nah

We can take bets, but I guess a spark plug must have gone jammed after clogs weren't oiled, so the diesel wouldn't ignited and the plane crashed.

indeed, the mechanics was on vacation in the UK to check out cathedrals in small towns.

These plane things are terribly unreliable.

Diesel engines don't have spark plugs.

Planes rarely have diesel engines as well.

I also am unsure how you are supposed to "oil the clogs" to prevent "jamming"

It's satire. It's not supposed to be any more accurate than the suggestion the mechanic was touring cathedrals.

Do private planes just crash or can it glide to a landing ona road

That depends on the kind and severity of the failure. You could have a full electrical failure and the plane would still fly. But when you miss a wing the rest doesn't really matter any more.

they usually do

but for unknown reasons, the passengers refused to glide and decided to plunge the plane to wilfully die.

now, since they wilfully died, there is no reason to trigger further investigations.

And supreme leader Putin will seek damages from the families of the passengers, as they destroyed his plane.

Usually, after they are shot down by air defense missiles, what’s left just crashes.

Perhaps some private planes (Cirrus) are better equipped to survive losing a wing, since they have rocket-deployed parachutes.

Somewhat boring video of the parachute in action ("boring" being a synonym for "an amazing triumph of safety engineering"):

https://www.youtube.com/watch?v=gBCUQlF3MMU

14m video essay about the system:

https://www.youtube.com/watch?v=zT58pzY41wA

(Reporting says this was an Embraer, this is strictly a tangent.)