The Bell Helicopter 407 has a workhorse reputation gained over two decades of performing both glamorous missions and tough ones, such as firefighting, utility, air ambulance and law enforcement work. While it has great capabilities, the 407’s performance falls off above 6,000 feet and above 25 degrees Celsius. This leaves many operators with the need for more power and limited ability to perform some missions.
At the turn of the century, Bell launched the 417 program as a response to what it called “customers' demand for a powerful, single-engine helicopter with unmatched hot and high hover capability." The company chose Honeywell’s turboshaft HTS900 engine for the 417, and for its U.S. Army derivative, the ARH-70A Armed Reconnaissance Helicopter. With the HTS900, Honeywell had demonstrated once again its ability to design and produce a powerful, highly efficient, maintainable powerplant. However, both the 417 and ARH-70A programs were canceled due to customer budget cuts.
First delivered in 2015, the Eagle 407HP is enabling operators in the United States, Canada and the South Pacific to fly longer, further and higher. It also allows them to carry more people and payload with greater reliability and lower costs than they could with their standard 407s and comparable helicopters. The Eagle 407HP surpasses the performance of the Airbus Helicopter AS350 family and the standard 407 variants at higher altitudes.
For parapublic and utility missions, the 407HP’s ability to carry both full fuel and full payloads enables operators to work a target longer and more efficiently. This is demonstrated by the case studies below of Helicopter Express, Yellowhead Helicopters, Nevada's Department of Wildlife, and Heli Niugini.
The challenge Honeywell faced was how to build a more powerful engine with roughly the same size and weight as the 407’s standard Rolls-Royce M250. It was answered with the expertise of the company's engineers, using modern design tools to build on the legacy of its engine products. That legacy includes the engine design experience and technology of Garrett AirResearch, AlliedSignal, and Lycoming, melded through mergers and acquisitions into Honeywell.
The HTS900 includes a twin centrifugal compressor, a longtime and highly refined feature of AlliedSignal and Honeywell engines. The compressor section includes a ported shroud that provides additional surge margin, or stability margin. And the overall compressor design gives the engine an 11-to-1 pressure ratio, which drives its better specific fuel consumption.
The engine also uses a segmented shroud around the high-pressure turbine section to meet the challenge of maintaining the tight turbine-blade-tip-to-shroud clearance. That tight clearance keeps the burning, expanding fuel air mixture from escaping and reducing the engine’s efficiency.
The HTS900 design is simple and robust, said Honeywell HTS900 Program Manager Dave Lopez. For example, the ported shroud has no moving parts. Unlike some competitor engines, he said, “you don't have surge valves that open and close and rob the engine of efficiency.”
The compressor’s blades “are more substantial than an axial compressor system,” Lopez said. “In a helicopter that's going to be exposed to all kinds of contaminants when it kicks up dirt, that's a good thing. You can stay on wing longer.”
A key feature of the HTS900 is the on-condition maintenance philosophy. Disassembly and inspection of major components like the hot section, gearbox and fuel and oil pumps are not required until 2,400 hours. A full inspection is set at 4,800 hours.
“Our operators like the on-condition maintenance approach,” said Doug Kult, Honeywell’s helicopter engines product line director. “It evens out the engine maintenance event costs and lowers the overall cost of ownership.”
As a result of Honeywell's development work, Eagle Copters can replace the 407’s original 813 shaft-horsepower Rolls-Royce 250-C47 with the 1,020 shaft-horsepower HTS900. The new engine offers numerous benefits beyond the added power.
Under their 407HP partnership, Honeywell provides the HTS900D-2 engine and configuration while Eagle Copters performs the engine installation and related modifications and handles flight testing and certification.
Modified under Eagle Copters’ 2014 Transport Canada and FAA supplemental type certificates, the 407HP is a single-engine that delivers up to 22 percent more takeoff power (at sea level and International Standard Atmosphere), significantly improved hot-and-high performance, and improved payload, speed and operating costs when compared to the standard Bell 407. The Eagle 407HP can also lift 500 pounds more than the standard Bell 407.
