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Has everyone suddenly forgotten how to build airplanes?

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

Has everyone suddenly forgotten how to build airplanes?

Old 13th Sep 2019, 15:21
  #21 (permalink)  
 
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Originally Posted by Joe le Taxi
It's an interesting point - how come Airbus gets away with this exemption just because the stick is on the side, while Boeing are required to create perfectly progressive stick feedback force, all the way to the extremes of the envelope, and in trying to meet the requirement, create MCAS? Progressive pitch force is a major design headache, from single engine homebuilts, right through to airliners. Meanwhile there have been several Airbus incidents, arguably attributable to the lack of stick force feedback.
....because Boeing philosophy is to give haptic feedback to the PF, whereas Airbus does not. So if that feedback is expected then it must be given.
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Old 13th Sep 2019, 15:36
  #22 (permalink)  
 
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Originally Posted by DaveReidUK
But the designer will have determined the C of G envelope within which the airlines can configure the cabin...
So, was the envelope specified incorrectly? Or did the 'airline' mis-configure the cabin. 'Airline' because (on this side of the pond) it's actually Boeing that builds the cabin per the customer's requests. The original envelope is checked as a part of the type certification using analysis and perhaps a few flight tests with test ballast. If it flies OK, the design is signed off. Then the customer comes along and requests a certain seating and cargo configuration. The design for that particular aircraft will again have to be analyzed and signed off for it's airworthiness certificate to be issued.

So, where did the process break down? A poor envelope specification up front? Or marketing caving in to a customer to cram in just one more row of seats? The article says Lufthansa is affected rather than all customers. So I suspect it's the latter.
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Old 13th Sep 2019, 16:37
  #23 (permalink)  
 
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Originally Posted by EEngr
So, where did the process break down? A poor envelope specification up front? Or marketing caving in to a customer to cram in just one more row of seats? The article says Lufthansa is affected rather than all customers. So I suspect it's the latter.
Good questions. The reduced C of G envelope that EASA has imposed obviously applies to all A320neo and A321neo aircraft, but it could well be that only Lufthansa's particular LOPA causes them a problem as a consequence.
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Old 13th Sep 2019, 17:04
  #24 (permalink)  
 
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Balance.

All you need is fatter folk in row 0.
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Old 13th Sep 2019, 19:00
  #25 (permalink)  

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When I trim my Airbus in DCT law for clean speed and then bring towards stall using a pitch up command on the stick, there is progressive force that needs to be overcome. No issue.

Next.

Oh, wait. If I have a stroke mid-way and let go off the stick, the nose drops down and does not hang up, or - heaven forbid - keep raising.

For those interested in the particular CG restriction on A320, please see my comment on the A321 thread.

Speaking of which: if the manufacturer discovers on a test rig something about the pitch response is not aligned with the book exactly, WITHOUT any prior in-service event or SIM observation, just by doing their QA homework properly, that is actually how you DO build an aeroplane. Not faultless, but responsible is the key word.

If I wanted to be mean, a little note would slip about how you can fully trim the Bus manually in and out of all settings at all corners of the envelope. But I am a much nicer person than that.


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Old 13th Sep 2019, 23:21
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Expecting a pilot who had 250 hours years before he started flying Airbus airplanes to actually know how to fly a normal airplane is a little much. I flew the A320 and loved it, but I spent years flying most of the Boeings first. There is a huge difference.
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Old 14th Sep 2019, 03:01
  #27 (permalink)  
 
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It’s “stick forward to lower the nose” type skills, not something esoteric like landing a tail dragger.
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Old 14th Sep 2019, 04:40
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I cannot understand how being a pilot of an FBW airliner is any lesser than a cables and pulley airliner pilot.

Does anyone criticise F16 or current FBW fighter pilot as being a lesser pilot than an F4 or A4 pilot?

Strange logics (no pun intended).

You are there to fly/operate a flying machine that 'makes money' for 'shareholders'. If you're lucky you have an aeroplane that makes doing that day in, day out easier and 'backs you up'.

If you wanna go 'flying', dislodge some quids out of your wallet and go fly a Maul!
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Old 14th Sep 2019, 04:54
  #29 (permalink)  
 
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Having flown both, I'd say “not at all”. Each has their challenges. But please do note that somewhere in the first few pages of the Airbus FCTM is the helpful advice that, when in direct law, one simply flies the aircraft like a conventional jet transport.
What do you expect that pro tip might mean to somone who has never done that?

i never really loved the manual flying on FBW, but then again I never HAD to, it was always done for skill retention only.
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Old 14th Sep 2019, 07:45
  #30 (permalink)  
 
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Is the C of G issue because of too much of a forward or an aft trim, or both scenarios?

