[rebel-builders] ATTENTION Murphy Elite Operators: Inspectio

[Alan Hepburn]

Yes, it's certainly easy to over-torque these AN3 bolts. They recommended
number is not much more than finger tight. But with the crack being
horizontal, it looks to me like something tried to pull both bolts
backwards. That is also supported by the vertical crack on the tip rib
flange.

I don't imagine Murphy will do anything unless, as you say, several builders
report the same problem (and maybe not even then?!). Even production
aircraft don't usually see any corrective documentation unless there is
evidence of a problem affecting multiple aircraft.

If I were you, I'd be inclined to repair it using a slightly heavier spar
section spliced to the existing spar (overlap maybe half way to the next
rib), with a flange bent forward and riveted to the flat surface of the tip
rib.

Al

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ken
Sent: Sunday, September 05, 2010 11:49 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] ATTENTION Murphy Elite Operators: Inspection
Update 1 For Cracks Found In Horizontal Stab

Interesting observation. On engine bolts I've noticed that it is not
difficult to tighten AN bolts and washers enough to permanently deform
the aluminum under the washer. Work hardening the aluminum under the
washer like that could create a crack sensitive area I think. On
critical engine fasteners I go to the trouble of finding hardened
washers to prevent this sort of thing.

Based on history I'd be very surprised if MAM puts out any bulletins on
this unless there are multiple reports of similar problems.

Ken

Alan Hepburn wrote:

It's kind of interesting that the cracks seem to lead to the edge of the
washers, rather than to the bolt holes themselves. I assume the cracks in
the filler and those in the spar are unrelated. The cracks in the filler
were bound to happen sooner or later. In fact, use of filler like this is
not standard practice. Getting back to the spar cracks, you have to

wonder

if the elevator hinge was subjected to some unusual downward force at some
point in its career.

Al

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of John

&

Lee
Sent: Saturday, September 04, 2010 11:24 PM
To: rebel-builders@dcsol.com
Cc: murtech; kits@pattersonaerosales.com
Subject: [rebel-builders] ATTENTION Murphy Elite Operators: Inspection
Update 1 For Cracks Found In Horizontal Stab

Service Difficulty Report:

Date: 21 August 2010
Model: Murphy Elite
Serial #: 549
Built: 2004
TTSN: 273 Hours
Damage History: None, all time on wheels (tail dragger) except last 33

hours

on Murphy 1800 amphibs (installed end of June 2010).

Findings:

Further to my initial report, I have removed the horizontal stabilizer,
elevator and outboard hinges and conducted further inspections with the
assistance of an AME. I have posted new photographs of these inspections

at

http://www.dcsol.com/murphy-rebel/ under Files>Elite>301 E-Horizontal
Stab.

The hairline fractures in the horizontal stabilizer rear spar extend

almost

the complete width of the right hinge (underneath it), and about 1/3 of

the

width of the left hinge. Interior examination (through access panel)
disclosed hairline fractures at the corner of both tip ribs. The parts

were

inspected in the as-found condition, and then after cleaning.The hairline
fractures were difficult to detect optically, and a magnifying glass and
flashlight were used to aid the exterior and interior inspections.

Murphy Aircraft Mfg Ltd Technical Support and Patterson Aero Sales were
advised of these new findings on 4 Sept and photographs were sent to them.
I am currently waiting for modification/repair parts and instructions from
Murphy Aircraft Mfg. Ltd.

Take Care

John Garstang

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