Prestolite vs. Sky-Tec

kyleb said:
Didnt require any on the RV-6. Since it sits under the engine, I can’t see why it would involve baffle work.
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Difference in starter size, baffling is tight in that area on the 172m
 
Gary Ward said:
I did have to install a larger baffle around the NL since it is smaller. It was not hard to do.
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Exactly what I was expecting. I think it’s metal baffling up close to the original starter but filling the gap with baffling material appears to work well also.
Thanks for the photo!
 
Jdm said:
Exactly what I was expecting. I think it’s metal baffling up close to the original starter but filling the gap with baffling material appears to work well also.
Thanks for the photo!
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your welcome.

Pretty sure mine did have a smaller black baffle around the original starter riveted to the aluminum baffle. It was mostly missing. So I made one a little bigger.
 
That’s a good looking 172 Gary. What field was the photo taken? I’ve done a lot of Cincinnati flying over the past few years. Mostly Clermont, but some Lunken, Butler, and Grimes.
 
Jdm said:
Does anyone know how much baffling work has to be done to fit the NL properly? 172M O320E2D
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kyleb said:
Didnt require any on the RV-6. Since it sits under the engine, I can’t see why it would involve baffle work.
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The 172M and on have baffling around the starter. It's not an RV. The area circled in red is the starter cutout, and you will have to trim some of it and make a closure plate to fit around it. The power stud on the starter is right there at the baffle metal, too, so careful fitting is needed to avoid shorting. Make sure to use a nipple on the terminal anyway. Leaving gaps could cause loss of differential pressure and maybe heating problems.

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Don't do it like this guy did. He just shoves the baffling back together and leaves that big gap around the starter. Doesn't do the cooling capacity any good. Like the disclaimer up front says, he's giving advice without any training or experience to do so. But the video does show the M's baffling setup.



Edit: I see others beat me to it. Oh, well.
 
Thanks Dan. Good info! Yeah I watched that video before I posted. Wasn’t exactly impressed but better than nothing.
 
Jdm said:
That’s a good looking 172 Gary. What field was the photo taken? I’ve done a lot of Cincinnati flying over the past few years. Mostly Clermont, but some Lunken, Butler, and Grimes.
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Thanks,
I am a frequent flyer out of I67. I learned to fly at Lunken and Clermont county.

The photo is my buddies cheerokee and my 172 in Virginia I think somewhere down that way if remember right?
 
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Ok, never been to I67 but that Clermont is sure a nice one! Butler was good also. Tons of history at Lunken! I’ve done a couple prebuys and deliveries for a gentleman there. He hooked me up with a local lead on an A36. Doing a lot of work on that one now. Hope to have it up and going as our primary airplane soon.
 
i FOUND A PICTURE BEFORE THE BAFFLE WAS INSTALLED.
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Thank you sir. That’s quite a difference in size. Knowing me I’ll spend all day screwing around with the baffling. Ordering the NL tomorrow.
 
Jdm said:
Thank you sir. That’s quite a difference in size. Knowing me I’ll spend all day screwing around with the baffling. Ordering the NL tomorrow.
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Get the right tooth count for your ring gear.
 
Yep, I checked the tooth count carefully before ordering. It’s the standard 149.
I don’t care for the lack of information or customer assistance at skytec. I called tech support. No answer. Left a message. They never returned my call. All paperwork is online. Very basic.
Received the new starter. It looks nice! Quite a difference in size an weight. I have noticed a few interesting things right off the bat with this starter. First of all, it uses metric hardware at the terminals. Seems really odd that they would do that in aviation, but whatever.
Also noticed they do not use flat washers under the star washers. The internal tooth locking washers are to be installed under the nuts/bolt and grips right into the mounting flange of the starter, rather than a typical flat washer. Not a problem, just interesting that they differ so from common installation. Out of curiosity I checked the lycoming parts manual and sure enough it shows zero flat washers for mounting. The parts manual also calls for a different length (shorter) 1 bolt for mounting the sky tec vs original.
Lastly, I noticed the installation instructions says it’s ok to cut off the unnecessary mounting. bosses.
(BOSSES 'B', 'C', & 'D' MAY BE TRIMMED TO WITHIN 1/8" OF THE STARTER CASE AND DISCARDED WHERE REQUIRED TO CLEAR OTHER DEVICES NEAR THE STARTER.)

