[DeTomaso] FW: NPC Probably not new to you aeroheads but wow-

[jgkrenton at comcast.net]

All:

CF can be and is regularly repaired. Boeing designed numerous repair schemes for their airplanes prior to introduction to service.  It does take specalized tools and training, but these repairs are successfully executed regularly. Remember we now have decades of battle damage repair experience with CF to draw from and decades of records of the type of damage an airliner experiences. 

Additionally, one of the advantages to CF is the ability to continuously change the thickness of the CF, so areas of the fuselage such as the door frames where the food service trucks often hit the fueslage are thicker to minimize the likelyhood of damage.  One of the sales demonstrations was to hand the airline executives a hammer and let them beat on a section of CF and see if they could hit it hard enough to damage it. No one did.

It's pretty good stuff.

Jeff/2467 and recently retired from a major CF airliner manufacturer in Washington State.


----- Original Message -----
From: Charles McCall <charlesmccall at gmail.com>
To: MikeLDrew at aol.com, gow2 at rc-tech.net
Cc: detomaso at poca.com
Sent: Thu, 18 Jun 2015 17:43:49 -0000 (UTC)
Subject: Re: [DeTomaso] FW: NPC Probably not new to you aeroheads but wow-

I would be very nervous about repairing a ding in CF. I’ve spent a good
amount of time watching the fabrication of Ailerons and flaperons for the
Boeing 777… They build the parts up by laying one very specific shape of
fiber on top of another very specific shape of fiber, building a sandwich of
interwoven pieces of cloth. The shape of these pieces of cloth is quite
important to the structure and strength of the final part. They are not just
long pieces of cloth laid one on top of another – it is hard to explain, but
the pieces of cloth are not uniform at all, If you could simply cut out a
bad part and attach a new part, then the fabrication process would be a
whole lot simpler and less expensive – they would do it that way from the
beginning. They may have 10 layers of cloth, each one sandwiched in a
different manner..

 

From: MikeLDrew at aol.com [mailto:MikeLDrew at aol.com] 
Sent: miércoles, 17 de junio de 2015 21:27
To: gow2 at rc-tech.net; charlesmccall at gmail.com
Cc: detomaso at poca.com
Subject: Re: [DeTomaso] FW: NPC Probably not new to you aeroheads but wow-

 


In a message dated 6/17/15 11 33 50, gow2 at rc-tech.net writes:





Ironically one of the problem with composites is repair. When you run
something like carbon fiber in a solid line from wing tip to wing tip, if
you punch it with an ice pick you have compromised the strength of the
entire string.



>>>...and I think that's something that may have been overlooked in the
stampede towards CF construction of airliners.  There are a lot of
minimum-wage boneheads driving catering trucks and whatnot that routinely
bump into the airplanes they are servicing, causing localized damage.  Such
airplanes are immediately withdrawn from service and undergo an inspection,
and then often a localized patch is applied and the airplane is ready to go
again in just a few hours.  It's not uncommon to see airplanes with multiple
such patches on the skin; eventually they will go for a heavy maintenance
(akin to a ground-up restoration in automotive circles) and then the
offending panels are removed and replaced with new ones.

This begs the question--how does a CF airplane respond when a bozo crashes
into it with a catering truck?  CF doesn't 'ding' as far as I know.  Can
localized repairs be made?

F-1 cars may prove reassuring in this regard.  Recall that at this year's
Montreal GP, Lewis Hamilton comprehensively smashed his car on the first
day's practice, hitting the wall hard, pieces and parts flying everywhere
etc.  The whole side of the car was demolished; however the team was able to
drag the wreck back to the garage and rebuild it overnight; he went on to
win the race.  So that gives some cause for optimism perhaps?

Mike