Brad do you have a pics of the old and new latches?

On May 6, 2010, at 5:11 PM, Brad & Tracy Simmons wrote:

> I have replaced 6 IVP windows; 5 from the inside and 1 from the outside. I have bodyworked and painted one additional door with the window replaced from the outside.  
>
> Brent is correct in that replacing from the outside is actually easier in many ways. However, it is probably more difficult for a beginner to properly scarf in the carbon plies after reinstalling the glass, thus the door perimeter ends up a little proud of the fuselage.
>
> In the past, Lancair's position has always been to replace from the inside. When replacing oven cured prepreg skins (such as the cabin door skin)with hand laid wet layups, Lancair's rule of thumb is to rebuild with 1.5 wet lay-up plies for each original ply of cured prepreg. This gets pretty thick on the outside of the door. On the door window that was replaced elsewhere and brought to us for painting, we were not able to fair it in flush with the surrounding fuselage. Obviously the time and expense is much greater if you have to bodywork and paint the fuselage perimeter. If you can guarantee the shape can be retained, cutting the stiffner may prove to be less work overall.
>
> I have a jig to bondo the door into before we cut the stiffner away that guarantees the original shape. We'll also bolt a couple of temporary door latch receivers onto the door that allows the relocation of the latch to it's original location, minimizing or avoiding issues with latch adjustment. Typically two of the four studs can be saved anyway. If you cut the stiffner on the innermost angle, it can be rebuilt without even having to remove the seal!
>
> Some years ago, Lancair modified the latch brackets to eliminate the two countersunk screws per latch that were previously drilled through the plexiglass window perimeter. Every blown out window that we have replaced shattered because of these screws. I would encourage everyone to eliminate these by switching to the new style bracket if you have the opportunity.
>
> Regards,
>
> Brad Simmons
> Airframes Inc.
> Milan, TN
>
>
> -----Original Message-----
>> From: Brent Regan <brent@regandesigns.com>
>> Sent: May 4, 2010 3:23 PM
>> To: lml@lancaironline.net
>> Subject: [LML] Re: Cabin Door Window-IV-P
>>
>> Replacing the windows from the outside is the common practice and much
>> easier than attempting a replacement from the inside. This is especially
>> true for the door due to the stiffener and latch geometry and
>> placement.  I too had a bit of trouble accepting the concept but after
>> some thought and analysis it became clear that replacing the window from
>> the outside was the preferred option.
>>
>> The reason for original installation of the windows from the inside is
>> less a function of strength and more a function of labor and cosmetics.
>> Imagine the sanding work needed to fair in all the windows and the high
>> chance of slipping with some 60 grit. Ouch!
>>
>> Remember that the entire fuselage is a series of layers that are glued
>> together so it becomes a question of if you can get reasonably close to
>> the prepreg bond strength with a wet layup. A quick analysis shows that
>> the window area is about 400 square inches. If we assume a 10 PSI burst
>> pressure we get 4,000 lbs force. The window bond perimeter is about 100
>> inches so the stress is about 40 pounds per linear inch of bond, which
>> is about the peel strength. But the loading is cantilever, not pure
>> peel, and the tensile strength for Jeffco (now Rhino) 1307LV is better
>> than 2 KSI. Bottom line, no problem.
>>
>> The trick is to grind the door down about 0.060" around the window and
>> taper it out about 4" so that when the 6 bid carbon is applied the
>> original thickness is preserved. I made patterns to cut the wet layups
>> to shape to minimize the work around the window edge. Once the 6 bid is
>> on you can taper it back. The bid layers leave lines like a topo map so
>> it is easy to get an even taper BUT, this is NOT a repair for an epoxy
>> newbie.
>>
>> The BIG advantage of replacing the door window from the outside is that
>> you don't mess with the door shape or latches. When my friend blew a
>> window climbing over Colorado he landed in a remote town. He removed the
>> door and shipped it to me. I was able to replace the window,  paint the
>> outside of the door in primer, reassemble and adjust the latches, pack
>> and ship it to Colorado in less than a week. He was able to install the
>> door in about an hour and flew the plane home.....pressurized! Once home
>> he removed the door and took it to the paint shop. Now you can't tell
>> any work was done. You have to love composites.
>>
>> Regards
>> Brent Regan
>>
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>
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