Engine structural components

[Tom-D]

FAR 43-A
(2) Powerplant major repairs. Repairs of the following parts of an engine and repairs of the following types, are powerplant major repairs:

(i) Separation or disassembly of a crankcase or crankshaft of a reciprocating engine equipped with an integral supercharger.

(ii) Separation or disassembly of a crankcase or crankshaft of a reciprocating engine equipped with other than spur-type propeller reduction gearing.

(iii) Special repairs to structural engine parts by welding, plating, metalizing, or other methods.

What is a major structural part ?

Would an oil sump of a 0-300 be a structural part ?

Is this a major or minor repair?

 

[Skylane81E]

Good question, I think one could argue it either way.

 

[Skylane81E]

Now that I see where the repair is relative to the mounting for the carb I'd lean towards calling it structural in this case.

Now if it were the stamped sump from my O470 I'd lean the other way.

 

[Tom-D]

Now that I see where the repair is relative to the mounting for the carb I'd lean towards calling it structural in this case.

Now if it were the stamped sump from my O470 I'd lean the other way.

Why would the area welded be a factor in if the decision?
You welded the part. why would it matter where?

 

[Skylane81E]

It wouldn't, but the fact that parts hang from it may. I'm not used to TCM bits having a sump like that.

 

[Tom-D]

It wouldn't, but the fact that parts hang from it may. I'm not used to TCM bits having a sump like that.

0-125- thru-0-300-D and the G0-300.

all becoming very rare due to corrosion in the front sump.

 

[Apache123]

0-125- thru-0-300-D and the G0-300.

all becoming very rare due to corrosion in the front sump.

For someone who doesn't often gaze upon the insides much, would you consider this light, major, severe, or extreme corrosion?

 

[Tom-D]

For someone who doesn't often gaze upon the insides much, would you consider this light, major, severe, or extreme corrosion?

These castings are about .250" thick in this area. these last 3 pictures show these pits to be about half way thru the casting. That's pretty severe to me.

If we were to use these casting in this condition we will have an oil leak in a few years. most of these sumps haven't seen daylight in 20 years.
the reason i posted this thread is to see if any one had a good definition of what a "structural part" was.

 

[Capt. Geoffrey Thorpe]

These castings are about .250" thick in this area. these last 3 pictures show these pits to be about half way thru the casting. That's pretty severe to me.

If we were to use these casting in this condition we will have an oil leak in a few years. most of these sumps haven't seen daylight in 20 years.
the reason i posted this thread is to see if any one had a good definition of what a "structural part" was.

You would have to ask the guy who designed the engine. Did they use a casting to stiffen up the block and support other things? Or did it just come out cheaper / lighter / easier than a stamping?

 

[Old Geek]

You would have to ask the guy who designed the engine. Did they use a casting to stiffen up the block and support other things? Or did it just come out cheaper / lighter / easier than a stamping?

I think that's the answer. As a totally unqualified part-time mechanical engineer and prototype engine designer I'd say that the casting is also there to stiffen the case and thus, a structural component.

 

[Tom-D]

I think that's the answer. As a totally unqualified part-time mechanical engineer and prototype engine designer I'd say that the casting is also there to stiffen the case and thus, a structural component.

IAW the phone conversation with my ASI/PMI at SEA FSDO it is a NON structural part and the weld can be made as a minor repair and logged as that in the engine log book entry for the overhaul.

 

[Old Geek]

IAW the phone conversation with my ASI/PMI at SEA FSDO it is a NON structural part and the weld can be made as a minor repair and logged as that in the engine log book entry for the overhaul.

I'd still maintain (in my totally unqualified opinion) that the part is structural, but would qualify that by saying your weld would not affect it in any structural way.

 

[Tom-D]

I'd still maintain (in my totally unqualified opinion) that the part is structural, but would qualify that by saying your weld would not affect it in any structural way.

Read 43.13 (a)

and tell me if you believe using the proper welding rod and a TIG method IAW with ASTM standards is acceptable method of welding this sump?

its a question not a test.

 

[N801BH]

Read 43.13 (a)

and tell me if you believe using the proper welding rod and a TIG method IAW with ASTM standards is acceptable method of welding this sump?

its a question not a test.

Are ya gonna sign your name to the "repair / weld" of the engine part?

 

[Old Geek]

Read 43.13 (a)

and tell me if you believe using the proper welding rod and a TIG method IAW with ASTM standards is acceptable method of welding this sump?

its a question not a test.

How do you know the proper filler rod to use? And whether stress relieving or heat treating is required afterwards? Assuming you have some idea of the answers to those questions, I'd say yes.

Again, with my totally unqualified opinion...

 

[Tom-D]

How do you know the proper filler rod to use? And whether stress relieving or heat treating is required afterwards? Assuming you have some idea of the answers to those questions, I'd say yes.

Again, with my totally unqualified opinion...

we know the alloy, we know the recommended filler rod.

It is a SO casting with no heat treatment. it will be the same after it is welded.

In order to weld a magnesium casting you must either heat it to a stable temp, or not get it hot while welding. That is the advantage of T-I-G the heat is very quick and local, you weld a puddle then allow to cool to room temps, then weld another puddle, repeat until the defect is repaired.

other wise it will crack as the uneven heated areas equalize.

 

[N801BH]

we know the alloy, we know the recommended filler rod.

It is a SO casting with no heat treatment. it will be the same after it is welded.

In order to weld a magnesium casting you must either heat it to a stable temp, or not get it hot while welding. That is the advantage of T-I-G the heat is very quick and local, you weld a puddle then allow to cool to room temps, then weld another puddle, repeat until the defect is repaired.

other wise it will crack as the uneven heated areas equalize.

You might know the Alloy Family... There is 99.9999% chance you do NOT know the exact batch ingredients of that particular casting...

I have to admit.... you always end up with the most clusterf*uck repair projects of any mechanic I have ever seen...

Ps.... are ya gonna sign your name to the welding repair

 

[Tom-D]

Are ya gonna sign your name to the "repair / weld" of the engine part?

why wouldn't I ?

 

[Tom-D]

You might know the Alloy Family... There is 99.9999% chance you do NOT know the exact batch ingredients of that particular casting...

Close enough, they won't vary that much.

I have to admit.... you always end up with the most clusterf*uck repair projects of any mechanic I have ever seen

I deal with a lot of antique support projects, if we can't save these old parts by finding ways to repair them they will simply go away.

Ps.... are ya gonna sign your name to the welding repair

How else would you return it to service?

 

[Skylane81E]

If you have the ASI's opinion then go with it!

I would

 

[Tom-D]

If you have the ASI's opinion then go with it!

I would

It's already repaired.