About two weeks ago, I posted a blog entry about the redefined 737-7 (click here). It attracted a lot of discussion. The firm configuration of the 737-7 was publicly announced during Farnborough airshow this year although the aircraft was launched in 2011.
The 737-7, both the initial version and the redefined one have not attracted many orders so far. Southwest, Westjet and Kunming are the three known customers of the seventy 737-7 orders and commitments to date.
It is highly likely the total orders for the smallest version of the 737 MAX family would reach several hundreds units during the life of the program. It is even possible it would ultimately reach about 15% of the 737 MAX family’s total orders. It depends much on how airlines would change their approach to address the market.
It might also depend on the definition of the MOM (Middle of the market) aircraft. I am sure people are puzzled by my statement. This is my rationale, the way airlines will address air travel might change, the definition of the hypothetical MOM aircraft will be the result of the way airlines will address the market. Basically, if there is a significant change in that MOM segment then perhaps there will also be some changes in the smaller narrowbody market.
Getting A Little Bit Bigger
The redefined 737-7 is about 12 seats bigger compared to the 737-700 or the “old” 737-7 MAX. Let us take a rounded number and say that the redefined 737-7 has 8% extra seats compared to the “old” 737-7.
Usually, when an aircraft gets bigger, it increases the fuel efficiency if expressed on per-seat mile basis. Basically, one would expect the redefined 737-7 would be about 3% to 4% more fuel efficient than the “old” 737-7 on per seat-mile basis.
Now, the way the redefined 737-7 is done would not allow to obtain the full benefit of the “stretch”. Indeed, the 737-7 will have many more common parts with the 737-8 than the “old” 737-7, thus the redefined 737-7 is heavier than it could have been if it were “optimized”.
Basically not only the seat count is increased, the design weights (MTOW, MLW, MZFW) are also increased. Therefore the redefined 737-7 needs a stronger (and thus heavier) landing gear and wing structure.
The obvious benefit of the increased design weight is the increased maximum range, so the redefined 737-7 becomes a good platform for a long-range business jet when equipped with auxiliary tanks.
All in all, I think the redefined 737-7 is about 14% to 15% more fuel efficient than the 737-700NG on per seat-mile basis or similar to the difference between the 737-8 and the 737-800NG.
One obvious reason that could potentially drive 737-7 order up is the “Family Concept”. Indeed, the commonality between the 737-8 and the 737-7 is very high. If my flair is not too mistaken, almost 100% of the LRU is common between the 737-8 and the redefined 737-7.
I can mention other things like the engine maintenance optimization. It is already the case with the 737-800NG and the 737-700NG. Usually, the thrust requirements on the 737-700NG is lower than on the 737-800NG or 737-900NG and thus an engine with a reduced EGT margin for a 737-800NG can be transferred to a 737-700NG. Of course, this is not always valid, but it might add some kind of flexibility in term of shop visit scheduling.
An operator that has many 737-8 and needs some smaller aircraft might well order some 737-7. It is also possible an airline would like to start with a fleet of 737-7 and then order some 737-8 or convert some order to the bigger version if the traffic grows.
This being said, the family concept this is also applicable to Airbus A320neo family. There is little doubt about it.
I must have omitted other possible benefits of the family concept, I hope readers can provide us with these possible other benefits.
Since there is significantly higher commonality between the redefined 737-7 and the 737-8, there must be a significant reduction of part numbers. Obviously this could end up with reduced complexity in term of part manufacturing and logistics.
The drawback is that the real production cost of a redefined 737-7 and a 737-8 maybe quite similar whereas the pricing difference between the two could be around US$ nine millions. In reality there is no incentive for Boeing to push the sales of the 737-7.
The redefined 737-7 is an interesting case where the manufacturer is certainly not very interested to produce it, but the market might ask for it.