Delivering a new version of the 737 is old hat at Boeing. Eighteen major models have entered service since the debut of the 737-100 in 1968, including 10 versions of the NG series over the past 19 years alone. In all, 9,448 individual 737s have rolled out of the factory doors in Renton, Washington, through March 2017.
Adding to the tradition later this spring will come the 737 Max 8, after a six-year development. The Max 8 received US Federal Aviation Administration type certification in March. Already following on its heels is the larger Max 9 variant, the first of which rolled out on 7 March and will enter service next year.
As major derivatives of the 737 go, it’s arguable whether the 737 Max is even Boeing’s most ambitious leap in technology. In the late 1990s, the 737NG series introduced a glass cockpit, larger wing and improved engines. The 737 Max updates the glass cockpit and adds new winglets plus a new engine – CFM International‘s Leap-1B.
Despite this depth of experience, introducing the 737 Max into operational service will test Boeing’s skills in unprecedented ways. Boeing will have to deliver more aircraft to a larger and more diverse group of operators faster than any other model in the company’s storied history. It will have to manage the maturity of the 737 Max’s onboard network server (ONS), a new and perhaps under-appreciated feature that could prove revolutionary in operating the single-aisle – if it is not undermined by undetected software bugs.
Amid these challenges, Boeing is counting on cash flow from the 737 line in Renton, Washington, to offset declining revenue from the 777 line as it transitions to a similarly re-engined version in 2020. As 777 deliveries drop to as low as 2.5 a month by 2019, Boeing plans to keep pushing 737 deliveries ever higher.
With production already 50% higher than 10 years ago, Boeing plans to increase current output by another 35%, from 42 single-aisles each month to 57 by 2019.
That escalating rate requires the careful orchestration of ramping down deliveries of 737NG-series models, ramping up the Max series, and managing fluctuating rates for special versions such as Boeing Business Jets and the P-8 maritime patrol derivative.
In the past 10 years, Boeing has gained experience from the troubled introduction of the 787-8 in 2011, compared with the relatively smooth entry into service of the stretched 787-9 in 2014. In both cases, Boeing steadily ramped up output while delivering to new customers one at a time. No such luxury will be possible on a 737 assembly line reaching 47 aircraft deliveries a month later this year.
“The deliveries are going to be coming so fast and so furious,” says Keith Leverkuhn, Boeing vice-president and general manager of 737 programmes.
From May until December, the 737 Max will account for about 10-15% of Boeing’s single-aisle deliveries, numbering potentially more than 50 aircraft handed over to multiple customers. Boeing opened a third assembly line in the Renton hangar to directly support 737 Max deliveries this year. As deliveries increase, one of the 737NG lines will transform into a mixed line, building CFM56- and Leap-powered models at the same time. Within four years, Boeing expects to be delivering only a handful of 737NGs annually, with the 737 Max occupying the remainder of the production slots at a monthly rate of 57.
Instead of inviting a single customer at a time to come to Renton for flightcrew and maintenance training, Boeing will prepare multiple new customers for the 737 Max 8 at the same time.
“That’s going to require some special attention on our part,” Leverkuhn says.
Boeing began turning its focus from airworthiness certification to the entry into service last September. In a six-day series of flights using the fourth 737 Max 8 test aircraft, which is equipped with a full interior, Boeing launch customer Southwest Airlines conducted a service-ready operational validation (SROV).
The goal of the SROV is to simulate a typical week in airline service, flying a routine airline schedule to multiple airports. For the 737 Max, Southwest pilots flew the aircraft from Dallas Love Field to Albuquerque, Denver, Chicago, Austin and Phoenix. Every routine function was practised and evaluated, from towing and fuelling, to line maintenance, to checking whether the ground service equipment fits around the gates of various airports.