Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures

Old 10th Oct 2019, 18:48
  #3001 (permalink)  
 
Join Date: Dec 2002
Location: UK
Posts: 1,907
Interesting aspects emerging from the link (8 Oct) @#3004
Checklist discussions involve those listed below; the last three could (or should) involve new annunciations / alerting.
Unreliable airspeed
Unreliable altitude
Angle of Attack (AoA) disagree
Speed trim failure
Stabilizer out of trim
Runaway stabilizer trim

Unreliable airspeed and altitude are linked to the ADC, as is unreliable AoA which invokes all three together; thence current discussions on multiple alerting, distraction, surprise, workload.
Might these now be separated somehow. Also how might unreliable AoA be integrated with stick shake; with only two sensors a difference can be identified but not which is correct, implying that stickshake cannot be differentiated true or false (as today).

Speed trim failure - new ? How engineered.
Stab out of trim; very interesting, how determined.
Runaway stab trim; similarly challenging, with significant issues involving crew alerting, crew reaction (drill and switching - modified switches?), and an unambiguous memory items.

No MCAS ‘FAIL’ (inhibited) annunciation ?

There is also the need for both flight control computers to be available for dispatch (MMEL). This suggest use of dual computing paths involving the critical trim functions.
safetypee is offline  
Old 10th Oct 2019, 19:01
  #3002 (permalink)  
 
Join Date: Jun 2019
Location: VA
Posts: 210
Originally Posted by safetypee View Post

Speed trim failure - new ? How engineered.
Stab out of trim; very interesting, how determined.
No MCAS ‘FAIL’ (inhibited) annunciation ?
  • Speed Trim failure is not new and has an associated annunciator on the overhead panel. Loss of Speed Trim is not a serious issue.
  • Stab Out of Trim is an annunciated malfunction that occurs when there is excess elevator displacement with the autopilot engaged. Also not new. This occurs when the A/P is unable (or slow) to trim the stabilizer. However, the current NNC procedures for Stab Out of Trim would actually delay the appropriate response if this occurs as a result of a Stab Trim Runaway with A/P engaged.
  • MCAS is a sub-function of Speed Trim, so presumably a MCAS inop malfunction will be indicated by the existing "Speed Trim" annunciator. Loss of MCAS would also not be a serious issue as long as the pilots maintained vigilance in regard to avoiding high-AOA situations.
Tomaski is offline  
Old 10th Oct 2019, 19:34
  #3003 (permalink)  
 
Join Date: Jul 2001
Location: London
Posts: 12
Originally Posted by Drc40 View Post

The industry duopoly exists for many reasons but that duopoly metric is probably going to shift heavily in one direction now. Not good for the industry, innovation and competitiveness
and here is the evidence of that ........ https://www.mro-network.com/maintena...s-mro-invoices Airbus would not be able get away with this if Boeing did not have the issues that they have.
STN Ramp Rat is offline  
Old 10th Oct 2019, 20:00
  #3004 (permalink)  
 
Join Date: Sep 2019
Location: leftcoast
Posts: 2
Originally Posted by STN Ramp Rat View Post
and here is the evidence of that ........ https://www.mro-network.com/maintena...s-mro-invoices Airbus would not be able get away with this if Boeing did not have the issues that they have.
Interestin- Airbus like Boeing is by definition a sole source supplier for the MRO data for their aircraft.
That puts them in the position nearly identical to an old U.S railroad executive - Colis P Huntington- about 140 years ago.
His motto was 'Charge all the ($) the traffic will bear plus a penny"
So airbus comes up with " Charge all the ($) the market will bear plus 1 % "
Grebe is offline  
Old 10th Oct 2019, 20:41
  #3005 (permalink)  
 
Join Date: Aug 2017
Location: Europe
Posts: 103
Originally Posted by STN Ramp Rat View Post
and here is the evidence of that ........ https://www.mro-network.com/maintena...s-mro-invoices Airbus would not be able get away with this if Boeing did not have the issues that they have.
That really is taking the p*ss !
Although IMHO Airbus have been taking the p*ss out of their customers for several years now.
I know they recently increased the price of their engineering support by several thousand, there is also more and more specialist tooling in the manuals that now have to purchased from Airbus, no alternatives are authorised. One example of this is one tool that if locally manufactured from an approved supplier would cost around 1500 - 2000 USD, Airbus charge 18,000 USD.
Webby737 is offline  
Old 10th Oct 2019, 22:11
  #3006 (permalink)  
 
Join Date: Nov 2006
Location: Auckland, New Zealand
Posts: 456
Originally Posted by Drc40 View Post
The bean counting pin heads and their MBA enablers are getting a long overdue and well deserved lesson in the importance of professional engineering, skilled end user (flight crews) critical input and quality control. The constant push of enhancing every possible smidgeon of “share holder value” might very well cripple the very same shareholders they supposedly held so near and dear. At the end of the day (or months/years) this dumpster fire will be extinguished with a dollar value of damages virtually impossible to fathom.
The trouble is that the bean counters and MBAs won't see it like that.

