Aluminum Body and Lightening

NRALIFR wrote:
It’s likely that wasn’t a typical cloud to cloud, or cloud to ground lightning strike. Helicopter triggered lightning strikes are a studied but not well understood phenomenon. The part of the helicopter struck is almost always the main or tail rotor blades. As you are probably aware, helicopters acquire a strong negative charge when they fly through air because of static charging. Strong enough that if you were to touch a hovering helicopter while standing on the ground, you could be seriously hurt or killed. I suspect the “strike” you experienced was induced when the helicopter you were flying flew into a positively charged area around a storm cloud. It was probably of lower intensity than a typical cloud to cloud or cloud to ground lightning strike, but strong enough to cause the damage you found.

:):)

You're probably right about the lightning being a different beast but the bit about getting killed by the static shock is a bit of an exaggeration. Half the Helicopter Handlers in the British Army would be dead if that were the case. The Puma I flew generates a healthy jolt I'll admit but only about 1 1/2 to 2 times that of a regular cattle fence. That aircraft is 7000kg, (14000lbs), maximum all up weight.

I know people who have been hit by a Chinook and a Puma - at different times ;-) - that say the Chinook, which has a max all up weight of over 30000lb, can throw you a few feet onto your behind but I have never heard of anyone being injured and with all the underslung load stuff Army Support Helicopters do in the British Forces, (and NATO), there would be examples.

am1958 wrote:
Many years ago in Belize a pilot and I were returning from tasking in the middle of the country in an RAF Puma helicopter. It was the rainy season and we found ourselves cornered by thunderstorms and in an area of the jungle where there were no landing sites so we pushed on through the weather. After landing I got out to do the After flight checks which included checking the rotor blades. There was a small "blister" about the size of a quarter on the underside of one of the blades so I got the ladder out to inspect it. There was an identical "blister" on the top side of the blade in the same place. I called over a senior tech and showed it to him. He immediately identified it as a lightning strike. Funny thing was neither the pilot nor myself had any idea it had happened...

It’s likely that wasn’t a typical cloud to cloud, or cloud to ground lightning strike. Helicopter triggered lightning strikes are a studied but not well understood phenomenon. The part of the helicopter struck is almost always the main or tail rotor blades. As you are probably aware, helicopters acquire a strong negative charge when they fly through air because of static charging. Strong enough that if you were to touch a hovering helicopter while standing on the ground, you could be seriously hurt or killed. I suspect the “strike” you experienced was induced when the helicopter you were flying flew into a positively charged area around a storm cloud. It was probably of lower intensity than a typical cloud to cloud or cloud to ground lightning strike, but strong enough to cause the damage you found.

:):)

Chum lee wrote:
Not to hijack the thread, but, out of interest: (I'm a pilot)

What did the tech recommend as a repair?

A. Replace the blade
B. Repair the blade
C. Nothing
D. Other (please specify)

How was the blade fabricated? (material)

Thanks,

Chum lee

It was "many years ago" as I said - think mid 80's so my memory of the blade construction is gone but it was a composite, hollow blade and in many cases the techs placed Black Duct tape, (yes you read that right), along the leading edges to protect them from small debris damage when we were close to the ground. The techs did nothing as the basic integrity of the blade was intact and the blisters were only slightly raised from the surface. A "green line"* was written in the log book so future crews would be aware and check on it before and after flights as would the techs.

* A green line in the RAF is an entry in the logbook "faults" page that is highlighted in green. This means that it has the potential to affect operation of the aircraft but it is not likely. The pilot signs the log and part of what he is signing for is that he is aware of any green or red line entries and accepts them. We would often take airframes with as many as a dozen green lines and even the occasional red line though they were more likely to be fixed prior to the aircraft being designated serviceable.

Hope that helps

When my F53 V10 runs at highway speed and 2250 RPM, the "spark plugs" cause about 1125 lightning fires a minute. Fortunately, they are all contained within the combustion chambers.

Chum lee

mich800 wrote:
So it is a shocker lighting can cause a fire? Must be a conspiracy about the forest fires started by lighting strikes.

Yes, but that lightning-caused forest fire was in a forest that previously looked like this: :)

am1958 wrote:
Many years ago in Belize a pilot and I were returning from tasking in the middle of the country in an RAF Puma helicopter. After landing I got out to do the after flight checks which included checking the rotor blades. There was a small "blister" about the size of a quarter on the underside of one of the blades. There was an identical "blister" on the top side of the blade in the same place. I called over a senior tech and showed it to him. He immediately identified it as a lightning strike. Funny thing was neither the pilot nor myself had any idea it had happened...

Not to hijack the thread, but, out of interest: (I'm a pilot)

What did the tech recommend as a repair?

A. Replace the blade
B. Repair the blade
C. Nothing
D. Other (please specify)

How was the blade fabricated? (material)

Thanks,

Chum lee

Rover bill, you need another hobby.....

Rover_Bill wrote:

JaxDad wrote:

What does the truck being made of aluminum have to do with it being struck by lightning? It’s no more or or less conductive than any other metal used in automotive body construction.

The heat of the lightning strike starts the interior on fire instantly and it doesn’t matter what metal it’s behind, it all conducts heat the same.

Pictures from the recent California wild fires showed a lot of burned out steel body pickups and cars. None that I can remember showed any with a totally burned off roof or engine hood like in this one. Just sayin.

What's still more fascinating is to read some people comments ...... then read what brand of truck they drive.......

A gasoline fire burns at 1500F
Carbon steel melts at 2600-2800F
Aluminum alloy melts at 1200F

The conclusion drawn was the aluminum truck was destroyed because of electricity from lightning conducting through an aluminum body vs a steel body. Really???

free radical wrote:

Rover_Bill wrote:
Aluminum wiring was band many years ago because it can cause house fires when arching. This is what happened when lightening hit an aluminum body Ford pickup. :E

Clicky

FAKE NEWS

Lightning cannot start car fire aluminum or any other


https://youtu.be/olxaFBtCV4Q

It's not that black and white. Obviously convertibles or cars made of non-metal wouldn't have the "Faraday cage" effect. And any place wiring comes close to the metal body can be impacted, as well as the electronics (perhaps due to magnetic fields induced? Not sure)

click

pt2