Engine Mount Clearance Mod
Here is the IO-540 Engine Mount Clearance Modification
photo set sent to me by Scott Risan at Van's.
They have been very very good at dealing with this issue for me.
I think that hearing it from a few people now, they
that there may be a potential issue for some customers and they wanted
to figure it out a.s.a.p. and come up with a correction or a plan.
I sent them my engine mount via FedEx and they got it the
week. They actually analyzed it right away the first day they
it in, and dropped me a note. Then, on Friday (the next day),
they actually had someone come in to perform the welding so they could
ship it out that same day. (This is extra special, since the
who do this work 4 tens, and don't usually work Friday). They
also offered to powder coat the weld if I wanted to wait a week or so
for powder coating, but I opted to get the mount back a.s.a.p. so they
were going to try to ship it back Friday. Great
around in one day.
Here are some facts:
When they placed the engine mount in their test case, they had 3/16" to
almost 1/4" clearance. That's still not 1/2", but it's about
double what I had (.063 to .125") They feel there must be a
difference in the sumps. I gave them my sump numbers because
they want to investigate what the difference is. My numbers
and a number that looks like Z1902
They say they aren't seeing any problem with the brand new
Lycoming engines they're selling. Their first-glance look seems to
indicate that my sump may be an off number from what they are used to
seeing. Remember that any engine you buy, Aerosport, or any other
non-factory-new, will be a rebuild that will potentially be built out
of cases and sumps from any model year or number. This could cause some
of these small variations. There is no such thing as an "Aerosport
IO-540" as one list member wrote. They are all just rebuilds of other
IO-540's that aren't factory new....and can be of various previous
It is also interesting to note that according to Van's, the cross bar
in question was determined unnecessary by engineering, but someone
working with the engine mounts decided to add it anyway to add more
structure and support. Given the solid design, I'd believe this, but
when you see the mount, I think it's still best to have the bar there.
That said, I can't picture there being hardly any stress on this
particular joint. I could picture the "fix" being done without
welding....cutting the tube, and bolting in a curved piece. Of course,
a bolted joint would give more opportunity for corrosion where the
tubes meet, so I'm happy with the welding option.
So my modded engine mount is now enroute back to me, and I should be
able to hang the engine for next weekend. It was a bit of a pain, but
at least it didn't cause a major slowdown. My advice? Get your engine
and mount hung while you're working on the canopy and fuselage. Then
you can tell if you have any issues, and can pull it immediately and
send it out for rework without slowing anything down. I am under the
impression that Van's might be willing to work with future builders on
this problem. I am not sure if they plan to make this mod part of their
general contstruction in the future. If anyone gets that answer, let me
know. They have been very good dealing with this for me though. Thanks
Scott! (and Bruce)
Update after Engine Mount Returned
As you can see by the photos below, the engine mount came back
sucessfully, and it now has more clearance than it used to. I
don't think I have anywhere near 1/2" on the outside edges, but
probably at least 1/4" everwhere, and more in the center. I would
sure think this is enough, except I recently heard that the
throttle/mixture cables were actually supposed to go between the engine
sump and that bar....that I just don't think would be a good idea,
given the current state of that gap. One other thing I'd do
slightly different....The new bar curve is about 6" in length.
The sump is also about 6" wide. If they would have made
that curved piece about 7" wide instead, there would be more clearance
on the outer corners of the sump.
For those who might be interested in this tidbit:
I repainted that bar of the mount, because I didn't want to wait
for Van's to send it out for powdercoating. I mixed up a batch of
K36 Primer/Sealer, which uses 4 parts K36, to 2 parts Concept Paint,
plus DCX61 Hardner and reducer. This stuff almost perfectly
matches the powdercoat color, so it's amost unnoticeable and you'd
never know it was different unless you were looking really closely...in
person. I don't think you'll see any difference in the photos.
All in all, I think Van's did a good job on taking care of this for me.
Thanks to Scott Risan, and Bruce Reynolds, who were great to deal
with on this issue. I suggest to other builders that if you have
a problem with a part, definitely send them a photo, and call them by
phone to follow up. I think you'll get a better response if you
take the time to illustrate your issue for better understanding.
Same goes when posting to the RV-10 List....a picture is worth,
well, you know... :)