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chrisg

Problems with the 737MAX ?

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Great posts! Love the history.

 

MD might have infected the bean counters at Boeing, but when aviation companies were falling over in the 70s Boeing were the beneficiaries gaining new design engineers from across the industry. Culmination; the amazing 767. Everything Boeing have done with commercial airliners since  basically follows 767 suit.

 

The 747 is frequently considered to be a conversion of Boeings failed pitch at the previous airforce heavy lift freighter competition, but Joe Sutter says in the book 747 (https://www.amazon.com/747-Creating-Worlds-Adventures-Aviation/dp/0060882425) that it was a completely fresh design. There were engineers who came from the freighter design group to help design the wing, but Sutter binned their work! The Pratt & Whittney engines are probably the closest thing from the freighter program to make it onto the 747. And while the 747 was designed in the back office, Boeings 'best' engineers were spending the big bucks in the SST room. I guess the B-1 probably came out of some of that work.

 

Damn shame that UK aviation imploded. They had an amazing ability to think outside the square & some very funky designs. I love UK aviation museums! And I did get to see a loud & spectacular Tornado flying at the 1988 Australian International Airshow which came in fast & low then pulled straight up in a blaze of afterburners until it disappeared into space!

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It's hard to know MEC.

 

I totally agree on the 767, the mystery to me is why they did not let it take over from the 737, scale it down or up, the design had a lot of legs and it's a very human aircraft, one you can be comfortable in. Not something I can really say of any 737, they are just a conduit.

 

I'd assume the 747 concept was pretty much a reinvention of the heavy lifter but it needed a complete rethink. A Heavy lift for the airforce would have had to have been high-wing just for starters, 747Fs are ok freighters but they can't do what a C-5 or C-17 does, not designed for it.

 

The engines were a bit of a concern in the early days of the 747 and they may be in the initial service entry of the 777X, that aircraft is going to have some proving to do to get ETOPS approval.

 

Early 747s were almost routinely arriving at Heathrow transatlantic with an engine out - something the airlines stayed quiet about - still had three left 🙂 It was a different world then but the 747 went a very long way before they lost one, at Nairobi, and that was a mix of poor cockpit ergonomics and pilot error.

 

Dunno about the B-1, that was a Rockwell effort but behind the scenes the industry does a lot of co-opertition . The Bone was really only intended to be interim but it has given sterling service beyond its use-by date, which is now being extended again by a few years.

 

Through it all the B-52 just keeps soldiering on, 2050 is not unreasonable at the moment - amazing aircraft when grandsons of its original pilots are flying it.

 

UK aviation was done in by idiot politicians, with the best of intentions.

 

Post WWII there really were too many companies with too little money so the pollies forced mergers. Simply put they went too far and took competition out of the mix.

 

They were never really big sellers but the VC-10, BAC-111 and Trident were all excellent aircraft.

 

It was just that Boeing had gone the hard yards and figured out how to sling engines under the wings leading, paradoxically, to a lighter more flexible wing than the rear engine designs had to adopt. Given that the 727 is a bit of a mystery 🙂

 

The Tornado was way after my time and never seemed to garner much respect but I do know a couple of guys that flew them and thought it was a perfectly ok aircraft, although as one once remarked not a terribly good fit for UK needs.  That was probably a very correct statement, the Mark III at best was a stand-off interceptor, you would never have wanted to turn and burn in it, despite the swing wing a Tomcat it was not.

 

Endemic of the UK pollie interference for decades that seems to finally be over with the Typhoon II - I kind of ache to know I will never have a hope of flying one  🙂

 

Good to have you back talking aviation   🙂

 

Cheers

 

 

 

 

 

 

 

 

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It would be nice if Boeing would come clean on just how much of an issue, if at all, these cracks are.

 

I suspect not much, to give a somewhat well known example every single Lockheed Orion always developed a crack in the main spar within a few hours of entering service but the crack never developed any further, no wings ever fell off and Orion pilots continued to throw them around with gay abandon.

 

On the other hand a Lockheed Hercules had its wings fold up on it whilst working as a water bomber in California in a horrible accident that killed all on board. There are a lot of C-130s in service and never any reports of cracks.

