.E.5, the H.E.9 was used in the DVS. Some aircraft of the type H.E.9d were delivered to the Soviet Union. The last aircraft flew even after 1933. As powerplant different versions of the twelve-cylinder liquid-cooled BMW VI were installed, the 750 hp BMW VI 7,3 ZU in the H.E.9a and H.E.9d, the 660 hp BMW VI U in the H.E.9b, and the 600 hp BMW VI 5,5 ZU in the H.E.9c.
Of the H.E.9a version, probably only one aircraft was built under the c/n 319 and registered D-1617. Also of the H.E.9b version just one aircraft is known, this had c/n 325 and was registered D-1625 (later D-IPYF).
Four examples were built of the H.E.9c, c/n 328 to 331, registered D-1688 (later D-IKAQ), D-1689 to D-1691. The latter was subsequently converted to a H.E.9d and later reregistered D-ILIQ.
Of the final H.E.9d version eight aircraft were built under the c/n 101 to 103, 360 to 362, 382 and 383, these were registered D-2003 (later D-IPYV), D-1976, D-1966 (later D-IXOX), D-1941, D-1947, D-1950, D-2095 (later D-IXAV) and D-2158."