Originally Posted by
tdracer
I don't recall that weight was as big a concern during the 767 development relative to the 757, although I couldn't say why that was the case. I do know that when I was working the 757 (late 1990's) we worked several changes that resulted in heavier parts but with much lower manufacturing costs. It's probably worth noting that neither the 757 or 767 were envisioned to morph into the longer range aircraft they eventually became - in the case of the 767 it went from 320,000 lbs at EIS to over 400k less than ten years later (helped considerably by the upgraded engines that came along in 1988).
It's not really fair to compare the 767 with the A330 - the A330 came along over 10 years after the 767 and hence the more direct 767 comparisons would be with the A310 and A300-600.
The 320,000 lbs a/c was also the 767-200. The 400K+ was the 767-300 with 61,500 lbs of thrust vs the 48,000 lbs available on the 767-200. Our 767-200's were originally limited to 310,000 lbs (?), then 320,000, then 351,000 lbs, all with the same thrust engines.
I flew the A300-600. The 767-300 was more capable. Guys used to say "but the A300 uses less runway." Looking at the books and the 767-300 could lift more weight off of the same runway and cruise faster, and farther, on the same gas. The A300 did out climb it because they didn't use CLB 1 or CLB 2 to baby the engines.
I don't know what the 757 was originally certified at but ours were originally limited to 220,000 lbs takeoff weight. Then it went to 240,000 lbs, then 250,000 (?), then 255,500 lbs. USAF guy said they flew there's at 270K (280K???).
As the RR engines faded their max thrust was derated from 44,100 to 43,700. A seat of the pants comparison - a STD/FLEX power takeoff with RR engines producing 44,100 felt similar to a max power takeoff with the 37,500 P&W engines. It wasn't uncommon, especially on your first flights with the 37.500 thrust engines, to think the engines weren't producing full thrust. I've also experienced that after months of flying into SFO with a 767-300 only to have it replaced with a 767-200 on one flight.