Podcast: Boeing 737 MAX Changes—A Complicated Matter

More details have recently emerged about changes Boeing is implementing in the 737-10 cockpit. But the looming certification deadline not only threatens the -7 and -10 variants. It also raises the question whether and how Boeing can introduce future modifications or even derivatives should the U.S. Congress decide in favor of an extended certification timeline for the latest MAX models.

Aviation Week editors Jens Flottau, Guy Norris and Sean Broderick discuss scenarios and future challenges.

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Rush Transcript

Jens Flottau:

Hello, and welcome to the latest edition of Aviation Week at Works Check 6 podcast. My name is Jens Flottau and I'm Aviation Week's executive editor for commercial aviation. Today I'm joined by Guy Norris, our senior propulsion and technology editor from Colorado Springs, and by Sean Broderick, our senior air transport and safety editor in Washington. If Guy and Sean are on one of our programs together, you might already be guessing that we will talk about the Boeing 737 MAX. After all, both have covered the program intensively for years. And yes, that's our topic today, but the topic is also change. Boeing is currently working to get the 737-7 and the -10 certified, which is a long story in itself, as we all know. At the same time, cockpit modifications are being tested for the -10, that will also be introduced on the other family members, and we've seen some of that in Farnborough recently, as we will get to in just a moment.

            Then our colleague Lori Ranson just came back from our CAPA Latin America conference with a story that GOL, the Brazilian low cost carrier, wants Boeing to develop a 737-8 ER, so it can fly to Europe. That obviously raises a lot of questions. And then finally, we just published a story by Guy who has been looking at future propulsion options for the next generation of narrow bodies. So, lots to discuss, but let's get started with the current cockpit upgrades that we have really just seen in Farnborough. Guy, do you want to fill us in about that?

Guy Norris:

Yeah. Thanks, Jens. Yeah, it was very interesting actually. Farnborough, Boeing brought the 737-10 there, which is, as you mentioned, still in the throes of certification, and in the flight deck for the first time, where I guess the outsiders could get access to see it, was this little, small, but I guess significant, set of switches, which have been added to the cockpit as part of the enhanced angle of attack sensor upgrade, which was required as part of the return to service needs of the aircraft. Sean will fill us in, I know, on more details of this, but just to give you the sort of 50,000 foot view of it, really. It's basically a system which backs up the existing angle of attack sensors with an independent set of data which allows the system to double check itself.

            And one of the issues of that, or one of the incorporations in the new system, is that you get a cockpit warning of the stick shaker itself when there's a stall imminent, but because this could be a false warning, it's a huge potential distraction to the crew as well. So one of the recommendations was to eliminate or at least reduce this distraction by giving the crew different ways of disabling it if they felt the need. So this is one of the ways of disabling in it. It's right there in front of the control column, just to the left hand pilot commander seat on the right hand side of the control column. So yeah, it was surprising that nobody else spotted it, but anyway, we seem to have revealed this to the world. So anyway, Sean, I'm sure you can say a bit more about that.

Sean Broderick:

Sure. The most interesting aspect to me is, the addition of these switches closes a gap that existed between some of the prominent regulators involved in the re-certification. Many pilot groups and regulators from Europe, so EASA, Transport Canada and a few others, were concerned about these nuisance alerts. The nuisance stick shaker alerts were both present in the two 737 MAX accidents. And the human factors examinations that resulted from those accidents really cast light on these as being unnecessarily risky additions to a potential emergency. The only choice before this, before the switches, was to pull the circuit breakers to shut off the stick shaker.

            The Canadians and the Europeans both said, yes, we like this, and we're going to codify the procedure by putting special colored caps on the circuit breakers to help the pilots pull the correct one, if you will. The U.S. FAA was concerned that sort of blessing this could create more problems than it would solve. So they stayed away from that during the return to service instructions. It was an interesting split that is now irrelevant because Boeing has gone... And clearly it doesn't seem like it was part of the requirements that EASA put in, like the enhanced angle of attack, because EASA originally came out and said, look, the circuit breaker procedure, we're going to make that easier for you. So it's an interesting step by Boeing. One of the things that Dave Calhoun told us when we talked to him, couple of months ago now, is that there were some enhancements to the -10 that Boeing had not talked about, and this clearly is one of them from a safety aspect. And I was surprised when Guy found that on the flight line out at Farnborough.

Guy Norris:

The other thing to add to what you just said, Sean, is that the other element of it, of course, is that as well as eliminating or at least reducing the potential danger of distraction by having to lean over their shoulders to find the circuit breaker, by deactivating the stick shaker in this way, during a recovery or whatever, it also helps the crews to improve the recognition of the stall warning itself. Because by using these switches or even the breaker, you actually removes these increased column forces that are applied to the 737's elevator feel shift system, which obviously changes the control column feel force, and that probably will be just another level of added safety now that's been brought in as part of these upgrades, I think, these enhancements.

