As I said, bullets don't cause pressurised propane cannisters to explode.

> aluminum aircraft contacting a building cause enough of a spark

Read the accident report - static electricity, not a bullet, not a pressurised propane container.

> Does there have to be another existing fire for punctured [propane] tanks to rocket upward like in the movies?

Usually a pulley system or another Hollywood trick.

> Does a drone RPG carry a light?

No. Also, not a bullet, it's a Rocket Propelled Grenade.

Just to clarify, here's a slow motion video of a bullet fired into an unsecured pressurised propane tank (small) with a lit flare next to it.

https://youtu.be/ptend5StNB8?t=62

You can see the tank outgassing and falling off the 44 gallon drum (doesn't "rocket into the air"), the gas eventually (in slow motion it takes a while) lights up from the lit flare and there's a dramatic fireball (burning gas) but no explosion as such - after all is over and done with the propane tank will look a little singed, have two holes in it, but won't look "exploded".

There are other videos with no flares .. much the same happens save there are no fireballs, the gas just expels and expands out into the atmosphere.