Putting it on the line: Koala proves its salt at Life Flight

 - May 29, 2008, 9:53 AM

For the helicopter owner, operator or flight program looking to cut costs while simultaneously maintaining or expanding existing levels of service, Agusta’s A119 Koala may be the answer. Certified in 1999, the single-engine Koala has many of the same capabilities of, and in fact is faster than, most light twins. While the A119 is certainly not the cheapest single-engine helicopter on the market (priced at $2.25 million equipped), the fact that the Koala can do the same job as twin-engine ships costing twice as much makes it a relative bargain.

In creating the Koala, the engineers at Agusta essentially took the popular twin-engine A109E, replaced its two Pratt & Whitney Canada W206C engines with a venerable PT6B turboshaft (in this case a beefy PT6B-37A) and attached skids in place of the retractable landing gear. What resulted is a high-speed, high-performance multipurpose helicopter capable of carrying a pilot and seven passengers.

Because the interior cabin size exactly matches that of the A109E, the Koala can easily be adapted to corporate aviation, EMS, law enforcement, external loads and a host of other missions and equipment previously engineered and certified for the A109E. Configured for EMS, the aircraft can handle a broad range of complex aeromed missions, accommodating two stretcher patients, and carrying the equipment needed for on-site cardiac care, as well as isolettes for transporting newborns.

The A119’s PT6B-37A engine produces 1,007 shp at sea level, delivering that power to a transmission capable of receiving 900 shp. One nice feature of the installation is that the reduction gearbox is at the rear of the engine and extends downwards.

The one-way sprag clutch for the main driveshaft is contained in the reduction gearbox, allowing driveshafts to run forward to the main transmission and aft to the tail-rotor gearbox. This design negates the need for any type of combining gearbox or clutch on the transmission, reducing weight and making the whole installation much easier to maintain.

The fuel metering system on the PT6 permits fuel-flow control three ways. In normal operation an electronic engine control (EEC) maintains rpm with very little transient movement during collective changes. Should the electronic system fail, a backup mechanical governor with full droop compensation picks up the load so smoothly that the only noticeable indication to the pilot should be the eec fail caution light. In the extremely unusual circumstance that both an electronic and mechanical governor should fail, the pilot still has a backup in the manual throttle. The manual mode is easy to use, however, making this emergency not that critical.

The A119’s main rotor system is similar to that of the A109E, using elastomeric bearings in the blade grips and self-contained viscous lead-lag dampers. However, the Koala’s blade grips are shorter than the A109E’s. Rotor diameter was reduced to 35.5 ft, the weight of the rotor head was reduced and forward speed was enhanced.

The only drawback to the lighter head is that it results in a lower inertia during autorotation, so rotor rpm must be conserved until the very bottom for cushioning. This is not a significant problem, however, because while rpm can degrade quickly with the collective up, it also recovers just as quickly as soon as the collective is lowered.

The rest of the Koala’s systems rely heavily on proven Agusta technology. One established feature of all Agustas is the dual-channel autopilot system. Although the Koala does not currently incorporate the flight director, the pilot still retains the choice of either having attitude hold or stability augmentation via the SAS. Since the autopilot computers, gyros and actuators are the same as those found on most IFR twins, it will be a relatively simple operation to add the flight director as the aircraft moves toward single-pilot IFR certification.

Proof Is in the Performance

At sea level the aircraft is a horse. During factory school training in Philadelphia with Agusta’s chief pilot, Larry Graves, I had the opportunity to experience unbelievable performance from this muscular single. Due to conflicting traffic at Northeast Philadelphia Airport, we were restricted to using about one-third of a runway next to the tower for 180-deg autorotation training.

At a temperature of 32 deg C, engine torque and temperature were both reaching the top of their respective green arcs at about the same time. By keeping the limitations in the green, and not even using allowable takeoff transient limits, I was able to maintain a 3,000-fpm rate of climb in the turn while setting up for the autorotations.

Speed comes hand-in-hand with all that power, and speed is one of the strengths of the Koala. At a cruise speed with a reasonable fuel burn of 400 pph, a true airspeed in excess of 140 kt straight and level can be expected. With a full tank of fuel in the mains, this provides about 2.6 hr to burnout at better than 140 kt.

From my experience, this airspeed holds true in a wide range of temperatures and altitudes. For example, at 6,500 ft indicated altitude, 9 deg C OAT, 82 percent torque (TQ), 740 deg inlet turbine temperature (ITT) and 132 kias, the true airspeed (TAS) is 147 kt.

