Dominic Gates of The Seattle Times has this story in which he has the following observation:
Wyse revealed that Boeing, through structural efficiencies, has also beefed up the allowed maximum take-off weights for the three MAX variants.
Each is 5,000 to 7,000 lbs heavier than the maximum take-off weights of the current 737s.
That means each 737 MAX model, even though heavier than the corresponding current model of the 737NG, can either carry a heavier payload or carry more fuel and so fly farther.
This is good. But we’re hearing from airlines that runway performance may be worse than the 737NG. The airplane is heavier but the wing is the same and the engine thrust is still somewhat of a mystery. CFM International, maker of the LEAP-1B that will power the MAX, lists thrust on its website of 20,000-28,000 lbs without identifying the sub-types and thrust to which the engines will be applied.
These thrust ratings are similar to those now on the NG, rather than being increased to compensate for the increased weight.
One airline tells us that runway performance for the -8 MAX and -9 MAX is longer than the -800 and -900. (The airline is not considering the -7 MAX and doesn’t have the -700.) This, the airline tells us, makes the airplanes problematic at some airports it serves.
This illustrates the dilemma Boeing and CFM have with the physically-constrained 737. CFM could build any engine it wants that would get the job done. It has, after all, two LEAP engines in development for the COMAC C919 and the Airbus A320neo. But the 737 presents special challenges and CFM is constrained unless Boeing lifts the entire airplane with new main gear. But this would mean a new wing box and associated structural changes, adding significantly to the cost. And Boeing won’t to this.
There’s still a lot about MAX we don’t know. And many customers are also waiting for the information.