How Gulfstream Ensures Data Integrity for MBD
We discussed “The MBD History and Successes at Gulfstream” and “The MBD Experiences at Gulfstream in Software and Hardware” previously. Let’s continue the topic in this article to learn how Gulfstream, a subsidiary of General Dynamics, ensures data integrity when it is dealing with the ocean of digital airplane representation data and tough Federal Aviation Administration (FAA) regulations.
As Dan Ganser (staff scientist with Gulfstream) shared, “We model everything, including fasteners, shims, veneer and so on.Our 3D representation is everything that you see in the G650 model.”The high-fidelity digital representation brings many benefits such as real-time bill of materials (BOM)creations and accurate assembly processes as discussed in the two articles just noted. In addition, it enforces consistency. Modeling everything means that nobody can decide subjectively what to model and what not to model, which has been a problem for many manufacturers. However, the digital representation introduces a huge amount of complicated data. For example, the forward fuselage as shown in Figure 1 illustrates how complex one system can be.
Figure 1. Aforward fuselage. (Image courtesy of Gulfstream.)
Let’s also keep in mind that Gulfstream aircraft have a lifecycle of 50 to 75 years. The data for the aircraft must be usable for an extended time frame to support ongoing maintenance and upgrades. Furthermore, the company has to consider the continuous evolution of the software and hardware to create and use the digital data. Jeff Kreide, vice president of Business Solutions with Gulfstream, shared several examples of such considerations. How will the engineering data work across software releases? What happens if a software company goes out of business? What hardware will be used 50 years from now?
In short, the challenge is to ensure the data integrity across design iterations, engineering updates, software releases, CAD formats and hardware platforms over an extended period of time. Of course, the data must serve all the key stakeholders seamlessly, such as the six Gulfstream facilities shown in Figure 2, along with the entire supply chain. The data integrity is also one of the key requirements for the FAA in the United States to certify an electronic model-based definition (MBD) system.
Figure 2. Six Gulfstream facilities. (Image courtesy of Gulfstream.)
The first task is live archiving, which is storing new data while maintaining the entire data system’s integrity, or protecting it from corruption. Ganser mentioned that the change validation process is one of the biggest hurdles for Gulfstream to meet the FAA’s certification requirements. Initially, the team thought that since the data storage was secured, nobody would have the access to make unintentional modifications. But that wouldn’t prevent the database administrators or system administrators from making alterations. Designers and engineers request that administrators update data all the time: “I released my design by mistake. Please change it.” or “There is a spelling error. Please fix it.” The FAA even asked Gulfstream, “If an administrator were given $5 million, could he or she change the system?”
Facing these rigorous regulations, Gulfstream developed rigorous tools and processes to validate the data every night at the bit and byte level. For example, the company compares the hash values of files and attributes to make sure they aren’t unintentionally altered from one design release to another.
The data validation used to take 24 hours. Then the company redesigned the data storage process to shorten it to 12 hours and minimize the impact on working hours. The goal is to catch any data corruption as soon as possible. The sooner you can catch the issues, the easier it is to identify the root causes and resolve them. The hash values used to be pulled after a design was released. In 2015, the values were extracted at the release phase. Going forward, the team plans to move the hash value extraction process to the design review phase.
Beyond all the data and checking steps, Ganser stressed the importance of the environment as shown in Figure 3 because it’s a key factor in determining the final interpretation.
Figure 3. Stored data, presented data and interpreted data. (Image courtesy of Gulfstream.)
No matter how good the data quality is, if it’s not presented correctly and consistently, the final interpretation can be at risk. Therefore, Gulfstream controls the environment tightly too. Whether the data is presented in a native CAD tool, in a viewer, in a hologram, on a laptop, on a workstation, or by a projector, the presentation should be the same to ensure that the interpretation is the same. Any software applications or hardware tools must be verified before they are added to the environment.
Here is one example of software upgrades being controlled rigorously.As a background,when working from one CAD software version to an upgrade, engineers have run into unintentional data migration issues such as critical color differences or product and manufacturing information (PMI) changes. Therefore, the team at Gulfstream validates the same dataset between the current CAD version and the upgrade. An application (Kubotek Validate) is used to run the topology analysis by comparing surface changes. Similarly, another tool (ITI CADIQ) is deployed to compare the point changes. On top of the models, these tools are also used to compare the PMI differences.
If the separate results by Kubotek Validate and ITI CADIQ both confirm zero changes between software revisions, then this dataset is regarded as well preserved and the software upgrade is deemed safe for it. If there are any changes between CAD revisions or inconsistencies between the results by the two different validation tools, then the software upgrade can’t take place until the issues are resolved.
As mentioned in a previous article, once a CAD software revision is qualified for an upgrade, then all the internal teams and external suppliers must upgrade to the same revision at the same time.
In order to move data in and out of CAD applications, Gulfstream needs to export the released models to the STEP format per the ISO 10303 AP203 standard as required by the FAA. To support the standard, the modeling practice intentionally limits the content allowed into the CATIA models. A simple check is to export a model to STEP and then import it back in. Only the content that remains intact after the export and import is allowed in the CATIA model.
Then the STEP data is validated against the CATIA data using the above two validation tools. Besides the model comparison, the PMI is compared at the polyline level and Unicode string level. Only when the STEP output confirms the source CAD model and the validation results by a match from two different tools can a STEP export be qualified.
In this article, we reviewed the Gulfstream experiences in maintaining its data integrity across design iterations, engineering updates, software releases, CAD formats and hardware platforms. I hope these practices can provide several insights to reference at your organization. To learn more about how SOLIDWORKS MBD can help you with your MBD implementations, please visit its product page.
About the Author
Oboe Wu is a SOLIDWORKS MBD product manager with 20 years of experience in engineering and software. He is an advocate of model-based enterprise and smart manufacturing.