News about MAX

Jon Ostrower (Flightblogger)  and Scott Hamilton both are reporting about a presentation given by Boeing Commercial Airplanes CEO Jim Albaugh at Goldman Sachs.

The B737 MAX now will get a 68" LEAP-1B engine and the nose gear will be extended by 6-8 inches. Also. Boeing is talking to CFM about a "custom core". This is consistent with what I heard recently. But as everybody would suggest that the engine for the MAX would get a smaller core as the aircraft needs less thrust than the A320 (at least this is the situation today), I heard that the LEAP-1B would get a larger core than the LEAP-1A.
This would lead to:

• Additional risk as there is a second core to develop -or a third if you take the core for the GE Passport 20 engine for the Bombardier Global 7000/8000 into account. The Passport certification is already announced to be delayed by a year and it features a scaled LEAP core. You read about the delay first here... ;-)
• Additional manpower at CFM needed to develop the extra core.
• Higher SFC, as the bypass ratio will go down for a given thrust level.
• Lower temperatures in the core and therefore lower maintenance costs.

But what could be the reason for the larger core engine - is it really lower maintenance costs? With the larger core and the lower bypass ratio, the LPT could end up having less stages than the LEAP-1A (six or even five compared to the seven stages in the LEAP-1A).

The other possibility would be that the thrust needed for the B737 MAX is higher than for today's B737NG family.  Driving a higher thrust requirement could be a B737MAX-9 with 4000nm of range. The airlines would then have a real B757-200 replacement. But at what costs? The whole structure of the wing would have to be beefed up, subsequently the main landing gear and at the and the center wing box. To make it short -it would end up in a mess...

So it is not clear what this "custom core" means - maybe my information's were wrong and it is really a smaller core. That would lead to an optimized SFC (for the 68" fan diameter restriction), but then core temperatures would go up and so would do maintenance costs relative to the CFM56-7BE - is that what the customer makes happy?

According to Albaugh, Boeing now has 600 commitments for the B737 MAX - this is remarkable for an aircraft that is still in definition...

UPDATE: Boeing just said that the MAX will see final definition in 2013... with first flight in 2016 and EIS still planned in 2017!