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Engine back from overhaul... A1A to A3A and Kenmore STC for PA-12

daedgerton

daedgerton

PATRON
Arlington, VA
My engine is back from overhaul after the prop strike in the PA12 last August. Was converted from A1A to an A3A... The Kenmore STC that was used to upgrade to the O320 does not mention the A3A.. Mattituck (Continental) sent a 337 with the engine for the conversion from the A1A to the A3A. Would this separate 337 cover the reinstallation back on my PA12?
 
I suspect the 337 only covers the engine, you would need approved data cited on another 337 for installation.

The 337 for the engine change likely has no aircraft info in blocks 1 & 2, once installed, you need to fill those fields in and forward a copy to Oklahoma City.


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dgapilot said:
I suspect the 337 only covers the engine, you would need approved data cited on another 337 for installation.

The 337 for the engine change likely has no aircraft info in blocks 1 & 2, once installed, you need to fill those fields in and forward a copy to Oklahoma City.


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Click to expand...

Actually the 337 does have my airplane data in those fields...
 
PA-22/20-160 said:
Why did they convert your engine? Did you ask them too? The only difference between the 2 is the prop bolt bushings so your original prop won't fit if they really changed them to 7/16 bushings.
Click to expand...

not sure why the change... I'm trying to get to the bottom of this. A condemned crank was found in the engine and had to be replaced. Engine was originally overhauled in 2006...
 
Last edited:
This was what my IA got back from Continental...

I was told the A3A supersedes the A1A. The A1A is a narrow deck, replaced by the wide deck A3A. It should not be a problem.

The prop bolts on the A1A were 3/8” and on the A3A they are 7/16”. This one is an A3A with 3/8” bolts.

What you have is an A3A that has been configured for the prop that originally went on the A1A.

You should be good to go.


 
daedgerton said:
This was what my IA got back from Continental...

I was told the A3A supersedes the A1A. The A1A is a narrow deck, replaced by the wide deck A3A. It should not be a problem.

The prop bolts on the A1A were 3/8” and on the A3A they are 7/16”. This one is an A3A with 3/8” bolts.

What you have is an A3A that has been configured for the prop that originally went on the A1A.

You should be good to go.
Click to expand...

Lycoming or Continental? Confused.
 
A3A could be nd or wd, only difference is the prop bushings. The only thing that designates a wd is a A at the end of the serial number.
 
SuperCub MD said:
A3A could be nd or wd, only difference is the prop bushings. The only thing that designates a wd is a A at the end of the serial number.
Click to expand...

Correct, A1A and A3A can be narrow or wide deck. The only real difference is the bushings on the prop flange. If the serial number ends with an A it is a wide deck. If no A, it is a narrow deck.


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Glad I got it right...

My guess would be that whoever did the 337 is misinterpreting SSP-488. TC E-274 shows model differences. This is not a model change.
 
Got it on the model change... My big question now that I know I have correct prop bush.

My Kenmore STC for 150 on the PA12 doesn't list the A3A... That is my biggest question? Is my Kenmore still good? Or does my 337 from the overhaul now cover me.

I feel like I am overthinking this...

My learning experience from this whole thing is that I had "cheap" annuals... I had faith in my guy... The luckiest thing that ever happened was the ground loop... Engine somehow had a condemned crank shaft... How did that get in there??? I flew my kids in that plane... 2 cylinders affected by the AD... I didn't think I was skimping on annuals, I just trusted the guy. Now I have taken maintenance on my planes much more serious. One of the reasons why I sent this off for a factory overhaul. I think the only part of this engine that is original is the data plate!

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If your engine data plate shows O320-A3A, you will need either a Field Approval or a DER approval for a deviation to the STC.


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Not sure... i need to drive out and confirm.

my guess is that as said above i’ll need a deviation from the stc.
 
Look. If the only difference is prop bushings (go verify this!) and they have installed the original size prop bushings, you have an A1A for all intents. Install the engine and note that the new engine meets the specs of an A1A as per the Lycoming specification manual.

Web
 
wireweinie said:
Look. If the only difference is prop bushings (go verify this!) and they have installed the original size prop bushings, you have an A1A for all intents. Install the engine and note that the new engine meets the specs of an A1A as per the Lycoming specification manual.

Web
Click to expand...

If you go that route, verify with your IA that it is acceptable to him/her. From a practical standpoint, I wouldn’t accept it. Your mileage may vary.

