Boeing CH-47 "Chinook"

Model Comparison and Usage

 

 

The A Model

 

Boeing Chinook CH-47A 60-03451 Located at the Aviation Museum, Fort Rucker, Alabama.

 

 

On June 25, 1958 the Army issued an invitation for a General Management Proposal for the U.S. Army Medium Transport Helicopter. Five aircraft manufacturers submitted proposals for the project. In March of 1959 the Army selected Vertol to produce the YHC-1B as the Army’s new medium transport helicopter. Shown to the left is the cover page for the 1963 CH-47A Systems Familiarization Manual.

The Boeing Vertol Model 114, tail number 59-04983 (Boeing build number B-002), made it's first hovering flight on 21 September 1961. Initially designated the YHC-1B helicopter in Fiscal Year (FY) 1959, the first 8 helicopters, Boeing build numbers B-001 through B-008, were powered by the Lycoming T55-L-5 engines, generating a maximum of 1,940 Shaft Horsepower (SHP). Beginning with 60-03450, Boeing build number B-009, the Lycoming T55-L-7 engine, producing 2,650 SHP, was utilized. Boeing build numbers B-001 through B-005 were designated YHC-1B helicopters. Build numbers B-006 though B-029 were originally designated as HC-1B helicopters. In July 1962, the Department of Defense redesignated all U.S. military aircraft to a new system. All YHC-1B helicopters became YCH-47A and all HC-1B helicopters became CH-47A.

The CH-47A, was a tandem rotor medium lift transport helicopter. The Chinook's primary mission was moving artillery, ammunition, personnel, and supplies on the battlefield. It also performed search and rescue, aeromedical evacuation, deployment of troops via parachute, downed aircraft recovery and special operations missions.

Early production CH-47A’s operated with the 11th Air Assault Division during 1963 and in October of that year the aircraft was formally designated as the United States Army’s standard medium lift transport helicopter. In June 1965, the 11th Air Assault Division was redesignated as the 1st Cavalry Division (Airmobile) and readied for deployment to the Republic of Vietnam (RVN). Chinooks from the 11th Air Assault formed the nucleus of the 228th Assault Support Helicopter Battalion (ASHB) - " Winged Warriors" which began operations in the RVN in September 1965. The 1st Cavalry Division had brought their organic Chinook battalion with them when they arrived in 1965 and a separate helicopter company, the 147th Assault Support Helicopter Company (ASHC) - "Hillclimbers", had arrived in the RVN on 29 November 1965. This latter company was initially placed in direct support of the 1st US Infantry Division. As of February 1966, 161 aircraft had been delivered to the Army. CH-47A’s deployed to the RVN were equipped with Lycoming T55-L7 engines generating 2,650 SHP. The aircraft had a maximum gross weight of 33,000 pounds allowing for a maximum payload of approximately 10,000 pounds.

As of 11 July 2009, of the 355 A model Chinook helicopters produced for the U.S. Army, there were only seven surviving, although non-operational, airframes: 59-04984, last seen at Fort Eustis, Virgina in February 2006 where it was utilized as a training device for the 67U aircraft maintenance course; 59-04986, for many years, was utilized as a Category C sheet metal repair training device at Fort Eustis, Virginia and was eventually given to a private individual in Georgia approximately 2003/2004; 60-03451, pictured above on display at the Army Aviation Museum located at Fort Rucker, Alabama; 61-02408, at one time on display at the California Army National Guard Museum near San Luis Obispo and later moved to Fort Campbell, Kentucky; 64-13149, nick-named "Easy Money" and on display at Redstone Arsenal. Of the four produced, "Easy Money" was the sole surviving ACH-47A Armed Attack Chinook. The ACH-47A helicopters were also known as "Guns-A-Go-Go"; 65-07992, an A model heavily modified into the only BV-347 aircraft produced and now stored in the museum at Fort Rucker; and finally 65-08025 on display near Khe Sanh Battle Field, in the old demilitarized zone (DMZ) Area, Central Vietnam, at least as late as July 2008.

In speaking about the last flight of 60-03451, Colonel Kenneth C. Kleine, retired, reported: "I was fortunate enough to have flown 60-03451 from Stockton to Fort Rucker on its last flight. When we landed at Guthrie Field, next to the museum, the aircraft was running like a top. No problems to even write up."

Click-N-Go Here to view a 1979 CH-47A Chinook helicopter Operator's Manual [TM 55-1520-209-10].

