NTSB report shows pilot and passenger were in plane “not to be flown”

As is often the case - a wet ticket and a fat bankroll = disaster. I've seen it many times.

This is worse than normal RR, about a third of the plugs were affected. That black 'smoke' exhaust tells me fuel rich partial combustion rather than an active fire.

Yet another pilot lost NOT immediately pushing the nose down and maintaining more than the minimum air speed.

I don't want a regulation for this but maybe a recommended minimum number of hours before before you start flying passengers for all new pilots.

Not a mechanic, an ATP but I own a Cessna Cardinal. I believe mechanics generally will replace on condition. Don’t know what you consider expensive but aviation plugs start at about $45 each. There are two in each cylinder of a Cherokee (4 cylinder air cooled motor) so $360 plus mechanic’s time to replace them all. Seems like the issue was pretty clearly PIC poor decision making.

Aviation spark plugs are $50 bucks EACH!

All this discussion about "lockout" is not applicable.

The pilot and the regulations govern.

You don't fly an unairworthy plane. PERIOD.

I got into a dispute with my mechanic. He wanted to tear a third of my engine apart because two non-load bearing nuts were missing. I got a peer check from industry experts, and declined. He said he could not sign off the plane as airworthy.

I put the plane in my hangar, contacted and contracted with another A&P mechanic, who came out, installed the two nuts, torqued them properly, and signed off the plane.

In the time between the original mechanic saying NO and the new mechanic signing off, 30 days elapsed. I didn't fly the plane in those 30 days BECAUSE IT WASN'T AIRWORTHY.

And if the mechanic had tried to "lock out" my plane, I would have had to sue. It's my property, and per the FARs, it's my responsibility to maintain the plane.

Summary: There are the Federal Air Regulations, which detail the responsibilities of the pilot. Not flying an unairworthy plane is responsibility 1.

Surely you know nothing of aircraft maintenance practices or regulations.

As you said, he paid for it with his life; let’s save the name-calling for another time.

Even if the mechanic was wrong, he did not release the airplane before he was sure of his diagnosis and repair.

We always check the simple things first...35 years experience and would have troubleshot the problem the same way.

When troubleshooting you start with the simple things or the most likely things. Engine had a miss and a power problem so pulling the plugs and check them is a good start as the plugs themselves can tell a lot about the engine. The plugs can tell you if the fuel mixture is lean or rich, if you have a valve seal leak, a timing problem…an experienced mechanic reads them like you read this post.

...be careful with that...not everything is cut and dry...