What are the trade-offs between hydraulic and electric steering actuators for aircraft?

Hydraulic actuators are a more simple system, hydraulic in and out. The trouble shooting skills that go along with this kind of system is beginner troubleshooting

Hydraulic actuators offer raw power for heavy aircraft but require complex plumbing and maintenance. Electric actuators are lighter, simpler, and more efficient, but may lack muscle for the biggest planes.

Electric motors will lack torque. In the event of a hydraulic failure most systems will have a way of diverting either left or right system to at least have a reduced operation. Anyone intimidated troubleshooting hydraulic systems just needs to learn the flow. High flow causes heat. You can use a metal extension or tool and listen to the lines to see which lines are indeed flowing. Complexity of hydraulic NWS is the integration with electrical systems such as weight on wheels, and position transducers for the rig. Servicing is still required for the overall hydraulic systems. The type of actuator used will not reduce this the struts are the only thing that should receive custom servicing. The overall hydro is serviced as a whole system.

Electric actuators can offer lower weight, lower noise, and lower maintenance costs than hydraulic actuators. They are also easier to integrate with digital control systems and sensors.

The steering system doesn’t matter much of the availability or quality of the power source, because it is using engine power as its source of electricity. It doesn’t care about what is considered “dirty” power from a ground power source. So as long as the generator from at least one engine is running then it has a source of “clean” electricity. The issue really faced is not knowing it doesn’t work until trying to taxi away. Loose wire bad or dirty sensors could be time consuming to troubleshoot where the simple hydraulic system is it is leaking or it is not. If it’s not then typically it is working as it’s supposed too.

Arguably John, the electric steering system heavily depends upon the availability and quality of power. Without it, it simply will not work. With reduced quality, the actuator will not perform as required. Regardless of where the power is drawn, it needs to be available and of a suitable quality.

Here is the easiest way to explain why hydraulic is safer than electric. Anyone with electrical troubleshooting background should know that a voltage drop is likely a cause of a component not working at all. Example position light that requires 28 VDC is only seeing 22 VDC. It is not going to work because there will not be enough current flowing with the poor connection. Hydro on the other hand can still function with reduced capabilities in the event of a failure. A 30GPM system will still function slowly with 15GPM. Electricity will not act the same way as fluid in this case.

I have conducted a feasibility study where all actuation is done using Electromechanical Actuators (EMA). My conclusion was, for this to work, we need a clean sheet design unlike most studies that focus on retrofitting traditional aircraft. What is needed is: • New fuel efficient engines that solely produce high voltage DC for the aircraft, no bleed air or hydraulics. • Smart Integrated EMAs (Motor, Screw, Inverters and control electronics in one unit). • Redundant DC power networks for all avionics • Passive Optical Networks to replace nearly all copper in the data networks. • Integrated avionics that integrate all functions into multiple redundant “servers” that host avionics software. This could be decades away or may never happen.

Electric steering also known as "Fly-By-Wire" systems are more advantages than hydraulic because they offer precision control and monitoring, lower maintenance , eco-friendly , easily integrated into digital and smart control systems. They are also less complex in nature and more energy-efficient because they only consume power when in motion or adjusting position.They offer enhanced safety , weight reduction and flexibility in design. With all the industries currently trending towards sustainability, it is imperative that the aircraft systems also adapt accordingly and offer greener and intelligent solutions by leveraging all the technology available. Most of the latest fleet of Airbus and Boeing have adapted the fly by wire concept.

Hydraulic systems naturally dissipate heat through the hydraulic fluid, which helps maintain system stability during prolonged use. In contrast, electric actuators generate heat through their motors & electronic components, requiring careful thermal management. In one case, where electric actuators were used in flight control systems, we encountered overheating issues during extended operations at high loads. We had to introduce additional cooling mechanisms, such as heat sinks & airflow management, which added weight & complexity to the system. This demonstrates the trade-off between the simpler cooling of hydraulic systems & the more complex thermal management needed for electric actuators in high-demand environments.

Electric steering is the way forward in aircraft systems. The main reason being precision control and monitoring (real time control and feedback), less complex design structures, lower maintenance effort, redundancy, enhanced safety , optimal performance and stability. In addition , it also easily integrates with other aircraft systems offering enhanced features such as autopilot, flight envelope protection, and automated landing systems.