Similar to DUC, who don't consider that a cracked ferrule is significant (and
decline
to replace under warranty).
Duncan McF.
----Original Message----
From: air.guerner@orange.fr
Date: 22/05/2018 12:35
Subj: Europa-List: Re: Airmaster thrust bearing witness marks
Jonathan,
I had a similar symptom on my prop years ago. I questioned Airmaster and they
answered
that it was not critical (see below). I have 1100 hours on this prop now
and there are a few more scratches on the ferrule. I am considering replacing
the blade/ferrule assembly in a near future.
Regards
Remi
Hi Remi
The ferrules are not anodised, but are painted. This is to ensure the surface is
not hardened and made susceptible to fatigue failure. This is relatively soft
and gets scratched by the thrust bearings that slide against it. FEA analysis
has shown this area to be of relatively low stress compared to the adjoining
radiused area which is the area that should be inspected.
Even thought the scratching is visually obvious, it is not subject to corrosion
since the area is surrounded by grease. We have had no reports of any failures
---From this scratching.
Our advise at this stage is that the scratching from the thrust bearings is not
of concern, however keep an eye on this when you do your inspections and let
us know if you feel the surface scuffing deteriorates.
Regards,
Martin Eskildsen
GM
Airmaster Propellers Ltd
Phone: +64 9 8360065
Fax: +64 9 8360069
View our web-site at www.propellor.com
E-mail us at support@propellor.com or sales@propellor.com
-----Original Message-----
From: Remi Guerner [mailto:air.guerner@orange.fr]
Sent: Tuesday, May 12, 2009 7:30 AM
Subject: Questions to Product support
Dear sirs,
I have a few questions regarding discrepancies discovered during inspection of
my propeller today.
The ferrule is marked (black anodization removed showing bare aluminum alloy)
probably
due to the thrust bearing and retention nut rubbing on the surface of
the ferrule. See attached pictures of blades # 1 and 3. The ferrule on blade
2 looks the same as on blade 3. The ferrules are marked on about one third to
one half of the circumference. The marked area is not deep but it can be felt
with your finger nail.
The prop is an AP332 serial 386 with AC200 controller serial 486
Blades number: N14998
Installed on my Europa by myself in April 2006
Engine: Rotax 912ULSFR
Prop total time 267 hours
No damage history
Maintenance done according to the Airmaster Manual
Everything else on the prop is ok: no problem in flight, no play in the blades,
no humidity, no corrosion.
Questions:
1. What may have caused this wear after a so short time?
2. How to determine if it is safe or not?
3. How to avoid the wear to continue?
4. How to protect the the bare aluminum alloy?
Any advice wil be welcome
Looking fwd to read you soon.
Regards
Remi Guerner
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