 

So it is worth inspecting but whether or not there is a need for rectification is not yet being admitted to. Because it is on 737s Boeing may rectify it just to keep that model above suspicion but it is more likely that they will simply keep an eye on it. Cracks can and do appear in airframes that relieve stresses and then progress no further.

 

The only reason I'd be worrying over it is that the "pickle fork" serves not only to join the wing to the fuselage but also supports the undercarriage so a hard landing could worsen the cracking. However the aircraft would be on the ground so perhaps they will just add an accelerometer to report hard landings then necessitating further inspection.

 

There could of course be a completely opposite outcome, that replacement/rectification is required on the entire NG fleet. That would be extremely non-trivial and quite likely not even possible.

 

I really do not think so though. Boeing keep a test article running ahead of the fleet in a mix of ground and airborne stress testing, they have done since the 707, the immortal Dash 80 that is now in the Smithsonian collection, so they get alerted to any stress issues before it affects the fleet.

 

That approach has only failed once, with the Aloha flight that lost the roof. Boeing, and everyone else had not factored in the frequency of pressurisation cycles that  Aloha's unusual short flight scheduling involved.

 

RyanAir are primarily a short haul carrier so if cracks in NG airframes are going to appear you would expect them, and Qantas with the Sydney/Melbourne route, to be the canaries.

 

Alert but not alarmed probably sums it up at this stage.

 

Cheers

 

 

 

 

 

 

 

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787 ... potentially 25% of oxygen cylinders will not work when it's needed. We hope they actually fixed the problem

 

 

Edited by Jeruselem

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 Never know with those reports, when was the last time anyone was saved thorough use of an emergency oxygen mask ?

 

No excuse of course but it can be difficult to know if the damned things actually work or not.

 

Cheers

 

 

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Sound like the non-union South Carolina plant has quality control issues

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That's possible, but I have no idea where the oxy generators were sourced from.

 

So far as I know Boeing do not make them themselves.

 

In the end it is an imperfect world, most of the time the holes in the cheese do not line up, some times they do...

 

Cheers

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The problems with the MAX go deeper than just MCAS but at least we now know that Boeing are getting to the bottom of it:

 

https://www.businessinsider.com.au/boeing-737-max-flight-computer-redesign-delay-simulator-2019-11?r=US&IR=T

 

A re-design of the actual computer design goes a lot further than rewriting some code.

 

The question arises, yet again, how did the aircraft get certified when a non-duplicated or better system was in the design, one that if it failed would not be taken off-line but would be believed ?

 

It really is crazy to the point of criminal stupidity.

 

Throughout there have been mutterings from first world pilots about training and that may well be a factor but if Boeing pilots had trouble in the simulator under certain conditions then it is not a safe design - end of story.

 

At least the FAA are, finally, really holding Boeing to account and are not going to let anything slip by by the sound of it, about time but the whole debacle is going to tarnish the reputation of the FAA for a good time to come.

 

Cheers

 

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Well give the pilots the ability to turn of bloody MCAS off if they have to.

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Ah.

 

It has always been possible, in fact easy, to turn off MCAS even if you do not know what is causing the misbehavior because the manual doesn't mention it.  The switches to disable auto trim are at the rear of the throttle quadrant. It was those switches that the dead heading pilot on the Lion Air flight the day before the crash selected off.

 

The problems lie in recognising that you have "trim runaway" which you don't really, that is a different situation but same outcome, and in the software laws that cause it to operate.

 

Agreed the simplest is indeed  to turn off MCAS but it appears that it can be rather persistent or was, in turning itself back on. That comes about by the non-intuitive way in which it was set up to interact with flap settings and autopilot engagement. When the crew ran into problems in the simulator in June it would appear Boeing had at that stage only reduced the authority of MCAS.

 

Now they are having to, or rather are in the process of, a complete redesign of the Flight Control system bringing it in line with current best practice.

 

What is not apparent and may or may not be an issue because MCAS is absent in other earlier designs is if the somewhat antiquated way in which the flight control computers operate is also the case on for example the NGs.

 

I don't THINK it is the case but not being a 737 pilot I don't know for sure.

 

For Boeing's sake I hope it is not and that the MAX was an aberration brought on by oversight when dealing with the pitch up issue.

 

However one thing we can be pretty certain of, if I'm asking that question the FAA will ask it as well.

 

It seems the deeper things go with this the more issues are uncovered.

