Boeing 777X heading towards design freeze a bit heavier than planned.

By Bjorn Fehrm

Subscription required


July 12, 2015, © Leeham Co. As we reported from Boeing’s Paris Air Show briefing, Boeing’s 777X project is progressing to a design freeze later in 2015. At the briefing everything was presented as being on track with no changes of key data. There have been signs that this in not fully the case. The 777X program is suffering the same disease that hits other aircraft programs, weight gain flu.

To understand it better, we compiled the many indications that points to weight increase and ran them through our proprietary model to understand why and see what it means for the aircraft’s performance.


  • Weight increase is an evil that all aircraft programs battle with. Our analysis shows that 777X is no different.
  • Engine thrust is one of the areas which will be increased to mitigate increased weight. We give the latest status of GE9X thrust development, now beyond 105,000 lb.
  • A number of airframe changes have been made. We analyze their consequences and make predictions for future maximum weight increases.

To read the rest of the article Login or Subscribe today.