Wikipedia

Bell 525 Relentless

The Bell 525 Relentless is an American super-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] The aircraft is the first fly-by-wire civilian aircraft and suffered a crash of its prototype, and is still slowly working towards certification. As of 2024, Bell is still working towards completing flight certification[2] it has secured its first order.

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

It is a twin turbine engine helicopter with a composite and metal airframe that is in the latter stages of its development.

Development

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Bell announced its new project after the Bell 429 and Bell V-22, the super medium Bell 525, previously it was known as Project X or Magellan. The Helicopter is overall designed for trips of 50 to 500 nautical miles, and has a 5-blade main rotor powered by twin engines, digital controls and Garmin G5000H screen, with planned seating for 16-20 people.[3] The flight software is intended have features that enable single-pilot operation of the helicopter.[3]

The Bell 525's maiden flight was planned for late 2014.[4] PHI, Inc. was the launch customer for the type,[5] but as of 2016 is no longer the launch customer.[6] 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.[7][8] The FAA suggested special rules in May 2016, to address the fly-by-wire concept.[9]

July 2016 crash

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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.[10] The aircraft, registration N525TA, broke up in flight[11] while traveling about 229 mph (199 kn) at an altitude of about 2,000 feet (610 m).[12] During flight testing of the prototype, a severe vibration in the main rotor lead to sequence of events causing the break up of the aircraft. An oscillation in the main rotors of scissoring type caused a 6 hertz vibration in the airfame, which lead to a bio-mechanical feedback loop transmitted from the pilot seat to the pilot and controls among other issues. The accident happened during simulated one engine out test, that used special software to lower the output of both engines. There are many other aspects to conditions that lead to the accident.[13]

The crash delayed the expected certification[12] beyond 2017.[14] 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 were to be tested in cold weather in Yellowknife, Northwest Territories, Canada, as a third prototype was to validate performance in snowy north continental US.[15]

Bell has worked with the FAA to work towards certifying the new design, and examples of tests include running simulated icing conditions.[16]

Intended market

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The helicopter is the largest civilian helicopter made yet by Bell, and can carry 16 passengers and two crew.[17]

Bell has also pitched the Bell 525 to military customers as a 20-passenger utility and troop transport or search and rescue (SAR) aircraft.[18] Bell sought to sell the 525 to the United Kingdom for its New Medium Helicopter program, which aims to replace the RAF's Puma (SA330) helicopters,[19] but Bell's proposal did not make it past the pre-qualification questionnaire stage for the UK's medium lift programme.[20]

In 2019 Bell displayed the Bell 525 at the Paris Air Show, updating the market on its progress and demonstrating some of the aircraft systems.[21]

In 2024, Bell announced its first customer for the Bell 525, an order for ten to operate in the North Seas offshore market by the Norwegian oil company Equinor to be delivered in the late 2020s. The customer noted its thirty year relationship with Bell and its products.[17]

Design

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Bell 525 on display at the Paris Air Show of 2019

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,[22] with tactile cues. The system is triple redundant, and is developed in two simulator environments.[23] The 525 is powered by a pair of GE CT7-2F1 turboshaft engines, with a new composite five-blade main rotor system.[5] 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.[24][25]

The Bell 525 is designed to fit the emerging "Super-Medium" size category suited ideally to support offshore oil and gas operations.[26] Half of the customers come from that sector.[23] Helicopters under development in the same class are the Airbus Helicopters H175 and the AgustaWestland AW189.[5] 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.[27]

Specifications (Bell 525)

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Data from "Bell 525",[28] Flight Global[29]

General characteristics

  • Crew: one or two
  • Capacity: 16 or 20 passengers
    8,200 pounds (3,700 kg) useful load
  • Gross weight: 20,500 lb (9,300 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

