# why a lead bar on an airplane **URL:** \ **Category:** Factual Questions\ **Created:** [June 27, 2013, 7:52pm UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052 "2013-06-27T19:52:10Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![DataX](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@DataX](https://boards.straightdope.com/u/DataX)\ **Post date:** [June 28, 2013, 12:54am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/21 "2013-06-28T00:54:55Z")
> [@Lord\_Mondegreen](#): > > And after waiting those two days they called 911. I don’t live in the US, but isn’t that number only for emergencies? Calling the local equivalent here (000) for a non-urgent matter would not make you at all popular with the authorities. Technically it is supposed to be only for emergencies, but I’ve actually called the police station before for a non emergency call - and they told me to hang up and call 911. I think in at least some areas - it is easier for it all to go through one system (and they get recordings too). Now there is 311 in some areas, but I don’t think you will usually get in trouble for calling 911 for a relatively serious, but not technically urgent call. ---
**Author:** ![moriah](https://avatars.discourse-cdn.com/v4/letter/m/b2d939/32.png) [@moriah](https://boards.straightdope.com/u/moriah)\ **Post date:** [June 28, 2013, 12:56am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/22 "2013-06-28T00:56:13Z")
> [@Johnny\_L.A](#): > > It could be weight added to the airframe to balance it about the CG. Airplanes from around/before WWII sometimes had external counterweights on their control surfaces. Nowadays they are internal, where they exist. Wow, that took a really long time to fall, then. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [June 28, 2013, 1:13am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/23 "2013-06-28T01:13:26Z")
Single engine Cessnas use small lead bars as counterweights towards the outside of the wings. They aren’t exactly internal, but they are hard to see if you don’t know where to look being in the gap between the ailerons and the wing proper. If I recall correctly, they also use them for the elevators. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [June 28, 2013, 1:39am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/24 "2013-06-28T01:39:02Z")
> [@Broomstick](#): > > If I recall correctly, they also use them for the elevators. In the tip of the part of the elevator that is forward of the hinge. The inboard part is not skinned, so you can see the D-shaped ingot there. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [June 28, 2013, 3:25am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/25 "2013-06-28T03:25:25Z")
The first 747s built carried a serious amount of depleted uranium in the engine pylons. This was part of the mass damping design for the flexible wing. The early builds didn’t quite meet the requirements, and so they needed extra mass in the pylon. Using depleted uranium means you can get the centre of mass much closer to the place where you need it. If they used lead they would need more mass than when they used uranium. Boeing sorted the design out and later planes didn’t need the extra mass. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [June 28, 2013, 3:58am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/26 "2013-06-28T03:58:23Z")
remember this thread when an accident report lists aileron flutter as the reason for structural failure. ---
**Author:** ![PatriotGrrrl](https://avatars.discourse-cdn.com/v4/letter/p/9dc877/32.png) [@PatriotGrrrl](https://boards.straightdope.com/u/PatriotGrrrl)\ **Post date:** [June 28, 2013, 4:16am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/27 "2013-06-28T04:16:50Z")
> [@DataX](#): > > I’m pretty sure they didn’t test it - and are probably using “lead” as shorthand for heavy metal. At least that would be my guess. Is there an easy way to test for lead? Can a novice tell by looking at it? I don’t know the answers to either of those, but based on what I know about precious metals, my guess would be no. I’m thinking a bar of lead would look and feel extremely similar to lead bullets, lead shot, lead sinkers, lead battery terminals, lead wheel balancing weights, lead sash weights, lead for stained glass, and so on. Except, y’know, for being bar shaped. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 28, 2013, 12:01pm UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/28 "2013-06-28T12:01:41Z")