 

 

The B Model

 

 

CH-47B Chinook 67-18476 bringing a destroyed sister ship onto the helipad at Tan Son Nhut airbase in Saigon, in the Republic of Vietnam (RVN), circa 1969.

 

 

The CH-47B was introduced by Boeing after a production run of 355 CH-47A's, including 2 airframes that never actually flew (59-04982 and airframe B-006). The hot mountainous conditions of Vietnam limited the A models performance capabilities and generated a requirement for increased

payload and better performance. The B model introduced the Lycoming T55-L7C engine rated at 2,850 SHP, a beefed up airframe, non-symmetrical rotor blades to increase lift, and for better stability - a blunted aft pylon, spoilers on the forward pylon, and strakes on the under side of the fuselage just forward of the ramp hinge. Boeing began delivering the CH-47B in May of 1967, starting with 66-19098, and eventually produced a total of 108 B models for the United States Army, Boeing build numbers B-356 through B-463, before production shifted to the CH-47C. There are no surviving U.S. Army CH-47B helicopters. Click-N-Go Here to view a Boeing information pamphlet describing the CH-47B Chinook helicopter [19.0 Mb].

 

 

The C Model

 

 

74-22280, a CH-47C assigned to the 242nd Assault Support Helicopter Company (ASHC) - "Sugar Bears", located at Fort Wainwright, Alaska.

 

 

The U.S. Army's continued need for further performance improvements led to the development of the CH-47C. Designed to meet an Army requirement to transport a 15,000 pound sling load over a 30 mile radius, the C model boasted an increased gross weight to 46,000 pounds, four additional auxiliary fuel tanks that increased fuel capacity to 1,068 gallons, the Lycoming T55-L11 engine developing 3,750 SHP at 100 percent indicated torque, and additional structural improvements. The aircraft had a transmission torque limit of 84 percent. The C model had a maximum cargo hook capacity of 20,000 pounds. The initial U.S. Army version of the CH-47C had only a single cargo hook below the center of the aircraft. Later on other customers, including the United Kingdom, procured or modified their C models to a triple hook configuration. 67-18494 was the first of 270 C models, Boeing build numbers 464 through 733, manufactured by Boeing at their facility in Philadelphia, Pennsylvania, for the United States Army. 67-18494 conducted its first flight on 14 October 1967. The C model became the mainstay of the Chinook fleet until the advent of the CH-47D. Production of the C model continued until 1980 with improvements such as the crash worthy fuel system and fiberglass rotor blades being incorporated into the fleet. One of the better documented CH-47C helicopters is 70-15032. There are no surviving U.S. Army CH-47C helicopters.

 

 

The D Model

 

 

86-01654, an A Company - "Flipper", 159th Aviation Regiment, from Fort Bragg, North Carolina, helicopter on deployment to Honduras, November 1999 to February 2000.

 

 

The CH-47D was the result of June 1976 contract for a modernized Chinook. The Army recognized that that the Chinook fleet was rapidly reaching the end of its useful life and signed a contract with Boeing to significantly improve and update the CH-47. Three airframes, one each of a CH-47A (65-08008, re-serial numbered as 76-08008 for the prototype testing), a CH-47B (67-18479, re-serial numbered as 76-18479 for the prototype testing), and a

CH-47C (67-18538, re-serial numbered as 76-18538 for the prototype testing), were stripped down to their basic airframes and then rebuilt with improved systems to provide three CH-47D prototypes. The first CH-47D was rolled out in March of 1979 and the aircraft became operational with the 101st Airborne Division in 1984.

Improvements included upgraded power plants, transmissions with integral lubrication and cooling for the transmission systems, and fiberglass rotor blades. As part of the D model conversion, most (if not all) C models were retrofitted with the L-712 engine and the fiberglass rotor blade prior to their induction into the D model program. Other improvements included a redesigned cockpit to reduce pilot workload, redundant and improved electrical systems, modularized hydraulic systems, an advanced flight control system, and improved avionics. The CH-47D Chinook had two tandem three-bladed counter-rotating fiberglass rotors. The CH-47D was powered by two Allied Signal (Lycoming) T55-L-712 turboshaft engines producing 3,750 SHP at 100 percent indicated torque. The dual engine transmission torque limit increased from 84 percent in the C model to 100 percent in the D model helicopter. Additionally, during emergency single engine operations, up to 4,500 SHP was available at 123 percent indicated torque. The helicopter had a maximum speed of 170 knots. The CH-47D could carry twice the load of a CH-47A. The CH-47D was certified to operate at night and in nearly all weather conditions. Certain specially modified aircraft, designated as MH-47D helicopters, were equipped with an in-flight air-to-air refueling probe. As with all models, this version of the Chinook could accommodate a wide variety of internal payloads, including vehicles, artillery pieces, seating to accommodate from 33 to 55 troops, or 24 litters plus two medical attendants. The Chinook could be equipped with two door mounted M60D 7.62mm machine guns on the M24 armament subsystem and a ramp mounted M60D using the M41 armament subsystem. The "D" model could carry up to 26,000 pounds externally using a combination of any three of the external cargo hooks.

