[rebel-builders] ATTENTION All Murphy Elite Operators: Cracks Found In Hori
Posted: Sun Feb 19, 2012 6:31 pm
John
Thanks for bringing this up.
Here are a few observations to promote discussion:
It appears filler material has been used to "clean up" the tooling holes
and bend clearances etc, in the outer rib of the stabilizer and also
between the skin and the outer rib (Cracks_Left_Stab_Outer_Hinge2.jpg).
The characteristic radius of the crack in the rib at the top of the spar
(Cracks_Right_Stab_Outer_Hinge2.jpg) looks like the shape of one of the
bend clearances for the rib tabs. If it's there's filler in there it
would make sense that some of the cracks are in the filler or being
highlighted by the filler. The outer face of the elevator rib appears
to have been smoothed up in a similar manner.
The crack in the spar beside the hinge mount hole
(Cracks_Left_Stab_Outer_Hinge2.jpg) is definitely of concern as is the
gap that has been created between the spar and the filler on the outer
rib. That is a telltale that the spar has seen some fair fore-aft
loading and has been deformed. It looks like at the least a "heavy"
doubler may be needed in there to support the fasteners at the hinge
mount location or even an angle between the spar and the outer rib to
tie them together and transmit the load better.
When you get this apart it will be interesting to know what the spar
looks like at the inner of the two (outboard) hinge mounts, whether the
same damage is in process. While you're at it I'd be interested to know
what the centre hinge mounts look like not to mention the hinge mounts
on the elevator in all 3 locations.
Looking at Bob P's site, it looks like a similar looking problem has
shown up on the Moose in the ailerons and the elevators, see
http://www.pattersonaerosales.com/Aircr ... chSpt.html
CLICK: Horizontal_Stabilizer_tip_rib_repair.pdf and 3500_WING_TIP_MOD.pdf
Any other flying Elite builders out there with any experience to add?
Cheers,
Dave
elite583.cjb.net - A work in progress.
John & Lee wrote:
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Thanks for bringing this up.
Here are a few observations to promote discussion:
It appears filler material has been used to "clean up" the tooling holes
and bend clearances etc, in the outer rib of the stabilizer and also
between the skin and the outer rib (Cracks_Left_Stab_Outer_Hinge2.jpg).
The characteristic radius of the crack in the rib at the top of the spar
(Cracks_Right_Stab_Outer_Hinge2.jpg) looks like the shape of one of the
bend clearances for the rib tabs. If it's there's filler in there it
would make sense that some of the cracks are in the filler or being
highlighted by the filler. The outer face of the elevator rib appears
to have been smoothed up in a similar manner.
The crack in the spar beside the hinge mount hole
(Cracks_Left_Stab_Outer_Hinge2.jpg) is definitely of concern as is the
gap that has been created between the spar and the filler on the outer
rib. That is a telltale that the spar has seen some fair fore-aft
loading and has been deformed. It looks like at the least a "heavy"
doubler may be needed in there to support the fasteners at the hinge
mount location or even an angle between the spar and the outer rib to
tie them together and transmit the load better.
When you get this apart it will be interesting to know what the spar
looks like at the inner of the two (outboard) hinge mounts, whether the
same damage is in process. While you're at it I'd be interested to know
what the centre hinge mounts look like not to mention the hinge mounts
on the elevator in all 3 locations.
Looking at Bob P's site, it looks like a similar looking problem has
shown up on the Moose in the ailerons and the elevators, see
http://www.pattersonaerosales.com/Aircr ... chSpt.html
CLICK: Horizontal_Stabilizer_tip_rib_repair.pdf and 3500_WING_TIP_MOD.pdf
Any other flying Elite builders out there with any experience to add?
Cheers,
Dave
elite583.cjb.net - A work in progress.
John & Lee wrote:
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).
Preliminary Findings:
Cracks were found during pre-flight (21 Aug 2010) beside both the left and
right outboard elevator hinges. Some appear to be hairline fractures in the
rear spar extending from the outboard hinge bolt holes to the outboard edge
of the horizontal stabilizer rear spar. The hairlines were difficult to
detect without a magnifying glass. I routinely applied spray lubrication
to the hinges, and this (plus dirt accumulation) covered over some, but not
all of the cracks. After removing some lubricant from the area, I
took photographs and have posted them at
http://www.dcsol.com/murphy-rebel/ under
Files>Elite>301 E-Horizontal Stab.
Murphy Aircraft Mfg Ltd Technical Support and Patterson Aero Sales were
advised on 21 August and photographs were sent to them (awaiting action by
Murphy Mfg Ltd.). I tried to list findings at Transport Canada's Service
Difficulty Reports Web Site but was unsuccessful.
Has anyone else found something similar? I am in the process of hiring an
AME to work with me to conduct some disassembly and further inspection work
this coming week. I will provide further inspection findings when I am
able.
Take Care
John Garstang
Ladysmith, BC
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