> [@Sigene](#): > > The tub grinder thing certainly seems a strong possibility except for the statement that the piece is lead. > > I’m sure lead makes a poor grinding material If it’s from a tub grinder, then it’s probably [tungsten carbide.](http://en.wikipedia.org/wiki/Tungsten_carbide) This is an _extremely_ hard material often used in industrial cutting tools, and it’s also extremely dense - even more dense than lead. A layperson who is unfamiliar with carbide might pick it up and think “hm, this must be lead because it’s extraordinarily heavy for its size.” Someone more familiar with carbide would try to scratch it, which would be a definitive test. Lead is easily gouged; carbide is just about impossible unless you’re using a diamond. ---
**Author:** ![Sigene](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Sigene](https://boards.straightdope.com/u/Sigene)\ **Post date:** [June 28, 2013, 12:17pm UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/29 "2013-06-28T12:17:06Z")
> [@Machine\_Elf](#): > > If it’s from a tub grinder, then it’s probably [tungsten carbide.](http://en.wikipedia.org/wiki/Tungsten_carbide) This is an _extremely_ hard material often used in industrial cutting tools, and it’s also extremely dense - even more dense than lead. A layperson who is unfamiliar with carbide might pick it up and think “hm, this must be lead because it’s extraordinarily heavy for its size.” Someone more familiar with carbide would try to scratch it, which would be a definitive test. Lead is easily gouged; carbide is just about impossible unless you’re using a diamond. I follow your point with the tungsten carbide then, if it is that dense, could be mistaken for lead. The images however show that it is pretty marred and disfigured as I would expect from a soft metal like lead. Interesting. So it could be tub grinder tooth or not; but my original question has been answered to my satisfaction that lead weights are indeed found on aircraft. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 28, 2013, 12:59pm UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/30 "2013-06-28T12:59:43Z")
> [@Sigene](#): > > The images however show that it is pretty marred and disfigured as I would expect from a soft metal like lead. After looking up more info on tub grinder teeth, it seems the typical construction is a base block of steel (this is what the hex bolt heads drop into), with thick, carbide-infused weld beads on either end. In the pics [at this link](http://www.komonews.com/news/local/Mysterious-metal-bars-falls-from-the-sky-crashes-into-Seattle-home-213236311.html?tab=gallery&c=y&img=1) the carbide-infused weld beads run vertically at the left and right ends, and the steel is in the middle. The carbide areas are rough-textured even when new, so no surprise at their condition in the photos. A chunk of the carbide is cracked off of the upper left corner. The underside of the steel base is pretty chewed up, but that’s to be expected if it’s been tossed around inside a tub grinder before being somehow catapulted out. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [June 28, 2013, 11:55pm UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/31 "2013-06-28T23:55:12Z")
Ballista shot? :dubious: ---
**Author:** ![fumster](https://avatars.discourse-cdn.com/v4/letter/f/e9c0ed/32.png) [@fumster](https://boards.straightdope.com/u/fumster)\ **Post date:** [June 29, 2013, 12:37am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/32 "2013-06-29T00:37:56Z")
A similar thing happened in Oregon near a general aviation airport, but it was a hammer. At first they though it had fallen off a plane where it had been left after maintenance. Turned out to be a hammer that had fallen in a chipper. ---
**Author:** ![rbroome](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@rbroome](https://boards.straightdope.com/u/rbroome)\ **Post date:** [June 29, 2013, 1:15am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/33 "2013-06-29T01:15:08Z")
I was impressed to read that counter-weights are used all over: including Mars! > **[Curiosity's Landing Leftovers](https://www.universetoday.com/100409/curiositys-landing-leftovers/)** > > During its “seven minutes of terror” landing on August 6, 2012, NASA’s Mars Science Laboratory dropped quite a few things down onto the Martian surface: pieces from the cruise stage, a heat shield, a parachute, the entry capsule’s backshell, a sky... ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [June 29, 2013, 1:52am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/34 "2013-06-29T01:52:27Z")
> [@DCnDC](#): > > “They waited 2 days to call authorities?” I’m thinking that they probably never intended to call the police since there were no injuries and no crime. They called their insurance company who told them they would need a police report to file a claim. Just a guess though. ---