All they can see is $$$$ signs and for some of them the 346 lives lost is probably just collateral damage.
Chris2303 is offline  
Old 10th Oct 2019, 22:15
  #3007 (permalink)  
c52
 
Join Date: Sep 2007
Location: Surrey
Posts: 1,377
The remarkable thing to me is that A320 sales have not soared this year. In fact if BA buy their 200 737max Boeing look like winning the year;s sales battle handsomely. I guess a lot of customers are hoping for rock-bottom prices from Boeing and with Airbus unable to deliver for years, there's no incentive to buy from them.
c52 is online now  
Old 10th Oct 2019, 23:19
  #3008 (permalink)  
 
Join Date: Aug 2019
Location: Rocket City
Posts: 4
Originally Posted by bill fly View Post
Common sense should dictate the safest solution possible be used.
Ah, but the answer is safest practical, not possible.

Deciding what's practical is the hard part in light of diminishing returns.
The first million dollars reduces risk a lot. The next million much less reduction. The next million even less reduction.
How do you decide when it's not worth spending another million?

If an engineer said they could spend 5 million and delay the aircraft another year to mitigate a risk that was thought would never occur, would you as a manager say do it?

How about spending $100k to hurricane proof a house. On the gulf coast sure. 100 miles north, maybe.
But 300 miles north? Could be hit, but that's such a slim likelihood than no sane person would do it.
ST Dog is offline  
Old 10th Oct 2019, 23:38
  #3009 (permalink)  
 
Join Date: Jul 2002
Location: Ireland
Posts: 595
Originally Posted by ST Dog View Post

How do you decide when it's not worth spending another million?
When it starts to affect the forecast profitability of whatever product is being developed.
Speed of Sound is offline  
Old 10th Oct 2019, 23:40
  #3010 (permalink)  
 
Join Date: Jan 2008
Location: Melbourne
Age: 73
Posts: 11
As the financial crisis of the MAX drags on, compounded by potentially more costs and disruption with the NG pickle forks and delay with the 777X, if I was the CFO of an airline I would be concerned as to how secure my deposits for all Boeing model jets ordered was. I would be looking at how to protect my money in case Boeing do a repeat of GM where it was able to wipe out all its debts but keep on trading.
Giant Bird is offline  
Old 10th Oct 2019, 23:47
  #3011 (permalink)  
 
Join Date: Sep 2019
Location: leftcoast
Posts: 2
Originally Posted by Chris2303 View Post
The trouble is that the bean counters and MBAs won't see it like that.

All they can see is $$$$ signs and for some of them the 346 lives lost is probably just collateral damage.

Nope " lives lost" is/was a .000000x decimal point on the power point reference to failure probility versus $$$ to prevent- simply not worth it per MBA analysis.

Just business ..nothing personal . .

Grebe is offline  
Old 10th Oct 2019, 23:54
  #3012 (permalink)  
 
Join Date: Jul 2014
Location: Harbour Master Place
Posts: 625
Just business MBA style...
FIGHT CLUB Insurance Claim Scene | HD Video | 1999




Morphs into a real life case:Fight Club vs GMC Recalls



CurtainTwitcher is online now  
Old 11th Oct 2019, 00:35
  #3013 (permalink)  
 
Join Date: Aug 2019
Location: Rocket City
Posts: 4
Originally Posted by OldnGrounded View Post
Also, remember that we have been told that major changes to FCC operation are in the offing. Definitely a big deal.
This. The basic change to MCAS was simple and quick. Boeing had been working on it since Lion Air and it was probably ready in May or June.

Then changes with the FCC, based on the injected faults (when everyone went crazy over the use of a i286) that the FAA wanted, is taking a lot longer.

And from the WSJ article, looks like EASA is the one not liking the current iteration.
ST Dog is offline  
Old 11th Oct 2019, 01:12
  #3014 (permalink)  
 
Join Date: May 2011
Location: NEW YORK
Posts: 599
Originally Posted by c52 View Post
The remarkable thing to me is that A320 sales have not soared this year. In fact if BA buy their 200 737max Boeing look like winning the year;s sales battle handsomely. I guess a lot of customers are hoping for rock-bottom prices from Boeing and with Airbus unable to deliver for years, there's no incentive to buy from them.
Seems like a unique opportunity for a new market entrant. If the C919 were ready, the Chinese could be really making hay.
Even as is, this example of Western profit maximization at the expense of safety will not be forgotten. Few in Asia have reason to love the West and this incident will remind everyone there of the reason why.
etudiant is offline  
Old 11th Oct 2019, 12:21
  #3015 (permalink)  
 
Join Date: Apr 2008
Location: Paris
Age: 70
Posts: 274
Reuters JATR summaty

Reuters has the summary of the JATR report on both FAA and Boeing. It’s neither better nor worse than expected. Add pilot training issues and maybe maintenance errors and you get a few hundred so fortunately mostly not american dead.