I suppose that’s another ounce or two if I want to chop off the unused bosses that hang out in the wind for no reason on this engine:)
 

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Jdm said:
Yep, I checked the tooth count carefully before ordering. It’s the standard 149.
I don’t care for the lack of information or customer assistance at skytec. I called tech support. No answer. Left a message. They never returned my call. All paperwork is online. Very basic.
Received the new starter. It looks nice! Quite a difference in size an weight. I have noticed a few interesting things right off the bat with this starter. First of all, it uses metric hardware at the terminals. Seems really odd that they would do that in aviation, but whatever.
Also noticed they do not use flat washers under the star washers. The internal tooth locking washers are to be installed under the nuts/bolt and grips right into the mounting flange of the starter, rather than a typical flat washer. Not a problem, just interesting that they differ so from common installation. Out of curiosity I checked the lycoming parts manual and sure enough it shows zero flat washers for mounting. The parts manual also calls for a different length (shorter) 1 bolt for mounting the sky tec vs original.
Lastly, I noticed the installation instructions says it’s ok to cut off the unnecessary mounting. bosses.
(BOSSES 'B', 'C', & 'D' MAY BE TRIMMED TO WITHIN 1/8" OF THE STARTER CASE AND DISCARDED WHERE REQUIRED TO CLEAR OTHER DEVICES NEAR THE STARTER.)

I suppose that’s another ounce or two if I want to chop off the unused bosses that hang out in the wind for no reason on this engine:)
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Yea I don't like the 13MM nut either on that starter. Don't tell anyone that I have a metric nut on my cessna. lol
I used one of the unused boss to safety wire a baffle bolt to it.

I think mine uses 2 bolts and 2 nuts for mounting?
 
Gary Ward said:
Don't tell anyone that I have a metric nut on my cessna. lol
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Well Cessna makes parts in China now so we’re ok!
Still can’t wrap my head around deleting the flat washer. They don’t seem to care that the shiny mounting flange will get all scared up by direct contact from lock washers. It all adds up to this being a disposable starter.
 
Also find it interesting that they are PMA’d now. Didn’t they used to be STC’d only? I was looking forward to doing more paperwork but didn’t get any:)
 
The SkyTec motor section looks almost identical to the starter motor section on my Toyota truck.

Truck recently had an interesting failure mode for the OEM starter. It would not disengage. Ignition off and key out, starter continued grinding away. Assumed an ignition switch issue. Cheap easy fix to replace switch behind lock cylinder. Starter behavior returned. Disassembled old switch. Looked perfect.

Relatively easy and cheap starter replacement. No recurrence in about 100 starts. Disassembling the old starter is on my To-do list.
 
Domenick said:
Truck recently had an interesting failure mode for the OEM starter. It would not disengage. Ignition off and key out, starter continued grinding away. Assumed an ignition switch issue. Cheap easy fix to replace switch behind lock cylinder. Starter behavior returned. Disassembled old switch. Looked perfect.
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Sticking contactor. That starter has an internal contactor. Even the usual firewall-mounted contactors can stick. They had a heavy copper disc that is pulled down against the flat head sides of the heavy copper bolts that are the big terminals. Every time the contactor opens it arcs at the contacts, caused by the voltage spike coming off the starter's windings. That arcing erodes the heads and the disc starts settling lower and lower into the depressions formed, and when it gets hot due to contact resistance it expands and locks itself into that depression.

Yup, the starter motor itself will be an automotive thing adapted to aircraft use. Why not? The old Prestolite starters and generators were modified auto parts. Some not modified at all. The current alternators are all adapted from cars.
 
Jdm said:
Well Cessna makes parts in China now so we’re ok!
Still can’t wrap my head around deleting the flat washer. They don’t seem to care that the shiny mounting flange will get all scared up by direct contact from lock washers. It all adds up to this being a disposable starter.
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I have always looked at starters as disposable as I have never rebuilt one. Yesterday I swapped a starter on a 7.3 ford diesel in the gravel. It was either that or pay for a tow truck. There was a 80 dollar core charge on it.
The starter on my plane probably could have been saved and put back in service with a good cleaning and lube? I'd rather start with new and replace it when it wears out. I liked how the new one was lighter.
 
The skytec NL works great. Very impressive compared to the worn out Prestolite. Baffling was a pain but I expected that.
Question about the w&b please... Does anyone know if the exact starter reference station is published anywhere? Otherwise I’ll need to measure FWD from the lower portion of the firewall.
 
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The 172M POH shows the engine's CG location in the Equipment list in the W&B section. It includes the weight of the starter. -20", or 20" forward of the lower front face of the firewall. The TCDS for the O-320-E2D shows the engine's CG to be 14.25" aft of the propeller flange face. So the prop flange face is 34.25 inches forward of the datum. Might make it easier. This section of the TCDS says the starter max overhang is 150 in-lb; does that mean that a 25-pound starter, (if that's what the old one is) is 6" ahead of the engine CG?

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I certainly didn’t think to check the equipment list for that info. Very helpful.
 
Dan the man! I checked the equipment list and sure enough it’s “considered” part of the engine at -20”. Interesting that it shows the alternator at -29” even though it’s the same distance forward of the lower firewall. Difference being the alternator is not grouped with the engine as the starter.
I haven’t looked at that list in many years. Only used it when determining required equipment previously.
Learning has occurred!
 