A total of 447 D model Chinook helicopters were produced, including the three 1976 prototypes that led to the production runs beginning in the early 1980s, continuing through the mid 1990s. The three prototypes were given new serial numbers during the prototype period. Two prototype airframes were later re-inducted into the D model program after testing to complete the D model conversion, again receiving new serial numbers. One prototype airframe, the B model, was not inducted again, becoming a Category B maintenance training device assigned to Fort Eustis. One airframe was lost when it crashed during a Boeing Company test flight. As a result, 445 airframes were delivered to the U.S Army. The deliveries included 426 airframes that were previously U.S. Army owned A (165), B (76), and C (185) model airframes. Also included in the conversion process were nine CH-47C airframes manufactured by Augusta and intended for the Shah of Iran prior to his displacement as head of state, and seven CH-47C airframes previously owned by the Royal Australian Air Force (RAAF), that were purchased in 1985 and 1991, respectively. This brought the total number of converted airframes to 442. The D model production line eventually included three newly manufactured D model airframes, raising the total number of delivered airframes to 445. The extra numbers apparent in the total count above (447) are a result of two prototypes (the A and C models) receiving new serial numbers when they were inducted into the final D model production line. 443 production D models were delivered the the U.S. Army (445 actual airframes minus the pre-delivery Boeing Company crash and the B model prototype). As a side note, two of the newly manufactured airframes, delivered in 1994, were the first original Chinook airframes produced since the last C model was completed in 1979 - a time span of 15 years. The final and most recent D model airframe, 98-02000, was delivered to the U.S. Army in 2002, made up mostly from left over parts laying around the Ridley Park production facility. Subsequent to their delivery, 22 airframes have been lost due to accidents and 1 was shot down. Two have been converted to F models and one was converted to a G model. As of October 2005, there were 417 surviving D model airframes.

The Fatcow was a special CH-47D mission. An Extended Range Fuel System [ERFS] II system could be installed in the main cabin area. The configuration consisted of one to four fuel tanks attached to a refueling system. The system provided up to 2,400 gallons of JP4/8, exclusive the CH-47 internal fuel load of 1,068 gals. The Fatcow could be set up with 1 to 4 refuel points to deliver fuel to other aircraft on the ground in the combat theater.

 

 

The E Model

 

 

 

 

The MH-47E Special Operations Aircraft (SOA) was a derivative of the standard Boeing CH-47 Chinook. Included with other modifications was a significantly increased fuel capacity with modified main and auxiliary fuel tanks. The aircraft had modified integrated avionics suites and multi-mode radars intended to provide adverse-weather infiltration / exfiltration and support to US Military Forces, country teams, other agencies and special activities. The CH-47D Chinook had been specially modified to perform the special operations mission and was tested in combat on several occasions. As of 2002, the three versions of the CH-47 were in the Army inventory: the CH-47D, the MH-47D, and the MH-47E. The MH-47D and the MH-47E were air refuelable, providing long-range penetration, medium assault helicopter support to special operations forces far away from the base of operations and deep into hostile territory. Depending on the helicopter version, the CH-47 could be ferried 1,100 to 2,000 nautical miles unrefueled. During Operation Just Cause (Panama), CH-47s conducted H-hour assaults to support other elements who were air-landing SOF to disrupt enemy responses and seize key facilities. During Operation Desert Storm (Iraq), the CH-47 conducted infiltration and exfiltration of SOF and Combat Search and Rescue (CSAR) of downed pilots. During development MH-47E testing was limited to the major change to the aircraft which affects vulnerability. In the case of the MH-47E, this was the addition of an 800 gallon Robertson Auxiliary Fuel Tank internally loaded in the main cabin and Boeing designed external fitted sponson tanks with expanded capacity and honeycomb shell construction. Up to 3 internal tanks could be fitted inside the helicopter. However, the third tank could not be filled to capacity as it would cause the aircraft to surpass the 54,000 lb gross weight limit. Analyses conducted during the test planning phase revealed that the largest potential vulnerability was associated with projectiles entering the fuel tanks in the volume (air space) above the liquid fuel. Such impacts could ignite the fuel vapors and cause explosions and/or fires with serious consequences. During test planning, United States Army Special Operations Command (USASOCOM) decided to add an inerting system to the fuel tanks to avoid such fires/explosions. This was a lead-the-fleet system that was also available for similar helicopter variants in other fleets as well. The MH-47D/E aircraft were assigned exclusively to the special operation units at Fort Campbell, Kentucky, and at Hunter Army Airfield, Savannah, Georgia, in the continental United States (CONUS); and outside the continental United States (OCONUS) in the Republic of Korea (South Korea). A total of 26 MH-47E model Chinook helicopters were produced.

