REFLECTOR: MT Prop damage

Dave T Nelson dtnelson at us.ibm.com
Mon Jun 20 09:54:48 CDT 2011


Bob, I had a similar (but not as severe) damage situation on my MT three
years ago.  I observed a big ding to the leading edge of my prop upon
arrival at the Oshkosh airshow.  My damage was approx. 1/4 - 5/16 in
length, and had significantly dented the stainless leading edge.  I went
and grabbed Eric from the MT prop booth in the airshow and pretty much
dragged him out for a look.

Eric told me after a close examination that as long as the stainless
leading edge wasn't cracked, broken, or delaminated (separated or unglued
from the prop), that I could make a field repair with JB Weld.  He told me
to keep a close eye out for any cracks or delamination, and that if I saw
any, it needed repair.

Your damage looks much more severe than mine.  Given the input I got from
Eric, and knowing what kind of extreme stress the prop is under, I would
recommend against a field repair.  Your leading edge is clearly separated
and likely delaminated.  Having it detach in flight would result in
vibration that could further weaken the blade.  Also, the lengthwise
surface cracking an inch or so below the damage area could indicate
delamination of the fiberglass wrap... which would seriously weaken the
overall structure.

I know having a broken airplane during prime flying season is pretty much
like finding a turd in your punchbowl, but having a blade separation would
be allot worse...

Dave

Dave T. Nelson
T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
Program Director, ISC ECAT NPI & Test Engineering


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  |reflector-request at tvbf.org                                                                                                                        |
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  |reflector at tvbf.org                                                                                                                                |
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  |06/20/2011 09:03 AM                                                                                                                               |
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  |Reflector Digest, Vol 75, Issue 81                                                                                                                |
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  |reflector-bounces at tvbf.org                                                                                                                        |
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Today's Topics:

   1. Re:  Reflector Digest, Vol 75, Issue 76,		 Leading Edge Damage
      (Fred Anderka)
   2. Re:  Leading Edge Prop Damage Advice (Douglas Holub)


----- Message from Fred Anderka <fred at holohil.com> on Mon, 20 Jun 2011
09:46:35 -0400 -----
                                                                      
      To: "reflector at tvbf.org" <reflector at tvbf.org>                   
                                                                      
 Subject: Re: REFLECTOR: Reflector Digest, Vol 75, Issue 76, Leading  
          Edge Damage                                                 
                                                                      


Bob:

Have various dents on my MT prop due to stones and cowl screws (they are
now Lock Tighted).  Repairs were accomplished with J B Weld epoxy to fill
the divots.  The leading edge stone divot which deformed the leading edge
but did not separate from the blade was built up with J B and sanded to
original profile.  Over 300 hours later all the repairs are still intact
with no sign of separation, etc.

My only concern is the pitting on the trailing face of all the blades, the
forward face of the blades do not show any pitting or abrasion.  There are
over 450 hours on the prop now.  I only operate off of paved strips,
unfortunately I cannot vouch for the cleanliness of the runways and suspect
there is a certain amount of sand etc. on all but the large airport runways
with commercial traffic.

Anyone have similar pitting?  Any thoughts?

Fred Anderka
XL-RG, C-GHOL


Today's Topics:

   1. Re:  Leading Edge Prop Damage Advice (Douglas Holub)

----------------------------------------------------------------------

That looks similar to damage one of my valve cover screws did to the edge
of my Prince fixed pitch P-tip prop (maple core with carbon fiber
overlaid.)  The damage was about that size and took a little bite out of
the maple, too. We were traveling at the time in Amarillo, Texas. I emailed
pictures of the damage to Lonnie Prince and he told me how to fix it: clean
up the wound with sand paper, fill in with JB Weld, then sand it smooth in
the morning. Worked great. I'm not sure if the procedure would be the same
with a metal prop.

I replaced all the star washers on my valve cover screws with split ring
lock washers.

Doug Holub
2009 Velocity Standard FG
  ----- Original Message -----
  From: Bob Jackson
  To: 'Velocity Aircraft Owners and Builders list'
  Cc: Bob & Ann Jackson
  Sent: Sunday, June 19, 2011 8:40 PM
  Subject: REFLECTOR: Leading Edge Prop Damage Advice


  We 'vacuumed' up another screw (looked like a Lycoming valve cover
fastener, when we 'swept' the runway afterward is what did the damage) on
takeoff yesterday and this time damaged the leading edge of our MT prop --
we need your repair advice:

     The damage is about 3/8" in size, with the two most troubling aspects
being the break in continuity of the leading edge, and

  the obvious separation and bending out of the lower part of the leading
edge strip on the one side.  The damage is about

  8" from  the tip of the blade.

  I assume if I were to ask MT, they would say 'scrap that blade and build
a new one from scratch'!

