Bell won’t commit to 2020 certification for 525 as flight testing continues


Bell has said it will not commit to a certification timeline for its upcoming super medium 525 Relentless, as certification flight tests continue across the fleet of four aircraft.

The Bell 525 Relentless continues flight testing as it works towards type certification. Bell Photo

Advertisement



When the 525 was unveiled in 2012, Bell was targeting certification around 2015, but that timeline has gradually slipped to the right as flight testing progressed. However, during a recent media visit to Bell’s headquarters in Fort Worth, Texas, Josh O’Neil, manager, technology and evaluation, talked enthusiastically about the strides the 525 program team has made of the last year, and his firm belief that the cutting-edge technology employed throughout the clean-sheet design will mean the aircraft will prove successful once it does get certified.

“It’s a matter of having a look at where we are, looking ahead and trying to be accurate about setting expectations,” he said, when asked if the aircraft will be certified in 2020. “We can’t set that kind of an accurate expectation right now. I think we will be there soon . . . but we’re still going through that and understanding the ramifications of everything we’ve seen this year.”

When it does happen, the 20,500-pound (9,300-kilogram) max gross weight 525 will become the first civilian fly-by-wire helicopter.

Powered by two General Electric GE CT7-2F1 engines, the aircraft has a fully articulated five-blade main rotor, a four-blade canted tail rotor, and a Garmin G5000H glass cockpit.

It has a range of 500 nautical miles for offshore transport, and a 250-nm radius for search-and-rescue operations (allowing for 20 minutes on the scene, and 30-minutes of fuel reserves).

The aircraft has a long-range cruise speed of 145 knots, a maximum cruise of 160 knots and a hover out of ground effect ceiling of 8,100 feet (2,470 meters).

“It is a very fast aircraft and especially at high speed, a very smooth aircraft,” said O’Neil. The 525 has flown beyond 200 knots in flight testing, and O’Neil said he believed it could potentially have gone even faster.

“Your main rotor is what you’re watching when you go that fast,” he said. “It’ll talk to you — an instrumented rotor will tell you when it starts to feel it. And we flew until we said, ‘Well, we’re done,’ but the rotor wasn’t done. They could’ve gone appreciably faster.”

The aircraft will be certified in its oil-and-gas configuration first, despite this primary target market for the aircraft continuing to suffer from an ongoing downturn. VIP and search-and-rescue configurations will follow.

“When you talk about the market for an aircraft of this category, [oil-and-gas] is still really the sweet spot,” said O’Neil. “Yes, it may have declined, but it’s still a pretty active market . . . with opportunities.”

Once the 525 Relentless is certified, it will become the first civilian fly-by-wire helicopter. Oliver Johnson Photo

Now over four years into flight tests, there are four aircraft flying on the program: Ship 2, Ship 3, Ship 14 and Ship 15 (the numbers for the latter two are slightly misleading — they are the fourth and fifth 525s produced). Together, they have amassed more than 1,500 flight hours.

Ship 1 was destroyed in a fatal accident during flight testing in July 2016, in which two Bell test pilots lost their lives. That accident resulted in a 12-month grounding of the flight test program.

The most recently-constructed is Ship 15, which has a production configuration with a 16-seat, oil-and-gas interior. In this configuration, there are four rows of four seats, each 20-inches wide. This allows every passenger to be no more than one seat away from an emergency exit at any time.

The test program spent 2.5 months in Yellowknife, Northwest Territories, earlier this year, working on cold weather certification tests. Two aircraft (Ships 2 and 3) were there for much of the time, recording over 100 flights and seven cold soaks (leaving the aircraft outside in -40 C/-40 F, then turning it on). The ferry flight took two days, spanning 2,200 miles (4,100 kilometers) each way.

Ship 14 flew to Rome, New York, to experience flight in full blowing snow conditions, and has completed engine/APU compatibility testing. The year also saw Ship 15 complete high intensity radiated field testing, as well as low level lightning tests. It has now begun customer evaluations, with some potential buyers allowed to pilot the aircraft.

The team is also working on certifying the 525’s autorotation entry assist capability, in which the aircraft’s fly-by-wire system steps in instantaneously to input suitable responses to an engine failure.

“In an autorotation situation, the most important time is that first second in terms of maintaining your motor speed and your controllability of the aircraft,” said O’Neil. “To certify aircraft, you have to show that for a second that pilot might not do anything and then you’re allowed to be on the controls. . . . But that second you lost; the most important time to control that maneuver is usually put aside. With a fly-by-wire flight control system, you can actually have computers get in immediately when you have an engine failure, and they can begin to put inputs to the controls to put you in a better state.”

O’Neil stressed that it’s not a completely autonomous autorotation capability, and that as soon as a pilot starts manipulating the controls, they have complete control of the aircraft. “It’s just if you do have a pilot who takes a second for whatever reason to get on the controls, he’s in a better spot than you would be if you don’t do anything.”

Advertisement


cover


The GE CT7 engine was certified in March 2019, and O’Neil said Garmin was keeping pace with the program’s certification needs, and was on track for qualification of the G5000H in the second quarter of 2020.

Icing certification will be offered as a kit following type certification (TC). The blades are heated by an electric thermal system, with the heated windshield being the other major component of the kit. “We will launch the effort to certify that capability after TC,” said O’Neil. “It’s one of a list of many kits that are actually already designed. They are part of the aircraft already and the only thing to do is to go certify those kits.”

The 525 features a Garmin G5000H glass cockpit, and is powered by two General Electric GE CT7-2F1 engines. Oliver Johnson Photo

Looking ahead at the remaining work to do on the flight test program, Ship 2 will work on handling qualities and noise testing, before being used as the ground endurance test vehicle. After that, it will be retired and modified to become a maintenance trainer.

Ship 3 will be used for one engine inoperative, flight control failure modes, and handling qualities tests, as well as the search-and-rescue load level survey.

Ship 14 is set for inlet distortion, propulsion/avionics cooling, flight director, and float testing; while Ship 15 will work on fuel system calibration, fire extinguishing, emergency egress, electrical and avionics, and functional and reliability testing. It will then serve as a demonstrator aircraft.

Five of eight drive system certification tests have now been completed, with the remainder set to finish by the second quarter of 2020. Bell expects to complete bird strike tests by the end of 2019.

  
Social Messaging