Lion Air crash: Jakarta Boeing 737 'had prior instrument error'

[Nusa]

Twas simply your use the future tense of your statement, rather than past tense.

As for Canada, they accepted the changes to the MAX last month, although the airworthiness directive is still "soon". But you just said your comment had nothing to do with regulation part, so that's beside the point.

I'm not sure exactly where EASA is on approval for the EU, but I suspect it's not far in the future.

[jmelson]

Basically it incorrectly got tied to the paid AOA indicator, which is where the confusion comes from, I think. This wasn't what the design intended, but due to a misunderstanding/miscommunication between Boeing and Collins on a related trouble report, it is what ended up being implemented. Collins actually found this bug some years ago, and informed Boeing, but it was requested that Collins hold off on a fix until a future anticipated firmware update or some such weak reasoning, and Boeing never informed its customers. This is documented in the Congressional report, I haven't really seen it discussed much elsewhere.

So, if you DON'T pay for the extra indicator, the AOA disagree light NEVER goes ON?  YIKES!  How could Collins just SIT on that malfunction??!!??
That seems like something they really NEEDED to report to the FAA pronto!

However, I strongly believe that this concept of 'update the 50 year old airframe on the same type certificate under relaxed rules and with minimal pilot training' is fundamentally flawed.

Yes, I understand how they got here, between pressure from SouthWest Airlines and just making incremental changes on a really successful product line, and wanting to just deliver a more fuel-efficient machine, quickly, to existing customers who were chomping at the bit for a lower fuel burn.

But, YES, you are right, that keeping adding more hacks to a 50 year-old design eventually needs to end!

There was a lot else going on at Boeing that was problematic, but this is where I think the regulators really need to step up and redesign their type certification scheme.

Well, they have got the MAX back into the air, with additional fixes on top of the MCAS fixes, and are probably going to crank out a bunch more of the MAX aircraft over the next few years.  But, I suspect that there's going to be a LOT more scrutiny over ANYTHING Boeing comes up with next for certification.  And, then, eventually, they will need to address the narrow body market, and I can't IMAGINE it well be another hack on the 737 carcass.  But, I could be wrong.

Jon

[boffin]

Currently airborne in 737MAX  (2021-01-10 1839Z)
3 American Airlines passenger flights
3 Aeromexico passenger flights
4 GOL (Brazil) passenger flights
1 COPA (Panama) passeger flights
2 SouthWest (USA) repositioning flights

[ve7xen]

So, if you DON'T pay for the extra indicator, the AOA disagree light NEVER goes ON?  YIKES!  How could Collins just SIT on that malfunction??!!??
That seems like something they really NEEDED to report to the FAA pronto!

Yup. This is beyond my understanding of the legal situation, but my guess is that Collins isn't directly beholden to the FAA. They work for Boeing from Boeing's design requirements, and it's the entire aircraft that is subject to FAA certification, and honestly they probably don't really have experts on exactly what the regulations require of Boeing to address issues like that. Should someone at Collins have blown the whistle? Maybe, but I'm willing to cut them a bit of slack, it seems like an honest mistake and they reported it to Boeing as soon as it was discovered. How Boeing let that sit when it clearly meant there were planes flying around that didn't meet their certification basis though is beyond comprehension. How serious would it have been to at least notify customers and offer a firmware update FFS, even if it was only recommended. What is that, an hour of engineer time at most, that customers can probably slot in to the rest of their maintenance schedule? I just don't get what Boeing gains from denying this information and fix to customers and pilots, it's really worrisome how they arrived at this decision for such a relatively trivial thing.

And, then, eventually, they will need to address the narrow body market, and I can't IMAGINE it well be another hack on the 737 carcass.  But, I could be wrong.

Let's hope so. As I understand it, they basically canned their next-gen narrowbody project to focus on 737MAX. Maybe they start a clean-sheet design today and it's flying in 20 years, but I'm not very optimistic about that...

[NiHaoMike]

[boffin]

Let's hope so. As I understand it, they basically canned their next-gen narrowbody project to focus on 737MAX. Maybe they start a clean-sheet design today and it's flying in 20 years, but I'm not very optimistic about that...

Boeing have the problem that  they've tried to use the 737NG and 737-MAX series to simultaneously replace the 1500 mi / 125 passenger 737-200 and the 4500mi 190-220 passenger 757-200/767-200 with the same airframe, and you're running into issues that it's hard to do both effectively.

I think if they go 'clean sheet', they may end up having to make two aircraft; or work with another vendor (Embraer?) to fill the smaller side.

Same thing is happening on the prop-side of the world, no one at all competes with ATR and the ATR42 at the 40-50 seat size, with DHC only making 75 seater DHC8-400s.  And at the smaller 20 seat size, the only current production aircraft I can think of are the new Cessna 408 &  DHC6-400s both of which are really special purpose (the former being a cargo hauler and the latter highly optimized for STOL/rugged operations),  which isn't really ideal to replace things like the B1900s of the world.