 

Cheers

 

 

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Re pickle forks, they are airframe fittings which distribute major loads around and along the fuselage, and also also incorporate failsafe functionality where the fuselage meets the wheel well, wing aft spar, landing gear load point. If you find cracks "repair before further flight". Boeing say you cannot fly the aircraft until the issue is resolved... and I've heard the fix is presently about 1800 man hours over 11 days using an expert Boeing team. Intensive! Boeing are working on a better solution.

 

AD: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/b7003a93c909869e8625848800467eb9/$FILE/2019-20-02.pdf

 

From the AD: "Do a detailed inspection for cracking of the left and right hand side outboard chords of the STA 663.75 frame fittings and failsafe straps adjacent to the stringer S-18A straps, in accordance with Boeing MultiOperator Message MOM-MOM-19-0536-01B, dated September 30, 2019. If any crack is found, repair before further flight using a method approved in accordance with the procedures specified in paragraph (k) of this AD. Repeat the inspection thereafter at intervals not to exceed 3,500 flight cycles" (which is roughly every 2 years).

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Yeah, essentially it sort of holds the aircraft together.

 

They are not really giving out much info on where and how severe the cracking is but obviously are treating it seriously.

 

Cheers

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That pickle fork thing was obviously under-engineered as it's supposed to last the lifespan of the plane.

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Hmm.

 

As I alluded to with Orions structural members can crack as a means of stress relief and the cracks go no further. I've no idea if that would or could be the case with pickle forks.

 

The other possibility is heavy landings I suppose but a question could be raised over whether the  structure has been beefed up as the 737 has become heavier or if it is still stuck at the size or whatever of earlier models of 737.

 

It' s not something my friends who fly them are likely to know, pilots don't generally get THAT far under the skin of their aircraft.

 

Qantas have been at pains to say it is no big deal but from what MEC has found it's a pretty intensive rectification.

 

Really there is not much info around about it at all apart from the fact they have been found, not in particular just how. I'd suspect boroscopic examination for such a deep structural member but again, don't know.

 

Cheers

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Yeah,

 

 That problem has been bubbling along for a while, RR have some serious issues to resolve with the Trent-1000.

 

It's a shame, the 787 is from all accounts a lovely aircraft.

 

A mate of mine in Perth has flown on it a few times on the Christchurch service, thoroughly enjoyed it.

 

Cheers

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Yes.

 

RR make great engines but in their war, essentially, with the American manufacturers they have it seems pushed the envelope a bit far.

 

They have been in that mess before so I'm pretty certain they will get over it but that is not very helpful right now.

 

It does make me a little concerned though about the ETOPS rating on the 787 - that rating is directly relevant to engine reliability. I'd imagine the operators of the aircraft are having to be particularly pedantic over maintenance schedules.

 

Which possibly explains NZ having to cancel the Perth flights. It might not look it on a map but potentially a Christchurch/Perth flight can be entirely over water with long gaps between diverts although not out to the extent that it OUGHT to impact the rating.

 

I suspect it is as much as anything NZ tearing their hair out a little over only having four engines in reserve and RR having big production delays.

 

Cheers

 

 

 

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737 = Old

737 NG = Pickle fork issues + other issues

737 Max8 = MCAS and other issues

787 = Engine issues

777 = OK

777x (not flying) = Engine issues

747 = Old

 

 

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🙂

 

To a degree you can line up Airbus much the same.

 

Nothing as old as the 737 of course but the 340 is gone the 380 is going and everything else is a 300 derivative including the 350.

 

That is however how Airbus intended it to be, a scale up/scale down/scale out platform. It's only now that they need to be thinking of something new. Which will be interesting, what new is there apart from supersonics ?

 

Boeing will get over it, but they are in a decided mess at the moment. Incidentally you missed the 767, so would I but actually because of the KC-46 the line is still open.

 

That could be a good thing for Boeing the 767 was persistently overlooked when really it is a great aircraft that has not been marketed for years.

 

Cheers

 

 

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10 hours ago, chrisg said:

The problems for Boeing seem to be never ending...

Ye don't seem to be able to take a trick do they.

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Yeah,

 

It is actually starting to impact scheduling with so many aircraft being taken off-line or not able to be delivered. I guess that may even push fares up - hope not, my daughter is due to come visit 🙂

 

Cheers

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