Aircraft Certification
Certification basically says that the aircraft is safe to fly in so far that it has been designed in conformance with the required standards, e.g., British Civil Airworthiness Regulations, Section A for the aircraft in general, RTCA DO-178a,b,c for the aircraft’s software and DO-297 for the Distributed IMA fly-by-wire system. It also has to be flown by a certification authority test pilot to ensure that there are no ‘nasties’ in the way it is controlled and behaves in the air. Similar strictures are applied to how the aircraft is manufactured and maintained.
For the helicopter and all other VTOL aircraft, a key issue is how the aircraft gets safely to the ground in the event of a total power or flight control system failure. The Autocopter, being essentially a helicopter, can go into autorotation in the event of a power failure, and into an almost manual flight control mode (called the Primary Mode) in the event of a total FBW failure. Multi-rotor machines, e.g. the Joby, generally cannot autorotate but could use their wing if in high-speed flight. Clearly, this would not be possible in the hover or at low forward speed so something else would have to be proposed. This would be a major certification issue in the UK as power systems most frequently fail during a near-to-max-power take-off or landing.
Furthermore, because multi-rotor aircraft generate all their lift at some considerable distance from the aircraft’s centre of gravity (CG), multi-rotors must in some failure states be prone to generating high levels of asymmetric lift when a power or flight control failure of a particular type occurs. This will make the aircraft more difficult, even very difficult, to handle and so less safe. This also would be a certification issue in the UK.
At the risk of appearing unduly biased in this matter, the Autocopter’s main rotor can autorotate and at all times its lift is directed through the aircraft’s CG to within a very small distance, any distance being due mainly to shifts in the CG caused by movements in the payload, usage of fuel etc. The moment effects of these movements are then trimmed out by the flight controller. Because the Autocopter is more ‘normal’ in this respect, the implication is that it will be easier to certificate.
Modular Certification – Easier Adaption to Change
Certification is one of the most expensive parts of an aircraft’s development, not without reason because of its critical influence on safety. Horizon has however chosen to opt for a modular type of certification because the Autocopter in software terms has about 70-80 separate nodes or global modules, which even with some of the technology in use today would have to be certificated as one – just then think of the cost of modifying one element. The reason for choosing a Distributed IMA flight control system is then to allow for the independent certification of one module. You have to see this in the light of the Autocopter’s requirement for adaptability to technology change, how the use of the aircraft changes and so therefore its future-proofness. Horizon expects the Autocopter to change significantly each and every year as the technology advances. Hydrogen, for example, becomes a more practical fuel or we learn more about how to make the aircraft easier and safer to fly. Each and every one will involve some change In the flight control system that has to be recertificated. IMA Modularity is vital to this.
Certification in a Worldwide Sales Scenario
It is important for an Investor to know that an aircraft being developed and certificated in Country A will automatically be given equal ‘certification rights’ to fly in Country B. For instance, for the Autocopter designed and certificated in the UK, will it be able to fly in the US without going through essentially the same certification process there? The answer is ‘Yes’, and this is because of a bilateral agreement between the CAA in London and the FAA in Washington.
Bilateral agreements and arrangements allow the airworthiness certification of civil aeronautical products to be shared between two countries.
A Bilateral Aviation Safety Agreement (BASA), Memorandum of Understanding (MoU) or Working Arrangement (WA) and their associated implementing procedures provide for technical cooperation between national civil aviation authorities. They help reduce duplication of activity and aim for mutual acceptance of certificates.
In addition to airworthiness certification, BASAs, MoUs and WAs provide for bilateral cooperation across other areas of aviation, including maintenance, flight operations, and environmental certification. The World is covered by a whole web of BASAs between the US, the UK, the EU, Canada, Brazil, Australia, Singapore, Japan and many others.