substitute aluminum for 4130?

Phil wrote:
As I remember , it was the substitution of alum. instead of AN Steel bolts
that caused a Thorp T-18 to lose a wing panel at the EAA International
fly-in many years ago , would really want to do the numbers before I would
substitute any material on an aircraft , just the opinion of an old A/C
welder.
Phil Lohiser


I remember another that crashed because the builder used pop
rivets in the spar fittings instead of the AD rivets the plans called
for. Too many homebuilders have died because they made substitutions or
other changes without the knowledge necessary to do it. The designer
often has obscure but important reasons for the materials he specifies,
and the naive builder doesn't realize the peril he creates for himself
and others when he decides that he knows it already.

Dan