Manufacturing Process Improvements for the Boeing 787 Horizontal Stabilizer

Abstract PDF: 

Boeing produces an airplane called the 787. The plane is around 50% composites, which improves its fuel efficiency around 20% over prior aluminum models. Currently Boeing has hundreds of back orders for these airplanes, so anything that could reduce the production cycle time would help immensely. Our project is focused specifically on the carbon fiber horizontal stabilizer (H-stab), which currently requires a time-¬≠consuming, messy process for application of sacrificial fiberglass fillers. The fiberglass fillers are applied after the H-stab has been cured in an autoclave, and then they are machined to create accurate datum surfaces needed for downstream assembly processes. The current process to apply fiberglass fillers requires about 24 hours after the H-stab emerges from the autoclave, so the market opportunity is to eliminate or reduce this extra time. This could be accomplished by applying the fillers during the layup of the H-stab, rather than post-cure. However, there are technical challenges that must be overcome in order for this option to be viable.

The team focused on overcoming three main technical challenges to reach our solution. The three challenges were:

  1. Bow wave, which occurs when a hard, pre-cured filler is placed on a green carbon fiber layup. The pressure of the vacuum bag creates a notch at the interface between the filler and the carbon fiber during cure.
  2. Residual stresses can develop between the pre-cured fiberglass filler and the carbon fiber material after cure, because of differences in the thermal expansion coefficient of the two materials.
  3. If fillers are placed on the H-stab prior to cure there will be interference between the tooling and the fillers after cure, making extraction of the tooling difficult, or impossible.

Each of these problems was addressed by the team. After testing and experimenting we recommended the co-cure solution as the first choice for adding fillers to the H-stab, pre-cure.

School Year (term): 
Team Name: 
Stable Cure
Michael Miles
Team Members: 
Tyler Albertson, Jonathan Politis, Jordan Hepworth, Cameron Gygi, Eric Smith, Taeseon Lee

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