2011-May-24 Thankfully this is as rare as it is fearsome
Last month a pilot with nearly 50 flights under his belt was foot
launching his paramotor. After a good inflation and run he stumbled,
hitting the ground hard enough that his propeller flexed into the fuel
tank, slicing through and causing a mist of fuel which burst into a fireball.
A nearby instructor ran to him, pulling him out before the flames
completely engulfed him and his machine. He is recovering with 2nd and 3rd
degree burns to his back and arms. It could have been much
worse—imagine if he was alone. Still, he will never look the same.
We've seen it numerous times where prop tips dug into the fuel tank,
causing an explosive misty cloud of fuel vapor as the prop
disintegrates. It had never ignited until now. This was a carbon fiber
prop which may be more likely to cause a spark when struck against
metal. It could have been other sources, too, such as something from the
engine exhaust. Maybe the electric starter got activated accidentally
during the fall. It's hard to say.
But what we can say is what needs to be done in the future to prevent
it. I've seen plenty of paramotors where the prop tips come within 6
inches of the gas tank. Generally 4 inches on shorter props is probably
sufficient but, anything over about 44 inches should have at least 6
inches of clearance. Look at the diagram. It shows how a change to the
gas tank shape would dramatically improve clearance.
Pilots should demand this sort of change. Ask about gas tank
clearance when you're buying your paramotor. If there are two sets of
motor mounts, you need more prop clearance because the motor would flex
more in a fall.
I've been told of one other fire incident on launch from a similar
cause in England.
Here is the forum discussion. To summarize, an experienced pilot
fell while forward launching in a way that caused the prop to
disintegrate on ground contact. A shard pierced his fuel tank near the
cap and a fireball erupted—thankfully, this pilot, too, was rescued by
pilots nearby and recovered.
It is obviously
EXTREMELY rare but, given the consequence, and how easy it
would be to fix, it SHOULD be fixed! The fact is that pilots are going
to fall and, now that we know its possible we should collectively take action.
Something that any pilot might consider is putting either an
aluminum/foam (foam towards the gas tank) or lightweight wood protector
around the vulnerable parts of their gas tank. This way if any part of
the prop tried to puncture the tank, it would hit the protector first
and make it much less likely to cause a vapor cloud, even if it does
poke a hole in it.
The protector would only need to prop side and down low--not around the whole tank. In a crash
everything flexes, from the frame to the prop tips, and it's surprising
how far forward it can come.