Test time: certification and the aeronautical revolution

Certify the revolution

Not unlike anything that has flown before, Australian company AMSL Aero predicts that its first tilt-rotor VTOL electric air ambulances Vertiia will fly for Sydney-based EMS operator CareFlight by 2023. Likewise, the Israeli manufacturer Urban Aeronautics recently announced that the US-based EMS operator Hatzolah Air will be the first customer for its CityHawk, a light and compact jet VTOL aircraft that will go into production “within three to five years”, although that it has not yet received FAA certification for EMS use.

Exciting vehicles like these that will occupy the direction of FAA rotorcraft and its international counterparts for years to come. However, for most designers and manufacturers aiming to meet the demands of buyers of airborne special missions, evolution continues to be more important than revolution.

For example, Textron Aviation’s Cessna Citation Longitude, which received FAA certification in 2019, is a direct descendant of the Citation Latitude, which is already in service with EMS operators such as Babcock Scandinavian AirAmbulance, is also in a direct descent line. previous Cessna models. , but with several refinements. For such aircraft, type certification can normally be expected to be a fully transparent process.

The FAA says its flexible certification process allows the agency to deal with new and advanced materials and technologies when companies submit them for certification, without the need for prolonged formal regulation. However, the path to certification of a new type of aircraft is not always easy. The Kopter Group’s experience with the development of its SH09 helicopter is a classic example of how certification issues can become obstacles to bringing a revolutionary product to market.

Kopter, now part of Leonardo, says the SH09 will be the most versatile rotorcraft platform on the market, combining long range and five-hour endurance, with low operating costs. Kopter aims to achieve this by using new composite materials a step further, using the type of monocoque composite airframe that has only been used in small two-seat rotorcraft. The SH09 was scheduled to enter service in 2021, and Kopter previously attributed the delays in the deployment of the SH09 to the complexity of the certification process, saying this highlighted the need to establish new certification guidelines for new materials. hybrids. However, following the acquisition of Kopter by Leonardo and the relocation of primary production to the Vergiate plant in Leonardo, the helicopter will not be ready for the market until the end of 2022 at the earliest.

Cécile Vion-Lanctuit, Kopter Group Marketing, said: “We are not experiencing any certification delays as such. We are strengthening some activities and fine-tuning others to ensure that the SH09 is a mature Leonardo Helicopters product when it hits the market. We are targeting the entry into service of the SH09 by the end of 2022 or the beginning of 2023.

Vertiia VTOL © University of Sydney

This is in part due to design changes to make the SH09 more durable, including a new main rotor head design, a new main gearbox with an extended mast, and the installation of the state-of-the-art Garmin G3000H integrated cockpit that will fly for the first time in a helicopter.

Leonardo also faced delays in the certification of its AW609 tiltrotor machine. Leonardo expected the FAA to certify the long-awaited civilian version of the US Army’s V-22 Osprey in late 2019, but now says he expects operational activities to begin “in about two years. “, although the first two production planes are currently being assembled.

Airbus angle

The Airbus H145 is the latest version of a rotorcraft designed almost 30 years ago, under the name EC145, born from the merger that gave birth to Eurocopter. Since then, along with its sibling the H135, this model has grown into the most popular type of HEMS in service, accounting for up to half of the total HEMS fleet worldwide. Replacing the conventional tail rotor of the EC145 with a ducted rotor and the four-bladed main rotor with a bearingless five-bladed main rotor system, Airbus Innovations aimed to lighten pilot workload and improve operational safety. on HEMS missions ranging from synthetic vision systems to satellite communications and self-learning AI algorithms.

Airbus Helicopters spokesperson Jörg Michel said: “Today helicopters are carrying out more and more missions in difficult circumstances than in the past. This means that more complex systems are on board and must be certified. Despite this, the risk of a longer and more complex certification process and a more demanding test pilot task should not be ruled out. Michel continues: “When introducing new technologies into the design, we have to make sure that the certification rules remain appropriate.

