LDRA
Topic Author
Posts: 262
Joined: Fri Jan 15, 2016 3:01 am

Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Mon Jul 08, 2019 7:07 pm

What you all think about requiring transport class aircraft to have fly-by-wire in order to get certified?

Fly-by-wire architecure provides opportunities for major safety features such as alpha protection, overload protection, over rotation protection etc.

Most newly developed models are FBW anyways. If a particular aircraft program chooses to use conventional control, they can always use the prove equivalence argument
 
GalaxyFlyer
Posts: 3141
Joined: Fri Jan 01, 2016 4:44 am

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Tue Jul 09, 2019 12:42 am

No good idea—it’s about meeting standards, not HOW the OEM meets them. Any new airliner is going to be FBW as it pretty essential. Even the bizjet manufacturers are increasingly going FBW even if there’s little performance advantage. It’s easier to design and build.

GF
 
strfyr51
Posts: 3768
Joined: Tue Apr 10, 2012 5:04 pm

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Wed Jul 10, 2019 9:19 pm

LDRA wrote:
What you all think about requiring transport class aircraft to have fly-by-wire in order to get certified?

Fly-by-wire architecure provides opportunities for major safety features such as alpha protection, overload protection, over rotation protection etc.

Most newly developed models are FBW anyways. If a particular aircraft program chooses to use conventional control, they can always use the prove equivalence argument

So? Exactly why would you need to mandate FBW? If it's efficient? People will seek it out? And? are you going to BAN Non FBW airplane Models?
There are Many airplanes flying today that are NOT FBW nd they fly safely daily. The only advantage I can see to FBW airplanes is in rigging and maybe Autopilot functions, It certainly is not easier to troubleshoot. FBW has it's place, But it need not be Mandated. It will mandate itself. By efficiency.
 
LDRA
Topic Author
Posts: 262
Joined: Fri Jan 15, 2016 3:01 am

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Wed Jul 10, 2019 11:53 pm

strfyr51 wrote:
LDRA wrote:
What you all think about requiring transport class aircraft to have fly-by-wire in order to get certified?

Fly-by-wire architecure provides opportunities for major safety features such as alpha protection, overload protection, over rotation protection etc.

Most newly developed models are FBW anyways. If a particular aircraft program chooses to use conventional control, they can always use the prove equivalence argument

So? Exactly why would you need to mandate FBW? If it's efficient? People will seek it out? And? are you going to BAN Non FBW airplane Models?
There are Many airplanes flying today that are NOT FBW nd they fly safely daily. The only advantage I can see to FBW airplanes is in rigging and maybe Autopilot functions, It certainly is not easier to troubleshoot. FBW has it's place, But it need not be Mandated. It will mandate itself. By efficiency.


Reason is FBW architecture offers envelope protection. Yes the current non-FBW models Are safe, but FBW will enhance safety. The technology for FBW is readily available and mature, hence there is no execuse for not making aviation safer
 
GalaxyFlyer
Posts: 3141
Joined: Fri Jan 01, 2016 4:44 am

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Thu Jul 11, 2019 3:45 am

There are other planes than airliners certified under Part 25, many wouldn’t justify FBW. No new airliner will be built without FBW. I thought pilots were supposed to be “envelope protection”; must be a new generation.


GF
 
SAAFNAV
Posts: 564
Joined: Wed Mar 17, 2010 5:41 pm

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Thu Jul 11, 2019 7:29 am

LDRA wrote:
Reason is FBW architecture offers envelope protection. Yes the current non-FBW models Are safe, but FBW will enhance safety. The technology for FBW is readily available and mature, hence there is no execuse for not making aviation safer


And yet you still have pilots crashing fully FBW aircraft.
Envelope protection is usefull, but not the only protection. You make it sound like non-FBW, non-envelop protected aircraft are falling out of the sky every day. For the biggest part, building something FBW is a cheaper/easier/more sophisticated solution than cables and pulleys and pushrods. The rest comes afterwards.
L-382 Loadmaster; ex C-130B Navigator
 
JayinKitsap
Posts: 1334
Joined: Sat Nov 26, 2005 9:55 am

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Fri Jul 12, 2019 3:28 am

Telling engineers a specific way to design is dangerous and also kills innovation. Its another field but a perfect example of the problems with this approach.

In steel building design the US building codes for 2 decades required moment frames to be designed in strict accordance to a prescriptive sketch, even calling out the type of the welds, stiffeners, etc. It prohibited alternates unless detailed testing was submitted, bolted connections that had more ductility were not allowed. DO IT BY THE SKETCH if you want your permit, certainly don't complain.

The 1994 Northridge quake happened. In the inspections afterwards one 14 story building that reported only minor damage was found to have every column cracked at some elevation with some cracked in up to 4 elevations. BAD WELDS, must be Bad Welds. However, it was found that the bad weld locations the weld broke, at the good welds the column failed. It turned out that Mohr's Circle and other Mechanics of Solids M201 identifies if you stretch a metal in the elastic range the other two directions shrink. Also, stresses must be considered in all directions. Well the Structural Engineer field forgot that, the beam to column weld was locked in 2D and sometimes 3D. So once the steel hit yield it just snapped as it couldn't stretch, no plastic behavior which was most of the safety factor.

The City of Seattle would not approve a moment frame building for over 6 months once this came out. It took almost 5 years to get the US codes fixed and solutions done - no required sketch these days. The basic answer was to create a plastic hinge location some distance away from the connection or to increase the intersection capacity to 125% of the strongest attaching beam. The critical location then would not ever go into plastic behavior.

The lesson learned - one must be 1,000% sure that everything has been checked before a prescriptive design approach must be used. For if it doesn't work the Agency is on the hook for huge damages in the lawsuits. Imagine the cost to replace all the pitot tubes on 10,000 airplanes to a design that is different!
 
426Shadow
Posts: 122
Joined: Tue Sep 11, 2007 8:13 am

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Fri Jul 12, 2019 11:45 pm

I think what the OP was really saying is "I want to take a piss on Boeing, so how can I disguise this so it doesn't get locked".

What the hell has happened to this website?
Do it on three, One.....THREEEEEEE! Just got the nuts hangin out.
 
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7BOEING7
Posts: 3017
Joined: Fri Oct 12, 2012 5:28 pm

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Sat Jul 13, 2019 12:18 am

426Shadow wrote:

What the hell has happened to this website?


it's the "clicks". Just like online news which have click bait headlines, a.net forums have trolls. How many pages would you see on a plane crash if it was a friendly/technical discussion -- at least 50-75% less. Without the trolls they wouldn't make any money.
 
N1120A
Posts: 26491
Joined: Sun Dec 14, 2003 5:40 pm

Re: Mandate fly-by-wire for transport class aircraft through Part 25 regulation?

Sun Jul 14, 2019 9:06 pm

Non-FBW aircraft contain envelope protection all the time. Sometimes to their detriment.
Mangeons les French fries, mais surtout pratiquons avec fierte le French kiss

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