We all know it’s not just about engine capacity. The advantages and expense of twin-engine rotorcraft over single-engine are well recognized, and twin-engine rotorcraft such as the Airbus H135, Bell 429, and Leonardo AW169 among others are mainstays in SAR and HEMS operations. But the shift has occurred more recently than you may think, and pilot experience and training, budgetary considerations, and differing regulations across the world mean, for some operators, making the switch from single- to twin-engine aircraft may require considerable forethought.

Regional differences often dictate whether one or two engines are more popular

Twin-engine aircraft have a ubiquitous presence in the air medical sector, but it would be disingenuous to suggest that that presence is universal. A Leonardo spokesperson told AirMed&Rescue: “HEMS is very fragmented around the globe. Some countries including the US, Australia, and much of Europe have deployed [air medical] services for years while other countries are historically totally lacking. Due to the current Covid-19 outbreak, many are just now evaluating air medical in support to the national healthcare system. These are more oriented towards small platforms, i.e. single-engine, just to limit the initial investment while developing the overall system and infrastructures required.”

Chris Emerson, then-President of Airbus Helicopters, remarked on the anticipated growth of twin-engine sales, citing changes in the air medical industry along with the growing needs of patients. In comments to AIN Online, Emerson stated: “I think you are going to see a pickup on the twins. Over the last four years in air medical, we have sold more twins than singles.

“The needs of the population are changing. The demographics are such that helicopters need to do more. The famous air medical golden hour has given way with the need to get the emergency care onboard immediately. It’s getting the equipment and the medical know-how on the helicopter to provide the service immediately, not in the golden hour. An H145 is now a flying hospital.”

Sounds familiar. But these comments were made in 2018. Come 2021, and Airbus’ comments, through a spokesperson to AirMed&Rescue, are much more reserved: “From our perspective, it depends on a variety of factors whether an operator chooses a single or a twin-engine helicopter including mission types, geography, and regulations among others. In some regions, like in Europe, a twin-engine helicopter is required by regulations.”

Don’t read too much into it that professional prudence. AirMed&Rescue doesn’t think it is reflective of some apprehension. Especially as Leonardo was effusive about the prominence of twin-engines in mature markets: “While Europe is mandatorily asking for twin-engine platforms, a large market such as the US is accepting both motorizations. In such contest, four main points that may undisputedly be accounted in favor of twin-engine motorizations are safety, performance, kit availability, and, last but not least, cabin size.

“In the US, despite not being mandated by the government, many organizations such as hospitals require the helicopter operator to utilize twin-engine aircraft just for safety benefits (i.e. capability to grant a safe landing or safely continue the mission even in case of one engine inoperative).”

Moving from single to twin-engine isn’t too much of a learning curve for pilots

Most pilots receive their training in single-engine rotorcraft, a time colloquially referred to as flying hands-on. However, Leonardo was keen to avoid overemphasizing the adjustments needed in making the switch to twin-engine: “Generally, the largest differences from the pilot perspective is related to emergency procedures, which are quite different among the two different motorizations. HEMS is a very demanding environment for a pilot as, especially for primary missions, the operational site varies from mission to mission. Twin-engine machines mean larger cabins, hence a larger helicopter footprint on the ground.

“These differences can be pared through appropriate training plans. Several different aids are available to reduce the pilot workload along landing and takeoff maneuvers and to help pilots familiarize themselves with all these features and increased avionics complexity. Full flight simulators represent the perfect tailored solution to accompany pilots during their transition from single to twin-engines. This is true not only for the initial type rating, but also for frequent training to keep skills and system knowledge readily available.”

Twin-engine helicopters are almost invariably equipped with more sophisticated avionics and feature larger cabins to house a more diverse suite of medical equipment, enabling them to provide more flexibility in supporting a greater variety of missions. But pilots looking to make the switch from single- to twin-engine rotorcraft not only need to consider the increase in size but also the greater array of information delivered through additional avionics.

Leonardo highlighted its Obstacle Proximity Lidar System – a system not unlike parking aids on a car – that can increase the pilot’s situational awareness while operating in proximity of obstacles, cliffs, or trees: “This system works with the same philosophy of the parking aids, a laser system that provides immediate information to the pilot upon the distance between the helicopters’ main rotor disk border and obstacles nearby. This unique feature also grants more safety to operations by reducing the pilot workload during approach to a HEMS operational site.”

Additionally, Leonardo was also keen to stress that it is not just the pilot that needs to be familiar with the differences in aircraft: “The medical crew should be trained with the larger cabin and increased medical capabilities. It is fundamental that a proper training inclusive of cockpit and cabin occupants be considered. HEMS operations are performed by a team of different professionalism and proper co-ordination, especially during emergency procedures, is mandatory, such as using medical simulation combined with aviation simulation to create a more realistic total experience for the entire team.”

Two engines provide a welcome safety net for operators

RACQ LifeFlight Rescue, based in Queensland, Australia, transitioned from single- to multi-engine rotorcraft around 10 years ago. Brian Guthrie, Director of Helicopter Operations, commented: “Although it was a contractual requirement introduced by Queensland Health at the time, LifeFlight was already moving toward the transition, in line with other Australian HEMS providers.

“The idea behind the shift was, and remains, that a twin-engine machine is safer and offers greater options to our pilots, should an engine fail. Thankfully, LifeFlight has never reported an incident involving an engine failure but having that safety net, which protects our crews and the community, is important to our trusted aeromedical rescue service.”

LifeFlight maintains a nine-strong twin-engine fleet: six Leonardo AW169s, two Bell 412, and an MBB/Kawasaki BK117 helicopter positioned around its nine bases across Queensland. As Australia’s second-largest state, with an area of 1,727,000 square kilometres, there were more considerations on aircraft capabilities that twin-engines could provide. Guthrie continued: “Our helicopter bases are situated across Queensland, with the aircraft and crews covering a wide expanse of this far-reaching state. Twin-engine aircraft enable our rescue teams to carry two patients, should the need arise. The larger aircraft can carry more fuel than a single-engine, which means greater range and faster outcomes for the patient, who is seriously ill or injured.”

Single-engine helicopters can still be employed elsewhere

Despite a decade since the switch, Guthrie stated that there remains some use for single-engines: “RACQ LifeFlight Rescue still operates a single-engine AS350 helicopter, for training and education purposes only.”

Leonardo also iterated its commitment to single-engine aircraft, having achieved the ‘first full IFR certification from the FAA for a single-engine aircraft in decades with the AW119Kx featuring a Genesys Aerosystems core avionics’, which Leonardo claims has already received orders in the US EMS market.

Leonardo continued: “With an IFR AW119, Leonardo is able to meet the requirements of operators which want to keep single-engine economics while accessing unprecedented IFR capabilities, adding one more option to the traditional VFR single- and twin-engine capabilities.”