If the corpses had been American in majority the response would have been more effective, the Boeing CEO would have been dumped, and very probably the airframe and training would get properly updated.

https://www.google.fr/amp/s/mobile.r.../idUSKBN1WQ0H8

Edmund
edmundronald is offline  
Old 11th Oct 2019, 13:47
  #3016 (permalink)  
 
Join Date: May 2000
Location: London, UK
Posts: 328
Seattle Times has a similar summary of the JATR findings:

https://www.seattletimes.com/nation-...oeing-737-max/

Is the JATR report public domain? Does anyone have a link to it?
SLF3 is offline  
Old 11th Oct 2019, 14:52
  #3017 (permalink)  
Thread Starter
 
Join Date: Apr 2015
Location: Under the radar, over the rainbow
Posts: 625
From the Reuters story on the JATR report:

The JATR report recommended the FAA review the stalling characteristics of the 737 MAX without MCAS and associated systems to determine if unsafe characteristics exist and if so, if a broader review of the system design was needed.

JATR said MCAS and those systems could be considered a stall identification or stall protection system, depending on how the aircraft handled without them.
It seems the panel may have some of the same questions and concerns as some posters here, who have sometimes been answered rather harshly.
OldnGrounded is offline  
Old 11th Oct 2019, 15:42
  #3018 (permalink)  
Thread Starter
 
Join Date: Apr 2015
Location: Under the radar, over the rainbow
Posts: 625
Originally Posted by SLF3 View Post
Seattle Times has a similar summary of the JATR findings:

https://www.seattletimes.com/nation-...oeing-737-max/

Is the JATR report public domain? Does anyone have a link to it?
Yes, it's public domain, but it hasn't been published yet. Reuters and NY Times got advance copies. Coming very, very soon.
OldnGrounded is offline  
Old 11th Oct 2019, 17:15
  #3019 (permalink)  
 
Join Date: Dec 2002
Location: UK
Posts: 1,907
Tom, #3002.
Thanks for the explanations; these are today’s aircraft - ‘as is’. The interesting issues are ‘what could be’ based on the latest reports, after modification.

The number of ‘Disagree’ alerts and attention-getting stick shake, all result from one failure (AoA), is a concern for the NTSB - pilot workload. Additionally, the consequential ‘Feel Diff ’ alert, AP disengage, and inaccurate EFIS low speed awareness, add distraction.

MCAS modifications could introduce further confusion. If MCAS remains part of the existing Speed Trim (I am not convinced that it is), then the necessary Speed Trim alert would also be given - exacerbating NTSB concerns, and also difficulty in selling the change to other regulators.

There is also need to consider AoA failures where MCAS would be unavailable immediately, not just after takeoff.

After takeoff, even with many distractions, pilots should conclude that stall avoidance and unreliable airspeed actions are required, neither require immediate awareness of MCAS state - it would be distracting.

However, with an AoA failure flaps up, then awareness of MCAS state is important. If MCAS failure / inhibit has to be deduced from many coincident alerts, more than currently deemed acceptable in other 737 variants, would again conflict with the NTSBs views.

There is little if any information on the extent of the flight envelope affected without MCAS operative - no ‘church arch’ diagram of speed / altitude.

‘Stab out of trim’ is currently only with AP engaged; so why raise the point now. If AoA for MCAS is to use both FCCs (most likely) then might this imply that there is a change in AP - MCAS relationship, AP remains engaged, but MCAS unavailable would again have to be deduced, strengthening the need for a new MCAS Unavailable alert.

Without technological detection and alerting for Stab Trim Runaway (not MCAS related after modification), these tasks still depend entirely on human perception. Thence irrespective of how much training is given, correct and timely perception cannot be assured, but in engineering terms assurance is essential for a range of situations including extremes of an uncontrollable aircraft and /or unrecoverable situations due to maximum trim offset.

safetypee is offline  
Old 11th Oct 2019, 17:44
  #3020 (permalink)  
 
Join Date: Jun 2019
Location: VA
Posts: 210
Originally Posted by safetypee View Post

‘Stab out of trim’ is currently only with AP engaged; so why raise the point now.
Because the current procedure actually delays the crew response to an actual runaway stab trim. I believe this may have been one of the issues in the E-CAB test failure in which the FAA determined that the procedure took too long to implement.
Tomaski is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.