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. 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 but already has its first order.

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

Development
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. The flight software is intended have features that enable single-pilot operation of the helicopter.

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

July 2016 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. The aircraft, registration N525TA, broke up in flight while traveling about 229 mph at an altitude of about 2000 ft. 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.

The crash delayed the expected certification beyond 2017. In February 2018, Bell predicted certification to be completed by late 2018 or early 2019. 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.

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

Intended market
The helicopter is the largest civilian helicopter made yet by Bell, and can carry 16 passengers and two crew.

Bell has also pitched the Bell 525 to military customers as a 20-passenger utility and troop transport or search and rescue (SAR) aircraft. 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, but Bell's proposal did not make it past the pre-qualification questionnaire stage for the UK's medium lift programme.

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.

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.

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

The Bell 525 is designed to fit the emerging "Super-Medium" size category suited ideally to support offshore oil and gas operations. Half of the customers come from that sector. Helicopters under development in the same class are the Airbus Helicopters H175 and the AgustaWestland AW189. 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. It is designed for two pilots with 16 passengers in the standard configuration and two pilots with 20 passengers in high-density seating.