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Safety wire for oil sump plugs ?

Larry DeCamp

Well Known Member
My new Superior engine has 4 sump openings with NPT fittings. One is a square head plug safety wired to a boss in the sump casting. The other is where I installed my quick drain and saftied it to another boss in the sump.

There are two other ports with Allen hex NPT plugs with no wire and no boss to drill for safety wire. Why are NPT plugs OK without safety wire ?
 
Most parts mounted on the engine is safety wired, if vibration is a concern.
This is also true for certain parts inside the engine. See manual.
But it also depends on the builder. What level of safety is comfortable.
The Allen hex NPT plugs have no external mass that can vibrate, so the risk level is very low.The square head plugs does not need to be safety wired to be safe, but sometimes there is an oil return line connected and then a safety wire is called for. If an engine is delivered to the customer without a safety wire on the square head plugs, it just does not look professional. Is there a risk ?
No I don´t think so, but why not safety wire ? No time, no cost.

https://www.faa.gov/news/safety_briefing/2020/media/SE_Topic_20-05_Safety_Wire.pdf

Good luck
 
Most parts mounted on the engine is safety wired, if vibration is a concern.
This is also true for certain parts inside the engine. See manual.
But it also depends on the builder. What level of safety is comfortable.
The Allen hex NPT plugs have no external mass that can vibrate, so the risk level is very low.The square head plugs does not need to be safety wired to be safe, but sometimes there is an oil return line connected and then a safety wire is called for. If an engine is delivered to the customer without a safety wire on the square head plugs, it just does not look professional. Is there a risk ?
No I don´t think so, but why not safety wire ? No time, no cost.

https://www.faa.gov/news/safety_briefing/2020/media/SE_Topic_20-05_Safety_Wire.pdf

Good luck

I have had to fight those unsafetied NPT plugs more than once, they are not backing out without a safety if properly installed.
I imagine that engine manufacturers that have been building the same engines for 80 years know what they are doing.
 
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