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Related development

Aircraft of comparable role, configuration, and era

References

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  1. ^ a b c d Osborne, Tony (February 23, 2018). "Bell Pressing Ahead With Fly-By-Wire 525 Certification". Aviation Week Network. Retrieved October 22, 2021.
  2. ^ "Bell aiming to wrap up 525 certification flight tests in first half of 2024". Vertical Mag. Retrieved April 26, 2024.
  3. ^ a b "New Aircraft Preview: Bell 525 Relentless". Business Jet Traveler. January 27, 2015. Retrieved April 26, 2024.
  4. ^ "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. Archive link appears dead.[dead link‍]
  5. ^ a b c Norris, Guy (February 20, 2012). "Bigger Bell (web title: Bell Rings In Changes With Super-Medium 525 Relentless)". Aviation Week & Space Technology. 174 (7). New York: McGraw-Hill: 36–37.[permanent dead link‍]
  6. ^ Drew, James. "VIDEO: Bell relentlessly pursuing 525 despite market troubles". FlightGlobal. Reed Business Information. Retrieved August 15, 2018.
  7. ^ Perry, Dominic (July 2, 2015). "VIDEO: Successful first flight for new Bell 525 Relentless". Flightglobal.com. Retrieved August 16, 2015.
  8. ^ "Eclipse Special Edition and Bell Model 525 News from The Weekly of Business Aviation". Aviation Week Network. July 7, 2015. Retrieved October 22, 2021.
  9. ^ "Federal Register – Special Conditions: Bell Helicopter Textron, Inc. (BHTI), Model 525 Helicopters; Interaction of Systems and Structures". May 27, 2016. Retrieved August 6, 2016.
  10. ^ Ramirez, Domingo (July 6, 2016). "Bell helicopter crashes in Ellis County, two reportedly killed". Fort Worth Star-Telegram. Retrieved July 6, 2016.
  11. ^ "NTSB Identification: DCA16FA199". NTSB. Retrieved August 6, 2016.
  12. ^ a b "NTSB releases preliminary report on Bell Helicopter crash". Fort Worth Star-Telegram. Retrieved August 6, 2016.
  13. ^ Rotorcraft, Mark Huber • Contributor-. "NTSB: Severe Vibration Triggered Bell 525 Breakup | AIN". Aviation International News. Retrieved April 26, 2024. {{cite web}}: |first= has generic name (help)
  14. ^ Grady, Mary (January 16, 2018). "NTSB Cites 'Adverse Feedback Loops' In Bell Crash". AVweb. Retrieved January 17, 2018.
  15. ^ "Bell 525 helicopters head to Canada for cold-weather testing". Flightglobal. December 18, 2018.
  16. ^ Editor, Kerry Lynch •; magazine, AIN monthly. "Bell 525 Certification on Horizon This Year | AIN". Aviation International News. Retrieved April 26, 2024. {{cite web}}: |last1= has generic name (help)
  17. ^ a b Editor, Kerry Lynch •; magazine, AIN monthly. "Bell Lands First Purchase Agreement for 525 Super-medium Helicopter | AIN". Aviation International News. Retrieved April 26, 2024. {{cite web}}: |last1= has generic name (help)
  18. ^ Perry, Dominic (August 25, 2017). "PICTURES: Bell targets military market with 525 helicopter". Flight Global.
  19. ^ "Bell touts 'ideal' 525 for UK New Medium Helicopter requirement". Janes.com.
  20. ^ Jennings, Gareth (November 2, 2022). "UK downselects New Medium Helicopter contenders". Janes.com. Retrieved December 4, 2022.
  21. ^ "Bell Helicopter will showcase a number of updates and aircraft at Paris show". Helicopter Investor. Retrieved April 26, 2024.
  22. ^ "Bell's 525 is Relentless". Sport Aviation: 14. April 2012.
  23. ^ a b "'Flight Testing' the Bell 525 Relentless". Vertical Mag. June 30, 2016. Retrieved October 22, 2021. Archived on 23 July 2014.
  24. ^ "Bell 525 Brochure" Archived October 5, 2013, at the Wayback Machine. Bell Helicopter, February 2012. pdf
  25. ^ "'Relentless' 525 To Be Largest Bell Helicopter" Archived September 7, 2014, at the Wayback Machine. AINOnline, February 2012.
  26. ^ CFM, In association with; Airshow, In association with Singapore; Recruitment, In association with GOOSE; Trimble, Stephen (February 23, 2015). "ANALYSIS: Oil prices create super uncertainty". Flight Global. Retrieved October 22, 2021.
  27. ^ "Bell 525 Relentless". Bell Flight. Retrieved October 22, 2021.
  28. ^ "BELL 525 RELENTLESS". bellflight.com. Archived from the original on July 11, 2019.
  29. ^ CFM, In association with; Airshow, In association with Singapore; Recruitment, In association with GOOSE; Perry, Dominic (September 21, 2015). "Bell confident on further 525 performance boost". Flight Global. Retrieved October 22, 2021.
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