[james_s]

Same thing is happening on the prop-side of the world, no one at all competes with ATR and the ATR42 at the 40-50 seat size, with DHC only making 75 seater DHC8-400s.  And at the smaller 20 seat size, the only current production aircraft I can think of are the new Cessna 408 &  DHC6-400s both of which are really special purpose (the former being a cargo hauler and the latter highly optimized for STOL/rugged operations),  which isn't really ideal to replace things like the B1900s of the world.

Seems like a DC-3 would be a nice fit there, maybe they should put those back into production. Lots of planes are faster and bigger and more luxurious but nothing I can think of has really quite hit that perfect sweet spot that has kept dozens of DC-3 airframes in revenue service for ~80 years.

[bw2341]

I thought that DC-3s are still flying because there were so many made that they'll never run out of old planes to take parts from. If we're talking about safety, I don't think a unpressurized plane built to safety standards from 80 years ago would be appealing to current operators.

I think there are a few companies that have rebuilt DC-3s and modernized them with turboprop engines. If they made sense for airlines, we would see them everywhere.

I haven't looked up the regulations myself, but I think there is a difference between small planes with up to 19 passengers versus the big airliners. This would explain the hole in the market between 19 and 50 passengers.

If an airline has to meet tougher safety standards and have higher levels of staffing per flight, it might be impossible to make money flying a 20 or 30 passenger plane.

[james_s]

They're already running out of parts, prices on used DC-3s have gone up sharply in recent years but they keep going because they are still relatively affordable for a plan of that size and capability. It probably wouldn't make sense to start producing them again, given all the regulations I'm guessing it would be impossible to build them the same as the old ones, I can dream though. It's hard to think of an aircraft that is more timeless and classic, it's the grandfather of modern airliners. A great many of the planes meant to replace it went out of revenue service decades ago, many have no airworthy examples remaining at all.

[SilverSolder]

They're already running out of parts, prices on used DC-3s have gone up sharply in recent years but they keep going because they are still relatively affordable for a plan of that size and capability. It probably wouldn't make sense to start producing them again, given all the regulations I'm guessing it would be impossible to build them the same as the old ones, I can dream though. It's hard to think of an aircraft that is more timeless and classic, it's the grandfather of modern airliners. A great many of the planes meant to replace it went out of revenue service decades ago, many have no airworthy examples remaining at all.

The first plane I ever flew on was a DC-3.  I was 5 and it was very exciting, flying alone - taken care of by a stewardess in full, impeccably pressed uniform, with impossibly shiny brass buttons and badges!  I remember being awestruck at the thunder of the engines as they started and revved up, massive amounts of blue and black smoke (I guess fuel and piston oil control rings were "good enough for Australia" back then, and mufflers etc. was not something real men or women had any use for whatsoever)...   I remember the feeling of the small miracle as the plane accelerated down the runway with incredible noise, watching the ground disappearing under the plane...  I still feel that way at every take-off and always sit by the window for that reason alone, even if modern planes are a quite anodyne experience compared to a DC-3!   

[Nusa]

I thought that DC-3s are still flying because there were so many made that they'll never run out of old planes to take parts from. If we're talking about safety, I don't think a unpressurized plane built to safety standards from 80 years ago would be appealing to current operators.

I think there are a few companies that have rebuilt DC-3s and modernized them with turboprop engines. If they made sense for airlines, we would see them everywhere.

We're down to a few hundred in active service now, out of the 16000 DC-3/C-47 variants that were built. But they fill a niche. The tail-dragger configuration is simply superior at operating on short rough fields compared to modern aircraft of similar size. Rough fields were common in the era/war they were designed for.

As for turboprop conversions, the Jeopardy clue would be: This aircraft worth $300,000 is now worth $8,000,000.      Answer: What is a DC-3 turbo-prop conversion? 

Why? A lot more than the engine has to be upgraded to be properly certified, and it's nearly all hand labor...but you end up with a like-new aircraft you can fly another 50 years. So your commercial reality has to be pretty strong to invest that much to replace something that is still working.
Here's the longer story on that:

[SilverSolder]

Don't the airframes have a limited number of take-offs and landings, like modern planes?  Or are they simply so strong and over-engineered that it isn't an issue?

[Nusa]

Don't the airframes have a limited number of take-offs and landings, like modern planes?  Or are they simply so strong and over-engineered that it isn't an issue?

No, the DC-3 requires regular inspection and maintenance like every other aircraft. However, your implication that airplanes have to be discarded at a certain point is not correct. Barring obvious calamities, aircraft can be kept flying for generations, so long as they are properly maintained. Airlines get rid of old planes and buy new ones for economic/business/pilot training reasons, not because the old ones are suddenly unusable.

Modern or antique, there are all sorts of maintenance requirements triggered by hours of use, cycles, landings, age, or unusual events. All documented in the maintenance manual with updates from airworthiness directives over the years. Some things you just have to inspect, some things you test, some things you overhaul, some things you replace.

[Gixy]

Hum, aircraft structure is designed and certified for a given number of cycles (a cycle is complete flight, with take-off and landing). Once this number is achieved, either the aircraft manufacturer make additional tests and computations to certify more cycles, either the aircraft is grounded for ever.

