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Boeing 737 Max Recertification Testing - Finally.

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Boeing 737 Max Recertification Testing - Finally.

Old 21st Aug 2020, 18:38
  #241 (permalink)  
 
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I wonder, wouldn't it have been faster and cheaper just to fit the thing with a blue ring radar?
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Old 28th Aug 2020, 13:52
  #242 (permalink)  
 
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Testing by EASA set

https://www.easa.europa.eu/newsroom-...boeing-737-max

COLOGNE, August 27, 2020 - The European Union Aviation Safety Agency (EASA) has been working steadily, in close cooperation with the FAA and Boeing, to return the Boeing 737 MAX aircraft to service as soon as possible, but only once it is convinced it is safe.

While Boeing still has some final actions to close off, EASA judges the overall maturity of the re-design process is now sufficient to proceed to flight tests. These are a prerequisite for the European agency to approve the aircraft’s new design.

EASA has been working with the FAA and Boeing to schedule its flight tests, a process which has been hindered by COVID-19 travel restrictions between Europe and the United States.

The parties have now reached agreement that EASA’s flight tests will take place in Vancouver, Canada in the week commencing September 7, 2020.

Simulator tests will take place in the previous week (from Sept 1, 2020) in London Gatwick in the United Kingdom. The Joint Operations Evaluation Board (JOEB), will also take place in Gatwick, in the week beginning September 14, 2020.

[end quote]
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Old 28th Aug 2020, 14:23
  #243 (permalink)  
 
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What actions has Boeing to close off?
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Old 28th Aug 2020, 14:44
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Don't know - saw the EASA notice only.
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Old 28th Aug 2020, 16:04
  #245 (permalink)  
 
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If I had to take a guess it would be relating to the outstanding AoA integrity issue that Patrick Ky referred to in his EASA presentation "the four conditions that must be met before return to service". Therefore assume that EASA is waiting on Boeing's plan to get a 3rd or equivalent AoA sensor input into the system architecture.

I imagine that hell would have had to have frozen over before Boeing will commit to it. Hope they prove me wrong.
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Old 29th Aug 2020, 04:22
  #246 (permalink)  
 
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However, the Max engine / nacelles resulted in aerodynamic effects (similar to LEX) which required mitigation involving several parameters
Don't lose sight of the fact that hanging the CFM on the -300 and subsequent required the installation of the STS to overcome the very same issue that MAX presented with its still larger nacelle. Boeing patent here

https://patents.google.com/patent/US4676460A/en
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Old 29th Aug 2020, 14:10
  #247 (permalink)  
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While Boeing still has some final actions to close off,
This important consideration deserves a little more attention than Boeing and the FAA are enabling. One of two situations exists before an aircraft is presented for design approval evaluation - either it conforms to a defined design (that for which approval is being sought), or it does not. If the aircraft has some "final actions to close off", is it appropriate for Boeing to present it for evaluation, and approval? Sure, there may be developmental test flying, we all agree what that is, but if the plane is being presented for certification flight testing, it should be 100% compliant with the design configuration for which approval is sought.

I believe that EASA and the other international authorities are aware that Boeing and the FAA may have the cart before the horse a little with the MAX recertification, and are asserting that correct process be followed. After all, it was an apparent breakdown of the certification process which got them here in the first place! The certification testing process usually requires that the applicant present a completed "Declaration of Conformity" report, to certify to the authority that what is being presented for test conforms entirely to the design for which approval is sought. I hope that Boeing has had the courtesy to the authorities to complete the process in the intended order of operations.
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Old 29th Aug 2020, 22:10
  #248 (permalink)  
 
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The “what” in certification standards is black and white, the “how” in terms of how the aircraft meets that certification standard has many shades of grey. Rumour I am hearing is that with the new MCAS lite, the airplane can’t meet the certification standard in all circumstances, all though it is close to compliance. The FAA has apparently approved it anyway on the basis that sometime in the future there will be a third synthetic AOA input added.

