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Old 07-09-2008, 03:40 PM
  #1304  
Grodus
 
Join Date: Mar 2006
Location: Hensley, AR
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Default RE: Bob Cat Copy Falcon 120 Jet


ORIGINAL: tim777jet

Following a bounce that damaged my L/H main gear mounting last month, I had a really good inspection around the airframe. I noticed a slight hairline crack around the side of the fuselarge at the front of the engine mounting structure. I found that both sides of fuse had in fact cracked right through and after loading the engine mounting, i opened up the hairline cracks to show the extent of the damage. The structure in this area is adequate, but if the large balsa block (which is fitted inside the extreme rear the fuse during manufacture) had been extended say a couple of inches further fwd, it would have increased the strength in this area considerably. It is a nasty area to have to work in and there were many different ways to repair and strengthen the area, but I used simple engine bearers each side, bonded to the top of the engine mount area and one bolt fitted trough for extra piece of mind. The bearers are glued to the wind root ply formers and a 3/4 inch balsa block was shaped to fit inside the fuse right at the back and two additional balsa/ply blocks bonded to the rear but one frame to carry the ends of the bearers. Seems to be nice and strong now and bear in mind, my home built engine is a lot heavier than a comercial engine and to be fair, the plane has endured quite a few less than perfect landings and all on grass.
Tim,
After reading your post, I thought I should check my engine deck for cracks. I dont have any yet after 40 or so flights. Thanks for posting, I will check that area often.
Did you install the small cf rods that go from the trailing edge of the wing into the engine mount plate? Looking at your pics, It looks like you did. I am working on another Falcon with some improvments. The newer falcons have 4 wing bolts rather than 2 and I though about omitting the small cf rods but after this, I will make sure I put them in. The cf rods have to help some. I overlooked the need for additional support in that area until you pointed it out.

Cody