Gidday,
Not sure who was asking but I dug up an old e-mail regarding this bolt
length problem and here it is. Hope it helps.
Hope the original owner of the message doesn't mind.
Reg
Tony Renshaw
>In mounting the quick connect bellcranks to the wing, I found that the port
>bolt seems too short unless the counterbore is substantially deeper than the
>5mm specified. I calculate the bolt lengths required as follows:
>
> Port Stbd
>
>Spar 1.256 1.276 Includes 3 layers of bid added
>each side
>S03 1.273
>3 Washers .173 .173
>BC4W10 .560 .560
>Nut .210 .210
>2 Threads .050 .050
> -.200 -.200 Counterbore reduces length
>required
> ------ -------
> 3.322 2.069
>
>The bolts supplied were: port = AN4-31A, stbd = AN4-20A. The port bolt
>supplied is 0.2in shorter than I expected while the starboard bolt agrees
>with the calculated length. In practice, the starboard bolt is fine and the
>port bolt does not go all the way through the nut. The manual indicates that
>the port counterbore may need to be slightly deeper that the starboard
>counterbore, possibly to accommodate this.
>
>So, has anyone else run into this? I am hesitant to double the depth of the
>counterbore since this seems more than "slightly" deeper. Bob Berube says I
>am the only one who has called about this (probably because I am a first time
>builder so I don't have a sense of what might cause trouble later so I try to
>err on the side of conservatism).
>
>In the same area, what is the typical clearance between the bolt ends holding
>the wing mounted bellcrank vs the CS14 mounted bellcrank? I have less than
>0.1in on the stbd side. Might these come in contact as the wings are inserted
>or will the lift pins prevent this?
>
>John, A044
>
In answer to your concern about the counterbore depth for the AN4-31A bolt,
you will need to counterbore to a depth of around 15mm, which I agree is
more than "slightly deeper than 5mm".
The pivot bolts of CS15 and W16 do end up very close to each other. Some
clearance is necessary, of course.
You may find that the bolt end of CS15's pivot will contact the edge of the
spar mounted bellcrank W16 unless the aileron is held in its neutral
position when rigging or derigging the wings.
Regards
Andy
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Web Site at www.europa-aviation.co.uk
Fax No 44 1751 431706
-------------------------------------
Reg
Tony Renshaw
Builder No.236
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