Boeing CH-47 Chinook MH-47E

The MH-47E is the Chinook designed from the outset for US Army special operations, and the version that gave the family its reputation as a helicopter able to fly very far, very low and at night. Its roots lie in the improvisations of the early 1980s. In 1980 Task Force 158, forerunner of the 160th Aviation Battalion that would grow into the 160th Special Operations Aviation Regiment, received from the 101st Airborne Division twelve CH-47Cs adapted for night-vision goggles; they entered active service in 1981 with radar altimeters, long-range navigation and communication equipment and four metal fuel tanks inside the cabin. In 1983 sixteen CH-47Ds followed, with better navigation, satellite communications and electronic warfare systems, in service from 1984. These were stopgaps: the regiment needed an aircraft designed for its mission.

The key technology was the digital cockpit. In 1985 an engineering evaluation branch of the Army Communications and Electronics Command tested a digital avionics system that led to the "glass cockpits" of the MH-47E and the MH-60K Black Hawk, where computer screens replaced a clutter of gauges and switches. Several of these technologies, including the integrated displays, the forward-looking infrared (FLIR) sensor and the multimode radar, had been flight-tested on the Boeing Model 360 demonstrator and later on the V-22 Osprey tiltrotor. A December 1987 contract covered the development and flight testing of one prototype and 25 production aircraft; a June 1991 contract funded long-lead purchases and the induction of the first 25. IBM Federal Systems, later bought by Lockheed Martin, was the directed subcontractor for the integrated avionics system shared by Boeing and Sikorsky. The Army required that radios, mission computers and multifunction displays could be swapped between an MH-47E and an MH-60K in minutes, something unheard of between aircraft from different manufacturers and valuable far from normal supply lines.

The operational requirement was demanding: a 5.5-hour covert mission over a 300 nautical mile (555 km) radius, at low level, day or night, in bad weather, over any terrain and with a 90 per cent probability of success. To meet it the aircraft received two Textron Lycoming T55-L-714 turboshafts rated at over 4,000 shp, replacing the 3,750 shp T55-L-712s of the CH-47D, tanks doubling the CH-47D's fuel capacity and an in-flight refuelling probe. The Raytheon AN/APQ-174A radar provided terrain-following and terrain-avoidance flight, air-to-ground ranging and ground mapping; self-protection comprised the AN/AAR-47 missile approach warner, the ALQ-162 Shadowbox and ALQ-136(V) jammers, the APR-39A radar warner and the M-130 chaff and flare dispenser. A rescue hoist and a fast-rope system completed the fit.

The MH-47Es were not new airframes: they were CH-47Cs remanufactured on the CH-47D line, with a mission package and cockpit similar to those of the MH-60K, most E-model systems being installed in the final stages. The E-model prototype was built in 1991. Cost, at least 14 million dollars and up to 40 million per aircraft, cut the programme back: of the 51 planned, 26 were produced. The 160th had been flying them since 1994 while crews trained on the integrated cockpit, supported by two full-motion simulators, and the twenty-sixth was delivered in May 1995. All went to the 2nd Battalion, 160th SOAR(A), the "Nightstalkers", based at Fort Campbell, Kentucky. In testing, the first aircraft served as the flight-test prototype, while the second and third were used for electromagnetic effects and survivability equipment trials at the Naval Air Test Center, Patuxent River.

In 1995 they gained M134 miniguns, the fast-rope insertion and extraction system (FRIES) and two 800-gallon Robertson auxiliary tanks, and between 1995 and 2001 they were upgraded with changes identical to those of the MH-60K. Live-fire testing of the cabin auxiliary tank and the new honeycomb sponson tanks ended in May 1998: Special Operations Command had decided to add a fuel inerting system, and the tanks, self-sealing against .50 calibre rounds, also withstood larger projectiles; in 23 shots there was only one fire, which put itself out. In 1996 an MH-47E crashed at Fort Campbell, killing five members of the unit; the investigation found the most likely cause to be loss of electrical power from water in the primary distribution panels, which were then protected.

To restore the fleet, in December 1999 Boeing received a contract for long-lead parts for a replacement MH-47E, and in September 2000 another to convert an Army Aviation Center CH-47D nicknamed "Bearcat 3" into the MH-47E "Dark Horse", due in 2003. MH-47Es were also ordered to replace Air Force MH-53Js in the Pacific and European commands.

Their baptism of fire came in Afghanistan after 11 September 2001. With long-range tanks, refuelling probe, multimode radar and FLIR, they flew at night and in bad weather at nearly 150 mph (about 240 km/h) a few feet off the ground. In the first six months the regiment's MH-47s flew more than 200 combat missions and about 2,000 flight hours, as high as 16,000 feet and for up to 15 hours, with 99 per cent mission readiness. In Operation Anaconda in 2002, Taliban and Al Qaeda fire hit three MH-47Es: a Navy SEAL fell from one, a second was damaged and a third was brought down while landing reinforcements, five of whom were killed. That year they also deployed to the Philippines, where an MH-47E crashed at sea with ten servicemen aboard, and the regiment later took them to Iraq.

In 1995 the United Kingdom ordered eight Chinook HC3s, effectively a lower-cost MH-47E for its special forces, which never became operational with their original avionics. In the United States the MH-47G programme brought the MH-47D and MH-47E to a common standard with the CAAS digital cockpit and the new sections of the CH-47F; by the end of 2003, 25 MH-47Es and 11 MH-47Ds had been upgraded.