Bell 525 Relentless

The Bell 525 Relentless is an American medium-lift helicopter, under development by Bell Textron. The Bell 525 was unveiled at the 2012 Heli-Expo in Dallas, Texas in February 2012. The helicopter first flew on 1 July 2015. It is designed to transport up to 19 passengers.[1]

Bell 525 Relentless
Prototype of the Bell 525 in flight
Role Medium-lift utility helicopter
National origin United States
Manufacturer Bell Textron
First flight 1 July 2015
Status Under development
Produced 2015–present

Development

The Bell 525's maiden flight was planned for late 2014.[2] PHI, Inc. was the launch customer for the type,[3] but as of 2016 is no longer the launch customer.[4] After a six-month delay, the Bell 525 prototype first flew in July 2015. At that time, Bell predicted certification to be completed by the end of 2017.[5][6] The FAA suggested special rules in May 2016, to address the fly-by-wire concept.[7]

July 2016 crash
Main article: 2016 Bell 525 Relentless prototype crash

At approximately 11:48 AM Central Daylight Time on July 6, 2016, the prototype crashed during a test flight near Italy, Texas, killing the two occupants.[8] The aircraft, carrying registration N525TA, broke up in flight[9] while traveling about 229 mph (199 kn) at an altitude of about 2,000 feet (610 m).[10]

The crash delayed certification[10] from 2017 to 2018.[11] In February 2018, Bell predicted certification to be completed by late 2018 or early 2019.[1] In December 2018, 1,300 hours of turn time and 900 hr of flight were accumulated, towards a 2019 US type certification. In early 2019, two helicopters will be tested in cold weather in Yellowknife, Northwest Territories, Canada, as a third prototype will validate performance in snowy north continental US.[12]

Bell is pitching the Bell 525 to military customers as a 20-passenger utility and troop transport or search and rescue (SAR) aircraft.[13]

The company is also offering the Bell 360 Invictus military helicopter that uses a scaled down rotor system, fly by-wire system, and control systems from the Bell 525 for the U.S. Army Future Attack Reconnaissance Aircraft program.[14][15][16]

Design

The Bell 525 is designed to meet a requirement for a medium-lift helicopter. It will be constructed primarily from composites and metal and is to be the first commercial helicopter to incorporate fly-by-wire flight controls,[17] with tactile cues. The system is triple redundant, and is developed in two simulator environments.[18] The 525 is powered by a pair of GE CT7-2F1 turboshaft engines, with a new composite five-blade main rotor system.[3] The cost of the 525 has not yet been determined, but it is expected to be cost competitive on missions between 50 and 400 nmi, performed by helicopters such as the AgustaWestland AW139 and Sikorsky S-92.[19][20]

The Bell 525 is designed to fit the emerging "Super-Medium" size category suited ideally to support offshore oil and gas operations.[21] Half of the customers come from that sector.[18] Helicopters under development in the same class are the Airbus Helicopters H175 and the AgustaWestland AW189.[3] The 525 is to be certified in Category A Takeoff class, at maximum gross weight. This involves being able to continue a takeoff (or landing) after one of the helicopter's two turbine engines fails at any point. It should be capable of carrying 19 passengers, more than any existing super-medium helicopter.[1] It is designed for two pilots with 16 passengers in the standard configuration and two pilots with 20 passengers in high-density seating.[22]

Specifications (Bell 525)

Data from "Bell 525"[23] [24]

General characteristics

  • Crew: one or two
  • Capacity: 16 or 20 passengers
    8,200 pounds (3,700 kg) useful load
  • Gross weight: 20,500 lb (9,299 kg)
  • Max takeoff weight: 20,500 lb (9,300 kg)
  • Fuel capacity: 2,461 liters (541 imp gal; 650 U.S. gal)
  • Powerplant: 2 × General Electric CT7-2F1 turboshaft, 1,800 shp (1,300 kW) each
  • Main rotor diameter: 54 ft 6 in (16.61 m)

Performance

  • Maximum speed: 190 mph (306 km/h, 165 kn)
  • Cruise speed: 178 mph (287 km/h, 155 kn)
  • Range: 644 mi (1,037 km, 560 nmi) Max GW, Sea Level, ISA, standard fuel, no reserve, VLRC
  • Service ceiling: 20,000 ft (6,100 m) with 12,000 ft (3,700 m) hover in ground effect, 6,000 ft (1,800 m) HOGE

Avionics

See also

Related development

Aircraft of comparable role, configuration, and era

References
  1. Bell Pressing Ahead with Fly-by-Wire Certification. Aviation Week & Space Technology, 26 February 2018
  2. "Bell Helicopter Reveals the Latest in the Bell 525 Program during HELI-EXPO 2014" Archived 2014-04-29 at the Wayback Machine. Bell Helicopter, February 25, 2014.
  3. Norris, Guy (20 February 2012). "Bigger Bell (web title: Bell Rings In Changes With Super-Medium 525 Relentless)". Aviation Week & Space Technology. New York: McGraw-Hill. 174 (7): 36–37.
  4. Drew, James. "VIDEO: Bell relentlessly pursuing 525 despite market troubles". FlightGlobal. Reed Business Information. Retrieved 15 August 2018.
  5. Perry, Dominic (July 2, 2015). "VIDEO: Successful first flight for new Bell 525 Relentless". Flightglobal.com. Retrieved August 16, 2015.
  6. Bell Completes First Flight of Model 525. Aviation Week & Space Technology, 1 July 2015
  7. "Federal Register – Special Conditions: Bell Helicopter Textron, Inc. (BHTI), Model 525 Helicopters; Interaction of Systems and Structures". Retrieved 6 August 2016.
  8. Ramirez, Domingo (July 6, 2016). "Bell helicopter crashes in Ellis County, two reportedly killed". Fort Worth Star-Telegram. Retrieved July 6, 2016.
  9. "NTSB Identification: DCA16FA199". NTSB. Retrieved 6 August 2016.
  10. "NTSB releases preliminary report on Bell Helicopter crash". Fort Worth Star-Telegram. Retrieved 6 August 2016.
  11. Grady, Mary (16 January 2018). "NTSB Cites 'Adverse Feedback Loops' In Bell Crash". AVweb. Retrieved 17 January 2018.
  12. "Bell 525 helicopters head to Canada for cold-weather testing". Flightglobal. 18 Dec 2018.
  13. https://www.flightglobal.com/news/articles/pictures-bell-targets-military-market-with-525-heli-440587/
  14. https://www.rotorandwing.com/2019/04/22/bell-fara-offering-based-on-525-technology-company-says/
  15. https://www.defensenews.com/digital-show-dailies/aaaa/2019/04/23/us-army-picks-5-teams-to-design-new-us-army-attack-recon-helicopter/
  17. "Bell's 525 is Relentless". Sport Aviation: 14. April 2012.
  18. Maher, Guy. "'Flight Testing' the Bell 525 Relentless" Vertical, 10 July 2014. Accessed: 23 July 2014. Archived on 23 July 2014.
  19. "Bell 525 Brochure" Archived October 5, 2013, at the Wayback Machine. Bell Helicopter, February 2012. pdf
  20. "‘Relentless’ 525 To Be Largest Bell Helicopter". AINOnline, February 2012.
  21. Oil Prices Create Super Uncertainty. Flight Global
  22. Bell 525 web page. Bell
  23. https://www.bellflight.com/commercial/bell-525
  24. Bell Confident on Further 525 Performance Boost. Flight Global
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