Parker Explains Delay in Legacy 450/500 FBW
Embraer’s Legacy 450/500 program suffered a one-year delay, although the originally planned 3.5-year span to develop and certify a new airplane incorporating so much new technology might have been ambitious. The fly-by-wire (FBW) Legacy 500 will be first to enter service and is on track for certification in the second half of this year and entry into service by year-end or early next year, followed by the 450 about a year later.
Embraer chose not to comment for this article, but in November 2011, during a third-quarter investor call, CEO Frederico Curado said the design suffered a problem with “softness of flight control.” Embraer blamed software in the Parker Aerospace FBW remote electronic units. Parker Aerospace offered more detail during AIN’s recent visit to the company’s Irvine, Calif., Control Systems Division, which develops, tests and manufactures FBW systems.
In the summer of 2011, Parker engineers were busy with integration and validation and verification (V&V) testing of the Legacy FBW system, according to Mark Czaja, Parker group vice president of technology and innovation. “As Embraer was evolving the aircraft, we were working with them to incorporate changes in requirements.”
At some point during development, the design needs to be frozen so suppliers and the OEM can move forward with certifying and building the product. The freeze point is also known as critical design review (CDR). “There was a considerable amount of change to the requirements post-CDR,” Czaja said. “And it was a higher level of change than we’d experienced on other programs.”
Embraer also wanted to speed up the FBW development by planning on 100-percent functionality by first flight, according to Parker Control Systems director of marketing Michael Engers. And Embraer wanted “black label” or final configuration hardware installed in the first-flight aircraft, too. Engers said it was “commendable for wanting to get that aircraft out in such a short time.” But 100-percent functionality “removes the ability to ration your resources to what’s necessary for first flight,” he said. “Maybe the goal has some merit, but you’re spending a lot of time on items that could be postponed.” The black-label hardware presents “another huge challenge,” he explained. Most OEMs fly with flightworthy, easy-to-modify but not final-configuration hardware. In the end, the Legacy 500 first flew on November 27 last year–without 100-percent functionality in the FBW system, according to the Parker engineers.
More than a year earlier, Czaja said, “We were doing our best to work with [Embraer] to incorporate those changes in requirements and to complete the formal integration and V&V testing. And as we were marching through that process, we needed at one point to say, ‘The schedule that we’ve aligned and committed to you, we’re not going to be able to hold.’”
The amount of work remaining and the changes and requirements that needed to be incorporated simply couldn’t be done in the allotted time. “We said,” according to Czaja, “‘we’re trying to do too much now in the available time and we need to work with you to address the work scope or adjust the time schedule to complete the work scope.’”
Parker works with many OEMs and says it understands that changes happen. “There’s always learning that happens as the system evolves, and we have done our best to work with our customers to incorporate changes post-CDR,” he said. “However, on this program there was a higher degree of change and a later degree of change than what we’d experienced on other programs.” And this led to Parker’s determining that “we’re not going to be able to incorporate all of this change and adhere to the process and meet the date. We’re going to have to revisit this. And that’s when we came back to Embraer and said, ‘Let’s have a dialogue about what we can do.’”
“Even though we were late for Embraer’s hopes or aspirations, we still accomplished it within the range that is typical,” said David McLaughlin, Parker chief engineer, flight control systems.