Embraer’s E-Jets series have accumulated more than 23 million flight hours, and have achieved a dispatch reliability of 99.52%. Their goal is to have the E2 quickly reach operational maturity after entry into service and achieve the same level of success, with a goal of 99% dispatch reliability before 12 months in service. But how much of the experience carries over to an aircraft with virtually every system changed and improved, new engines, new avionics, and only 25% of the components the same as their E1 counterparts?
Embraer has taken a number of steps to “mature” the E2 and specifically chose to utilize their early schedule performance against the plan to continue to test and bring additional maturity to the E2 systems. Three specific actions were taken, including increased testing on the “iron bird”, the creation of their in-house Pioneer Airlines operation, and action on airline customer suggestions on how to improve the E2 over the E1 models.
The Iron Bird
The “Iron Bird” is a mechanical representation of the systems of the aircraft laid out on a frame rather than enclosed in a fuselage or wings, fully visible to engineers who can observe and test individual components. These systems range from engines to hydraulics and operational landing gear to cabin air handling to avionics and electronics. Virtually every system on the aircraft is represented and tested in the “Iron Bird” to ensure the robustness of components and determine the proper intervals for service checks. On the E2, extensive testing led to the establishment of 1,000-hour intermediate checks and 10,000 shop visits, up from 850 and 8,500 respectively on the E1 models.
More than 45,000 hours of tests were completed on multiple system rigs, including more than 20 endurance tests on specific systems and components. More than 170 components had highly accelerated life tests performed, which enabled corrective actions after some of the components failed, thereby improving the durability of E2 systems.
Embraer has an advantage in that it develops its fly-by-wire software in-house. This capability enables Embraer to quickly develop software with autonomy and flexibility, something it could not achieve through a supplier. The integration of flight controls was supported by more than 630,000 test hours on the test bench in an extensive hardware maturity campaign. The company has confidence in both its fourth-generation fly-by-wire capabilities and the maturity of the hardware as a result of extensive testing.
The E2’s bleed system and pneumatic stability are improving reliability, with no pressure bumps due to additional pressure sensors to improve system control and monitoring. Anticipated bleed pressure port switching monitoring will prevent large pressure variations, improving valve and ACM life, and eliminate the need for overpressure switches. Fourth generation control laws build on Embraer’s experience in using fly-by-wire on commercial, business, and military aircraft. Newly designed bleed valves normalize engine pressure variations and reduce wear.
Temperature control in the cabin has also been improved by several enhancements, ranging from air duct shapes to rubber sleeves and additional risers and returns in the cabin, the air handling system in the E2 has been improved.
The more forward positioning of the new wing and larger engines required a redesign of the landing gear, and Embraer, the only major OEM that designs and builds its own landing gear, implemented a trailing arm system for the E2. Based on customer feedback, with more than 70 suggestions to improve reliability and ease of maintenance were incorporated into the new design. Lessons learned includes a removable axle and pintle pins for lubrication points to reduce corrosion. The new landing gear was tested to an endurance of 82,400 cycles under high and low extreme temperatures.
Even the cargo compartment of the E2 has been improved, with new flat and curved floor sections and new materials utilized. One example is removing metallic strips between two panels and replacing it with a high resistance tape to eliminate protruding edges. In this area, Embraer has listened to its customers to improve baggage loading and unloading.
While the cockpit itself is new, components feeding avionics have also been enhanced. One example is the air data smart probes that provide for more precise anemometric calibration. The new probes have passed both highly accelerated life tests and highly accelerated stress screening to improve component maturity. Even antennas have changed, with all E2 antennas being accessible and removable from outside the aircraft, with no interior panel movement required.
The E2 is also e-Enabled, with its own 4G and wi-fi communications capabilities to download data and update the flight management systems. The data downloads communicate directly to the AHEAD 2 aircraft health management system, providing preventive maintenance alerts and dispatch of parts for more efficient MRO that eliminates potential delays. Data from 29 LRUs are reported to the AHEAD 2 system for analytics.
Embraer interviewed its customers for suggestions on improving the E-Jet and received more than 1,000 different suggestions. Of these, 97% were evaluated, and 94% implemented. Because operators understand best where potential bottlenecks or inefficiencies occur, Embraer sought out their advice to eliminate problems with the new aircraft before it entered service, based on the experience of 70 E1 operators in 60 counties around the world.
Pioneer Airlines is an in-house Embraer operation that simulates actual airline operations, flying with typical airline utilization and turn times to ensure the reliability of the aircraft prior to EIS. More than 600 dedicated maturity flight tests were conducted after the aircraft was certified to ensure that the systems delivered to customers were performing at mature levels.
The Bottom Line
Embraer was several months early in the development of the E2. Rather than rush the newly certified program into service, the company set out to ensure the robustness of the design and maturity of components through an enhanced test program. While the E2 is a very different aircraft from the E1, the lessons learned and design concepts utilized should result in a very short learning curve and a more mature aircraft at EIS than when the E-Jets were first introduced.