Originally Posted by
misd-agin
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.
The initial 767 engines (JT9D-7R4 and CF6-80A) topped out at about about 50k thrust, even on the 767-300. The new engines we certified in the 1988-89 time frame (PW4000, CF6-80C2, and RB211-524G/H) went from about 52k to 62k (they offered a 50k rating on the PW4000 but no one ever bought it). The highest rating they ever delivered for the 767-200 was 60k, while 62k was available for the -300 (the 767-2C/KC-46 uses the 62k PW4000 with an available bump). IIRC the max available MTOW for the 767-200 was 380,000 lbs, but I wouldn't swear to it (the 767-2C/KC-46 is 407,000 lbs.)