Moose tailwheel (stinger & bracket assembly) design

[Ted Waltman]

Early in our Alaska trip, we stopped at the factory to get a new
stinger. While there I showed them that the delrin washer that sits on
top of the bracket assembly didn't fit correctly. After examining my
bracket assembly and two others they had there, Kevin and Brent came to
the conclusion that all the bracket assembly were too thick by 0.040.
Brent's comment, "That's a design issue we should tell Daryl about."

Later we assembled the entire stinger/tailwheel (including the wheel
which I had there). At that point Kevin noticed that there appeared to
be excessive side-to-side play in the bracket assembly. In other words,
when holding the stinger stationary, one was able to hold the wheel axle
and get perhaps 1/8" or more play in the bracket assembly. We did not
measure exactly how much play there was, but simply noted that, "It's
not right." Kevin and Brent took the bracket assembly apart and noted
that the pivot pin seemed to be loose in the bracket assembly. The
bracket assembly pivot "hole" was .875 per specs but the pivot pin was
only .872. Kevin tried perhaps 10 other pivot pins they had in the box;
all were .871 or .872. Brent said this was within spec and that Daryl
wouldn't change things. Kevin, and I, said, "Look, it's just not
right."

Brent offered to machine me a new one, which would take hours. Or, I
could make do. Brent reiterated that "Daryl will say this is within
spec and not change anything." I decided I already spent the better
part of the day and wanted to get going. I took the assembly as it was
and left.

As a side note, while I was watching Kevin work on the bracket assembly,
and with my two teenage sons in the room too, in walked Stephane. He
met us the previous summer at Oshkosh. Stephane didn't say Hi to any of
us; he didn't even acknowledge that we existed. Stephane proceeded to
berate Kevin over some personnel supervision issue right in front of us.
Of course, when Stephane left he didn't say "bye" either. Now that's
customer service. On the other hand, Kevin and Brent were absolutely
outstanding--they bent over backwards to get us what we needed.

So, we spent at least 6 hours at the factory; 6 hours of Kevin's time,
perhaps 3 hours of Brent's time and a good 2+ hours of a machinists time
(who works for Brent I assume), as well as 1/2 hour of another
machinists time on the NC machine making inspection covers for us.
Total labor time: upwards of 12 hours. All that time just because the
stinger attach-point and bracket assembly design is not right in the
first place. Multiply that indirect labor cost by that involved with
others on tailwheel issues and one would think Daryl would be getting
the message.

At this point I have 91 flight hours, perhaps an hour of ground taxi
time and exactly 39 landings on my new stinger and remachined bracket
assembly. My rearmost bulkhead now has two cracks in it (there weren't
any upon leaving the factory). I bounced two landings, but there were
not by any means serious bounces. Yes, I was operating at near gross
weight for the entire time. I talked to Robin about these cracks
perhaps half-way through my Alaska trip. Robin is a super nice and
extremely qualified person, so please don't get me wrong here. Anyway,
Robin said that some folks are basically cutting that rear-most bulkhead
off about 1.5" from the bottom and therefore eliminating the cracking
problem through that approach. Hum, that sounds like treating a symptom
rather than the root problem. Robin also suggested that I try to wheel
land the plane as much as possible. Another way to avoid fixing the
real problem. I'm not blaming Robin; he has to deal with a
fundamentally flawed design in the best way he can.

I jacked up the tail yesterday. Now I have 1/4" to 3/8" play
side-to-side as measured at the tailwheel axle. Hence, there is both
play in the bracket assembly pivot assembly and play (elongation most
likely) in the forward stinger attach bracket. I don't have any
bending, cracks or other signs of anything breaking in any of the
additional tail wraps or stinger attach points.

I've talked to a bunch of folks with all kinds of planes about what to
do differently. Thus far the best consensus seems to be to copy the
C-185 stinger attach design (which uses rubber bushings in effect at
both stinger attach points). One person also mentioned perhaps lengthen
the stinger by an inch or two to provide more flexibility in the stinger
itself.

Searching for answers, and definitely not pleased with status quo,

Ted Waltman




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[Scott Aldrich]

I wonder if Darryl has a clue that he is losing sales of the Moose due to
the landing gear. I have flown with a couple of guys at work that find out
I am building Moose and have said, "that's the big radial, the one with gear
problems right?" These guys have no interest in building an airplane but
have "heard" of the Moose's gear issues. Who knows they may be working on
it, we will never know, right up until they tell us.

