Helicopter crash and hazardous materials

Factual Questions
1

A US Marine Corps transport helicopter crashed in Okinawa last week. Workers in protective gear were seen carrying away pieces of the wreck, causing some to speculate that the helicopter was carrying radioactive material, or something equally nasty. It didn’t help that the local (Japanese) authorities decided to measure radioactivity at the crash site.

Now I’m sure it’s pretty much all tinfoil-hat stuff, but I’m still curious:
[ul]
[li]What kinds of hazardous materials would you expect in a helicopter crash, that warrants a protective suit? Is it just fuel fumes? (There were no fatalities so I’d guess the, um, biological hazards are minimal.)[/li][li]Some suggested there were depleted uranium bullets. What are the chances of a Marine helicopter carrying DU, and would you need this type of protective suit to handle it?[/li][li]Is there any chance that a Marine transport helicopter would be carrying a radioactive material?[/li][/ul]

2

I’m not an aviator, and I’m sure one will chime in soon enough, but I would find it EXTREMELY unlikely that a Sea Stallion was transporting DU ammunition or any radioactives.

I would suspect that a protective suit is standard when cleaning up after a helicopter crash, considering they use standard JP4/JP5/JP8 jet fuel. If you look up the MSDS on any of them, you can see that it’s pretty nasty stuff, as it’s not only a severe irritant but contains benzene, as well.

3

Well, I am an aviator but I’ll qualify it by saying I’m entirely civilian and in no way an authority on helicopters.

My first thought was the possibiliy of deplete uranium, which, if fragmented finely enough by a crash, could pose a hazard and is highly toxic to one’s kidneys. Chemically toxic, not radioactively toxic. Well, OK, it is very slightly radioactive, but the chemical toxicity will kill you long before the very minor radiation will. But, truthfully, I have no clue how likely it would be to find DU munitions on any military helicoptor stationed anywhere in the world.

Jet fuel is a nasty irritant - I certainly wouldn’t want to bathe in it. That alone might justify a protective suit, given that such a helicoptor would carry a substantial quantity of fuel.

Certain types of medical equipment do contain radioactive substances… if they were transporting such cargo could the container, conceivably, be broken in a crash? Um… they package that stuff pretty good, but maybe you’d want to be sure. But no, I’m not aware of any standard equipment on any sort of helicoptor that would include radioactive anything.

It could be the locals were just being thorough… I mean, the Japanese have had personal experience with American aircraft bearing highly dangerous radioactive devices. I doubt the helicoptor was carrying anything of the sort, but people are often irrationally fearful.

Or maybe they genuinely believe that all Americans carry a collection of vials of radioactive dust around with them. I dunno.

But since there seems to be a highly vocal contingent urging closure of the base, it could be scaremongering on the part of local politicians seeking support for their anti-American positions.

4

Thanks for the replies - makes sense to me. I didn’t realize helicopters use jet fuel, or that it’s such nasty stuff.

By the way I read on one site that some aircraft use hydrazine for an engine starter power source. Is this true, and is this likely on this type of helicopter (CH-53D Sea Stallion in this case)?

5

Well, let’s not go too overboard on the jet fuel hazard… it’s fancy diesel fuel. With some additives that aren’t too healty for you. The stuff you put in your car is toxic and irritating, too, it’s just that cars don’t carry nearly as much fuel as a military helicoptor. Quantity is a factor, too.

At Palwaukee airport I once, in a moment of inattention, walked under a wing with a leaking fuel tank. Got a good splash in the face. Also got more or less picked up and my head rinsed thoroughly under a faucet for 15 minutes. It melted part of the frame of my glasses, and left a sort of sunburn like splash mark on the side of my face for a week, but no lasting harm done. (just ignore that third ear growing out of my cheek…) But that was aviation gasoline, not jet fuel. No, you don’t want to needlessly expose yourself to this stuff but it’s not some horribly flesh-dissolving fatal goo. As I said, I wouldn’t want to bathe in it, but a drop or two on your skin is not going to kill you. Still, if I had to clean up a giant puddle of it I’d probably prefer some sort of protection for me and my skin. Like I said, quantity counts.

It’s certainly possible, and hydrazine IS genuinely nasty stuff from what I’ve heard, but beyond that I just don’t know. Some extremely high powered engines do require a catalyst of some sort for initial ignition, but that’s completely out of the realm I inhabit. Someone else more knowledable will have to answer that.

6

Former military pilot here …

As Broomstick said, jet fuel is fancy kerosene. Taking a bath in the stuff, or more accurately, slogging around in a large mud puddle of kerosene-soaked dirt, would definitely trash a lot of skin for a few days.

And the fumes are kinda hard to breath. There’s a huge difference between you spilling a pint on the floor of your garage and an accident spilling a couple thousand gallons. The fumes from any petroleum product are going to be too dense to safely breath in that quantity. Fire Depts now wear oxygen tanks when beginning to deal with any large liquid spill for the same reason.

The military is also super-conservative about their own personnel safety outside of combat. They’d call in the guys in the moon suits when somebody spilled acid from an ordinary car battery in the auto-shop. This incident is probably mostly that attitude at work.

Hydrazine: The F-16 (which I used to fly), has a gizmo called the EPU or emergency power unit. It consists of a gas-pressurized tank with a gallon or so of hydrazine, a catalyst bed, and a turbine. The turbine is attached to a small electrical generator and a small hydraulic pump.

The F-16 only has one engine and hence does not have a lot of redundancy. The EPU was intended as an alternate source of electricity and hydraulic power to keep the airplane controllable if the engine quit, or if the main generator or hydraulic pump failed for any other reason.

Hydrazine was chosen (back in 1970) to power this thing because they needed something small and light that could be providing useful power within a second or so of getting the start signal.

