The Boeing 787 Dreamliner is widely described as a “more-electric” aircraft, but one of the clearest examples is below the wing rather than inside the cabin or cockpit: its main-wheel brakes use electrical actuation instead of the conventional hydraulic brake-actuation architecture used on many earlier commercial airliners. Safran Landing Systems, which supplies the 787 electric braking system, states that the 787 was the first commercial aircraft equipped with this electric-brake technology. Safran describes the system as replacing conventional hydraulic braking equipment with electronic control units and replacing hydraulic brake pistons with electromechanical actuators. [1] [2]
That does not mean the 787 has eliminated hydraulics from the aircraft. Boeing’s own airport-planning documentation describes the Dreamliner as having a more-electric design and specifically notes that several functions traditionally associated with pneumatic power are electrically powered, including engine starting, cabin air conditioning and wing anti-ice. The brake system represents a separate electrification step: the command and physical clamping action at the main-wheel brakes are provided through electrical control and electromechanical actuation rather than a central hydraulic pressure line dedicated to brake application. [3] [2]
What an aircraft brake actually has to do
An airliner wheel brake converts the aircraft’s kinetic energy into heat by creating friction within the brake assembly. On a carbon brake, multiple carbon friction discs are compressed together during braking. The fundamental job is the same whether the force squeezing the brake stack is generated hydraulically or electromechanically: the brake must develop controlled frictional torque at the wheel while remaining compatible with anti-skid control, commanded deceleration and the thermal limits of the assembly. The significant change on the 787 is therefore not the basic physics of friction braking, but how the commanded clamping force is produced and controlled. Safran identifies its 787 product as an electric carbon-brake system and states that electromechanical actuators replace the hydraulic pistons used in a conventional arrangement. [2]
In a traditional hydraulically actuated wheel-brake system, a control system meters hydraulic pressure to brake pistons. Those pistons apply axial force to the friction stack. The 787 changes that actuation chain. Safran says electrical wiring connects the actuators to electronic control units, which in turn connect to the aircraft electrical system. The supplier characterises this as a “plug and play” architecture because traditional hydraulic lines for brake actuation are replaced by electrical connections. The wording “plug and play” is Safran’s manufacturer description, not a claim that installation or maintenance is literally effortless. [2]
From a brake command to electromechanical force
Safran identifies the Boeing 787 system as using Electrical Brake Actuation Controllers, or EBACs, together with electric brake actuators. The EBAC is part of the electronic layer that manages the demanded brake action, while the actuators at the wheel convert electrical energy into mechanical movement and force. Safran’s description makes the core architecture explicit: electronic control units replace conventional hydraulic control equipment, and electromechanical actuators replace the hydraulic pistons that would otherwise compress the brake. [4] [2]
The FAA’s Boeing 787 Master Minimum Equipment List provides useful regulatory evidence of that architecture. In its landing-gear section, the FAA identifies eight installed wheel-brake systems and 32 installed electric brake actuator systems. The MMEL permits specified dispatch relief under defined conditions, including one inoperative actuator per wheel in certain circumstances, provided the inoperative actuator is deactivated, the remaining brake systems meet the stated conditions and the required performance adjustments are applied. An MMEL is not a system-description manual, but these entries independently confirm that the certified 787 brake installation uses multiple electric actuators distributed across the wheel brakes rather than a single actuator per aircraft or wheel. [5]
The arithmetic in the FAA MMEL is informative without requiring assumptions about proprietary internal design: 32 actuator systems across eight wheel-brake systems corresponds to four installed electric actuator systems per wheel brake. That relationship follows directly from the FAA-listed installed quantities. It should not, however, be extended into unsupported claims about actuator force, motor rating, gear ratio or individual control logic; those values require approved Boeing or Safran technical data that are not established by the public MMEL. [5]
Why four actuators per wheel matter
The FAA dispatch provisions show that the brake system is designed with actuator-level redundancy rather than relying on a single electromechanical device for each wheel. The MMEL states that one electric brake actuator system per wheel may be inoperative under the listed conditions, while the remaining wheel-brake systems on the associated truck must not be deactivated and appropriate performance adjustments must be made. This does not mean an operator may ignore a failed actuator: MMEL dispatch is a controlled regulatory process involving maintenance action, operational procedures, time limitations and performance accounting. [5]
