ORIGINAL: fly boy2
I finally got to madien my trainer, well I didnt madien it but I was still very pleased
, sun. was a learning experence for me, learned that I needed airspeed and to flare or I'll break my prop ( its was my first landing ) but still in one piece, I was told before we madiened it, that I needed longer screws and to use a nut, right now it just 4 40s treaded into the mount, What is longer than a 4 40 but same diameter, or will it be ok not to use a nut? I can get pics if needed
I suspect what you have are not machine screws (bolts) at all but instead self tapping sheet metal screws and number fours are appropriate for your size engine. Sheet metal screws in plastic beams are entirely approrpriate and work well and better in some cases where the bottom side of the beam has no flat for a nutted bolt and must be severely modified to work that way.
All Dave Brown mounts come with sheet metal screws for the beams and it works very well The screws do not generally protude all the way through the beam either. Different size srews are provided for the different sizes of mount from #2 to #8's and the proper bit size for the pilot hole is always indicated.
Its likely you do not need to do anything. Machine screws that have had a hole tapped or self tapping sheet metal screws works great and going through a big hassle just to have nuts is silly and in some cases not even pratical where the bottom of the beam is tappered.
John