How are those new 787

[CaptnKirk]

2 years late and counting

After all the ridicule that was directed at the development problems with the Airbus line it looks as if McBoeing isn't doing much better.
(Alan Mulallay of Ford Motors fame, used to be a big wheel with Boeing as well - wonder if he knows anything about automobiles)

Boeing didn't want to be just another Airplane Factory, they wanted to be a 'Just-in-Time'
final assembly house,
just outsource all the real work to other enterprises, off-shore as much as possible, and rake in the dough.

How about that little 'Fastener' problem

Engineering Mistake

Pictorial

Domestic parts outsourced to Wichita
(Spirit was one of Boeing's facilities which was sold off)
They are claiming that this doesn't affect the 'Dreamliner', but I expect that it does, and will, they just haven't anounced it . . . yet.

 

[PottedMeat]

I don't understand how making the bevel deeper could be hard - isn't there some jig + drill they could make with a stop?

 

[CaptnKirk]

Chamfer with a 90* countersink to accomodate the maximum radius of the head to shank interface clears the 'throat' of the fastener installation.
Most countersinks in metallic structures of an airframe - Rivets, Hi-Loks, Shear Pins use the industry standard of 100*.

Countersunk fasteners into composite structues use either a 120* or a 130* angle to allow for a larger head size feature to reduce tension loads
into the graphite to prevent a 'pull-through' of the head bearing load, because composite are less capabile of habdling that type of loading.

It appears the the specification for chamfer used too shallow of a cutter - either the 100*, 120*, or the 130* cutter bit recommendation
and instead of using the 'correct' cutter for fastener raduis relief, the took the cheapest way out.

Now they have micro-cracks due to compression interfenence for each fastener in each and every compromised position.
The replacement procedure for these fasteners will include have to remove each fastener at these locations, ream the hole to at least the next available oversize fastener,
which is 4 to 5 times the cost of the standard fastener, again chamfer and inspect the hole, then install the correct length fastener.
That will take a minimum of 30 minutes per hole to do, including mechanical labor and inspection action - 8,000 holes minimum per plane.
Times 12 planes.

If they have to go the the second oversize fastener, that in itself is a 10 times cost increase for that fastener used in the location, and
again - ream, chamfer, verify hole, install and seal fastener into structure.

It failed cabin pressurization - not a way be make FAA certification.

I'll almost bet that these defective parts were outsourced to a company that was overseas where the language was not English
(Japan Composites) and the discrepancy can eventually be traced back to translation and engineers with minimum experience in
their jobs, who were just cranking out documentation - words where they really didn't comprehend the impact of being incorrect.

Like hitting Mars at 33,000 miles an hour because they forgot that there was a difference between English and Metric measuring systems.

 

[Farang]

dear god man where did you go to school

 

[PottedMeat]

Originally posted by: Farang
dear god man where did you go to school

Sounds like experience heh.

I didn't know they had 12 planes put together though.

Wouldn't something this serious come up after the first one - how many planes are in the pipe?

8000 original -> 8000 larger fasteners = significant weight increase?

Will rechamfering the holes remove all the damage caused by the previous fasteners?

 

[umbrella39]

Originally posted by: Farang
dear god man where did you go to school

Indeed. Now I remember why I got out of machine tool design. Guys like the OP made me feel stoopid

 

[daniel49]

Originally posted by: CaptnKirk
2 years late and counting

After all the ridicule that was directed at the development problems with the Airbus line it looks as if McBoeing isn't doing much better.
(Alan Mulallay of Ford Motors fame, used to be a big wheel with Boeing as well - wonder if he knows anything about automobiles)

Boeing didn't want to be just another Airplane Factory, they wanted to be a 'Just-in-Time'
final assembly house,
just outsource all the real work to other enterprises, off-shore as much as possible, and rake in the dough.

How about that little 'Fastener' problem

Engineering Mistake

Pictorial

Domestic parts outsourced to Wichita
(Spirit was one of Boeing's facilities which was sold off)
They are claiming that this doesn't affect the 'Dreamliner', but I expect that it does, and will, they just haven't anounced it . . . yet.

Never enough time or money to do it right, but always enough time and money to do it over.
An all to often approach by management.

 

[filetitan]

His well informed, Thanks for the information there OP.

 

[ElFenix]

the many supplier approach using a lot of offshore suppliers was to try to get those countries' national airlines to buy the 787. same reason airbus tries to distribute stuff all around as well.

 

[skyking]

Failing initial pressurization tests does not sound good. Considering the stresses that repeated cylces will put into those parts, I am not getting a warm fuzzy secure feeling about the dreamliner.

 

[jpeyton]

Originally posted by: skyking
Failing initial pressurization tests does not sound good. Considering the stresses that repeated cylces will put into those parts, I am not getting a warm fuzzy secure feeling about the dreamliner.

Everyone dreams soundly with six feet of dirt tucking them in.

 

[freegeeks]

good news for the airbus A-350 program

 

[Squisher]

From the pictorial it looks like they bottomed out a chamfer of a low head screw. There isn't a good experienced mechanic that couldn't feel the difference between the feel of something bottoming out and something tightening correctly. I'd have to chalk this up to inexperience, although like CaptnKirk said an engineer doing his job correctly would have allowed them to be assembled by someone with less experience.

This is why people are your most valuable resource.