At the same altitude with a higher OAT of 18 deg C and a slightly lower ITT of 720 deg and torque of only 74 percent, the TAS remains high at 143 kt. The Koala’s high-speed cruise is a surprising pleasure. On a recent training flight at 5,000 ft and 20 deg C, with 94-percent torque and ITT at the top of the green, we were clocking 142 kias but the true airspeed was a blistering 156 kt straight and level.

A common misconception among some pilots is that autorotation in the Koala is pretty extreme due to its lower-inertia rotor head. I have had the opportunity to train in density altitudes ranging from sea level to more than 7,000 ft, and the aircraft is very predictable in all of these conditions.

Vertical speed is generally around 1,800 fpm steady state, and the aircraft is extremely maneuverable throughout the autorotation. To demonstrate the rpm recovery time during training, I retarded the throttle with the collective up at cruise speed. Simulating a long reaction time, we let the rotor rpm bleed down from 100 percent to the minimum of 90 percent before lowering the collective. By lowering the collective and raising the nose just a bit, it is amazing how quickly the rpm recovers and snaps back into the green. In fact, since the aircraft is so fast, any autorotation from cruise speed allows an extended glide while slowing back to the recommended 60 kt.

On the Line in Boise

The launch customer for the aeromedical version of the Koala is Saint Alphonsus Life Flight in Boise, Idaho. The program consists of three bases, two in Boise and one 125 mi southeast in Twin Falls. It operates a wide range of aircraft, currently a Bell 222 and 206, a Piper Cheyenne III and the A119. CJ Systems Aviation of Pittsburgh is the Part 135 certificate holder and provides Life Flight with pilots, mechanics and backup support aircraft.

Life Flight began transporting patients in 1986, and over the past 15 years has transported some 14,000 patients by air. The program covers 150,000 sq mi of diverse terrain ranging from hot-and-high desert conditions to cold-weather mountain flying. All in all, it is demanding environment to try out a new aircraft.

According to Chris Marselle, Saint Alphonsus’ program director, the Koala was selected for the remote base at Twin Falls for several reasons. “We had limited funds for this base and the Koala fit the bill with performance, cardiac balloon-pump capability and two-patient medical interior. It had good cost effectiveness with its purchase price and operating costs. We also believed that Agusta would support us and the aircraft.”

Change is difficult for any flight program, and Life Flight is no different. When asked how the medical crew has adjusted to the Koala, Ken Sheldon, Life Flight’s program manager, is quite frank. “That depends on which ones you speak to. Most like the new ship. However, there is a small contingent of staff, the more tenured ones, who feel that a single-engine aircraft is not as safe as a twin-engine aircraft. Additionally, they had limited involvement in aircraft selection for strategic hospital reasons, which did not help the situation either. Overall they like the aircraft, and if we can address their issues everything will work out for the better.”

Bill Patterson, aviation site manager for CJ Systems Aviation, the Part 135 certificate holder for Saint Alphonsus Life Flight, said that although the pilots really like flying the Koala, they have noted several areas that need improvement. The first ships off the assembly line did not have glareshields on the instrument panel, creating a hazard at night. These glareshields are now standard. The rotor brake had not been certified at delivery, but will soon be retrofitted on site. The oxygen system also lacks sufficient volume for long flights with two patients, but Life Flight is looking at several alternatives with higher volume.

The biggest anomaly noted by the pilots concerns engine torque. For some reason the aircraft will pull a lot more torque going straight up than in level flight. For example, if the aircraft pulls 90 percent torque on a maximum-performance takeoff, the torque will drop off to about 85 percent as the aircraft transitions into forward flight while the pilot maintains the same ITT with collective. This is the opposite of most aircraft, which have more of a temperature or torque problem going straight up than forward. Even though the torque drops off in level flight, I personally prefer having more torque available going straight up out of the hole from a confined area.

A True Test

Due to a recent contract change, I had the opportunity to fly the Koala on the line for 10 days at the Twin Falls site. An interesting test of the capabilities of the Koala occurred one afternoon involving a patient transport from Sun Valley to Boise. The three-leg trip involved departing from Twin Falls northbound to Sun Valley, flying the patient westbound to Saint Alphonsus hospital in Boise and then returning southeast to Twin Falls. On the westbound leg between Sun Valley and Boise I flew direct over the Trinity Mountains, which top out at more than 10,000 ft. During the flight we happened to see tendrils of smoke drifting upwards from some controlled forest fire burns to our south, located more in the foothills at 6,000 to 7,000 ft. We remarked on the burns, because at our altitude the smoke was creating a minor restriction to visibility, especially heading into the setting sun.

