Engine Structural parts

[Tom Downey]

What is a structural engine part?

(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.

would a oil sump for the 0-300 be a structural part?


Major repair or minor.

[WLIU]

The case halves provide the structure to the engine. So if you weld the sump you should not be doing a major repair. But it is a casting so caution is advised. Check out AC43-13.

Best of luck,

Wes

[martymayes]

Interesting as it provides mounting for the carburetor and other parts, it appears to have almost the same stuctural function as the case. Given that consideration I'd call it a minor repair and not worry over it.

Good pics Tom.

[Jerry Petro]

I think I would send this to either Divco or Crankcase Services. They have an approved welding process and can repair most any cast aluminum engine part. If you read the tracer when you get the part back you can see how they grind out the damage to remove any corrosion/impurities, the part is then heated prior to welding , I assume to reduce residual stress , then welded, stress relieved, then inspected with proper NDI processes. A failure of a weld in that area could result in the loss of the engine oil. There are people that have been doing this successfully for years why reinvent the wheel?

[Tom Downey]

I think I would send this to either Divco or Crankcase Services. They have an approved welding process and can repair most any cast aluminum engine part. If you read the tracer when you get the part back you can see how they grind out the damage to remove any corrosion/impurities, the part is then heated prior to welding , I assume to reduce residual stress , then welded, stress relieved, then inspected with proper NDI processes. A failure of a weld in that area could result in the loss of the engine oil. There are people that have been doing this successfully for years why reinvent the wheel?

I have a certification (pipe and plate) as a nukey boiler welder and weld mag quite often, and that is what this sump is cast from (Magnesium), I have a dye penetrant kit, a miller 500 AMP square wave welder, with 1/4 pound of mag filler rod.

IAW a phone call this AM with my PMI at FSDO we believe this part is not a structural part. and can be welded with out the major repair paper work of a field approval.

And Devco would be the last place I'd send it.

[nrpetersen]

Tom - FWIW I completely agree w yr position. It is a crankcase "fairing". I wonder why they made it from magnesium?

[Tom Downey]

Tom - FWIW I completely agree w yr position. It is a crankcase "fairing". I wonder why they made it from magnesium?

for whatever reason they made the accessory case from the same material.

[WLIU]

Magnesium is light and can be cast. Continental had previously used stampings for the oil sumps on the smaller engines (A series, C-90, O-200). For the larger engines (-470, -520) they went back to stamped steel oil sumps. So I will hazard a guess that they discovered magnesium did not provide the benefit they hoped for. But once that part was certified and in production, there was no incentive for product improvement and probably the cost of certifying a better part was a disincentive.

The C-125, C-145, and O-300 engines are heavy enough that you can "easily" replace them with a lighter and more powerful Lyco. A bunch of Skyhawks have been converted. And I did a C-125 to Lyco IO-360 200HP conversion on a Swift. The first take off after upgrading from 125hp to 200hp is a LOT of fun.

Best of luck,

Wes
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