“When we identify a regulatory gap, we should anticipate regulatory activities with authorities as much as possible, to ensure that certification requirements are frozen early enough to design provisions demonstrating compliance at an early stage of regulatory activities. development.”

Failure to anticipate such challenges, explains Michel, can lead to the need for redesigns, additional testing activities, and a longer certification process.

“Continuous evolution is a clear benefit for the new H145 helicopter as we are reusing a proven design and improving the aircraft in areas where we see additional benefits. Certification of an aircraft based on an older one is considered less demanding. It is not necessary to re-certify the complete aircraft but only the modified systems and associated affected areas. This reduces the range compared to a complete new aircraft. The compliance documents can be partly reused with adaptations.

Advances in information technology have helped manufacturers keep pace with more demanding certification processes, says Michel: “IT provides our teams with additional data for evaluation and analysis. The emphasis on safety has increased and the requirements and justifications for these requirements have become more stringent over the past 30 years. “

A US Army mechanic maintains a CH47 Chinook helicopter engine © United States National Archives

The test pilot is the key

Where do test pilots fit into the certification process? At the start of the jet age, flying aces like Chuck Yeager – the first man to fly faster than sound – were the glamorous boys of aviation development. Today, the task of the test pilot is less risky, but no less central in the certification process.

“Flight tests often consist of verifying the modeling and analysis of the engineering work carried out during the design phase,” explains Vion-Lanctuit. “The results are expected but still require flight tests to prove the data. “

However, she says, the introduction of increasingly complex systems into modern cockpits has led to a shift in focus in the testing process. “Helicopter handling skills are and always will be a major area of ​​the test pilot’s job, but increasingly it is the systems that require the most attention. The success of these depends on a good understanding of the role of the aircraft by the equipment manufacturer (OEM) and the test pilot is the key to this understanding at all stages of development.

Michel is also dedicated to the role of the test pilot: “The test pilot is an essential part of the entire development cycle before certification. Despite advances in computer modeling and automated data collection, nothing can replace human contact, says Alexander Heuhaus, Airbus Helicopters test pilot. “A test pilot must assess the aircraft, procedures, equipment regarding associated workload, intuitiveness, misleading indications, level of comfort, etc. These evaluations are rather subjective and require a lot of experience, so human test pilots will always be needed in the future. Experience is required not only in operations, but also in a wide variety of different aircraft in order to be able to properly assess new aircraft, systems, procedures or equipment.

“As a test pilot, you keep in mind the operational roots of what a pilot is looking for. Test flight certainly requires a level of experience and skill, ”says Mark Burnand, chief test pilot at Leonardo Helicopters. “You must be able to understand the role of the helicopter and the environments in which it will be operated, and have the ability, under certain difficult conditions, to assess the performance of the aircraft, and also to examine your own load. of work. You then decide whether the characteristics of the aircraft will allow a less experienced pilot to perform the task safely.

“Leonardo Helicopter test pilots come from a wide variety of applications. Many of us have engineering qualifications and certainly the inquisitive nature of engineers brings added value of interest. Then comes the obvious pleasure of flying great planes around the world and the challenges and rewards that this brings, ”said Burnard.

Like Heuhaus, Burnard believes that artificial intelligence is not yet able to oust human pilots. “Human beings have phenomenal sensors and processing powers that are difficult to replicate and free. When it comes to test flying, we already use a lot of technology to help us. For example, if the software has a problem or the plane decides to throw a curve ball at us, we always have the option for the test pilot to deselect the systems and use their experience and skills to recover the plane. We can then safely bring it back to base, debrief and work with engineers to incorporate changes that ultimately ensure a safe and efficient aircraft. So yes, the seat of the flying pants is still mandatory.

Airplanes, especially fixed wings and rotorcraft designed for EMS missions, are becoming increasingly complex creations. The certification of new types is also increasingly complex and sophisticated, but the human test pilot is still at the heart of this process.

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