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Boeing 737 Max Recertification Testing - Finally.

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Boeing 737 Max Recertification Testing - Finally.

Old 13th Jun 2020, 00:59
  #41 (permalink)  
 
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Update on Spirit's 2020 737 MAX ProductionWICHITA, Kan., June 10, 2020 /PRNewswire/ -- On June 4, 2020, Spirit AeroSystems [NYSE: SPR] received a letter from Boeing directing Spirit to pause additional work on four 737 MAX shipsets and avoid starting production on sixteen 737 MAX shipsets to be delivered in 2020, until otherwise directed by Boeing, in order to support Boeing's alignment of near-term delivery schedules to its customers' needs in light of COVID-19's impact on air travel and airline operations, and in order to mitigate the expenditure of potential unnecessary production costs.

Based on the information in the letter, subsequent correspondence from Boeing dated June 9, 2020, and Spirit's discussions with Boeing regarding 2020 737 MAX production, Spirit believes there will be a reduction to Spirit's previously disclosed 2020 737 MAX production plan of 125 shipsets. Spirit does not yet have definitive information on what the magnitude of the reduction will be but expects it will be more than 20 shipsets.

The 737 MAX grounding coupled with the COVID-19 pandemic is a challenging, dynamic and evolving situation. During this time, Spirit plans to work with Boeing to determine a definitive production plan for 2020 and manage the 737 MAX production system and supply chain.

Due to the matters described above, Spirit has elected to place certain Wichita hourly employees directly associated with production work and support functions for the 737 MAX program on a 21 calendar day unpaid temporary layoff/furlough effective Monday, June 15. In addition, Spirit will declare an immediate reduction of the hourly workforce in Tulsa and McAlester, Okla., effective Friday, June 12.
https://www.spiritaero.com/release/1...max-production
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Old 13th Jun 2020, 07:44
  #42 (permalink)  
 
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Originally Posted by rotorwills View Post
Whilst I am under a nda, it doesn't cover my entire life. I have physically seen more than 1 fully installed Max Sims outside the US. I have not been to Africa or the Far East for many years. So as one can see some previous posters are not up to speed. As to why they venture outside their realm of knowledge I sometimes take my own cynical view.

On the matter of the thread and it's contents, I have no direct knowledge of when any certifications will be made. One thing I can conjecture is that the FAA alongside Boeing are under pressure from Federal authorities to get the MAX into the marketplace as quickly as possible just solely based on the USA financial positions due to the pandemic.

If I was a betting man I may take a punt that the MAX will be in operation before this year is out.
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Old 13th Jun 2020, 09:15
  #43 (permalink)  
 
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Mayam13, is there a point you wish to make, as I don't understand the relationship to my post and your photo?
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Old 13th Jun 2020, 11:19
  #44 (permalink)  
 
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Originally Posted by rotorwills View Post
Mayam13, is there a point you wish to make, as I don't understand the relationship to my post and your photo?

Yes ..I have points, pardon me for not attaching my comments .
1. Both Lion Air and Ethiopian aeroplane pilots were not exposed to max simulators during their watered down 'difference' training
2. I admit one airline did acquire a simulator two months before crash.
3. The second photo I attached, gives EASA requirements, before re-certification. It asks for 70 test points in simulator.
4. The elaborate wiring re-routing suggests, the EMC-EMI checks integrity,is in question. It could be one of the delegated checks to Boeing engineers by FAA.
5. What about B 737 NG, does this aeroplane also require wiring changes?will Boeing clarify?
6. My point is that, Boeing underplayed simulator training for customer airlines .
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Old 13th Jun 2020, 11:56
  #45 (permalink)  
 
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Fine, obviously lots of comments regarding this have been made over the past year or so no need for me to add comment. I was only advising on available MAX sims outside of the USA.
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Old 13th Jun 2020, 22:15
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There are 3 MAX sims in the UK at Gatwick. 2 at Boeing Flight Training and one just round the corner at L3. I have trained/checked on both Boeing sims, while the L3 sim is still, I believe, to be certified.
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Old 15th Jun 2020, 06:07
  #47 (permalink)  
 
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Interesting facts here by Juan on the latest with the Max.
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Old 15th Jun 2020, 11:58
  #48 (permalink)  
 
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737 Max retrun to service / synthetic airpseed

This article seems well written and well informed. The interesting (at least to me) element is the simmering tensions between the FAA and EASA, the application of the ISSA process to the Max, and the idea that the Max may return to service and then have synthetic airpseed retrofitted later. Lots in here to disagree on!

https://theaircurrent.com/aviation-s...r-jets-return/
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Old 15th Jun 2020, 20:22
  #49 (permalink)  
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Correct me if I am reading this wrongly , but I deduct the following :
FAA could alone allow the return to service by September . so for US domestic use only.
EASA will need to perform its own re-certification process to allow it in EASA land, and that will take an extra few months.
Adding Synthetic airspeed could take 2 years and adding a 3rd mechanical AoA is really not feasible , and yet one of the two is required later by EASA ?
Yes lots to disagree on !
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Old 15th Jun 2020, 20:46
  #50 (permalink)  
 
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It's either synthetic airspeed or harware third vane,
Synthetic airspeed incorporates a modelled third vane so to speak.

