As Boeing test pilots create highlight reels flying the 737-10 through normal and extreme conditions, a group of engineers in Puget Sound is conducting testing that is just as critical to certifying the airplane.
Engineers like Nathan Bement are completing tens of thousands of hours of analysis to prove that the systems onboard the newest and largest 737 model are safe and function as intended.
These “System Safety Assessments” or SSAs are required to certify a commercial airplane. They often happen in parallel with flight testing and have to document all the ways that a system might fail and prove that the backup system would hold up in those scenarios.
This means accounting for everyday risks and extremely rare hazards, even those that have never been seen in the 60-year plus history of the 737 family.
‘One in a billion’
“If it's theoretically possible, it's something we have to explore,” said Bement, who works on the Air Data and Inertial Reference System that provides the airplane’s position and speed.
Bement and his colleagues evaluate events that are so remote that they have the probability of happening once in a billion flight hours. For context: All 737s combined have only flown about 482 million hours.
“Even if we are not aware of something ever happening in service, we are analyzing the system to ensure it accounts for that and other failure scenarios,” said Bement.
As many as 15,000-pages each
The engineers conduct qualitative and quantitative analysis, including extensive modeling and calculations. They then record the data in documents that span hundreds and thousands of pages. “I’ve seen one SSA document that was 15,000 pages long,” said Michael Akali, a senior manager in the group.
If Boeing is to achieve its goal of certifying the 737-10 later this year, the team has to submit a total of 31 completed SSAs, including the systems controlling the hydraulics and engines to the ones managing the flight controls and brakes.