In the mean time I said screw it and am sticking with my own
"reinforcements" for now. I will take it apart and redo when we come up
with a fix. Right now I know of at least seven guys with different fixes or
partial fixes (myself, Steve, Al, Hap, Bob, Jim and Skip). Maybe once more
of these get tested we will know which ones are the better or easiest ways
to go.

The put it on floats or do wheel landings is complete horseshit unless they
are working on it.

There is the other point of view, which maybe Darryl takes, that it is an
experimental - good luck, now it is your problem.

That is odd about Stephane, I had heard he was a good guy. Maybe having a
bad day?

Scott

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ted
Waltman
Sent: Thursday, July 28, 2005 5:40 PM
To: Murphy List
Subject: Moose tailwheel (stinger & bracket assembly) design

Early in our Alaska trip, we stopped at the factory to get a new
stinger. While there I showed them that the delrin washer that sits on
top of the bracket assembly didn't fit correctly. After examining my
bracket assembly and two others they had there, Kevin and Brent came to
the conclusion that all the bracket assembly were too thick by 0.040.
Brent's comment, "That's a design issue we should tell Daryl about."

Later we assembled the entire stinger/tailwheel (including the wheel
which I had there). At that point Kevin noticed that there appeared to
be excessive side-to-side play in the bracket assembly. In other words,
when holding the stinger stationary, one was able to hold the wheel axle
and get perhaps 1/8" or more play in the bracket assembly. We did not
measure exactly how much play there was, but simply noted that, "It's
not right." Kevin and Brent took the bracket assembly apart and noted
that the pivot pin seemed to be loose in the bracket assembly. The
bracket assembly pivot "hole" was .875 per specs but the pivot pin was
only .872. Kevin tried perhaps 10 other pivot pins they had in the box;
all were .871 or .872. Brent said this was within spec and that Daryl
wouldn't change things. Kevin, and I, said, "Look, it's just not
right."

Brent offered to machine me a new one, which would take hours. Or, I
could make do. Brent reiterated that "Daryl will say this is within
spec and not change anything." I decided I already spent the better
part of the day and wanted to get going. I took the assembly as it was
and left.

As a side note, while I was watching Kevin work on the bracket assembly,
and with my two teenage sons in the room too, in walked Stephane. He
met us the previous summer at Oshkosh. Stephane didn't say Hi to any of
us; he didn't even acknowledge that we existed. Stephane proceeded to
berate Kevin over some personnel supervision issue right in front of us.
Of course, when Stephane left he didn't say "bye" either. Now that's
customer service. On the other hand, Kevin and Brent were absolutely
outstanding--they bent over backwards to get us what we needed.

So, we spent at least 6 hours at the factory; 6 hours of Kevin's time,
perhaps 3 hours of Brent's time and a good 2+ hours of a machinists time
(who works for Brent I assume), as well as 1/2 hour of another
machinists time on the NC machine making inspection covers for us.
Total labor time: upwards of 12 hours. All that time just because the
stinger attach-point and bracket assembly design is not right in the
first place. Multiply that indirect labor cost by that involved with
others on tailwheel issues and one would think Daryl would be getting
the message.

At this point I have 91 flight hours, perhaps an hour of ground taxi
time and exactly 39 landings on my new stinger and remachined bracket
assembly. My rearmost bulkhead now has two cracks in it (there weren't
any upon leaving the factory). I bounced two landings, but there were
not by any means serious bounces. Yes, I was operating at near gross
weight for the entire time. I talked to Robin about these cracks
perhaps half-way through my Alaska trip. Robin is a super nice and
extremely qualified person, so please don't get me wrong here. Anyway,
Robin said that some folks are basically cutting that rear-most bulkhead
off about 1.5" from the bottom and therefore eliminating the cracking
problem through that approach. Hum, that sounds like treating a symptom
rather than the root problem. Robin also suggested that I try to wheel
land the plane as much as possible. Another way to avoid fixing the
real problem. I'm not blaming Robin; he has to deal with a
fundamentally flawed design in the best way he can.

I jacked up the tail yesterday. Now I have 1/4" to 3/8" play
side-to-side as measured at the tailwheel axle. Hence, there is both
play in the bracket assembly pivot assembly and play (elongation most
likely) in the forward stinger attach bracket. I don't have any
bending, cracks or other signs of anything breaking in any of the
additional tail wraps or stinger attach points.

I've talked to a bunch of folks with all kinds of planes about what to
do differently. Thus far the best consensus seems to be to copy the
C-185 stinger attach design (which uses rubber bushings in effect at
both stinger attach points). One person also mentioned perhaps lengthen
the stinger by an inch or two to provide more flexibility in the stinger
itself.

Searching for answers, and definitely not pleased with status quo,

Ted Waltman




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