 

 

 

 

 

 

 

 

 

 

 

The F Model

 

 

F model 98-00011 on it's maiden voyage, 25 June 2001.

 

 

The CH-47F program was an approved Army program that extended the service life of the CH-47 another 20 years, for a total program life of 60 years. As of 2002, the Chinook helicopter program was over 40 years old. The basic components of the CH-47F program were: extending the life of the CH-47D through the remanufacture process, reducing operation and support costs (O&S) through vibration reduction, and supporting the Army XXI battlefield by providing a digital communications and situational awareness capability.

The CH-47F concept began to materialize in the early 1990's following Desert Storm. The initial concept was a four bladed system called Aerial Cargo Transport (ACT) with long range external fuel tanks, internal cargo handling system, and low maintenance rotor system (dry hub). Unfortunately this concept was dropped as being too expensive. The Office of the Deputy Chief of Staff for Operations and Plans (ODCSOPS) recognized the heavy lift need but there was not enough money for a new start program. They directed an update of the current CH-47D Operational Requirements Document (ORD) to extend the life of the CH-47 fleet while maintaining an economic solution.

The purpose of the CH-47F was to bridge the gap until the funding became available for a new aircraft start (FY 2020 time frame). The cargo helicopter modernization plan included the CH-47F as an interim fix until the Joint (Future) Transport Rotorcraft (JTR) was developed.

The CH-47F program was an austere service life extension program (SLEP) designed to satisfy battlefield requirements for at least 20 years. It provided an additional 20 years of useful life through an airframe rebuild and incorporation of a new cockpit that supported the 21st century digital battlefield. Although separate programmatically from the CH-47F program, the introduction of the T55-GA-714A engines provided additional lift on high/hot days (4000 feet Pressure Altitude (PA), 95 degrees Farenheit).

The 101st Airborne Division, located at Fort Campbell, Kentucky, was scheduled to receive the first CH-47F in FY03 (Fiscal Year 2003). The First Unit Equipped (FUE) date to the 101st, a company of sixteen aircraft, was FY04. Units with the 101st, 18th Airborne Corps at Fort Bragg, 8th Army in Korea, and United States Army Europe (USAREUR), respectively, were scheduled to complete fielding through FY09. As of 2002, only 300 of the 431 remaining CH-47Ds were programmed for conversion to CH-47F. This figure was based on projected fielding of the JTR and the lack of additional funding. The CH-47F program was scheduled to complete the fielding of 300 aircraft in 2015. Future planning included the fielding of the JTR to Force Package One units and the CH-47F aircraft cascading to units that retained CH-47Ds. Those CH-47Ds would then be retired.

As of 1 June 2002, two CH-47F Chinook helicopters had been produced for the U.S. Army - 98-00011 and 98-00012.

 

 

The G Model

 

 

In the works as of late 2002 is the G model Chinook helicopter. Slated for delivery in the near future to the Special Ops community, the CH-47G is intended to upgrade the aging CH-47E fleet. The existing fleet will be inducted into an overhaul/modification program to accommodate the needs of the community. As of early 2004, there was some talk about producing several new build airframes to replace those lost during operations in the "War on Terrorism".

 

 

Related Sites

 

HC-1B Training Package

 

Fly-By-Wire Development [ .pdf ]

 

CH-47A FAA Type Certificate Data Sheet (H3EA) [ .pdf ]

 

Model 234 FAA Type Certificate Data Sheet (H9EA) [ .pdf ]

 

CH-47 Tail Number History

 

D Model Specifications

 

CH-47B to CH-47D Comparison

 

E Model Specifications

 

Fleet Historical Summary

 

 

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