Svein,
Thanks very much for a beautiful description, a great job!
Got it and will use it.
Thanks,
Ralph
MG
Reno, nv
Sidsel & Svein Johnsen wrote:
>
>
>On Saturday, I praised the cowling flange mod mentionded in Europa News 4
>years ago. A reader asked:
>
>
>>What is the Europa's flange mod? I'm rapidly getting to that point of the
>>
>>
>build.<
>
>For those not having that old issue of Europa News, I quote the description
>below. As it is not possible to send attachments, I hope the below "sketch"
>will suffice to replace the drawing accompanying Europa's text. It will
>perhaps be more clear if you draw one line through all the "u"s (upper
>cowling half), one line through all the "l"s (lower cowling half) and one
>line through all the "a"s (additional flange) (55 years since I last did
>this - remember the childrens' drawing books!).
>
> u
> u
> u a
> u a
> u a
> OUTSIDE u l a INSIDE
> u l a
> u l a
> l
> l
> l
> l
>
>quote
>As called up in the build manual, a total of 19 bolts are used with which to
>fasten the upper cowling to the aircraft. Adding a glassfibre flange to the
>inside of the upper cowling will enable you to reduce the number of bolts
>required down to 11.
>
>The additional flange holds the two cowlings together and prevents
>"quilting" or bulging between where the bolts are. To make the flange, tape
>the two cowlings halves together and set them such that you can get access
>to the inside. Scuff sand the upeer cowling where you will be laying up the
>glassfibre flange and apply some adhesive backed plastic tape to the lower
>cowling flange to act as a release agent.
>
>Lay-up two 3 bid strips at +-45 degr, about 1 m long and 5 cm (2") wide.
>Apply each strip to overlap half on the upper cowling and half on the lower
>cowling flange and allow to cure. Turning the edge of the flange away from
>the lower cowling will aid fitting the two cowlings together but it's not
>essential.
>
>The flange should be interrupted where the fasteners are on the joint line.
>Dimensions are measured around the cowling's perimeter. See below figure.
>unquote
>
>My substitute "sketch" )o = fastener):
> FRONT o 5" (127 mm) o 11" (280 mm) o 20" (508 mm)
>o REAR
>
>There must be misprint in the newsletter - the new number of fasteners will
>be 15, not 11, between the upper cowling and fuselage/lower cowling. You
>may wonder why all this effort to save just 4 bolts and fasteners. The main
>advantage is not this, but that you avoid the bulging - it is really
>significant if the new flange is not added.
>
>I did not figure out an easy way to make the edge turn away from the lower
>cowling, as called for in the above quote. Instead I cut the new flange back
>5 mm after cure. I can then press gently on the outside of the upper
>cowling and it enters over the lower cowling.
>
>Another recommendation: When you apply the plastic tape to the lower
>cowling flange to act as a release agent, do this AFTER you have placed the
>two cowling halves together, and let the tape go 1-2 mm onto the upper
>cowling. This seals off the joint and no epoxy gets in between the two
>original flange surfaces and bond them together. If that should happen, it
>would not be easy to pry them apart after the new flange is made.
>
>I don't think tape will hold the two cowling halves nicely together, as the
>text suggests, with the tendency for the cowlings to bulge and mechanical
>stress when handling the thing during this work. I used thin self-tapping
>screws with washer head, placed where I intended to have the fasteners and
>some in between - easy to fill the holes later.
>
>Regards,
>Svein
>A225 - now in Norway
>
>
>
>
|