I am reading some speculation about a possible "deal" between the lines to add the synthetic airspeed some time down the road. How feasible that is from a regulatory point of view ... I find it doubtful.
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Old 15th Jun 2020, 20:54
  #51 (permalink)  
 
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Wouldn't that require another major software change later on to integrate the "third" vane into the systems and protections?
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Old 15th Jun 2020, 21:11
  #52 (permalink)  
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Assuming the synthetic airspeed is only a software update, that can be done on the aircraft quickly and easily - a few hours, including any functional checks/validation. Such software changes are fairly routinely done on an overnight.
Flight critical software updates are not real common, but are not exactly rare either - once every year or two being fairly typical. The main reason they are not more common is that the validation and certification of flight critical (i.e. DAL A) software is very time consuming and expensive. What tends to happen is less important changes/updates go on a sort of wish list. Then, when something important comes down (or sometimes if the wish list gets long enough) that justifies a change, they decide which of the wish list items should also be included.
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Old 15th Jun 2020, 21:55
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A few hours?!?!?! This requires the programming of cascading sets of Kalman filters...the first set of calculations has to normalize the pitot/static differences due to the local flow effects of the respective locations. Since the MAX pitot are fixed, and AoA are free to rotate, the effects must be compensate for in the sideslip flow. (MAX does not have sideslip indicators.)
Since the MAX only has 2 ADIRU's, the computing power is already used up.
The second set of Kalman filters will balance the differences, and the third set of filter will provide the synthetic resultant.

Who expects this many levels of filter to provide an accurate resultant, especially given the software issue that BA currently has???

They should have simply added another AOA sensor to the tail, and either hard wired it in...What about replacing the 2 pitots with the combi pitot AoA??? now instead of 2 AoA, they would have 4, and how difficult would that wiring have been???
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Old 15th Jun 2020, 23:31
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In regards to Ian W’s post: Can you link to the expert assessments that this virus “will just stop”? I’ve never heard any such thing. And what’s with the term “hypochondriac' flights” after an accounting of hundreds of thousands of deaths worldwide between January and June just this year? We all hope for the best but this post is by Ian W doesn’t contain any factual or attributable information. The issue of restarting Max 8 production likely has rationale that Boeing, as a business, is justifying. Not the non-fact that Covid-19 will just stop.
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Old 16th Jun 2020, 00:28
  #55 (permalink)  
 
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Surely a synthetic airspeed system would be more than a simple software upgrade ? The sources used to calculate it would need to be tied in to some form of computer with the ability to reject an erroneous input, calculate a value and then display it. This is more likely to require a major upgrade of the system, possibly a hardware change as well.
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Old 16th Jun 2020, 00:30
  #56 (permalink)  
 
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Originally Posted by turbidus View Post
A few hours?!?!?! This requires the programming of cascading sets of Kalman filters...
I'm pretty certain tdracer was referring to the time involved in installing an update, not the time required to do the software writing.
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Old 16th Jun 2020, 01:22
  #57 (permalink)  
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Originally Posted by krismiler View Post
Surely a synthetic airspeed system would be more than a simple software upgrade ? The sources used to calculate it would need to be tied in to some form of computer with the ability to reject an erroneous input, calculate a value and then display it. This is more likely to require a major upgrade of the system, possibly a hardware change as well.
My educated guess is that they are going to use the flight control computers - which already receive data from several other systems (ADIRU, GPS, etc.) - to calculate a synthetic airspeed when the normal ones either disagree or are judged to be unreliable. So it would be a basic s/w update to the flight control computers.
If they can't do it all in s/w and need some sort of hardware update, all bets are off. But updating the flight control computer s/w is a long established process once the new software is certified.
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Old 16th Jun 2020, 08:03
  #58 (permalink)  
 
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It's fair to say, I think, that implementing synthetic airspeed is a far greater effort - development resource wise as well as computational resource wise - then validating two AOA readings against each other.
Given the time it took them (or better takes them, 'cause their are still not done) and the problems they encountered when implementing the later gives a pretty clear idea of a lower limit time and trouble wise synthetic airspeed is going to take. Do not forget that the synthetic airspeed information has yet to be included in other systems, their diagnostic routines, mode switching, warnings, etc.
Personally I would expect either upgraded hardware or maybe even another box (e.g. 3rd air data unit), which might be a more effective solution, becoming neccessary. Kalman filters are efficient but have tight real time requirements. From what we have learnt about that FCU ... difficult.
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Old 16th Jun 2020, 08:48
  #59 (permalink)  
 
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Originally Posted by BDAttitude View Post
It's fair to say, I think, that implementing synthetic airspeed is a far greater effort - development resource wise as well as computational resource wise - than validating two AOA readings against each other.
Was the latter ever a realistic option ?
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Old 16th Jun 2020, 08:49
  #60 (permalink)  
 
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With caveat that we do not have full details of the MCAS modification, it is difficult to connect what has been been disclosed with the reported certification differences - #48.

Cross monitoring two vanes shuts down MCAS, preventing a hazardous condition. This should enable the aircraft to be flown safely to complete the flight - with care. Three vanes would be better and could enable a higher level of safety.

AoA error post mod, apparently, also shuts down both ADCs and FGCs (?) (pressure error correction - UAS, no airspeed, and other system effects), this also degrades or removes stall warning (continuous stick shake); again three vanes would help.

MCAS mods could be acceptable in isolation, but the consequences of loss of AoA on a safe recovery might not (stby airspeed / alt, manual trim, no stall warning, autoslat, feel), i.e. technical mods meet CS 25, but the operational consequences would not meet CS 25.1301/1309; thus focus on JOEB, ISSA.
There could be technical agreement enabling return to service, operational modification could be deferred (exposure time / magnitude risk), but proposed action would have to be agreed before return to service.

A further puzzle is reference to Synthetic Airspeed. It could be a valuable aid with loss of ADC function, alleviating consequential concerns, but current SA designs appear to rely on AoA, the loss of which caused the loss of ADC in the first place !!!
Can inertial data alone replace AoA aspects used in SA (787), would it be sufficiently accurate for continued flight, approach, and landing, or to restore lost functions.

Airbus views the temporary use of BUSS for the management and recovery of ADC malfunction (AirbusWIN, flt ops support); what is the Boeing view re 787 - procedure detail?

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