Sean Broderick:

Right. And as you mentioned, important to point out, the location of the circuit breaker for these things on the NG and the MAX flight deck is basically the same. I think it's over the first officer's right shoulder. It's behind the first officer. So it requires not just doing something that you don't normally do, pulling a circuit breaker in flight, but it involves taking your eyes off of the instruments or stop looking outside the window. That's what the FAA was concerned about. But most of the rest of the world said, yeah, we'd rather eliminate that distraction. And it's something that they tested in the ramp-up to the return to service.

            I talked to one pilot that flew a simulator session. The way the FAA wanted it flown, you have a take-off, and let's say you have a bird strike on your angle of attack indicator. You have a stall warning that's inaccurate. You fly it all the way around and land it with the stick shaker going off. And this pilot said it was incredibly distracting. And the idea that you would need to do that while you're going through your checklist in a real emergency was mind-boggling to this pilot. Again, the problem is now solved with what Boeing is introducing on the -10.

Guy Norris:

It just goes to show how much the added burden is on the company in terms of certification and trying to get by this year end deadline, which seems increasingly improbable to be honest, given all of the other things that they have to certify for what is probably the biggest block change anyway of the MAX family series. And we're not just talking about a stretch fuselage, but now it's the EAOA, the flight deck changes, the main gear, for example brake system, on that. There's a lot going on here. So the burden is kind of intense for them to get.... Going through a lot.

Jens Flottau:

Have we heard anything about that? Whether or not they make the deadline? I guess the quiet assumption by everyone seems to be that they're not making it and it will shift well into '23, if not later.

Sean Broderick:

I think that's a fair assessment and Boeing is sticking to the approach. They are just simply trying to get the airplane certified. Timelines are secondary because it's going to take the time it's going to take. They don't have type inspection authorization, right, on the -10 yet. So I mean, to me, the more interesting question is, is the -7 going to make the deadline? At the beginning of the year, Southwest was going to take 70 of them, of course. We all know the story. We've written about it, we've talked about it here. We've got four months to go before the -7 needs to be subject to a law that allows the FAA to issue a type certificate to an airplane, transport category airplane, that doesn't have a certain flight crew alerting technology that neither the MAX nor the 737 NG have.

Guy Norris:

Yeah. And I think, wasn't Michael O'Leary recently quoted basically saying that... He was part of this urging on Congress to give it a pass really in terms of this year end deadline, as far as the EICAS changes, which we've talked about in previous podcasts, but at the same time, it also came out that it was pretty apparent certification was not likely to be before... It's going to be more like '23 than the end of this year.

Sean Broderick:

Right. And may not even be '23 on the -10, because of all the things we've just talked about and the difficulty of getting certification done these days.

Jens Flottau:

But let's look ahead a little further. So we have the MAX family, and let's imagine someone comes and says, I want further change. I want a derivative of this. I want a longer range version. And I'm saying this, of course, because GOL, the Brazilian low cost carrier, just said they would like to have a Dash 8 ER that can fly from northeast Brazil to Europe, and that of course would require changes to the Dash 8. An additional fuel tank, maybe increased maximum take-off weight. How hard is this or are similar things to get through, to get certified, for Boeing, given everything that they've gone through on the MAX?

Guy Norris:

Just looking at the family, okay. So 737, as we all know, dates back to 1967, first flight '67. Since then we've had four generations, 13 main family variants and 21, at least, major variants and derivatives. That's not including sub-variants and BBJs, for example, the business jet version. So you can't accuse them of not actually deriving the family as much as they can, of course. But what is different here is that it may be a derivative too far. The company has bent over backwards in the past to try and make the most of the family in as many ways as it can, but facing the -7 cert and the -10 cert and just trying to get these out of the hangar, getting a stable production system and getting that back into service, I think just means that they cannot entertain the possibility of more derivatives.

            Remember, it's the same as they had on the wide bodies. 747 was... Absolutely the 400, this was before they went to the Dash 8, was bedeviled by bespoke configurations. And the company said, "Never again." We had these three different engine types and multiple internal configurations. Every airline wanted a different set of cabin configurations. They began to simplify that with the 777 and with the 787 they said, it's like the Ford approach, you can have any color as long as it's black, kind of idea, and that's oversimplifying it. But they really, really wanted... They could see the confusion and the process that it involved in the production line, it just made things very difficult for conforming production and standardized work. And those are the things which really made it a problem for production. So I think they want to avoid that as much as possible.

Jens Flottau:

And Sean, from the FAA perspective, how willing would the FAA be to look at even relatively minor changes like adding a fuel tank?

Sean Broderick:

The FAA is not the hold-up in terms of, can it be done? The FAA will look at it. The question that we have here is, will they be permitted to issue a type certificate for yet another airplane that doesn't comply with the provision of the 2020 law that says, after December 21st, 2022, no more transport category airplanes or aircraft that don't comply to certain specifics in their rules related to flight crew alerting systems. The assumption is that the -10 and the -7 are going to be allowed to be certified. After the deadline they're going to be, I guess, grandfathered in, for the lack of a better word. That's going to take a congressional action.

