C-20B

Gulfstream III
C-20 Gulfstream III operated by the United States Navy
Role	Business jet
Manufacturer	Gulfstream Aerospace
First flight	2 December 1979
Introduction	1980
Primary users	United States Gabon India Italy
Produced	1979–1986
Number built	202
Unit cost	US$37M
Developed from	Grumman Gulfstream II
Variants	Gulfstream IV/G400/G450

The Gulfstream III, a business jet produced by Gulfstream Aerospace, is an improved variant of the Grumman Gulfstream II.

The Gulfstream III was built at Savannah, Georgia in the United States and was designed as an improved variant of the Grumman Gulfstream II. Design studies were performed by Grumman Aerospace Corporation in collaboration with Gulfstream American Corporation. Design of the Gulfstream III started with an effort to synthesize a completely new wing employing NASA supercritical airfoil sections and winglets. Optimization studies considering weight, drag, fuel volume, cost, and performance indicated that a substantial portion of the new wing benefit could be secured with modifications to the existing wing. As a result, the new wing concept was canceled and work began on design modifications that would retain the Gulfstream II wing box structure and trailing edge surfaces.

Compared to the G-1159 Gulfstream II, the wing has 6 ft (1.8 m) more span and 5 ft (1.5 m) winglets added, the leading edge is longer and its contour is modified. The fuselage is 2 ft (0.6 m) longer aft of the main door, the radome is extended and there is a new curved windshield. Maximum takeoff weight is increased to 68,200 lb (30,935 kg) or 69,700 lb (31,615 kg) and there are various changes to the autopilot, flight instruments, and engine instruments. The aircraft received its type certificate from the American Federal Aviation Administration on 22 September 1980. A total of 202 Gulfstream IIIs were built, with the last example built in 1986.

In 2013, the FAA modified 14 CFR part 91 rules to prohibit the operation of jets weighing 75,000 pounds or less that are not stage 3 noise compliant after December 31, 2015. The Gulfstream III is listed explicitly in Federal Register 78 FR 39576. Any Gulfstream III's that have not been modified by installing Stage 3 noise compliant engines or have not had "hushkits" installed for non-compliant engines will not be permitted to fly in the contiguous 48 states after December 31, 2015. 14 CFR §91.883 Special flight authorizations for jet airplanes weighing 75,000 pounds or less - lists special flight authorizations that may be granted for operation after December 31, 2015.

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