installation of bushing to fill elongated hole

[Svorek]

Hi,

during installation of a BFC on an ATR72, I have some elongated and parasite holes to fill on structure (frames, floor beams, ... )
To fill one elongated hole on two parts joined by fasteners, I would like to apply a bushing according to ATR SRM.
First, the ATR SRM doesn't give data for the dimensions of the bushings (especially thickness and diameter of the shoulder). Where can i find these informations ?
Second, as the bushing is used to plug the hole, it is plain bushings and not a through-hole bushings. Did I have to put a rivet to join my two shouldered bushing ?

Thank you for your help.

 

[rb1957]

remember you're getting advise from the internet ... beware!

without knowing details, to repair an elongated hole ... open up to clean hole, watch edge distance,
if elongated hole is only in one member, and you do't want to copy the damage into the other piece, open up to a clean hole that you can then plug and then drill the original hole back and still have between 0.03" and 0.06" wall thickness in the plug, watch edge distance. make sure the plug is trapped.

possibly fill with freeze fit plug ? 0.001" to 0.002" bigger than the cleaned out hole.

not sure what "parasite holes" are ?


another day in paradise, or is paradise one day closer ?

 

[LiftDivergence]

You mention this is an SRM procedure but lacking dimensions for bushings. Are you saying the final hole diameter is within the SRM limits, but there is no spec for the particular bushing to use in the SRM, or are you saying the hole diameter maximum is not specified / exceeded?

A huge hole with a bushing can be dealt with statically but is generally a nightmare for DTE. The ATR 72 is definitely transport category and frames / floorbeams are very likely to be FCBS - check the SRM. If so, an unreinforced blown-up hole is a very poor detail.

As rb1957 says, a freeze plug would be better because it gives you some residual compressive stress surrounding the hole. But it is still not great. Freeze plugs should in my opinion go the way of stop drilling.

If you can't accomplish this bushing repair exactly per SRM, you might save yourself some analytical effort in the future by reinforcing the enlarged hole now.

Keep em' Flying
//Fight Corrosion!