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14 Mar 2006
Brad,
Thanks for your apparent final reply below, I will pass it along to
the Lancair Mail List community with the recommendation that any users of such
E-MAG gears inspect them and if there is any damage, replace them with
certified gears. Furthermore, if purchasers have not yet used these
gears, they should return them and get certified gears. I am
doing this because your analysis doesn't give me much comfort.
It is interesting to note that you have seen others (as in plural,
different than your reply to Clark) and I am sure you will see more as
people check such gears after finding iron bits in their oil analyses. I
think it was useful to change your web site ordering information
to indicate that the gears are for E-Mag use only, but your reason, with
respect to my case, is incorrect. I am sure I made it clear that I
was not using the gear with a magneto, but with Light Speed Engineering's Hall
effect sensor, a device which is merely rotating a balanced light aluminum
arm with a small magnet imbedded in it. I suppose you are also
warning P-Mag (magneto like generator) customers that the E-MAG gears are
unsuitable for that more demanding application.
Again, your suggestion that the installation itself was a problem is
highly unlikely. There was no cocking of the flange or gear as seen by the
damage - the driving gear made its' marks in the middle of the driven gear teeth
and evenly where it made such engagement.
I am sure that others, more knowledgeable than me, will reply to
you directly at info@emagair.com should
they have further thoughts.
Scott Krueger
(Note to LMLers - Try to read the communications thread from the
bottom up)
<<<<<<<<<<<<<<<
In a message dated 3/14/2006 11:40:31 A.M. Central Standard Time,
info@emagair.com writes:
I am not the engineer in our shop,
so please pardon my somewhat pedestrian treatment of the drive gear
topic.
We have reviewed the gear sample
you sent, and do not see a safety issue when our gears are properly installed
on E-MAG ignitions. Your sample
is not unlike others we’ve seen.
Some (but not all) our gears show varying degrees of engagement
pressure (preload). Some are
simply polished while others show a light impression, such as your
sample. It is important to
understand the hardness requirement for E-MAG gears is less than it is for
gears used with traditional magnetos. (Note: We have changed the description
of our gear to say they match “as appropriate for E-MAG use only” certified
gears.) Because E-MAG shaft
assemblies are lighter and more compact, the inertia mass of our shaft is
relatively insignificant, compared to that of a magneto. With a hefty magnet attached to the
shaft, magnetos work the drive gear much harder. The dimensional requirements for E-MAG
gears are the same as certified gears, and we hold tight tolerances. If there was an underlying dimensional
discrepancy, we would see the impression pattern 100% of the time, which is
not the case. Note: For anyone wanting to compare, the
engagement points between gears determine the pitch diameter, which is
different than a measurement of overall diameter. We’ve seen no correlation to the length
of service, and no progression in the pattern over time, so we don't see this
as being a safety issue.
Variations in engagement pressure
could be attributable to several sources, but the most likely is installation.
Even small amounts of material under one side of the flange can cock the
ignition ever so slightly to one side. But regardless of the cause, the
question remains what to do about it, if anything.
We could:
1. Harden our gears further to
eliminate the pattern. This would
eliminate the impression, but not the underlying preload, such as it is. If the gear is not allowed to take the
impression, the force will be transferred to the bearings.
2. Keep the gears as they
are. In instances where a degree
of preload exists (from what ever source) the gear will accommodate by
accepting the impression. This in
turn relieves the pressure, and the gear ends up with a near perfect fit. So long as the impression does not
progress, and the evidence suggests it does not, this may be an acceptable, if
not preferable, approach.
We continue to monitor this issue,
and of course, welcome knowledgeable and thoughtful input.
Kindest Regards,
Brad Dement
E-MAG Ignitions
649 Boling Ranch Road
Azle, Texas 76020
(817) 448-0555
Brad,
I am waiting for any information or results concerning the gear I
sent back to you last week.
Thanks,
Scott Krueger
>>>>>>>>>>>>>>>>>>>>>
In a message dated 3/2/2006 5:58:13 A.M. Central Standard Time,
info@emagair.com writes:
Pardon my
delay in getting back to you. It's been quite hectic around
here.