The 407HP upgrade also provides an improved hover ceiling, with a 19 percent increase in gross weight capability at 10,000 feet, and a 40 percent increase in payload at 12,000 feet. The HTS900’s added power means the 407HP can “fill the transmission through 10,000 feet, all the way up to the max transmission torque limit,” Honeywell's Lopez said. In addition, fuel burn is reduced by up to 17 percent, while direct maintenance costs are about 12 percent less than those for the original Bell 407 model.
Another benefit comes from the HTS900’s dual-channel full authority digital engine control (FADEC) system, which eases pilot workload and facilitates engine maintenance planning and troubleshooting. “Because of the redundancy of the two channels,” Lopez said, “you have increased safety.”
Operators of the 407HP have been able to validate the benefits that Honeywell and Eagle originally predicted and are receiving more out of the upgrade.
“We were a little surprised when the operators started flying,” Lopez said. The designers knew operators would be able to fly longer, further and with more payload, “but what the upgrade also gives them is the ability to fly with a full fuel tank. On the Rolls-powered 407s, typically you should trade fuel for payload because you become temperature-limited so soon. With this engine, you don't have that problem.”
That lets operators carry a full fuel load, “and on these fire missions they can go out and fly back and forth with buckets of water a whole lot longer because they don't have to come back and get gas,” Lopez said. “That was one of the things we didn't expect. The utilization increased both because they could carry more payload but also because they can carry more fuel.”
Headquartered in Chamblee, Georgia, Helicopter Express primarily fights wildfires for the U.S. Forest Service in the American West and Southeast. The company operates a fleet of 23 helicopters, a mixture of the Airbus Helicopters AS350B3 and EC155, Bell Super 205A-1, 206L LongRanger and 407 and Kaman K-MAX.
Helicopter Express’ Bell 205s, powered by Honeywell's T53 engine, “are the best performers high and hot for what we do, and the best engine," said company founder Scott Runyan, when the operator first ordered the Eagle 407HP. “We felt like that would carry down into the 407 and were excited to try the new Honeywell engine in that light helicopter.”
Eagle Copters delivered the first 407HP, a conversion of a standard 407 from Helicopter Express’ fleet, in November 2016. The second one, delivered at Heli-Expo 2017 in Dallas, was a stock 407 that Eagle Copters converted to the HP configuration. The 407HPs have confirmed Runyan’s belief and exceeded customer expectations.
The HTS900’s installation made the 407's performance above 6,000 feet and 25 degrees Celsius substantially better than the standard 407 with its Rolls-Royce M250, said Helicopter Express President and COO Richie Kittrell. On a U.S. government firefighting contract, the operator is required to do daily load counts, “essentially a weight-and-balance calculation based on atmospheric conditions and anticipated loads,” Kittrell said. On its standard 407, Helicopter Express could carry a 120-gallon water bucket; its 407HP carries a 180-gallon bucket; and the AStar only carries a 144-gallon bucket. A gallon of water weighs about 8.3 pounds.
Compared to the AStar, “the 407HP has given us about 300 pounds of added payload on average at altitude, depending on atmospheric conditions, which is where we work,” Kittrell said. It can fly 500 extra pounds of payload over the standard 407.
In mid-2017, Helicopter Express was flying its first Eagle 407HP on a Forest Service contract in Bridgeport, California, a small town on the Nevada border west of San Francisco at an elevation of 6,343 feet. Its second 407HP was flying fire and other missions in the Southeast U.S.
Helicopter Express’ line pilot in Bridgeport, Joe James, has flown for the company since 1999. He told Kittrell that with Eagle Copter’s conversion, “the helicopter is now the aircraft that the 407 was always meant to be.”
Kittrell should know. He was on the customer advisory council that Bell Helicopter formed from firefighting, utility, oil and gas, tour operators and other operators in the mid-2000s to help it design the 417. While that aircraft program died, the idea of putting the HTS900 in a Bell light single airframe lived on with Eagle Copter, he said. “It has finally made the 407 a hot-and-high-altitude AStar butt-kicker. The 407HP is head and shoulders above everything”
Initially, Kittrell said, he was skeptical of Honeywell’s claims about the HTS900’s reduced fuel burn. But he said James recently flew from Minden, Nevada to pick up crew of three firefighters and their gear in Las Vegas, a distance of about 300 nautical miles. The 407HP flew that leg in 2.5 hours, burned about 100 gallons of fuel and "landed with plenty of reserves,” Kittrell said.