 

[CaptnKirk]

Originally posted by: Squisher
From the pictorial it looks like they bottomed out a chamfer of a low head screw. There isn't a good experienced mechanic that couldn't feel the difference between the feel of something bottoming out and something tightening correctly. I'd have to chalk this up to inexperience, although like CaptnKirk said an engineer doing his job correctly would have allowed them to be assembled by someone with less experience.

This is why people are your most valuable resource.

The fastener most likely would have been a Shear-Pin like a Hi-Lok or it's derivative the Eddie-Bolt.
Even a sandard type bolt or a specialty bolt could have been used, without a washer,
providing the chamfer was both wide enough and deep enouth.

If you add (2 x (max) radius) to the bolt diameter, and add another 0.005 you will clear the radius by the diameter and within tolerance.
IF you don't go deep enough, like too shallow of a countersink angle,
the bolt's lower radius contacts the inside chamfer before the head seats.

That's why you use 90* - to eliminate the risk. Depth and diameter are met together.

Countersink Cage to control depth of cut (by diameter readings) for 90* Cutter bit design, order specialty item.

You just have to put together the combination it takes do do it correctly.


And Airbus would have to do it right too.

 

[Squisher]

Originally posted by: CaptnKirk

Originally posted by: Squisher
From the pictorial it looks like they bottomed out a chamfer of a low head screw. There isn't a good experienced mechanic that couldn't feel the difference between the feel of something bottoming out and something tightening correctly. I'd have to chalk this up to inexperience, although like CaptnKirk said an engineer doing his job correctly would have allowed them to be assembled by someone with less experience.

This is why people are your most valuable resource.

The fastener most likely would have been a Shear-Pin like a Hi-Lok or it's derivative the Eddie-Bolt.
Even a sandard type bolt or a specialty bolt could have been used, without a washer,
providing the chamfer was both wide enough and deep enouth.

If you add (2 x (max) radius) to the bolt diameter, and add another 0.005 you will clear the radius by the diameter and within tolerance.
IF you don't go deep enough, like too shallow of a countersink angle,
the bolt's lower radius contacts the inside chamfer before the head seats.

That's why you use 90* - to eliminate the risk. Depth and diameter are met together.

Countersink Cage to control depth of cut (by diameter readings) for 90* Cutter bit design, order specialty item.

You just have to put together the combination it takes do do it correctly.


And Airbus would have to do it right too.

I still can't believe that someone didn't feel that something was wrong when they were tightening it. Even at the end of a torque wrench it is easy to feel the difference between something seated correctly and the sponginess of tightening against a counter sink. Also, maybe the bolts were in a counter bore but according to that pictorial I find it hard to believe someone didn't catch the fact the heads weren't flush against their mating surface.

I have caught thousands of engineering oversights. In this case it is pretty straightforward, but at other times there is just no way an engineer can see everything.

 

[CaptnKirk]

Originally posted by: Squisher

I still can't believe that someone didn't feel that something was wrong when they were tightening it. Even at the end of a torque wrench it is easy to feel the difference between something seated correctly and the sponginess of tightening against a counter sink. Also, maybe the bolts were in a counter bore but according to that pictorial I find it hard to believe someone didn't catch the fact the heads weren't flush against their mating surface.

I have caught thousands of engineering oversights. In this case it is pretty straightforward, but at other times there is just no way an engineer can see everything.

It should have been caught with a 'gap to shank' check under the fastener head, using a 0.002 feeler gauge.
I doubt that they would have been in a counterbore pocket, but even then,
a radius releif on the pilot to body if a cutter would have prevented this from occuring.

we'vde been doing this for over 40 years - it ain't a new problem, it's an old trap.

 

[da loser]

typical problem with oursourcing. internal documents aren't really clear and depend on the intimate contact with the designers.

"But the documents were confusing. The regular spec document for installing fasteners sent the mechanic to another spec if composite plastic was being drilled. This spec then correctly sent the mechanic back to the first if the fastener head was on the titanium side, as in this case.

But a sub-specification that supposedly superseded the second spec contradicted the main spec with a table containing different and inaccurate measurements. A separate document clouded the instructions further."

 

[wwswimming]

Originally posted by: PottedMeat8000 original -> 8000 larger fasteners = significant weight increase?

how did they make all those holes line up without CAD ?

i have to hand it to the 2 really good manual layout guys i've worked
with (draftsperson designer types) - their ability to make no mistakes
over a period of years - in the pre-CAD days - was very impressive.

 

[CanOWorms]

A lot of the hatred of Airbus comes from the French government threatening genocides if other countries do not purchase Airbus. Many people still have not forgotten the EU-led French airline purchase threats to the economic stability of countries devastated by the massive tsunami a couple of years ago.

 

[CaptnKirk]

Originally posted by: wwswimming

Originally posted by: PottedMeat8000 original -> 8000 larger fasteners = significant weight increase?

how did they make all those holes line up without CAD ?

i have to hand it to the 2 really good manual layout guys i've worked
with (draftsperson designer types) - their ability to make no mistakes
over a period of years - in the pre-CAD days - was very impressive.

Most of this is match drill/ream on assembly, locate pilots of smaller hole size within 0.030 & final fastener operation, then countersink.

 

[freegeeks]

Originally posted by: CanOWorms
A lot of the hatred of Airbus comes from the French government threatening genocides if other countries do not purchase Airbus. Many people still have not forgotten the EU-led French airline purchase threats to the economic stability of countries devastated by the massive tsunami a couple of years ago.

please take your meds