Re: PT Rudder Hinge-to-Bracket Interference

[Pete Crawford]

'Hi Group,
I was fit-checking the rudder to the vertical stabilizer on my PT-26
before closing up the stab after rebuilding. One of the two holes of
the center rudder hinge (p/n 6623) would not go in far enough to
engage the hole of the stab bracket (p/n 66313). Examination showed
the hinge was hitting the bracket bolt. There are also witness marks
on the hinge which showed this interference was present when the
rudder was previously installed, but maybe not to this extent.
(Note - this rudder had never been installed on this fin.)

I measured the leg of the hinge which would not engage and there was
about 0.050" more material on that side of the hinge than on the side
which would engage, which is why one side would engage and the other
wouldn't.

A similar condition exists on the bottom hinge (same p/n) - bracket
(p/n 66316) combination, to the extent that the bracket hole was
slightly egged-out due to the hinge bolt being driven home during its
previous life! There were even thread marks in the bracket hole!

Has anyone seen this condition before? It must not be that uncommon
as all my hinges seem to suffer from the same disease. Any guidance
would be appreciated.
Thanks,
Pete Crawford'

[Michael Denest]

'Pete,
Have you tried to fit your rudder to another fin?
Sounds like something happened to the alignment in the
rebuilding process or the rudder hinge post may be in
question. Out of round bolt holes are not a good
thing! I've not seen the condition you are
describing, something is really wrong here. Can you
engage the bolts doing one hinge at a time? Refitting
parts from one aircraft can be tricky when fitting to
another aircraft, given the age of the parts. Sorry,
I can't offer more.

Mike


--- Pete Crawford wrote:

>
> Hi Group,
> I was fit-checking the rudder to the vertical
> stabilizer on my PT-26
> before closing up the stab after rebuilding. One of
> the two holes of
> the center rudder hinge (p/n 6623) would not go in
> far enough to
> engage the hole of the stab bracket (p/n 66313).
> Examination showed
> the hinge was hitting the bracket bolt. There are
> also witness marks
> on the hinge which showed this interference was
> present when the
> rudder was previously installed, but maybe not to
> this extent.
> (Note - this rudder had never been installed on this
> fin.)
>
> I measured the leg of the hinge which would not
> engage and there was
> about 0.050" more material on that side of the hinge
> than on the side
> which would engage, which is why one side would
> engage and the other
> wouldn't.
>
> A similar condition exists on the bottom hinge (same
> p/n) - bracket
> (p/n 66316) combination, to the extent that the
> bracket hole was
> slightly egged-out due to the hinge bolt being
> driven home during its
> previous life! There were even thread marks in the
> bracket hole!
>
> Has anyone seen this condition before? It must not
> be that uncommon
> as all my hinges seem to suffer from the same
> disease. Any guidance
> would be appreciated.
> Thanks,
> Pete Crawford
>
>
>
>

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[Curt Kinchen]

'Hi Pete, Other ideas that come to mind.

1. Have you tried flipping the stab bracket? Unlikely, but perhaps
it's not entirely symmetrical?

2. Is the hinge casting smooth? or is there a casting mark that
could be ground off to provide the clearance?

3. Could rotating the bracket bolt head do enough to provide
clearance?

4. Shouldn't require this, but consider going to a low profile
(NAS1104) or 12 point reduced head bolt for attaching the brackets.

5. The other thing that often crosses my mind is, if you're using
NOS surplus parts, were they surplussed because they were rejected
parts that weren't built per drawing? Not likely in this case, but I
wonder sometimes.

The vertical was just rebuilt on my PT before I bought it and I
remounted the rudder. I do recall them being close, but I'll take a
look and see if they make contact. I also have a spare rudder and
I'll see if there are any witness marks on those hinges.

Curt Kinchen

--- In fairchildclub@yahoogroups.com, Michael Denest
wrote:

> Pete,
> Have you tried to fit your rudder to another fin?
> Sounds like something happened to the alignment in the
> rebuilding process or the rudder hinge post may be in
> question. Out of round bolt holes are not a good
> thing! I've not seen the condition you are
> describing, something is really wrong here. Can you
> engage the bolts doing one hinge at a time? Refitting
> parts from one aircraft can be tricky when fitting to
> another aircraft, given the age of the parts. Sorry,
> I can't offer more.
>
> Mike
>
>
> --- Pete Crawford wrote:
>
> >
> > Hi Group,
> > I was fit-checking the rudder to the vertical
> > stabilizer on my PT-26
> > before closing up the stab after rebuilding. One of
> > the two holes of
> > the center rudder hinge (p/n 6623) would not go in
> > far enough to
> > engage the hole of the stab bracket (p/n 66313).
> > Examination showed
> > the hinge was hitting the bracket bolt. There are
> > also witness marks
> > on the hinge which showed this interference was
> > present when the
> > rudder was previously installed, but maybe not to
> > this extent.
> > (Note - this rudder had never been installed on this
> > fin.)
> >
> > I measured the leg of the hinge which would not
> > engage and there was
> > about 0.050" more material on that side of the hinge
> > than on the side
> > which would engage, which is why one side would
> > engage and the other
> > wouldn't.
> >
> > A similar condition exists on the bottom hinge (same
> > p/n) - bracket
> > (p/n 66316) combination, to the extent that the
> > bracket hole was
> > slightly egged-out due to the hinge bolt being
> > driven home during its
> > previous life! There were even thread marks in the
> > bracket hole!
> >
> > Has anyone seen this condition before? It must not
> > be that uncommon
> > as all my hinges seem to suffer from the same
> > disease. Any guidance
> > would be appreciated.
> > Thanks,
> > Pete Crawford
> >
> >
> >
> >
>
>
>
>
> __________________________________
> Do you Yahoo!?
> All your favorites on one personal page ? Try My Yahoo!
> http://my.yahoo.com

'

[Curt Kinchen]

'Hi Pete, Other ideas that come to mind.

1. Have you tried flipping the stab bracket? Unlikely, but perhaps
it's not entirely symmetrical?

2. Is the hinge casting smooth? or is there a casting mark that
could be ground off to provide the clearance?

3. Could rotating the bracket bolt head do enough to provide
clearance?

4. Shouldn't require this, but consider going to a low profile
(NAS1104) or 12 point reduced head bolt for attaching the brackets.

5. The other thing that often crosses my mind is, if you're using
NOS surplus parts, were they surplussed because they were rejected
parts that weren't built per drawing? Not likely in this case, but I
wonder sometimes.

The vertical was just rebuilt on my PT before I bought it and I
remounted the rudder. I do recall them being close, but I'll take a
look and see if they make contact. I also have a spare rudder and
I'll see if there are any witness marks on those hinges.

Curt Kinchen

--- In fairchildclub@yahoogroups.com, Michael Denest
wrote:

> Pete,
> Have you tried to fit your rudder to another fin?
> Sounds like something happened to the alignment in the
> rebuilding process or the rudder hinge post may be in
> question. Out of round bolt holes are not a good
> thing! I've not seen the condition you are
> describing, something is really wrong here. Can you
> engage the bolts doing one hinge at a time? Refitting
> parts from one aircraft can be tricky when fitting to
> another aircraft, given the age of the parts. Sorry,
> I can't offer more.
>
> Mike
>
>
> --- Pete Crawford wrote:
>
> >
> > Hi Group,
> > I was fit-checking the rudder to the vertical
> > stabilizer on my PT-26
> > before closing up the stab after rebuilding. One of
> > the two holes of
> > the center rudder hinge (p/n 6623) would not go in
> > far enough to
> > engage the hole of the stab bracket (p/n 66313).
> > Examination showed
> > the hinge was hitting the bracket bolt. There are
> > also witness marks
> > on the hinge which showed this interference was
> > present when the
> > rudder was previously installed, but maybe not to
> > this extent.
> > (Note - this rudder had never been installed on this
> > fin.)
> >
> > I measured the leg of the hinge which would not
> > engage and there was
> > about 0.050" more material on that side of the hinge
> > than on the side
> > which would engage, which is why one side would
> > engage and the other
> > wouldn't.
> >
> > A similar condition exists on the bottom hinge (same
> > p/n) - bracket
> > (p/n 66316) combination, to the extent that the
> > bracket hole was
> > slightly egged-out due to the hinge bolt being
> > driven home during its
> > previous life! There were even thread marks in the
> > bracket hole!
> >
> > Has anyone seen this condition before? It must not
> > be that uncommon
> > as all my hinges seem to suffer from the same
> > disease. Any guidance
> > would be appreciated.
> > Thanks,
> > Pete Crawford
> >
> >
> >
> >
>
>
>
>
> __________________________________
> Do you Yahoo!?
> All your favorites on one personal page ? Try My Yahoo!
> http://my.yahoo.com

'