     We're just curious what anyone might have to say about their
experiences with this type of damage, and whether or not you guys would
recommend trying to fix it ourselves.  We have a new 4 blade MT prop
ordered (to improve our high altitude cruise performance),  but it won't be
here for 6 to 8 weeks, so if we can safely do it, we'd like to repair this
damage and continue flying it until the new prop arrives.

     What does everyone think?  We don't think we can re-bridge the missing
metal, but are hoping that by injecting some epoxy and filling the gap with
thickened JB Weld there would continue to be adequate rigidity and strength
in the remaining leading edge stainless material to prevent vibration in
flight and the lose of the outer 8" of this blade -- which obviously would
be bad!


  Thanks,

  Bob Jackson

  Custom Turbo XL/RG

  N2XF






----- Message from "Douglas Holub" <douglas.holub at gmail.com> on Mon, 20 Jun
2011 09:52:30 -0400 -----
                                                            
      To: "Velocity Aircraft Owners and Builders list"      
          <reflector at tvbf.org>                              
                                                            
 Subject: Re: REFLECTOR: Leading Edge Prop Damage Advice    
                                                            


I don't have anything to compare it with, but I love it. It's 68x78, turns
2400 RPMs static and will push the plane 200 MPH at 4000 feet. It will
climb more than 2000 ft/min with just me in the plane. I've got an IOX-360
(parallel valve) with dual Plasma IIIs that gives me about 195 HP, I think.
It took about 6 months to get the first prop 3 years ago because they were
pretty backed up, but I got it overhauled last fall in a couple of weeks.
Lonnie Prince is a prince.

Doug
 ----- Original Message -----
 From: Alex Balic
 To: 'Velocity Aircraft Owners and Builders list'
 Sent: Monday, June 20, 2011 9:03 AM
 Subject: Re: REFLECTOR: Leading Edge Prop Damage Advice

 Hey Doug-
 How are you liking your p-tip prop?  I want to get a properly sized prop
 to get my engine tuning done, and to get to flight testing,- the 160 hp 3
 blade I have on there now for that purpose goes to full speed at just ¼
 throttle at the moment, so I am sort of stuck until I can get a prop on
 there to absorb the HP.  will almost certainly upgrade to MT later on.  I
 contacted Catto, but he is so busy, I may not get one until the fall- so
 prince is another choice- how are they to work with?

 Alex


 From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
 Behalf Of Douglas Holub
 Sent: Sunday, June 19, 2011 7:56 PM
 To: Velocity Aircraft Owners and Builders list
 Subject: Re: REFLECTOR: Leading Edge Prop Damage Advice

 That looks similar to damage one of my valve cover screws did to the edge
 of my Prince fixed pitch P-tip prop (maple core with carbon fiber
 overlaid.)  The damage was about that size and took a little bite out of
 the maple, too. We were traveling at the time in Amarillo, Texas. I
 emailed pictures of the damage to Lonnie Prince and he told me how to fix
 it: clean up the wound with sand paper, fill in with JB Weld, then sand it
 smooth in the morning. Worked great. I'm not sure if the procedure would
 be the same with a metal prop.

 I replaced all the star washers on my valve cover screws with split ring
 lock washers.

 Doug Holub
 2009 Velocity Standard FG
 ----- Original Message -----
 From: Bob Jackson
 To: 'Velocity Aircraft Owners and Builders list'
 Cc: Bob & Ann Jackson
 Sent: Sunday, June 19, 2011 8:40 PM
 Subject: REFLECTOR: Leading Edge Prop Damage Advice

 We 'vacuumed' up another screw (looked like a Lycoming valve cover
 fastener, when we 'swept' the runway afterward is what did the damage) on
 takeoff yesterday and this time damaged the leading edge of our MT prop --
 we need your repair advice:



   The damage is about 3/8" in size, with the two most troubling aspects
           being the break in continuity of the leading edge, and
  the obvious separation and bending out of the lower part of the leading
              edge strip on the one side.  The damage is about
                       8" from  the tip of the blade.



 I assume if I were to ask MT, they would say 'scrap that blade and build a
 new one from scratch'!

 We're just curious what anyone might have to say about their experiences
 with this type of damage, and whether or not you guys would recommend
 trying to fix it ourselves.  We have a new 4 blade MT prop ordered (to
 improve our high altitude cruise performance),  but it won't be here for 6
 to 8 weeks, so if we can safely do it, we'd like to repair this damage and
 continue flying it until the new prop arrives.

 What does everyone think?  We don't think we can re-bridge the missing
 metal, but are hoping that by injecting some epoxy and filling the gap
 with thickened JB Weld there would continue to be adequate rigidity and
 strength in the remaining leading edge stainless material to prevent
 vibration in flight and the lose of the outer 8" of this blade -- which
 obviously would be bad!

 Thanks,
 Bob Jackson
 Custom Turbo XL/RG
 N2XF

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