The same MMEL section separately addresses an inoperative wheel-brake system. It lists eight installed wheel-brake systems and allows specified relief for one brake on one main-landing-gear wheel per truck under stated conditions, including deactivation, confirmation that the remaining electric brake actuator systems on the associated truck operate normally, and application of the appropriate performance adjustment. This distinction between a complete wheel-brake system and an individual electric brake actuator system demonstrates that the 787 braking architecture has multiple levels of functional segmentation. [5]
Electrical braking does not remove anti-skid logic
Changing the actuator power source does not remove the need to regulate wheel slip. Aircraft anti-skid systems exist to prevent excessive wheel slip and tyre skidding during braking. In an electrically actuated brake, electronic control can command the electromechanical actuators according to the braking demand and the system’s control logic. Safran specifically presents the 787 installation as an electronically controlled electric-brake system, but its public product pages do not disclose the full certified anti-skid algorithms. Those algorithms, sensor thresholds and fault responses should therefore not be inferred from generic automotive or industrial electric-brake systems. [1] [2]
Certification also matters. EASA’s current Boeing 787 Type Certificate Data Sheet identifies the 787 as a CS-25 large aeroplane type under EASA.IM.A.115 and records the applicable certification basis. EASA originally certificated the 787-8 in August 2011 after Boeing demonstrated compliance with the applicable airworthiness and environmental requirements. The existence of an unconventional electric-brake architecture therefore does not exempt the system from large-aircraft certification requirements; it is part of the certified aircraft design. [6] [7]
The carbon brake remains the heat sink
Electric actuation should not be confused with regenerative braking. The 787’s electric wheel brakes are carbon friction brakes. They do not recover the aircraft’s landing energy into the electrical system in the way an electric road vehicle can use regenerative motor braking. Safran describes the system as electric carbon brakes: the “electric” part is principally the actuation and control architecture, while the kinetic energy removed from the aircraft during wheel braking is still dissipated through friction and stored temporarily as heat in the brake assembly. [1]
This distinction also explains why brake temperature, carbon-disc condition and wear remain operationally important. Electrifying the actuator does not eliminate friction material. Safran states that its 787 system incorporates real-time assessment of carbon-disc wear and can transmit that information to the cockpit. The supplier also says the brake has a specific anti-oxidation coating intended to extend service life and provide protection against de-icing products. Those durability benefits are manufacturer claims about Safran’s product; the confirmed architectural fact is that wear-monitoring information is integrated into the electric-brake system. [1]
Built-in wear information changes maintenance visibility
Traditional brake wear can be assessed using physical wear indicators and scheduled inspection methods. Safran says the 787 electric brake adds continuous, real-time measurement of carbon-disc wear, with the reading made available to the flight deck. An electrically actuated and electronically controlled brake naturally creates an opportunity to gather system data close to the actuator, although the exact sensing implementation and maintenance thresholds are matters for the approved system documentation. What can safely be said from Safran’s published material is that the 787 product includes brake-wear assessment as an integrated “smart” feature. [2]
Safran argues that this architecture facilitates maintenance because electrical connections replace hydraulic brake lines and because system-condition information is available electronically. That is a manufacturer assessment and does not mean every maintenance task is shorter or simpler. Electric braking introduces motors, actuators, electrical connectors, control electronics and associated fault-isolation requirements that are different from hydraulic brake components. Operators still have to follow Boeing’s approved maintenance programme, component limits and troubleshooting instructions. The credible conclusion is narrower: electric actuation changes the maintenance tasks and removes conventional hydraulic brake-actuation hardware from the wheel-brake control chain. [1] [2]
Weight claims need careful attribution
Safran publishes specific weight-optimisation figures for its 787 electric-brake solution, stating savings of up to 141 lb (64 kg) per 787-8 and 244 lb (111 kg) per 787-9 in its product literature. Safran links those claimed reductions to lower fuel consumption and carbon-dioxide emissions. These figures are supplier claims and are configuration-dependent; they should not be interpreted as independently verified fuel-burn reductions for every 787 operator. The physically defensible relationship is that, all else equal, lower aircraft operating weight reduces the mass that must be accelerated and carried, but actual mission fuel consumption depends on aircraft configuration, payload, route, weather, operating procedure and many other variables. [8]
