The Murphy Builders Site

Posted: **Fri Feb 17, 2012 9:59 pm**

After reading the various postings on the subject, I decided to check the
hinges on my Elite stab. Sure enough, the holes in the hinge halves don't
line up. The hole IDs in some of the halves are rough enough that the shank
of a 1/4-in drill bit will not go through. I haven't decided what approach
to take (the skin is not yet riveted to the ribs). The easiest approach
seems to be disassembling the hinges, then reassembling using a bolt or the
shank of a 1/4-in drill bit as a jig. If that fails, it might improve the
alignment enough that reaming the hole with a 1/4-in drill bit would be a
reasonable option. How critical is alignment of the hole? Has anyone
developed a good technique for aligning the holes? I like Dave Ricker's
idea of MAM drilling the holes undersized (say, 15/64) and letting us ream
the holes to final size. Ed Kolano remarked about friction in the elevator
and ailerons in his tests of the SR (Sport Aviation, June 2001 and March
2002). Is that friction a problem, a minor annoyance, or nothing to be
concerned about?

I looked up bushings in a catalog. There are two types, oilite bronze and
1015 steel. The ODs of these bushings are 3/8, so that leaves only 3/16 in
between the hole and the end of the hinge half. Is that enough metal? I
vote for the 1015 steel because the copper in the bronze seems like a
formula for galvanic corrosion. What are others using?

I suppose the high-end solution would be the hinges I saw on a friend's
Lancair. The hinge on the stab is a single piece with a T cross section,
and it has a spherical bearing in the end. The spherical bearings have
negligible friction, and they eliminate any concern about misalignment. The
hinge on the elevator is also a single piece like a T with two stems (TT).
All of the aluminum parts are machined to a very smooth finish and anodized.
Maybe that is why Lancairs are so expensive. The Murphy airplanes seem
like a better value.
--
Roger Cole <rcole927@earthlink.net>
Elite 709

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Posted: **Fri Feb 17, 2012 9:59 pm**

The way I did my elevator and rudder is as follows: using a string, I made
sure all hinges were in alignment before trying to mate elevator to
stabilizer and rudder to fin. I took several old AN4 bolts and put a taper
on the end by filing them in the drill press. Also I filed enough off the
bolt to make them .010" or so under. These bolts were used for the first
fit. Once everything was together, one at a time the bolts were removed and
the hinges were reamed in place. I used a .25 " reamer and turned it with
needle nose pliers, holding it by the flutes, rotating back and forth. I
was not able to do full rotations. This was not easy, took better part of a
day, but everything seems to be a good fit.
Al
SR026

----- Original Message -----
From: "Roger Cole" <rcole927@earthlink.net>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, March 17, 2002 6:26 PM
Subject: Re - SR Stab hinge bolt fit

After reading the various postings on the subject, I decided to check the
hinges on my Elite stab. Sure enough, the holes in the hinge halves don't
line up. The hole IDs in some of the halves are rough enough that the

shank

of a 1/4-in drill bit will not go through. I haven't decided what

approach

to take (the skin is not yet riveted to the ribs). The easiest approach
seems to be disassembling the hinges, then reassembling using a bolt or

the

shank of a 1/4-in drill bit as a jig. If that fails, it might improve the
alignment enough that reaming the hole with a 1/4-in drill bit would be a
reasonable option. How critical is alignment of the hole? Has anyone
developed a good technique for aligning the holes? I like Dave Ricker's
idea of MAM drilling the holes undersized (say, 15/64) and letting us ream
the holes to final size. Ed Kolano remarked about friction in the

elevator

and ailerons in his tests of the SR (Sport Aviation, June 2001 and March
2002). Is that friction a problem, a minor annoyance, or nothing to be
concerned about?

I looked up bushings in a catalog. There are two types, oilite bronze and
1015 steel. The ODs of these bushings are 3/8, so that leaves only 3/16

in

between the hole and the end of the hinge half. Is that enough metal? I
vote for the 1015 steel because the copper in the bronze seems like a
formula for galvanic corrosion. What are others using?

I suppose the high-end solution would be the hinges I saw on a friend's
Lancair. The hinge on the stab is a single piece with a T cross section,
and it has a spherical bearing in the end. The spherical bearings have
negligible friction, and they eliminate any concern about misalignment.

The

hinge on the elevator is also a single piece like a T with two stems (TT).
All of the aluminum parts are machined to a very smooth finish and

anodized.

Maybe that is why Lancairs are so expensive. The Murphy airplanes seem
like a better value.
--
Roger Cole <rcole927@earthlink.net>
Elite 709

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Posted: **Fri Feb 17, 2012 9:59 pm**

Roger, you already have bronze running on steel bolts in the ailerons and
flaps, so why not the same on the tailfeathers. Haven't seen any signs of
problems on the rebel, with the same, for 9 years. Keep everything lubes and
should be no problems. Steel on steel is also liable to rust together, so
both have possible "problems"

The edge distance, although small, won't be a problem considering the "foot
print" area that the 3/8" OD bushing has.

Wayne G. O'Shea
www.irishfield.on.ca

----- Original Message -----
From: "Roger Cole" <rcole927@earthlink.net>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, March 17, 2002 9:26 PM
Subject: Re - SR Stab hinge bolt fit