After delivering the patient to St. Alphonsus, I topped off the tanks and headed to Twin Falls, a roughly 40-min flight in the dark. Now being a flat-lander and strict adherent to FAR 135.207, I had already briefed the crew that I do not fly backcountry without good visual reference and lights on the ground. So we took the highway southeast back to Twin Falls. Anyone who has flown in the high desert of the American west knows that it gets very dark in between towns, and there are not a lot of airports with which to flight follow. For that reason I was still monitoring Boise Approach Control even though we were 55 nm away by the time we heard of
the distress call.

The medical crew and I did not actually hear the distress call, but we heard Boise approach relaying the distress call to a pair of A-10s that the controller was vectoring toward the scene of a downed aircraft. We overheard that a single-engine aircraft had reported a loss of engine power somewhere back in the mountains. The last report from the pilot indicated that he was heading toward the light from the controlled burns that we had seen earlier in the afternoon.

The last reported location before he dropped off radar was 30 mi east of Boise, or only about 25 mi from our position. I called approach control, informed them of our position, indicated that we had a medical crew on board and offered our services.

My original intent was only to assist the A-10s in looking for the signal flares that would indicate if anyone survived the landing. There was no moon, so we took up an orbit at 10,000 ft above the fires, at least 3,000 ft above the foothills below and keeping the valley lights to our south in sight. As we flew over the valley below, it became apparent that we would not be able to see anything from that altitude. A ground-level search in the dark was out of the question, but the controlled burn of the grass and sagebrush below us illuminated the valley floor. We decided to make an approach to the lit area and make one sweep before heading home.

The Life Flight program uses night vision goggles as an aid to vision for the medical crewmember in the copilot seat only. On the pilot side, the aircraft is equipped with an SX-5 searchlight. With the flight paramedic wearing goggles and providing clearance on the left side, and the SX-5 on the right used by the flight nurse in back and myself, we descended to 500 ft above the valley floor.

The A-10s agreed to remain on station above us and provide a radio relay to Center. In spite of the illumination provided by the fire line and the SX-5, it became obvious that we were not going to find anything. We prepared to head home and return in the morning for a more complete search.

A mile down the valley and slightly above us were two smaller burns, and thinking that could have been started by the downed aircraft, we decided to check them out before returning to base. Investigating the area near the burns, we found the wreckage. We radioed the location and then landed nearby.

It became apparent that nobody had survived the accident. Fire department and rescue personnel took some time to find us, time we used to look around the wreckage. Flashlights and maps were strewn about, the pilots obviously looking for the nearest airstrip. The worst thing was sitting in the pitch dark waiting for the first responders to relieve us, and listening to the cellphone of one of the deceased pilots ringing–probably a friend or loved one, worried because of the overdue status.

The irony of the situation was not lost on the three of us. A single-engine helicopter at the scene of a single-engine aircraft crash. Did it bother me? Not a bit. Compared with the other leading hazards associated with aviation, flight into inadvertent IMC and high-speed impact with terrain during cruise flight, engine failure ranks way down on my personal list of things to be worried about. And as I pointed out to the crew, the biggest threat to a single-engine aircraft is fuel starvation, the same as it is for twin-engine aircraft.

The Koala performed admirably during the whole operation. Once we had been released from the scene by local law enforcement, we prepared for departure. The scene was at about 6,000 ft msl, and I wanted to get back up to 10,000 ft as quickly as possible. With many other underpowered aircraft, this would involve a climbing racetrack pattern over the scene until reaching altitude. We had a clear departure path up the valley, so with a maximum-performance takeoff and 85 percent torque at 60 kt, I was able to maintain an extremely high rate of climb of 2,000 fpm up to 10,000 ft.

Perhaps the most important consideration when selecting a new aircraft is the ability of the machine to keep pace with program changes and growth. When asked about the potential of the Koala to keep up with Life Flight in the future, Marselle has no reservations: “We believe that the aircraft will be solid in a cost-effective competitive marketplace.”

Until going through the Agusta factory school for the Koala, I had not flown a single-engine helicopter since 1984. After 17 years of flying twins, I was not too excited about the prospect of going back to a single. One flight was all it took to make me a convert, and after flying the aircraft both during training and aero med missions it has become apparent that this aircraft has a future. The Koala has a place, not only in program expansions requiring the purchase of new aircraft, but also in replacing aging and sometimes underpowered twin-engine ships.