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Jdm said:
Interesting that it shows the alternator at -29” even though it’s the same distance forward of the lower firewall.
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FYI: only when items are given their own wt&bal moment would you see the difference in the measurements. Had the alternator been part of the engine as well it would have been a -20". Seems they think you'll replace an alternator before a starter or there are different alternator options offered by the OEM.
 
Thanks. Yep, makes sense. Now that lycoming is using sky-tech as new equipment and show alternates available it might be different on the newer models.
 
One needs to figure out approximately what the arm of that starter is for the W&B amendment. We can't use the engine's CG for that, since the starter is forward of it. When I changed them I would weight both the old and new starters and see where they balanced on a small stick on the bench to get their CG, and go from there. We already know what the prop flange arm is.

And the airplane should become slightly tail-heavier, but weigh less. Easy to get the +/- confused when the datum isn't out front of the airplane somewhere.
 
Dan Thomas said:
One needs to figure out approximately what the arm of that starter is for the W&B amendment. We can't use the engine's CG for that, since the starter is forward of it. When I changed them I would weight both the old and new starters and see where they balanced on a small stick on the bench to get their CG, and go from there. We already know what the prop flange arm is.
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I think, based on the equipment list, it has to be considered part of the engine’s CG which is -20”.
 
Dan, check out the first line of the equipment list. It says the engine includes the starter.


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Jdm said:
I don’t care for the lack of information or customer assistance at skytec. I called tech support. No answer. Left a message. They never returned my call.
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Remember the Talon crash in February 2021? It crashed into their local telephone exchange building… The phone service has never quite recovered. Hartzell, owner of SkyTec, is installing a new phone system not served by that exchange building. In the meantime, both phone calls and voicemail are very dodgy…

The workaround is to just keep calling back. Voicemail is unreliable.

Paul
 
Jdm said:
Dan, check out the first line of the equipment list. It says the engine includes the starter.
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Maybe it does, but if you want the correct weight and balance, you use the location and weight of the respective starters or you pull out the scales and reweigh the entire airplane after the mod.
 
Jdm said:
I think, based on the equipment list, it has to be considered part of the engine’s CG which is -20”.
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Easy way out, but removing some weight from a point six inches ahead of the engine's CG will change the airplane's CG by more than if we called it at 20". I was fussy about that. Many times I had to take weights and find the arms for stuff in the airplane to get an updated equipment list. In 40 years a lot of undocumented changes can happen and the W&B is way off. An actual reweigh often triggered such work.
 
Had a Prestolite —- Problem with disengagement from gear-ring ——went to new sky tech, starts easier less weight, no problems 3 years —-O-320 160hp
 
kyleb said:
Maybe it does, but if you want the correct weight and balance, you use the location and weight of the respective starters or you pull out the scales and reweigh the entire airplane after the mod.
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Exactly what I was planning until I saw the wording in the equipment list. Not a problem to measure from the lower firewall, was just hopeful for a published station reference. The equipment list seems to provide that, but I certainly get your point.
It’d be interesting to know what most mechanics are doing in regards to this.
 
So I measured from the lower firewall forward and from the aft spinner bulkhead backward. Both directions work out to about -28.25. It makes .15 difference in the new EWCG as compared to the equipment list engine group station of -20.
 

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Jdm said:
So I measured from the lower firewall forward and from the aft spinner bulkhead backward. Both directions work out to about -28.25. It makes .15 difference in the new EWCG as compared to the equipment list engine group station of -20.
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That's better. Your W&B will be more accurate. If one keeps making small mistakes over a period of years, they add up to one big mistake. The CG of the engine assembly changes if a lighter starter is installed. It would move aft.

I did a bit more digging and found this, from Lycoming: https://www.lycoming.com/sites/default/files/SI1154W Approved Starters and Alternators.pdf

The Skytec starters are listed under Hartzell. Looks like Hartzell owns them now. And I think this document could be quoted as the approval for your starter installation.
 
Yep, I do appreciate your attention to the details Dan. Excellent points!
Yep, they indeed were purchased by Hartzell. It’s also a FAA/PMA part now.
Yes I’m am familiar with that SI from lycoming but only after researching the the situation. Not sure why I’d want to reference it though? The Lycoming IPC now lists the sky-tec as a direct replacement option. It’s also installed on new engines from the factory.
They did make a tiny mistake on that SI. Shows the 149NL at 9.4 but it’s actually 9.3 per Hartzell, confirmed. I went with that number:)
 
Ha, they are pretty screwed up when it comes to support and documentation. Seems like an easy fix but that’s a large company for you. It’s probably due to Covid. Seems like that’s the go to excuse for incompetence lately!
 
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