**Author:** ![Ranger\_Jeff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranger_jeff/32/2065_2.png) [@Ranger\_Jeff](https://boards.straightdope.com/u/Ranger_Jeff)\ **Post date:** [June 29, 2013, 4:02am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/35 "2013-06-29T04:02:37Z")
> [@DataX](#): > > I’m pretty sure they didn’t test it - and are probably using “lead” as shorthand for heavy metal. At least that would be my guess. Is there an easy way to test for lead? Can a novice tell by looking at it? I don’t know the answers to either of those, but based on what I know about precious metals, my guess would be no. I etched a crude crucifix in a .22 calibre lr bullet with my thumbnail. I wasn’t sure if it’d be effective against vampires or werewolves, but that’s what was available. So heavy and soft is a good test for lead. DU is anything BUT soft. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [June 29, 2013, 5:31am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/36 "2013-06-29T05:31:34Z")
> [@rbroome](#): > > I was impressed to read that counter-weights are used all over: including Mars! > [http://www.universetoday.com/100409/curiositys-landing-leftovers/](http://www.universetoday.com/100409/curiositys-landing-leftovers/) I think the counterweights in Curiosity’s lander are a great example of engineering trade-offs. Just as the idea that an airplane could need to carry lead weights, when everything else is engineered so carefully to minimise weight, seems insane, the idea that you would carry three hundred kilograms of dumb mass all the way to Mars along with a 900kg lander that cost about a billion dollars seems worse than insane. But the counterweights provided passive stability by moving the centre of gravity of the system, and did so in a very simple and bullet proof manner. One could imagine that all the competing solutions were both vastly more complex, and may eventually have weighed no less. It does seem a shame that the counterweights couldn’t have been used to do some sort of science, but getting the rover down was clearly way ahead in priority. Maybe they have impacted hard enough that they have uncovered stuff that the rover could not ordinarily get to, and one day it will be worth visiting the impact sites. ---
**Author:** ![fumster](https://avatars.discourse-cdn.com/v4/letter/f/e9c0ed/32.png) [@fumster](https://boards.straightdope.com/u/fumster)\ **Post date:** [June 29, 2013, 8:25pm UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/37 "2013-06-29T20:25:12Z")
I wonder if the piece in question is actually a lead space that is used between the tungsten carbide tooth and the steel used in the rest of the chipper. The lead would absorb some of punishment and make it less likely for the tooth to chip or shatter. ---
**Author:** ![Jamicat](https://avatars.discourse-cdn.com/v4/letter/j/c67d28/32.png) [@Jamicat](https://boards.straightdope.com/u/Jamicat)\ **Post date:** [July 1, 2013, 2:15am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/38 "2013-07-01T02:15:32Z")
> [@fumster](#): > > I wonder if the piece in question is actually a lead space that is used between the tungsten carbide tooth and the steel used in the rest of the chipper. The lead would absorb some of punishment and make it less likely for the tooth to chip or shatter. no… It’s tungsten/carbide braised directly to steel or the whole thing might even be tungsten. Lead would do nothing but wear away really fast in that environment. Some tools have backing plates, but they aren’t made of lead. It just looks like the bolt heads nubbed off that held the thing on to the holder. ---
**Author:** ![robert\_columbia](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@robert\_columbia](https://boards.straightdope.com/u/robert_columbia)\ **Post date:** [July 1, 2013, 6:05am UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/39 "2013-07-01T06:05:02Z")
> [@RedSwinglineOne](#): > > From > > [http://www.cnn.com/2013/06/27/us/seattle-lead-crashes-roof/index.html?hpt=hp\_t3](http://www.cnn.com/2013/06/27/us/seattle-lead-crashes-roof/index.html?hpt=hp_t3) > > Everyone’s a comedian. Except the ones who are plumb crazy. ---
**Author:** ![Blakeyrat](https://avatars.discourse-cdn.com/v4/letter/b/ecd19e/32.png) [@Blakeyrat](https://boards.straightdope.com/u/Blakeyrat)\ **Post date:** [July 1, 2013, 5:02pm UTC](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052/40 "2013-07-01T17:02:30Z")
> [@DCnDC](#): > > They waited 2 days to call authorities? Hey we Seattleites handle our own affairs. … seriously though that struck me too. I wonder if the insurance company prompted it. (“Well pay your claim when we see a official report.”) [Previous page](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052.md?page=1) [Next page](https://boards.straightdope.com/t/why-a-lead-bar-on-an-airplane/662052.md?page=3)