"Once the grounding occurred, then we said we need to take this to the next step, to build the mockups, we need to go out on the flight line and figure out how this is going to go."
"We immediately began working with the 787 program to understand where they were headed, what they were thinking and to go out on the flight line and to understand some of the scenarios. The engineers would say this is what we think it is going to look like, this is what we believe are the areas we're going to affect.
"Space was a huge deal. I would say that within two weeks we began to assemble that [mockup] room. We also had a live mockup out on the flight line."
Boeing designed a "robust" fix that includes separating battery cells, a new charging system, venting and a containment box.
The fix itself is far from the most complex job CAS has done in the field.
Boeing has in the past changed pressure bulkheads, grafted an entire nose onto an airplane and repaired badly damaged aircraft in the field.
It's not unique to Boeing: all aircraft manufacturers have to support their customers. Airbus had to undertake difficult and lengthy aircraft repairs for the A380 involved in an engine explosion over Singapore that badly damaged the wing, structures and components. Airbus also had to replace the entire tail of an A340 damaged in a takeoff accident in Australia.
Testin said the installation of the fix wasn't onerous, but tedious.
"We were worried about the logistics. Three hundred people around the world when you have 10 teams out, that's a pretty large package for us to do. The traveling behind it, moving the equipment. We had to go out and purchase the equipment to get multiple units."
The parts easily go into a lower cargo hold but the tools and logistics to do the work are more suitable for a freighter, Testin says. The equipment weighs close to 28,000-30,000 lbs.
"We have to take everything that we need with us, kitted by crew size. Once we determined what a crew size would be, we matched that up with kit. Hand tools, power tools. One kit would take up a good portion of a lower lobe on a 777."
"This was on such as large scale, this is probably the single largest thing we had to focus on, the logistics behind being able to accommodate the movement. We moved equipment sometimes several times to satisfy the customers."
CAS's 10 teams fanned out to Asia, Europe, Africa and the United States while awaiting the FAA review of the design and fix. Approval came April 26. The first 787 returned to service within days.
The last of the aircraft are expected to return to service next month.