Are you experiencing slow prop turning or
slipping of your starter? Assuming that your battery, starter and electrical
connections are all in good shape, you might be experiencing the beginnings of
the dreaded TCM starter adapter failure!
As for my personal experiences, I've only used
a SkyTec ST-3 starter for a little while (maybe 20 starts) before it died on me
and they told me I burnt it up
you think this CSOB operates things so they don't last a long time????) So it
was back to the full size monster starters for me and I have not had a starter
adapter problem in 1400 hours. Oh and I use AeroShell 100W oil. PS: For a really
great full size starter for your Continental engine at a phenomenal price, check
Anecdotally, these two operating conditions
(starter and oil weight) seem to be reported by many folks who have not
experienced the dreaded starter adapter failure. No science behind this, just
anecdotal references that I've seen in pireps from other Continental engine
Depending on your CSOB proficiency, this might
not mean a >$1,000 overhauled part purchase plus the mechanic hours to R&R the
Under the supervision of an A&P or IA the
removal of the starter adapter and replacement of the bearings, seals and large
drive spring is not rocket science, but that's my editorial opinion.
The shaft and spring interface clearances are
best left to be fitted by an aircraft engine machine shop or a place like
Niagara Air Parts,
especially if your shaft has been buggered up or experienced inordinate wear and
the shaft requires buffing or turning down, you'll need an undersized spring.
This is a key statement by the Bulletin
s-2008-01 (link below) and one that you might want to check carefully if you
select one of those "mini" starters:
For all old style starter adapters it
is imperative that the starter adapter input shaft unwind at least one full
revolution after engine start so that the clutch spring may fully release. In
order for this to occur, spring forces inside the starter adapter must be able
to overcome the resistance to rotation (drag) of the starter motor armature or
output shaft. If the torque required to rotate the armature of the starter motor
exceeds five (5) in/lbs, the clutch spring will not fully release. The rotating
shaft gear will then be forced to run with an interference fit inside the clutch
spring during engine operation.
Through extensive testing, Aircraft
Specialties Services, Inc. has demonstrated conclusively that nearly all wear of
the shaftgear and clutch spring occurs as a result of this condition which
considerably shortens starter adapter life and may cause metal contamination of
Personally, I have combined ~2,800 hours (as of 4/2013) on
two old style starter adapters using full size starters. You decide what starter
you want turning your adapter.
Check this out for your full size starter overhaul
Read Aircraft Specialties Service Bulletin
See the exploded view of a TCM
Starter Adapter Assembly
See the mysterious Starter
Adapter Spring and Shaft HERE
Doing your Own "Freshen Up" of
your Starter Adapter?
Check out these Low Cost Identical Replacement Part
Numbers for your TCM Starter Adapter at
The recent pirep from a Bonanza owner about
Airpower pricing was
excellent, in that they priced the Superior PMA'd lifters at about half the price of
Aircraft Spruce and the PMA'd exhaust valve was half of what the cylinder shop
See Superior's TCM Replacement Parts listings
Caution: Over the
years TCM used a few different starter adapter designs! Check your engine
parts catalog to be sure you get the correct parts for your adapter.
Here are pictures of the Starter
Adapter internals. Click thumbnail for a full size image.
Here is a picture of where the
E-Series starter bolts to the back of the engine.
It is a completely different configuration from
the current starter adapters used on the 470 and larger TCM engines. Good luck
to you guys who care for these E-Series birds!
2740 North Sheridan Rd
Tulsa, Oklahoma 74115 (800)255-9924
A Beech Lister/owner of an N35 Bonanza has
provided a pirep on Niagara's starter adapter repair kits and shaft and spring
Their fee to turn down the shaft to fit a new
spring is reported to be $75 and a new spring is from $140 to $250
(personally, I'd call one of Superior's
Distributors for a quote on the spring). Niagara could be a place to get
your shaft machined to specs for your CSOB sourced spring.
Check out these Starter Adapter
Kits from Niagara as a possible one-stop shop:
Kit reported to be approximately $100
Per Beechcraft owner and buyer's broker Bob S. of
Arizona, here is another potential source of good starter adapter repairs/parts:
Here is what Beech owner John P. says about his starter
I've done a couple of these the past few
years. First was on an IO-470K. Used Niagara parts and had the drum turned
down locally/gear machined locally. Did the reassembly myself. Kind of a PITA.
The last one I did I got the parts from Aircraft Specialties and then took the
unit over to LyCon in Visalia, Ca. Think the total for parts & labor was in the
$400 range. He had a special tool over there that made installing the spring on
the gear and getting the final assembly into the drum a snap. You do need to
pull it first before ordering any parts. Have to use a micrometer on the drum
to see what size spring to buy. The shaft WILL have a taper out of spec so
machining will have to be done. Anyone can grind the gear it's the shaft that
requires a "tool post grinder" to machine it and very few shops have one.
Overall easy job, assuming especially if you can find someone who has the
special tools to install
PS: Check above for sources on the spring.
Here is what BeechTalker Paul M. says about his starter
"I am a starter adapter vet. I think I saw some
advice on Niagara on this site when the adapter started giving problems in my
IO-550. We had a terrible ISKRA starter which eats these adapters. It started
slipping and then I made the mistake of going from W100 to W100PLUS and the prop
barely turned over despite hearing the starter going full tilt.
I put a Niagara replacement adapter on and it blew
apart before two blades went by. Niagara blamed it on bad mags. I was suspicious
and spoke to other people who have experienced the same failure and had the same
blame by NIagara. Not only were my mags not "on" but the mags were subsequently
checked and found in perfect condition. Niagara took its new broken adapter back
and that was generous of them.
Subsequently, we disassembled my slipping adapter
and measured the wear according to the manual, found the shaft and spring to be
worn beyond limits.
I sent the parts to Aircraft Specialties and they
ground the shaft and drive gear then supplied the new M15 undersized spring for
about $300 roughly. My A&P and I re-assembled and tested the unit thoroughly and
replaced it and it has worked perfectly for about 250 hours now.
The biggest change was going to the old Prestolite
starter which performs wonderfully. The spring needs high torque to operate
without slipping and the older TCM/Prestolites can do that.
The other IO-550s in my hangar still use the ST-3
and ST-5. The ST-3 is about to fail shortly and the ST-5 already had his adapter
fail and he upgraded his ST-3 to a ST-5 and it works much better.
I've included three pictures of the product returned
by Specialties, they did a really good job at a reasonable cost.
I was happy with the existing components in my
relatively new starter adapter and did not want to swap them out for an unknown
I Found Your Oil Leak!
This is not going to be a good day.
(Contributed by Dave B. from an IO470-C in a J35 Bonanza)
Here's what happens when the starter fails to
Not a pretty story.
See more troubleshooting info from Niagara on
See Lew Gage's Starter Engaged Warning Light