CH-47D Chinook

U.S. Army heavy lift cargo and troop transport helicopter

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History

The Boeing CH-47D Chinook program was initiated in 1976 as a means of upgrading the Army's fleet of CH-47A/B/C helicopters to a single standard. The first flight by a prototype rebuilt CH-47D occurred in May of 1979. After testing and evaluating, the Army placed its first production CH-47D order in October of 1980, and the first production flight occurred in February of 1982. The CH-47D officially entered service with the U.S. Army in February of 1984.

The upgrade program essentially required the aircraft to be stripped down to the frame and completely rebuilt. Upgrades included the installation of Honeywell T55-L-712 turboshaft engines, improved and uprated transmissions, NVG compatible instruments, improved avionics and flight control systems, composite rotor blades, and three external cargo hooks. In addition, equipment reliability was improved by simplifying the transmission lubrication system by eliminating or rerouting hydraulic lines to reduce potential leak sources.

Between 1981 and 1998 a total of 482 CH-47D Chinook helicopters were delivered to the Army, including several which were new production aircraft, to replace those lost to combat or training accidents.

The CH-47D is currently in service as the Army's primary heavy lift and transportation helicopter.

Description

Airframe and general capabilities
The CH-47D is a twin-engined, twin-rotor heavy lift transport helicopter. It is equipped with a two 3-bladed contra-rotating rotors and no tail rotor. The basic crew compliment for the CH-47D is three; pilot, co-pilot, and crewchief. The rotor blades are fabricated from composite materials and are resistant to AAA (anti-aircraft artillery) fire up to 23mm. The engines are mounted externally on the after section of the fuselage, at the base of the stern "tailfin" (rotor - transmission housing.) There is a flight deck access door mounted forward on the right hand side, just behind the cockpit. This door is of a split design, with the upper half opening upward and inward, and the lower half opening downward. The lower door portion features molded in steps for access to the helicopter. The upper portion of the door can be jettisoned in flight. The rear of the aircraft is equipped with a large cargo door/ramp that can be left open or partially closed while in flight to accommodate long cargo. This door does not seal, and the aircraft cannot be pressurized.

The CH-47D utilizes a quadricycle landing gear arrangement. The landing gear are of a fixed, non-retracting type, with the forward two having two wheels per unit, and the aft two being single-wheel units. For operations in arctic environments, the Chinook can be fitted with landing skis.

The D model will transport 33-55 personnel (depending on individual equipment load and seating configuration) or as many as 24 medical litters and two attendants.

The CH-47D is equipped with three external cargo hooks, mounted ventrally along the long axis of the aircraft. The central hook is rated at 26,000 pounds, while the fore and aft mounted hooks are rated to 17,000 pounds each. The combined carrying capacity of all three hooks is 23,000 pounds. The internal cargo area is sufficiently large to accommodate two HMMWVs or one HMMWV and a towed 105mm howitzer. Externally the CH-47D can transport as many as seven 3,500-pound rubber fuel bladders or it can sling load a single M198 155mm howitzer while transporting the gun's 11-man crew and 30 rounds of ammunition internally.

Powerplant
The CH-47D is equipped with two T55-L-712 turboshaft engines, rated at a maximum 3,750 shaft horsepower (shp) each. The engines provide power to both rotors through a central gearbox. Beginning in 1991 the Army began equipping Chinooks with external air particle separation filters on the engines to increase engine life and reduce the chance of flameout in high dust environments. Internal fuel is stored in two crashworthy fuel tanks mounted on either side of the airframe in external fairings and totals 1,034 gallons. In addition, the Chinook can be equipped with three additional auxiliary 800-gallon fuel tanks mounted in the cargo area in lieu of cargo. The CH-47D?s maximum fuel capacity is 3,720 gallons.

Flight characteristics
The empty weight of the CH-47D is 22,450 pounds, with a total cargo capacity of 28,000 pounds. The maximum take off weight is 50,000 pounds.

The maximum (do not exceed) speed of the CH-47D is 170 knots (193 miles per hour) while the maximum level speed is 160 knots (181 miles per hour.) The cruising speed is 143 knots (162 miles per hour.) The service ceiling is 11,100 feet (3,385m) and the maximum hover ceiling (out of ground effect) is 3,300 feet (1,005m.) Maximum range of the CH-47D on internal fuel and at maximum take-off weight is 651 nautical miles (750 statute miles.)

Electronics
The CH-47D is equipped with VHF-FM, UHF-FM, and VHF-AM/FM radios, as well as encrypted IFF recognition system. For self-defense the Chinook is equipped with an AN/APR-39(v)1 radar warning receiver, the AN/ARR-47 passive missile warning system, the AN/ALQ-156 missile approach sensor as well as the M-130 chaff/flare dispenser.

Armament
While not equipped with any dedicated weapon systems, the CH-47D is equipped with three pintle mounts (one located at the right side crew access door, one on the left hand side at the first window, and one on the rear ramp (ramp must be in the full down position for the aft mounted weapon to fire.) These pintles are capable of accepting a single machine gun, either an M-60D single barrel 7.62mm medium machine gun or a single General Electric M134 7.62mm 6-barreled minigun.