[Kleinstein]

The old DC3 has no pressurized cabin, which reduces the stress on the structure. It was also made to land on not so good runways. The stress from landings can vary a lot - so a fixed number of cyles does not make much sense with those old planes. So here it is more like regular inspections until cracks can no longer relaired.

It can make sense for a modern plane build to weight, where the stress from the pressure change can be the limiting factor. There a limited number of cycles makes absolute sense.

With the current situation, there may not be much demand for additional new planes in the next 20 years and chances are the airlines are short on money too. With the current reduced fligh plans they can scrap the old ones without buying new. For Boing and Airbus it is likely more about canceled orders for the 737 and A320. They still have a lot one the books - but what is it good for if the airlines can't pay.
If at all it would be about more fuel efficient models, in case the oil price and maybe taxes would go up.

[NiHaoMike]

It can make sense for a modern plane build to weight, where the stress from the pressure change can be the limiting factor. There a limited number of cycles makes absolute sense.

Newer aircraft like the 787 seem to be going in the direction of a higher cabin pressure which seems to contradict the goal of reducing stress on the structure to reduce weight and increase lifetime. I would have thought that lowering the cabin pressure and then using an oxygen concentrator to increase the partial pressure of the oxygen would be a good way to go, would be interesting to find out if it's merely a cost issue or if the weight/power use of the oxygen concentrator cancels out the benefit.

[SkyMaster]

Don't the airframes have a limited number of take-offs and landings, like modern planes?  Or are they simply so strong and over-engineered that it isn't an issue?

The "limited number of take-offs and landings" you are referring to is the maximum flight cycles that is applicable pressurized aircraft.

Typically, an unpressurized aircraft does not have a limited number of flight cycles imposed by its type certificate.

 

[madires]

FAA safety engineer goes public to slam the agency’s oversight of Boeing’s 737 MAX: https://www.seattletimes.com/business/boeing-aerospace/faa-safety-engineer-goes-public-to-slam-the-agencys-oversight-of-boeings-737-max/

[Larryc001]

The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.


https://en.m.wikipedia.org/wiki/Gimli_Glider

[langwadt]

The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.


https://en.m.wikipedia.org/wiki/Gimli_Glider

using that as a reason not to fly makes no sense, flying is statistically very safe compared to other forms of transport. And unlike
almost everything else every single accident and near accident is investigated to find the reasons and what measures to takes to
prevent it from happening again

[SilverSolder]

The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.


https://en.m.wikipedia.org/wiki/Gimli_Glider

This incident was made into a movie, right?  -  The incident should never have happened, but what a save!

[Nusa]

The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.


https://en.m.wikipedia.org/wiki/Gimli_Glider

That's a totally inappropriate comparison.  The Gimli Glider was an out-of-fuel situation at high altitude with a controllable airplane that could still glide for 50+ miles, even without engines. The Challenger, which I watched live on a 32" TV (big-screen for 1986), was an explosion due to a failed seal on a solid booster rocket, and there was literally nothing the crew could do about it. Not the same thing at all!

A much better match to the Challenger would be TWA flight 800 ten years later. That was a fuel tank explosion that destroyed the 747. Nothing the crew could do about it, although they did notice crazy readings several minutes beforehand.

In any case, all of those things happened 25-35 years ago and the aircraft industry survived just fine. Recent events that mangled the travel industry have had a much bigger impact, but the aircraft industry is going to survive that as well.

[Monkeh]

The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.


https://en.m.wikipedia.org/wiki/Gimli_Glider

You're in far more danger on the road from yourself, let alone everyone else, than you are on a commercial flight.

[james_s]

A much better match to the Challenger would be TWA flight 800 ten years later. That was a fuel tank explosion that destroyed the 747. Nothing the crew could do about it, although they did notice crazy readings several minutes beforehand.

With the benefit of hindsight they could have pulled the appropriate circuit breaker(s) to kill power to the center tank fuel pumps, but I can hardly fault them for not realizing what was going on at the time and taking that action. They couldn't reasonably have been expected to prevent the accident but they still had more control over the situation than the Challenger crew, who had no indication whatsoever that anything was wrong until it blew up.

[james_s]

It can make sense for a modern plane build to weight, where the stress from the pressure change can be the limiting factor. There a limited number of cycles makes absolute sense.

Newer aircraft like the 787 seem to be going in the direction of a higher cabin pressure which seems to contradict the goal of reducing stress on the structure to reduce weight and increase lifetime. I would have thought that lowering the cabin pressure and then using an oxygen concentrator to increase the partial pressure of the oxygen would be a good way to go, would be interesting to find out if it's merely a cost issue or if the weight/power use of the oxygen concentrator cancels out the benefit.

AFAIK it's the composite construction that allows for the higher cabin pressure. Composite materials have different fatigue characteristics than aluminum. I don't know how the lifespan compares but I assume they have calculated everything and can choose exactly how strong to make each individual component in order to achieve an acceptable number of flight cycles at the desired cabin pressure. Weight, lifetime, passenger comfort, pick any two to optimize for.