“We would have never even planned that before with the standard 407 – 250 nautical miles was the edge of our range previously,” he said. “So, the 407HP does have lower fuel burn. We've been pleasantly surprised.”
The Eagle 407HP’s added performance and fuel efficiency means that aircraft can carry one more firefighter and gear or more water in a shorter period of time than the Airbus AStar and spend more time dropping more water on a fire before it needs to refuel. Helicopter Express introduced the Bell 407 to Forest Service aerial firefighting back in the late 1990s, “when everyone was running around like us with JetRangers and LongRangers,” Kittrell said, adding that the standard 407 quickly became a preferred firefighting helicopter.
“I think 407HP is going to do the same thing to the 407 and the AStar,” he said. “It is set to redefine the Type III class of firefighting helicopters.”
Yellowhead Helicopters is based in Prince George, British Columbia. From multiple bases throughout the northern part of that Canadian province and its eastern neighbor, Alberta, the privately held company has supported the forestry, mining, petroleum, utility and tourism industries for more than 40 years.
Yellowhead Helicopters’ missions include long-lining, drip-torching, cone harvesting, aerial seeding, airborne geophysics, sock-line towing, powerline and pipeline patrols, drill moving, fire suppression, and heli-skiing. Included in its fleet are the Airbus Helicopters AS350, Bell 205, 206 JetRanger and LongRanger, 212 and 427, and the Eagle Single (Eagle Copters’ single-engine conversion of the Bell 212).
Yellowhead Helicopters also operates two Eagle 407HPs, which it has flown for more than 1,000 hours in total. “Now that our customers have actually seen how the aircraft performs, it's changed their way of thinking from what aircraft will best suit them. In a lot of cases now, it's the 407HP,” said Yellowhead Operations Director Sean Rickards.
“The benefit with the 407HP is that it carries the extra passenger over the Airbus models,” Rickards said. “That's an extra paying customer” whose carriage is made possible by mating the HTS900 to the standard 407's larger cabin. The more powerful and efficient engine makes it possible to carry that extra customer in situations where the standard 407 would be weight-limited.
“Typically, with an aggressive ski run, the passengers are sweaty, they’re hot, they've got snow on their clothes,” Rickards said. “As soon as they get in the aircraft, it will fog right up. With the Honeywell HTS900 not running as hot as a standard 407 engine, we’re allowed to run our anti-ice and our heat all day long, which, in my mind, has increased safety tenfold.”
The operations director observed: “Anywhere it's high and hot, the 407HP shines now,” adding that “4,000 feet is where you really start to see the spread” between the 407HP’s performance and that of competing aircraft.
Using Yellowhead’s performance calculator for 407HP, standard 407 and the AS350 B3e (which the company also flies), Rickards ran some numbers, starting with what he said is a standard day in northern British Columbia: 4,000 feet density altitude and 20 degree Celsius. The operator’s base at Prince George is at about 3000 feet above sea level, “so it doesn't take long to get the 4000 feet mark for us.”
On a 20-degree day at 4,000 feet, he calculated, the 407HP will lift roughly between 300 and 400 pounds more than the standard 407 and about 100 pounds more than the B3e AStar.
“If you step it up to 6,000 feet, the 407HP will outlift the standard 407 by about 600 pounds and the B3e by just over 300 pounds,” Rickards said. “Really where the 407HP shines is at altitude,” he added. “You get up to the same temperatures at 8,000 feet and now it's out lifting a B3e by about 600 pounds on the hook.”
The 407HP’s greater efficiency and better performance at higher terrain and hotter temperatures, Rickards explained, “gives you that margin to allow you to take your full gross weight through those altitudes.” That can be especially beneficial in firefighting missions
Yellowhead usually uses a 200-gallon bucket when attacking fires with the 407 and the 407HP. The standard 407's external-load weight limitations meant the operator had to limit the bucket to an 80 percent load or cut the aircraft's fuel load. “In the past, we would cinch down our buckets or we would reduce the amount of fuel we would take and shorten our drop cycles so that we could pack a full bucket load,” Rickards said. “Now we can take the full bucket load with roughly the same amount of fuel right through our usual cycle of about an hour.” That means dropping more water on the fire without having to cut and drop cycle short to refuel.
