He told me that his uncle who owns a Cessna prop aircraft and has his own strip has taken him up on several flights. So he does have some experience.
And I am not gonna tell a two time winner of the purple heart that he shouldn't do anything. I think he has earned the right.
Todd
Shall I congratulate your highly esteemed efforts now or when he plows into something killing himself and probably others?
This is a human factors nightmare in addition to being illegal. Let's start with the fact that your friend's airplane was just damaged... Most likely this airplane runs on magnetos, utilizes an opposed piston-type engine, and has mechanically operated flight control surfaces. This incident could have caused serious damage to either one or both magnetos. While a visual inspection may not reveal anything promising, the capacitor, magnet, and wire leading from the magnetos to the spark plugs could have been fractured or compromised. As we all know, electricity seeks the quickest path to a ground source. If the magnetos and/or associated wiring was damaged, there's a possibility electricity will find an alternate route to ground outside the spark-plug meaning no source of ignition for one or multiple combustion chambers.
As for the pistons and crankshaft... If the magnetos were damaged, timing could have been offset. If timing is offset, it can promote preignition. If preignition occurs on a regular basis, and the engine's piston heads are cracked or fractured internally, the pistons will begin to fail. Not only that, the irregularity of piston movement due to preignition can increase stress on the crankshaft. If the crankshaft is already damaged because of your friend's previous incident, there's a very good possibility of crankshaft failure.
To top everything off, these conditions can take some time to develop serious problems. For instance, while in cruising flight at 65% continuous power. While a failed engine will only result in a loss of power, there's still another factor to consider. Off-field landings. Granted he may land just fine, he's not expecting an engine failure and he probably won't be looking for adequate emergency landing sites while he's on his illegal joy-ride. Both combine to introduce some level of panic.
If panic causes him to yank his control yoke a little more rapidly than usual and his aircraft's flight control cabling and/or surfaces are damaged, the increased stress can cause new problems. Worst-case scenario, his cabling will loosen or snap causing a loss of control. No engine power and unresponsive controls.... you sure his Purple Hearts will save him? Sure, it's worst-case. Yet what's better? Seeing these tragic events unfold or pissing off a friend to see him live another day?
Ignoring the previous situation in which there's a terrific crash, what happens if he takes off, comes back, and lands successfully? Does that mean his plane is alright? Does that mean our pilot is now superior and all-knowing? Heck no! If anything, allowing him to fly again will only increase his dangerous attitude of invulnerability. His newfound success will grow on him until he makes a decision based on past success which results in a worst-case scenario, similar to one described above. Don't allow him to kill himself!
The fact of the matter is your friend is inexperienced and breaking the law. While I'm unaware which airspace is located in your region, to act as Pilot in Command of an aircraft within class E airspace, your friend must have at least a student pilot certificate. Since your friend doesn't seem to have any form of a pilot certificate, he is in violation of FAR 91.13. Sure, the FAR says "the life or property of another." However, have you considered all the homes your friend is flying over after he manages to take off? If an attitude of invulnerability is allowed to grow on him, and he decides to show off, he will kill himself and possibly others. He is wrong and just itching to create another wonderful news story, "Why GA pilots are cancers in our sides."
As others have mentioned,
don't promote his behavior of invulnerability by letting him continue flying without training! Be a friend and convince him his life is worth spending a few hundred dollars to make his passion for flying a certificated hobby. While he may already know most of what an instructor has to offer, he won't feel super-special because "he taught himself." This is not a case of "using the right stuff" or "showing I can do it." Both attitudes have been well documented and proven to cause major incidents and terrible accidents. Destroy your friend's macho and invulnerable attitudes before they get the best of him!
Who knows, you could be preventing an accident killing both him and a family.