Boeing 747-400 catalytic converter titanium welding "stupid spec

Engelhard making titanium catalytic-converter housings for cabin air ozone treatment. Boeing's x-ray spec called for no flaw > 10 thousandths — a limit chosen by NDT detectability, not by any analysis of the service application (low-pressure air). Half of all welds failed; with four welds per part and one allowed repair, virtually nothing could ship. Tom diagnosed the spec as bureaucratic CYA.

There's another reason for bulking up safety factors. Around 1990, I'd taken a trip to Japan, and I got back in my office and had a note to call Engelhard — which makes platinum. They needed me to come down because they were making titanium housings for catalytic converters going on the new Boeing 747-400. The 747-400 was a lighter-weight 747, redesigned to take thousands of pounds off so they could put thousands of pounds more fuel and fly direct flights to further distances. The first time I ever went to Japan, we always had to stop and refuel in Anchorage, Alaska — you couldn't make it all the way to Tokyo from the West Coast, or even the East Coast. Now you can get direct flights on the new 787 from New York to Tokyo, which we never could before. As planes get lighter with more fuel and more fuel-efficient engines, you can go almost halfway around the globe — which is as far as you need to go, unless you're the U.S. Air Force.