In exploration work with the 407HP, Yellowhead can lift the same loads it used to “but now we can lift them continuously all the way through altitude,” he said, “So we can typically go a little heavier on fuel and a little longer on cycles.”
Yellowhead Helicopters mechanic Robert Wittmack, added, “The support that we’re receiving from Honeywell and Eagle Copters is very good. I would recommend the Eagle 407HP to other operators. I believe, from a maintenance standpoint, the aircraft is easy to work with and easier to maintain.”
Nevada's Department of Wildlife has a long, incident-free history of both fixed-wing and helicopter operations. Its mission is to provide a safe, economical platform for allowing state biologists to complete game surveys and to conduct many additional tasks required to ensure a healthy wildlife population for the public to enjoy far into the future.
The state has a mean elevation of 5,500 feet above sea level and mountain peaks ranging from 7,868 to 13,147 feet. Its average temperatures range from minus 4 degrees to 30 degrees Celsius.
The air operations unit flies more than 1,200 flight hours each year, with a fleet that had included a Cessna 206G airplane and two Bell 206B3. The department’s missions taxed the fleet’s performance and safety limits. The aircraft were approaching airframe flight times of 16,000 hours, and maintenance costs and reliability concerns were increasing. Going into 2016, mechanical issues were forcing the department to rely on outside contractors to conduct game surveys, at a much greater cost to the state. In looking for replacement for one of its aging 206B3s, the Eagle 407HP was a natural choice.
“The Eagle 407HP with all of its advanced monitoring systems greatly enhances safety and reliability while reducing direct operating, maintenance and fuel costs,” then-Chief Pilot Greg Smith told state Board of Wildlife Commissioners in an October 2015 acquisition request. “With the increased reliability and the reduction in maintenance time required, we will see a decreased need to seek outside contract aircraft.”
“The Bell 407HP Eagle is also much faster, with greater maneuverability than our current aircraft,” Smith said in the request. “This added performance will decrease the flight time necessary” to complete surveys, reducing cost and time, “thus allowing us to be available for more in-house projects rather than contract those services out.”
That reasoning has proven solid, said Chief Pilot Rick Thielmann, who has about 500 hours on the 407HP that Eagle Copters delivered to the department at Heli-Expo 2016. The aircraft has accumulated more than 585 hours since delivery.
Most of the flight time has been supporting wildlife surveys, taking biologists around, counting animals and looking at habitat. About 50 hours have been in external load work, lifting "guzzlers" — man-made watering holes for the wildlife — to mountain locations and removing old ones. The HTS900's extra power enables the department's 407HP to climb Nevada's mountains faster and more swiftly deliver biologists and equipment to target areas. "You can use sea-level power all the way to altitude," chief pilot said.
Of the 407HP's attributes, Thielmann said, are the original 407’s “great tail rotor performance. Then there’s the fully articulated rotor head in mountainous conditions.” Inheriting those design aspects positions the 407HP well to handle the high-wind when often encountered in mountain flying.
With the standard 407’s fuel capacity and burn of 42 to 50 gallons an hour, “you're going to get two hours’ flight time and then you’re looking for a place to go get gas,” Thielmann said. “The 407HP, with the air conditioner running, burns 37 gallons an hour, 36 with it off.”
In addition, he said, the 407HP “really doesn't care how many extra people are on it. I had it fully loaded and you still get two hours and 45 minutes, plus reserve. When I'm doing survey flights, I get three hours and 10, three hours and 15 minutes, because I'm cruising around at 50 to 60 knots. Then I still land with around 150 to 200 pounds of fuel on board.” The 407HP’s fuel burn in cruise flight compares to the standard 407's consumption of 42 to 50 gallons an hour.