On start, the tank valve opened, the gas pressure drove the hydrazine (a thick oily liquid), over the catalyst bed, wherein it reacted to form a high-temperature, high pressure gas, gaining volume and energy by a factor of a few thousand IIRC. That gas was directed to the turbine and then dumped overboard.

Dumping the gas overboard in flight wasn’t such a hazard, but if that thing fired off on the ground the exhaust plume was deadly out to a few feet, and noxious as heck for anybody within a couple hundred feet downwind.

A hydrazine spill was also dangerous, but nearly as much as the catalytic exahust, simply because the volume of vapor was so much less. Spilled on the ground, the stuff just sat there and evaporated like any other liquid. The fumes were still dangerous in concentration, but the area of concentration was much smaller.

AFAIK, the F-16 is the only aircraft of any kind in the US inventory that carries hydrazine.

7

I don’t crash helicopters; Ijust fly them. :wink:

There was a hydrazine spill over by the F-16 hangars when I worked at Edwards AFB. (I was not in danger, as I worked in Ridley Mission Control; though we did have a team member or two over there.) I heard that hydrazine could cause health problems – IIRC, affecting the liver – that manifest themselves years after exposure. Any truth to this?

8

Hydrazine

Of course, that’s British Hydrazine, no doubt it’s different in the States :wink:

9

Just to add to what everyone else has said about the nastiness of airplane crashes.

I was a Flight Safety Officer in the Air Force, and attended the Air Force Accident Investigation course. One of the things they stressed in that course was sealing off the area of a crash and protecting everyone who entered the area.

For nasty liquids we have the aforementioned JP4/JP5 and hydrazine (not a factor in this helicopter crash). I’m fairly certain the Sea Stallion has a hydraulic system, and hydraulic fluid is even worse on your skin than jet fuel.

One thing that investigators are still getting a handle on is composite materials. If an aircraft has composite materials (the radome, maybe the rotor blades) then there is a very real danger to people. When composite materials are destroyed by force they can release microscopic particles into the air, which can be inhaled and cause serious problems in your lungs.

From this site (discussing the new Boeing 7E7):

Count me in for a hazard suit when sharp long glassy needles are floating around in the air!

10

Nothing to add here except that I think it’s extremely cool that someone can ask a question like this and get answers from not just one, but several pilots, providing much better information than one can get elsewhere!

Oh yes, and that JP5 is very useful stuff. I was asked to airbrush a cool design on our department’s door on the Nimitz, but the thick Navy paint I got from the guys at the paint locker wouldn’t go through the airbrush. A quick tip-toe down to the engineroom, a twist of a petcock on a JP5 tank, and I had a small can of jet fuel – it thinned the paint quite nicely. I had a vague idea that I was creating a serious fire hazard as I atomized the fuel with my airbrush, but the painting looked terrific.

11

Yes. Radioactive material is sometimes used in turbine engine ignition systems, normally cesium-barium 137 or krypton-85. The transformer units are hermetically sealed, but require special handling when damaged. I know the General Electric T700 turboshaft engines (like what you would find in an AH-64) use cesium-barium 137. The CH-53Ds T-64 turboshafts probably use a similar system, if not the same one.

Other nasty things, not necessarily found on the CH-53: Turbine engine igniter plugs may use aluminium oxide or beyllium oxide as an insulating material. They require special handling and disposal.

Small amounts of explosive materials are found in most aircraft (including commercial airliners) fire suppression systems. Not only that, but some fire extenguishing agents such as carbon tetrachloride (Halon 104) and methyl bromide (Halon 1001) are toxic or become toxic when exposed to heat, as fire suppression agents often are. They are not as common as they once were.

Aircraft vapor cycle cooling systems often use refrigerant (R-12) that will turn into toxic phosgene gas when exposed to an open flame, similar to the carbon tetrachloride mentioned above.

There’s all kinds of yucky stuff to be found at a crash site.

12

Three people were injured – one cannot discount the possibility that the suits were to protect against biological contaminants. Large quantities of blood or tissue my have been involved in the crash.

13

In Australia, air force workers have been found to have an increased risk of developing cancer.

Hey those microscopic shards of glass are ceramic. Wouldnt they get into your body and cause “burning for a woman after making love to her husband” and “running thru all the blood and passing thru the brain and all the organs in the body, are making very minute cuts” ? Mmmm, probably not.

14

You know, I’ve seen the results of a crash with a composite aircraft (many homebuilt kitplanes are composite in structure). The do shatter, sometimes they shatter like glass, and even after the dust settles there are sharp edges everywhere.

A local pilot crashed a Long-EZE - a composite design. Three months later the salvage crew showed up to dispose of the wreckage. All were wearing heavy duty overalls, gloves, and boots to guard against cuts. And while the pilot didn’t die and made a full recovery from his injuries yes, there were “biohazard” considerations. While the surgeons were removing bits of the fuselage from his left leg, the NTSB was removing bits of his left leg from the fuselage. The salvage guys found not only a lot of dried blood, they found a few more bone chips embedded in the remains of the plane.

It, uh, didn’t smell too good either, after a few days.

Aircraft wrecks are just icky on so many levels…

15

I’d guess aviation fuel is enough to call for the supplied-air respirators.
Remember, even if a few whiffs of fuel isn’t that immediately dangerous, the safety guys assume the cleanup crew is doing this every day (and they may be), so they’ll want the suits on for long-term protection even when the exposure levels are low enough that there’s no acute danger.

16

I usually don’t make comments like this, but this sounds like Dante’s version of the old Resse’s commercial. “You got your tibia in my fuselage!”

17

That’s also referred to as a “zen experience” - for a moment, he and the airplane became one.

Seriously, the guy was incredibly lucky, even if a lot of his hip and femur are now hardware instead of bone.