Yes it is. You wouldn't believe what I've seen stuffed in checked baggage. I remember filling in at LaGuardia several years ago and one guy had a complete motorcycle disassembled in several bags that was headed to Puerto Rico.
As long as there's no flammable liquids, etc..then it's good to go. Most likely many things will get hit for a search of that type and I'm not allowed to tell you why. But they should pass inspection and go on their merry way.
Just recently here in Little Rock....I've seen Quickstruts in checked baggage....along with a crankshaft and other parts. They were flagged for search and cleared. Electronics will get hit also...PCM, TCM probably ATC etc. Don't be surprised if you see that "Love Note" from the TSA that they searched your bag!