Safran also emphasises that replacing traditional hydraulic brake lines with wiring simplifies installation. Again, this is best treated as the supplier’s engineering and maintenance proposition rather than as universal proof that an electric brake always weighs less than every possible hydraulic design. The 787’s solution is a complete aircraft-specific system containing EBACs, actuators, wiring, sensors and carbon brakes. Comparative weight must be assessed at system level, not by assuming that an electrical cable is automatically lighter than a hydraulic pipe in every installation. [2] [8]
How electric braking fits the 787’s wider design philosophy
Boeing’s airport-planning document describes the 787 as a more-electric design and explains that the aircraft does not use a traditional pneumatic architecture for several major functions. Main-engine starting is performed with starter-generators; cabin air conditioning and wing anti-ice are electrically powered; external electrical connections can support an engine start when the APU is unavailable. Electric wheel-brake actuation therefore fits a broader design in which electricity performs functions that earlier airliners often supplied through pneumatic or hydraulic power. [3]
It would still be inaccurate to call the 787 an “all-electric aircraft”. Boeing’s description specifically says the remaining pneumatic system serves engine-nacelle anti-ice, and the aircraft retains hydraulic systems for other functions. “More electric” is the appropriate engineering term because the design shifts a greater proportion of aircraft functions toward electrical generation and distribution without removing every other power domain. The electric brake is a particularly visible example because it takes a function historically associated with hydraulic pressure and moves the actuation chain into electrical control and electromechanical force generation. [3]
What happens if an actuator becomes inoperative?
The public FAA MMEL gives the most useful high-level answer without speculating about proprietary failure logic. It recognises both complete wheel-brake-system inoperative conditions and individual electric-brake-actuator-system inoperative conditions, and defines dispatch provisions for each. For an individual actuator, the listed relief requires the actuator to be deactivated, places conditions on the remaining brakes and requires the applicable performance adjustment. For a wheel brake, the MMEL similarly requires deactivation and performance accounting, and includes a gear-down time condition after take-off in the specified relief. [5]
This illustrates an important distinction between redundancy and unrestricted operation. Redundancy can allow a system to tolerate particular failures while maintaining an acceptable level of capability, but operators may still need maintenance procedures, operational restrictions and performance penalties before dispatch. The exact approved relief for an individual airline is contained in that operator’s MEL, developed from the regulatory master document and approved by the relevant authority. A public MMEL should not be used as direct operational authority for a particular flight. [5]
Why the 787 brake is technically significant
The Boeing 787 electric brake is significant because it separates the concept of friction braking from the traditional assumption that a large transport aircraft must use hydraulic pressure to apply its wheel brakes. The carbon friction stack remains; anti-skid and controlled deceleration remain; energy still ends up as heat in the brakes. What changes is the actuation pathway. The control commands are handled electronically and electromechanical actuators provide the physical compression of the brake stack. Safran’s system architecture and the FAA’s MMEL both substantiate that distinction. [2] [5]
It also demonstrates why the word “electric” should be used precisely. The brakes are not motors reversing to recharge a battery and they do not make braking energy disappear. They are electrically actuated carbon friction brakes. Safran supplies the main-landing-gear carbon brakes and EBACs, and the FAA’s 787 MMEL records eight wheel-brake systems and 32 electric brake actuator systems. Within Boeing’s wider more-electric architecture, that makes the wheel brakes one of the clearest examples of a traditional aircraft power function being redesigned around electrical distribution. [4] [5] [3]
Verified Sources / References
- Safran Landing Systems — Boeing 787 Dreamliner electric brake.
- Safran Landing Systems — Boeing 787 electric brake: an advanced technology that meets airline requirements.
- Boeing — 787 Airplane Characteristics for Airport Planning, Revision P.
- Safran — Safran’s contribution to the Boeing 787 Dreamliner.
- FAA — Boeing 787 Master Minimum Equipment List material, ATA 32 Landing Gear.
- EASA — EASA.IM.A.115 Boeing 787 Type Certificate Data Sheet.
- EASA — Boeing 787-8 receives EASA certification.
- Safran Landing Systems — Boeing 787 Dreamliner Electric Brake product literature. Published weight and fuel/emissions benefits are Safran manufacturer claims.
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