EASA has indicated that they have not decided if they will accept this work around. The future of the MAX and maybe the company is hanging on the EASA flight test program in September.....
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Old 30th Aug 2020, 16:58
  #249 (permalink)  
 
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I don’t think it takes as long to add the necessary redundancy as it does for Boeing to conclude they must. The authorities should hold fast until the latter becomes reality. Forget about work-arounds and promises of changes to come. Compliance is compliance, and no partiality should be allowed, Taxpayer speaking!
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Old 31st Aug 2020, 21:28
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Pilot DAR

This times 1000%! Boeing is trying to get away with “we’ll address this later, take our word for it” crap. There should be no approval with a contingency for “final action”. Do it now, then get your approval. Simple. Why do they even chose this route after being through so much? Bloody nonsense.
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Old 31st Aug 2020, 22:04
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The lesson Boeing still doesn’t get. It is almost always cheaper to do to the job right than to do it over.....
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Old 1st Sep 2020, 08:12
  #252 (permalink)  
 
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As I understand it, once the Max has been rectified, each and every plane still needs to be updated and checked off as well.
How does the re-certification of the individual planes work? Will these planes need to be flown back to a Boeing facility? Many of these Max are on the ground scattered all over the world. Will local facilities be allowed to make the necessary changes? If done outside the USA, would each plane still require to be inspected by the FAA or will that be done by the respective local aviation authority?
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Old 1st Sep 2020, 08:39
  #253 (permalink)  
 
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We already know that, initially at least, the fix is purely to the flight control software (i.e. no third AoA probe or other hardware mods).

There seems no reason why, once the AD has been approved and issued, it shouldn't be able to be embodied locally.

That said, there will no doubt be issues on individual aircraft simply as a result of spending more than a year on the ground.
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Old 1st Sep 2020, 08:47
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No hardware mods? Boeing is said to have separated wiring harnesses as well.
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Old 1st Sep 2020, 15:46
  #255 (permalink)  
 
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I believe that some operators engineers have already been sent on training courses for the modifications so it looks like whatever is required will be embodied locally.
I've been joking with the engineers here that once the Max is back in service it would be a good idea for them to call in sick for a month or two, the first couple of weeks is probably going to be hell !
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Old 7th Sep 2020, 08:11
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Synthetic airspeed/AoA for the 737 MAX?

According to this and this (both dated 2020-09-06), which should not be considered as fact: under the pressure of European regulators, the Boeing 737 MAX would be modified to get synthetic airdpeed/AoA la 787, where multiple sensors are aggregated to get a more reliable airspeed and AoA indication.

There was mention of something on that tune in a Seatle Times article (2020-06-24) and another Bloomberg article (2020-08-24).

Any confirmation, details on the if, when and how? Or did I fell to clickbait or disinformation?

Last edited by fgrieu; 8th Sep 2020 at 12:57.
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Old 7th Sep 2020, 09:57
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Synthetic Air Data Estimation
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Old 7th Sep 2020, 18:38
  #258 (permalink)  
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Boeing agreed to come up with a synthetic airspeed for the 737 MAX - although not for return to service. It's something that would be developed and added per a timetable agreed to with FAA/EASA.
The difficulty for the MAX is that it doesn't have all the sophisticated inputs available on the 787 as inputs into a synthetic airspeed algorithm, so they need to come up with something new.
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Old 7th Sep 2020, 19:55
  #259 (permalink)  
 
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Boeing agreed but not for the rts? No, the authorities require it and accept some transition period without three independent sources. Only the authorities decide.
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Old 7th Sep 2020, 22:36
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The agreement with the authorities is that the synthetic airspeed is not required for return to service. However as part of the agreement, Boeing agreed to have synthetic airspeed available at a future specific date (I don't know the agreed to date, but it's part of the agreement).
This sort of agreement is not uncommon - particularly since (in this particular case) there is no regulation that specifies three sources, so the MAX technically is not out of compliance. No first hand knowledge, but I suspect the relevant regulation in this case is 25.1309 - which is basically a probability analysis - and hence can be open to interpretation of the probabilities.
The real question is what happens if Boeing doesn't have a workable synthetic airspeed algorithm available by the deadline...
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