            The idea of adding a fuel tank to the Dash 8 is not a big deal in and of itself. The bigger question, with the FAA is, how long will it take to get done? And then getting back to Boeing's side, even when they get the -7 and the -10 done, they still have a 777 to certify. So the idea of them taking on even something that historically is not a very complex project... I think there are no more simple projects in aircraft certification, whether it's-

Jens Flottau:

So I get it right here. Are you saying, even after the -7 and the -10 are eventually certified, the MAX is then essentially frozen because it's too complicated to do anything new, assuming that... I mean, taking into account that we still have this 2020 law that we need to comply with in the future.

Sean Broderick:

The language of any waiver will drive what could happen down the road. It is possible that Boeing says, listen, we're going to have to tweak some of these airplanes, maybe a new BBJ or something that falls into the category that Congress has defined. It's possible that the language permits more than the -7 or the -10. It's possible that they call out the -7 and the -10. And I suppose it's feasible that there is no waiver and then Boeing has to deal with the choices then. So a lot of it depends on what happens with the law.

Guy Norris:

Just following on from something Sean mentioned there. I mean, from a technical perspective, he rightly mentioned the BBJ there, this is something that could be done, but from GOL's vision, they want something which, from what I understand that Lori picked up at the conference, I mean, it indicates that they're looking at this range for transatlantic operations. So I just did a quick bit of maths, right? So the MAX 8 200, that Ryanair is taking, it shares the same maximum take-off weight with the other members of this family and the heavier BBJs at about 182,200 pounds. And with a max fuel load of just under 45,700 pounds of fuel and a load of 145,000, it can fly for 2,500 nautical miles. That's in still air, all the standard conditions. But with 10,000 pounds less payload, it can fly an extra thousand miles, 3,500, which would probably do it for GOL's range requirement.

            So if you look at how the BBJ MAX 8 version does that, it adds up to seven auxiliary fuel tanks, but the plumbing you need for those aux tanks immediately reduces the available under floor capacity, just even without the tank, and for every tank that you put in, okay, you get about 250 nautical miles extra range in good conditions, but of course you reduce your belly cargo space. So by the time you've filled it up with all those fuel tanks, you've only got 630 cubic feet of capacity. That's about the... I'm not going to guess at what size that is, but that's not many bags. So how many passengers will it make to be a viable service across the Atlantic? I know. It's a difficult one that.

Sean Broderick:

Carry-on only. No big deal.

Jens Flottau:

Yeah, exactly.

Guy Norris:

That's right, yeah.

Jens Flottau:

But I do want to look a little bit further into the future, and Guy, you just wrote a long piece about the future narrow body market and in particular, the technology options that everyone has available now on the engine side. We published a feature this week. Tell us what the scenarios are and what the big players are doing.

Guy Norris:

Yeah, absolutely. It's kind of interesting really. And it goes, again, back to Farnborough, when... I mean, everybody knows that there's this huge wave of technology which needs to be brought in to address the carbon reduction targets. Nobody's going to get anywhere without that. And we're talking above and beyond just SAFs, synthetic aviation fuels. We're talking about core technology changes here. Nobody really knows where this is going to go, and there's a bewildering choice now facing engine makers, which they didn't face even two years ago. You've got the assumption now that electric is coming in. You've got the assumption that at some stage hydrogen fuel is going to be there as well as a green fuel, a green hydrogen. And there's also the assumption that beyond a certain power level you're going to be stuck with gas turbines, at least for the foreseeable future. So where does this leave the narrow body, the single aisle makers?

            They're right in the middle between all of these factors. There's a bit of electric at the bottom, but are they big enough to just stick with a revised big turbo fan? Nobody really knows. So what I was really talking about in this story is the fact that it's everybody scratching their heads and they're having to do everything. You cannot afford to let any of these options go by, including hydrogen from Boeing's perspective. So we kind of traced a path where you can say, yes, CFM's put its marker down with the RISE program, which as listeners will know is this program to look at potential open rotor, but a lot of other technology besides, and Pratt & Whitney, of course, which is really the other contender in the market right now, with the gear turbo fan, has laid out its stall, how it wants this roadmap to go at least through the end of the decade. And it's hinted at some pretty novel hydrogen or other cycles which will allow it to perhaps even go further into the 2030s. So anyway, it was just basically a story to illustrate how uncertain all of this is. And that really the engine companies at the moment are at a bit of a crossroads.

Jens Flottau:

Yeah, and uncertainty really seems to be the theme across everything. The near term challenges on the MAX, the question whether there's future derivatives and the longterm technology choices that people have to make. Well, that was fascinating, but that's all we have time for today. So, thank you Guy, thank you, Sean. Thank you for listening in. Special thanks to our producer Guy Ferneyhough in London. If you are listening in Apple Podcasts and want to support this podcast, please leave us a star rating or write a review. Have a great day and thanks for your time.