We are reviewing our
gear finishing specs right now to make sure we provide a serviceable
product. We very much appreciate the data you sent and would like
to see the gear itself. Of course we will be happy to
refund your money.
I'll keep Clark
posted on what we find.
Kindest
Regards,
Brad Dement
Brad,
Thanks for your reply. I appreciate your offer to refund my money,
but that is up to you as the safety issue is uppermost in my mind. The
bad gear will be in the mail tomorrow (3 Mar 06). There are some marks
on the ends that were made in order to accomplish the testing.
I am a regular contributor the Lancair Mail List (LML, an E-mail forum
with over 800 viewers) and I have already described the appearance of the gear
(see below) to that crowd because I think it could be a serious safety issue.
I am looking forward to reading the result your analysis of this
gear and any other information so that I might further report this on the
LML.
I have not yet reported the intermediate test results because, at this
moment, I don't know if it might be more widespread. Without additional
information it would seem to me that it would be wise for a gear user to
examine the condition after maybe 25 or less hours of operation. I
am also concerned about a probably large number of experimental aircraft
builders that have purchased these gear (for whatever use) but have not
yet operated their engines in flight. Frankly, I hope that I am the
only one with a problem gear.
<<<<<<< Sent to LML 16 Feb 06:
.........................The real purpose of this missive is to note the
condition of an $85 mag gear (not certified,claimed to be to specs)
obtained from the E-Mag folks. I was able to transfer the
non impulse-coupled gear to one LSE mag sensor and I bought another for
the other sensor. While the gear that was used on the engine
for almost 700 hrs showed no wear other than slightly shiny engagement
area on the teeth, take a look at the one gotten from E-Mag and used for about
50 hours.
Some teeth are severely worn at the outer extremities, others are
galled at the mid point. I think I know where some of the shiny iron
particles found in my filter originated.
.....3 pictures of the gear .............
>>>>>>>>>>>>>>>>>>>>
Scott Krueger AKA
Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL
(KARR)
To: Brad Dement
E-MAG Ignitions
From: Scott Krueger
Date: 26 February 2006
Re: Magneto Gear
Brad,
On or about 10 March 05 I purchased a magneto gear from your
company. It was installed on a Light Speed Engineering Hall sensor timing
module mounted in the magneto opening on my Lycoming I/O 320. A second
sensor utilizing a gear recovered from my previous LASAR magneto was
installed in the other opening. I purchased the E-MAG gear because
the magneto impulse coupler gear was not compatible with LSE's EI.
This combination was first flown in May 2005.
Recently (early Feb), I removed the Hall sensors to replace them with
better crankshaft located sensors. When I pulled the gears from the
sensors, I was amazed at the condition of the gear made by E-MAG, especially
after only 55 hours of operation. The other gear had been used on my
engine for over 650 hours thru magneto changes and even an overhaul performed
270 hours ago.
I have attached additional pix (larger format). The E-MAG gear is in
the foreground. The other 650+ hour gear is in the background for
comparison.
I did get a report with the following noted:
<<<<
1) There was significant spalling and deformation of the contact area. The
metal was actually moved, not just worn.
2) The bad gear hardness was 31
Rockwell A, good gear was 43 Rockwell A. An automotive transmission gear I have
measured at 47 Rockwell A.
3) The bad gear was 0.0055" larger in diameter
then the good gear as measured over three 0.250 diameter pins. This was after I
removed the burrs in the deformed area.
Bottom line is I believe the gear
was too soft and of poor quality. Being oversize didn't help. The surface still
has the hob marks. The good gear appears to have been shot peened. What I
suspect we have here is a gear that hasn't been heat treated or finished.
>>>>
Also, Clark Baker is a friend of mine and he sent me your 18 Feb
06 response to his query. This may be your second case and there
were no installation or engine issues. Another friend, Arnie Christen,
runs two P-Mags with gears that he bought last summer in his I/O 360.
I have suggested that he check those gears for any damage. He has not done
so yet.
Although the gear is no longer a direct concern to me, I am writing you
because there may have been something wrong with the batch of gears that
produced the one I have. There may be others out there deteriorating as
did mine.
Please let me know if you have any ideas about this problem.
Scott Krueger
P2200004.JPG
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