Yes I know it is the same engine, but if the data plate specifies a different model then the TC or STC it isn’t in compliance.


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What criteria would you use for rejection? If the only difference between the models is the prop bushings and they've been changed, then the engine meets the specs for the application. The paper trail consists of the Lycoming specification manual detailing the differences. Then you have the overhaul shops paperwork showing that the smaller prop bushings have been installed. If this was an initial install under the STC, it would be a minor variance. As a replacement engine for the STC, just a log entry with an explanation.

Web
 
wireweinie said:
What criteria would you use for rejection? If the only difference between the models is the prop bushings and they've been changed, then the engine meets the specs for the application. The paper trail consists of the Lycoming specification manual detailing the differences. Then you have the overhaul shops paperwork showing that the smaller prop bushings have been installed. If this was an initial install under the STC, it would be a minor variance. As a replacement engine for the STC, just a log entry with an explanation.

Web
Click to expand...

Yup. Log entry. Approved manufacturers data.


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wireweinie said:
What criteria would you use for rejection? If the only difference between the models is the prop bushings and they've been changed, then the engine meets the specs for the application. The paper trail consists of the Lycoming specification manual detailing the differences. Then you have the overhaul shops paperwork showing that the smaller prop bushings have been installed. If this was an initial install under the STC, it would be a minor variance. As a replacement engine for the STC, just a log entry with an explanation.

Web
Click to expand...

What the data plate on the engine says vs what the aircraft TC or STC says. If they don’t match, it needs some “approved date” to make it match.


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I've actually performed this type of engine change in the past. The most recent was an engine that differed from that specified in the STC by having a prop governor drive at the front of the case. IA told me how to write it up as a minor variance. A fed looked at it and made me add an explanation on how I covered the drive pad. No different than described above.

This is a freshly overhauled engine with the overhaul shop documenting parts/work on the engine so swapping out the prop bushings is already documented. The 'C' is stamped on the data tag as per Lycoming. As long as the logs/overhaul show the work, where is the problem? If a fed asks questions at a later date, show the log entry. It documents work done as per part 43. The paperwork for the overhaul shop covers their work. The references to Lycoming's spec sheets cover the marking of the data tag and the parts change which makes it an -A1A.

So . . . ?

Web
 
Has anyone figured out that something just doesn't add up here.
They overhauled the engine and changed it to a Wide deck?? Sounds like the case was replaced also.
So Did they replace the Data plate or just change the data on it.
If they just changed the data on it, they shouldn't have changed it to an A3A, because it isn't an A3A.
I'd be raisng hell with the OH shop.

How bout a picture of the Data plate
 
S2D said:
Has anyone figured out that something just doesn't add up here.
They overhauled the engine and changed it to a Wide deck?? Sounds like the case was replaced also.
So Did they replace the Data plate or just change the data on it.
If they just changed the data on it, they shouldn't have changed it to an A3A, because it isn't an A3A.
I'd be raisng hell with the OH shop.

How bout a picture of the Data plate
Click to expand...
Also, Is the serial number the same on the engine now as the one you sent in for overhaul? Maybe they just changed engines without saying? Sending out a narrow deck with a wide deck coming back is suspicious. I thought only the manufacturer could change major parts while keeping the same serial number?
 
Sounds like the engine overhaul shop screwed up. I think they got their letters, engine models and paperwork mixed up.
 
dgapilot said:
What the data plate on the engine says vs what the aircraft TC or STC says. If they don’t match, it needs some “approved date” to make it match.


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Click to expand...

When the administration of paper becomes more important than the application of common sense we all have a problem.

Are baffles impacted by the change from narrow to wide deck?
 
stewartb said:
When the administration of paper becomes more important than the application of common sense we all have a problem.

Are baffles impacted by the change from narrow to wide deck?
Click to expand...

Alternator mounts are different. How they mount to the case.


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It would be an interesting exercise to sit a group of the highly experienced and talented technicians on this forum down with log books from a bunch of the 70+ year old airplanes owned by some of us! No, I’m not volunteering my logs.......
 
S2D and Mr Pierce have a good point. I'd like to see the data tags from the engine that left and from the one that returned. Getting a different engine back is not necessarily a deal breaker but getting a different engine back with the old data tag on it COULD be a goat rope.

Trust the overhaul shop. But verify.

Web
 
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