Seastar VT 01 (D-ICDS), with metal wing of Dornier Do 28 and glassfibre fuselage, first flew in Hamburg on 17 August 1984. It was damaged in a wheels-down water landing on Lake Constance on 24 July 1985. D-ICDS was rebuilt as a CD2 with the first all-composites wing and first flew from land on 24 April 1987.
Hull design was improved by a flatter planing bottom, enlarged cockpit, reprofiled nose and extended sponsons, and the original PT6A-11 turboprops were replaced by 373 kW (500 shp) PT6A-112s driving four-blade instead of three-blade propellers. Seaworthiness trials in the Baltic, off Kiel, and on Lake Constance were completed successfully, and a second pre-production aircraft (D-ICKS) joined the certification flight test programme in October 1988. It differs from D-ICDS only in having larger cabin windows and a fully furnished interior, a max T-O weight increased to 4,600 kg (10,141 lb), and the use of production type PT6A-135A turboprop engines.
The CD2 Seastar was certificated by the LBA on 30 October 1990 and meets US FAR Pt 23 Amendment 34 for commuter aircraft. The two pre-production aircraft had then flown more than 750 hours and made 200 water operations. The all-composites structure and manufacturing methods have been formally defined and structurally tested and a fatigue life of 30,000 hours agreed.
A market for 250 Seastars is expected and options and letters of intent for 50 had been submitted by the end of 1990. The first production Seastar should be delivered at the end of 1991 and rate of production should reach 25 a year in three years. Total development, certification and production preparation cost is reported to have been DM120 million.
The Seastar is suitable for a variety of missions, including feeder transport from water bases to airports; missions for which helicopters would be restricted by range, economics or safety factors, all cargo transport with flat floor in main cabin; search and rescue; law enforcement; air ambulance with six stretchers; maritime patrol; FEZ surveillance; and civil or military special missions, accommodating four people over range of 1,000 nm (1,850 km; 1,150 miles). Its ability to operate from land, water, snow or ice enables it to perform such other roles as sightseeing and hunting tours, fire control and firefighting. A typical maritime patrol or law enforcement mission could involve an outward flight to a distance of 80 nm (148 km; 92 miles) taking 30 min; a search pattern lasting 2 h 45 min at a speed of 120 knots (222 km/h; 138 mph), altitude of 610 m (2,000 ft) and taking the aircraft to a distance of 330 nm (612 km; 380 miles), a sea landing and 4 h surveillance of ships with power off and loading of 500 kg (1,102 lb) of seized cargo; and flight back to base with an intermediate stop to unload the cargo, taking 1 h. Total mission time 8 h 15 min. The Seastar can operate in wave heights of up to 1.0 m (3.3 ft), in sea state 1-2.
The following description applies to the second preproduction CD2 and planned production model:

TYPE: Twin-turboprop STOL utility amphibian

WINGS: Cantilever parasol monoplane, with modified NACA 23015 aerofoil section. Aspect ratio 10.35; taper ratio 0.691; dihedral 0°; mean aerodynamic chord 1.825 m (6 ft 0 in). The high-lift wing has drooped outboard leading-edges. Three-spar fail-safe structure constructed of GFRP with a foam core, with carbonfibre reinforcement of the front and rear spars. Low pressure cured (LPC) composites with subassemblies cured in mould at medium heat and large assemblies cured outside moulds. Special machines apply epoxy and hardener and hold material for lay-up in moulds. Single-slotted electrically actuated trailing-edge flaps and horn balanced ailerons. Flotation compartments are embodied. Leading-edge de-icing

FUSELAGE: Conventional unpressurised flying-boat hull, constructed almost entirely of glassfibre. Large chined sponson on each side contains fuel and main landing gear. Flotation compartments are embodied. No wingtip floats.

TAIL UNIT: Conventional unit, constructed of glassfibre and incorporating an electrically actuated variable incidence tailplane. Leading-edge de-icing. Horn balanced elevators and rudder, each with trim tab. Shallow dorsal fin on maritime patrol version.

LANDING GEAR: Hydraulically retractable tricycle type, with twin wheels on each main unit and single fully swivelling nosewheel. All wheels size 6.25-7.5. Main units retract forward into hull sponsons, nose unit forward into bow. Goodrich tyres: hydraulic double disc brakes.

POWER PLANT: Two Pratt & Whitney Canada PT6A-135A turboprops, each flat rated at 485 kW (650 shp), mounted in tandem above wing in continuous nacelle and driving one tractor and one pusher propeller at 1,900 rpm. Each is a four-blade McCauley C-760 series constant-speed reversible metal propeller. Front propeller has electric de-icing. Fuel tank in each sponson, combined max usable capacity 1,734 litres (458 US gallons; 381 Imp gallons). Gravity refuelling through top of sponson. Oil capacity 13,25 litres (3,5 US gallons; 2,9 Imp gallons).

ACCOMMODATION: Max accommodation for two pilots and 12 passengers in four rows of three in wide body cabin, at 81 cm (32 in) seat pitch, with single aisle. Dual controls standard. Aircraft approved for single-pilot crew. Alternative layouts for six executives in VIP seating, with a lavatory at rear of cabin and galley in part ol baggage compartment; or nine passengers, with lavatory. By utilising entire baggage compartment space, aircraft can accommodate six stretchers plus two attendants and medical equipment; or can be configured for all-cargo use with front and rear loading access, providing 10,00 m³ (353,1 cu ft) of space able to transport items up to 5.50 m (18 ft 0½ in) in length. Crew door on port side, plus roof hatch to observe water manoeuvres. Passenger escape door opening upward at front of cabin on starboard side and upward opening main door at rear on port side; latter has an optional airstair incorporated in the adjacent sponson structure. Baggage compartment at rear of cabin, with optional external door on starboard side, capacity 180 kg (597 lb). All accommodation heated and ventilated; air-conditioning optional. Crew of three and 450 kg (992 lb) of mission equipment in maritime patrol role

SYSTEMS: Hydraulic system for landing gear actuation electrically pressurised to 207 bars (3,000 lb/sq in). Flow rate 11 litres (2.9 US gallons; 2.4 Imp gallons)/min. Two 28V DC 200A starter/generators, two 28V DC to 26V/115V AC static inverters, one 40Ah Ni/Cd battery. Pneumatic de-icing for wing and tail leading-edges and engine intakes, optional on wing struts.

AVIONICS: Complete single pilot IFR Collins Pro Line II with EHSI-74 standard, optional Collins HF radio, EFIS-84, FCS-65 autopilot, CVR, Fairchild FDR, GPS, Loran C, Omega, Collins WXR 270 or 840 weather radar. For maritime roles, can carry nose-mounted Bendix/King RDR 1400 weather radar and Swedish Space Corporation SLAR.

ARMAMENT: Four underwing stations available for loads of 250 kg (551 lb) each.