As far as maintenance, Thielmann added, the aircraft just completed a 600-hour inspection; “through all the borescoping and everything, it still looks brand new.” In addition to the HTS900’s robust design, the department chose added protection for the engine in the form of an inlet barrier filter, which keeps dirt, dust, sand and other contaminants from entering the powerplant.
Given the performance and benefits of its first Eagle 407HP, Thielmann said, the department is considering acquiring a second in 2018.
For more than 30 years, Heli Niugini Limited has operated on the western South Pacific island nation of Papua New Guinea and throughout Australia, Asia and the Pacific. It specializes in helicopter support for the precision construction, mining and oil and gas industries, conducting both general visual and instrument flight rule operations. The company also provides charter services.
Heli Niugini is based on Papua New Guinea’s main island of New Guinea, which the country shares with Indonesia. An unbroken chain of mountains with peaks above 13,000 feet dominates the topography. Papua New Guinea’s highest peak, Mount Wilhelm, rises to 14,793 feet. In addition to those elevations, much of the country is covered by tropical rain forest. Year-round, temperatures in the capital of Port Moresby, on the southern coast of the main island, hover around 27 degrees Celsius. Humidity averages 80 percent at Heli Niugini’s main base at Madang, on that island’s northern coast.
All of which is to say Heli Niugini’s operating environment is among the toughest for helicopters. The experience of flying 12,000 hours a year in that environment, with a mixed fleet that includes the Bell 407, has made the operator’s staff severe skeptics of helicopter performance claims. When at May 2016’s Rotortech trade show in Australia they heard claims of what the Eagle 407HP could do, Heli Niugini executives wanted to see firsthand.
Shortly after the show, Eagle Australasia flew the Eagle 407HP to Papua New Guinea for trial operations. Privately owned Eagle Australasia is a joint venture set up by Eagle Copters and the Australian company Aero Assist, a long-term partner, to market and provide support to the aircraft.
In the trials, the Eagle 407HP, fitted with mission-specific equipment, replaced a standard Bell 407 on a drilling exploration contract. Among other work, it lifted various internal and external loads at around 6,500 feet (density altitude 8,000 feet). The 407HP showed it could launch with more fuel and loads similar to a 407, lift and move heavier parts of the drill rig reducing the need for disassembly, and land with a heavier internal load enabling it to complete a food resupply in one trip instead of two.
The trials also included testing on the 10,993-foot Mount Otto, which has a communication tower on it. Heli Niugini transports 420-gallon drums of diesel to the summit to keep the tower’s generator running. An experienced Heli Niugini 407 pilot calculated that on the day of the test, with the density altitude at 13,000 feet at the peak, the 407HP could have lifted four drums of diesel. With the drums, long line and cargo hook, that would be a load of 1,760 pounds. The standard 407 would lift only two drums under those conditions.
The trials proved the 407HP’s hot-and-high performance, demonstrating that it can outlift a Bell 212 above 8,000 ft., said Eagle Australasia CEO Grant Boyter,
The Eagle 407HP is torque-limited to around 10,500 feet, compared to around 3,500 feet on a standard Bell 407 in Papua New Guinea. That is one of many factors that make the 407HP a game changer. Heli Niugini officials said they are excited about now being able to bid for jobs at altitude that in the past have been done mostly been done by Bell 212s, standard 205A1s and Airbus SA315 Lamas.
Testament to the game-changing nature was Heli Niugini’s decision after the trials to lease that 407HP and to convert one of its standard 407s to the HP configuration. Eagle Australasia completed that conversion, with support from three Eagle Copter mechanics, in April 2017, on budget, and right on the six-week schedule.
With Honeywell's powerful, efficient and reliable HTS900, Eagle Copters’ 407HP upgrade turns a workhorse single-engine helicopter into a true hot-and-high performer with capabilities that outmatch competitors and, in some cases, surpassed those of bigger, twin-engine rotorcraft. The upgrade also gives 407HP operators added safety margin, reduced operating costs and the ability to execute missions longer and more effectively.
The 407HP provides the best possible performance, highest efficiency and lowest maintenance costs for the Bell 407. Experience the 407’s full potential powered by the HTS900 engine. Contact Eagle Copters or Honeywell today to learn more about the 407HP conversion.