What is lost in all the debate about structural integrity of the wing spar cap with holes is that this is no longer an engineering issue. It's a regulatory issue now. It doesn't matter if "unauthorized" holes will or won't cause a failure. The FAA and/or the NTSB has decided it's a problem and they are going to dictate a solution. The only choice we have now is whether of not to give them information to arrive at an acceptable solution or let them make a decision in a vacuum. We can armchair engineer the holes all we want, but the fact is this is not going away by denying there's a problem.
Dave --- In [email protected], Bob Swinney <bobst...@...> wrote: > > For what it is worth, I am a Mechanical engineer and have worked with > structural engineers all of my life. Whenever I needed to route pipe, conduit > or whatever, the structural engineers would allow holes in the structural > members(I beams or whatever). I have seen some beams that looked like swiss > cheese. If the holes are not over a certain size and if they are placed > properly the integrety of the beam is not compromised. IT just has to > engineered! >  > As far as the breaking point being at a hole, that is normal. If a structure > is loaded past its limit it will break. If there is a hole or a deep > scratch near that point it will take the path of least resistance and go to > the hole or scratch. That does not mean the hole was the cause of the break... >  > An aeronautical engineer needs to analize the situation to determine the > effect of the holes... >  > Bob > > --- On Tue, 9/22/09, Hartmut Beil <hb...@...> wrote: > > > From: Hartmut Beil <hb...@...> > Subject: RE: [ercoupe-tech] Re: Approved holes? > To: ebengui...@..., "Techlist Ercoupe" <[email protected]> > Date: Tuesday, September 22, 2009, 10:36 AM > > >  > > > > Ed >  > Yes I pointed out before that the Alons have holes drilled for the bucket > seat installation. > That's why holes per se seem not be the problem. > But it would be up to UNIVAIR to pull out the engineering data to proof that > to the FAA and at the same time give an evaluation when holes are ok and > when not. >  > I don't see that happening. > What I see happening is that all 415 Spars with not approved holes will be > damned to be replaced. >  > Is anyone having a 337 that shows holes drilled into the spar cap for seat > installation? >  > The only 337 I have on file does that not. http://www.ercoupe. info/?n=Main. > CessnaSeats >  > Hartmut > >  > > > To: ercoupe-tech@ yahoogroups. com > From: ebengui...@aol. com > Date: Tue, 22 Sep 2009 08:42:11 -0400 > Subject: [ercoupe-tech] Re: Approved holes? > >  > > > Morning All > Regarding holes in spar cap: > Alons basically have the same wing spar as the Coupe. > Without going into nomenclature details, > Alons have approximately 16 holes on the spar cap to accept seat brackets. > Does anyone know of any problems > with Alons falling apart because of these approved holes? > Ed > > > > > check out the rest of the Windows Liveâ¢. More than mailâ"Windows Live⢠> goes way beyond your inbox. More than messages >