If so, this maybe the case of a full Business class load in the front (and maybe cargo), and too few Y pax down the back, or vice versa...
Hardly anyone has checked bags anymore in Business so one cannot offset out of trim situations with the hold baggage.


We had a particular problem with Transavia Holland on a 737-200 used for the LGW-AMS scheduled services, which had a movable business cabin so you never knew much in advance of the variable loads - It was a pig to trim which for a 737-200 was unusual, but caused by a lot of extra metal installed in the front area due to some re-skinning (post Aloha HNL)
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Old 14th Sep 2019, 08:56
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Originally Posted by rog747
Is the C of G issue because of too much of a forward or an aft trim, or both scenarios?
If the reports are correct, Lufthansa is unable to seat pax in the rearmost row, which would indicate an aft C of G limitation.

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Old 14th Sep 2019, 19:59
  #32 (permalink)  
 
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Originally Posted by Joe le Taxi
...............how come Airbus gets away with this exemption just because the stick is on the side, while Boeing are required to create perfectly progressive stick feedback force, all the way to the extremes of the envelope, and in trying to meet the requirement, create MCAS? Progressive pitch force is a major design headache, from single engine homebuilts, right through to airliners..........
It’s not because Airbus has a “stick on the side”, and Airbus are not “getting away with anything” - they went through extensive certification to have the system approved. It is because the Airbus FBW has a well sorted, properly integrated fly by wire flight control system - as do many military jets. The side-stick instructs the five computers which in turn operate the flight controls, (even when flying manually). The Boeing 737 however, only has rods and cables and mechanical linkages from the 1950’s to operate its control surfaces.

An analogy might be modern cars having ABS braking systems. Cars without ABS require the driver to prevent locking the wheels in slippery conditions, ABS performs the anti-locking function ‘in the background’. Cars with ABS are safer in slippery conditions than those without.

(ABS also works on individual locked wheels. The driver of a non ABS car can only release or apply brakes to all the wheels simultaneously).
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Old 14th Sep 2019, 20:05
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The Lufthansa A320neo is tail heavy because they moved the lavs into the tail using the spaceflex option and did some modifications in the front to squeeze in two extra rows of seats. The tail heavy situation was known and because of it they didn't fit the inflight WiFi equipment either.
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Old 15th Sep 2019, 23:54
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i never really loved the manual flying on FBW, but then again I never HAD to, it was always done for skill retention only.
I never liked direct law in the simulator on the A320, in this case cables, pulleys and a yoke felt better as they gave the sort of feedback you needed to manually control an aircraft without the computers.

Any new type is going to have teething problems, the airlines always finish off the testing program for the manufactures by which stage anything major should have been picked up. It would be uneconomic and probably impossible to have a new aircraft absolutely perfect before the first delivery, some faults will only manifest themselves under very specific conditions or after a certain length of time in service.
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Old 16th Sep 2019, 13:30
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Lufthansa blocking off last row

This according to Aviation Week. Begs the question. If you removed the last row and re-configured the seat map so the ac would have one less row total but the 'new' last row would be in current position of the blocked row, would the CoG issue still remain?
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Old 16th Sep 2019, 14:19
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[QUOTE]would the CoG issue still remain?/QUOTE]

Maybe, the CG of pax stays at the same point but with a little less weight. So it depends.
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Old 16th Sep 2019, 15:15
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Originally Posted by b1lanc
This according to Aviation Week. Begs the question. If you removed the last row and re-configured the seat map so the ac would have one less row total but the 'new' last row would be in current position of the blocked row, would the CoG issue still remain?
Even if it cured the C of G issue, there would be little point.

Either way, you still have 6 sellable seats less than you started with, plus you'd have the cost of re-aligning all the PSUs, etc with the revised configuration.
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Old 16th Sep 2019, 21:00
  #38 (permalink)  

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Originally Posted by DaveReidUK
Even if it cured the C of G issue


There is a pitching moment attenuation issue, not a CoG one. To avoid manifestation of the problem a CoG restriction was put in place, until the flight controls are sorted out.
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Old 16th Sep 2019, 22:10
  #39 (permalink)  
 
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Originally Posted by FlightDetent
There is a pitching moment attenuation issue, not a CoG one. To avoid manifestation of the problem a CoG restriction was put in place, until the flight controls are sorted out.
Glad we got that sorted out.

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Old 16th Sep 2019, 22:22
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Originally Posted by robdean
The problem is essentially mitigated if the rear row of seats is unoccupied. Thatís not a fundamental aeronautical design issue, it is a 'Well, head office insist on another row up back' issue.
That sounds exactly like the Commercial Tail wagging the aeronautical dog.

Therefore, if there were no extra seats, the aircraft would have requisite stability?
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