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I have another data point on the starter
adapter issue. My Legacy has a dual-alternator/dual-battery system with two
20AH batteries. My primary EFIS is powered from battery A, and the starter from
battery B. During my early flights I would leave the cross-tie off to prevent the
EFIS from dropping offline during engine cranking.
The adapter would sometimes slip as you
can see here
around the 58 second mark. I was warned that this is a sure sign of impending
failure. Shortly after that I installed a new EFIS which has a backup battery. That
allowed me to start the engine with the cross-tie on. As expected, the engine
cranks faster now, but surprisingly, the adapter also stopped slipping.
My conclusion is that more cranking amps equals
more torque on the starter adapter, which prevents the spring from slipping. I
hope this helps someone out there.
BTW, I have a SkyTec light weight starter,
p/n C12ST3.
Adam Molny
Legacy #151, 180 hours
From: John Smith
[mailto:john@jjts.net.au]
Sent: Sunday, August 11, 2013 7:10
PM
To: lml@lancaironline.net
Subject: Re: [LML] Re: Legacy
Starter/Starter Adapter failed
Well – its
happened - the dreaded starter adapter failure at ~90hrs TTIS!!
The engine was
delivered late 2008 and and was first used in flight late 2010 – so I'm
well out of warranty time period. Anyways, beyond a few hints a few hours
prior, almost continuous slipping started almost overnight – very
difficult to get a start, and nearly got stuck a little way from home.
I did end up installing
the Skytec at about 70hours. It ran the starts like a trooper, until…..
The ST3 seems to test fine according to Skytec recommended checks. As I
still have the the old Iskra starter, I'm thinking of installing this just to
make absolutely certain that it is the adapter, and not the starter motor
– but its a very long shot as I think the ST3 is, not surprisingly,
absolutely fine.
For what its worth, I
can turn the starter adapter shaft quite easily both ways, but may be only
a quarter of a turn or so before sensing a "spring resistance" feel
and, if one lets go of the shaft, it just "springs back" - same in
both directions of rotation. I'll be talking to engine engineers on
Monday, but does this all sound like a failed adapter?
My main question now
– has anyone had any experience of replacing the starter adapter on the
IO-550 in a Legacy? Can it be done by lifting the engine off the engine mount
and moving it forwards a few inches? If this is possible then it might come
down to "just" disconnecting governor and throttle cables (may be
mixture), remove a few cable ties to wiring and P-clamps on fuel lines, and
unbolt the rear exhaust hangers? Make sense, or is it really a case of engine
right out?
As it happens, the left
hand side upper rear facing stud is really very long, and it doesn't seem
possible to pull the adapter off this stud without moving the engine forward
(BTW - this stud has been installed with two spacers setting the nut about 7/16
– 1/2" off the adapter housing itself – it is a TCM reman
engine – doesn't seem right to me, but may be there's good reason?)
Would be very grateful
any tips and suggestions…. Thanks!
John
John N G Smith
Tel / fax: +61-8-9385-8891
Mobile:
+61-409-372-975
Email: john@jjts.net.au
I would definitely
go with the ST3 over the ST5. I did and am very happy with it.
As for the adapter,
if you only have 50 hours, I would just replace the starter and wait. If
the adapter fails later, fix it then. As they say, if it’s not
broke, don’t fix it. I guess the risk is you might get stranded
somewhere, but, as I recall when the adapter in my former Cirrus started to
slip, I could still start it once before it gave up the ghost.
No, it wasn't mine that
was slipping but I'm on the case now to sort things out before something fails.
I have a regular CMI
starter adapter – incidentally, one that does not have a part number the
subject of the AD 2012-10-13 issued recently (this one extended the
applicability of the earlier AD on this subject to ALL engines manufactured
prior to Nov 2011 (not just in the period Jan 2011 to Nov 2011); but I do have
an ISKRA starter.
I had been thinking of
replacing the ISKRA unit with the SkyTec C24ST3 (the lower duty of the two
suited to the IO550 – being ..ST3 or ST5).
I noted your comments
about the SkyTec unit "finishing the job"…. I'm just wondering
if that outcome might be related to the duff CMI starter adapters the subject
of this AD? In other words, whilst the ISKRA starter does damage, certain
starter adapters were doomed anyway?
My engine has about
50hours on it, and prob somewhere around 50 starts.
Whilst I like the light
weight of the SkyTec ST3 unit (just over 6 lbs and lower torque than the ST5,
and my battery is in the back so SkyTec under this circumstance recommend the
ST3 anyway), appreciate any views around whether the SkyTec is a good option or
not, and whether I should be overhauling the starter adapter?
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