Lets talk real safety

Discussion in 'Safety Forum' started by clay, Apr 11, 2018.

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  1. Apr 11, 2018 #1

    clay

    clay

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    It seems almost every crash of an aircraft leads to a ground fire. It occurs to me this is similar to the 1960-1978 Formula one racing ars when they were losing 6-7 racers per year dues to safety and fires AND ACCEPTING THAT AS NATURAL OR JUST THE WAY IT IS. That bothers me and Jackie Stewart took the issue on in his sport and did something about it.

    1. What are the solutions to reducing ground fires on impacts GIVEN, we rarely see fires in F1 anymore when they impact at higher G's (Like 20+)than aircraft. Granted they are composite, I get that....but they focused heavily on fuel cell explosion proof issues when only metal was involved.

    Q: SO what are our options today to contain the fire aspect of an impact. Not all incidents are survivable, however a fire is probably controllable or at least diminished considerably at impact The PA25 impact in CA comes to mind.....no explosion proof fuel cells.

    Sorry about the soapbox it makes me mad. We CAN do something about this.
     
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  2. Apr 11, 2018 #2

    Dave Baxter

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    Clay My goal being on here is to help others so they will not get hurt either physically or financially. As for fuel systems, for certified, one has little choice, not sure if the newer airplanes are doing better, I suspect they are, but most every one is flying older ones. The home builts are another matter, and especially the smaller biplanes where the fuel tank, usually metal aluminum, and usually between the firewall and pilot on the single place, and on the two place between the fire wall and the passenger.

    You are correct about half of the hard ground contact results in a fire, and if one survives usually cannot get out with out being burnt! I asked some time ago why more pilots and passengers did not wear Nomex or kelvar flying suits or coveralls and doing so seemed to be blasphemy,and was not received well! Most all of the airshow pilots do, not that it would have saved those who flew straight into the ground!

    I do think the fuel tanks could be built with some sort of preventive design and construction! Not sure what the formula one and Indy car builders and fabricators are doing but you are correct this would be an area where some real progress could be made, some yrs ago Explosafe was something that was tried, but did not seem to do the job, I have no experience with it or other types of fuel tank containment system so am in unfamiliar territory, but am all ears? Dave
     
    Last edited: Apr 11, 2018
  3. Apr 11, 2018 #3

    TFF1

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    Bladders and foam just like race cars. Congress is about to force helicopters to require it; mandatory retrofit. Useful weight and fuel will go down some. Harder part is cost. Say airplane and the $500 race car bladder turned into $2000. You have to be careful of the foam, as poking it with a fuel nozzle can break little bits and clog up stuff down stream. Another pain is every one will be custom sized part. Lots of time to make.
     
  4. Apr 11, 2018 #4

    PittsDriver68

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    This has been tried with aerobatic airplanes. Fuel tank fill materials and flops tubes turned out to not be compatible.

    Aviation is all about risk management. F1 has more crashes per year than general aviation. Looking at per-mile stats. F1 is hugely more risky than general aviation. Apples and oranges.

    Like many, I have seen a number of crashes over the years. The vast majority of survivable crashes did not have a fire. Most of the non-survivable crashes did have a fire. So its a trade-off as to where you invest your time and $$. Airplane performance is very weight sensitive. Historically the "win" in the risk-reward trade-off is well into the performance side of the equation.

    Unlike F1, general aviation has no incentive to push operating performance on each flight to within 1% of the line where you crash.

    Best of luck,

    Wes
     
    Last edited: Apr 11, 2018
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  5. Apr 11, 2018 #5

    rvsuper8

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    After the Amanda Franklin airshow death, we installed these in all our planes. Similar to what many cars use, as well as various motor sports. An inertia activated G switch. This we place between the ground of the smoke pump and electrical fuel pump. False positive trips were solved during testing with ensuring the device is very hard mounted. Resetable. Available at Pegasus Auto Racing. Called Fuel Pump Shut-Off Switch - Inertia Activated. Link Here. $59.
    [​IMG]
     
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  6. Apr 11, 2018 #6

    Lotahp1

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    On the inertia shut off switch:
    Like many things I assume there is a million different ones that all “work”. Is the one you linked the “standard” switch used in the aviation world for smoke pumps? I guess you can easily mount this right next to your pump and if it somehow goes off the worse case is you won’t have a smoke system till you reset it. If you used one of those on a fuel pump, even a boost pump I’d think you would want to beable to reset it in flight. Or am I wrong?

    I’m wanting to mitigate the risk as much as I can. So far I see that we can use these inertia switches so they stop the pumps even if you can’t or forget to turn them off in a crash. On fuel cells, I’m not sure foam inside would do much? Isn’t the biggest issue the tank ruptures and spills fuel on on stuff? So to “fix” that wouldn’t the only think to solve that be either a tank that can be bent, collapsed etc without cracking or a “bag” inside? Either way, you’d be redesigning a tank as a “generic” tank as there is just to many sizes and shapes with not enough sales volume for the maker to be able to make something like your existing tank for less than stupid money.
     
  7. Apr 11, 2018 #7

    cwilliamrose

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    Is the fire issue a solvable problem for aircraft? Maybe not 100% but you could make things like post impact fires less likely. The problem is the cost in both dollars and weight and special needs airplanes like aerobatic airplanes add additional costs.

    Many aerobatic airplanes don't have electric fuel pumps that operate full time. Many of these airplanes have flop tubes and most of these airplanes have the main fuel tank in the cockpit. Some of these airplanes have smoke systems.

    Not having electric fuel pumps is a plus in my mind -- the fuel flow stops when the engine stops. Flop tubes are common but not the only solution to inverted fuel pickup. Standpipes work fine in small header tanks and those tanks could be foam-filled. But there will most likely be a second tank in the cockpit if you add a header tank. Smoke systems often add another tank in the cockpit. Finding a place for all these tanks in a small airplane is not easy. The smoke tank could be in the wing but not the header tank unless you're willing to install a high volume pump to keep it full.

    Unless mandated by the FAA I don't see people spending the money and weight to try to improve the situation. Isolating the fuel tank from the cockpit, adding foam and rubber bladders, adding a floptube-less header tank, moving the smoke tank to the wing, etc -- who's going to do that only to end up with a heavier and more costly airplane that is less practical to operate and has less performance?

    Comparing airplanes to F1 race cars is definitely apples and oranges. F1 budgets are other worldly and the environment they operate in is nothing like avaition's environment. F1 cars last one season and are replaced by new designs. Rules are updated each year so the entire fleet stays current. There are almost never any retrofit situations in a series like F1. The entire general aviation fleet would have to be retrofitted since new airplanes are the exception.

    This is a lot like the halon system, hard helmet and Nomex firesuit options -- very few chose to go all the way for various reasons and these are easy and fairly cheap retrofits by comparison.
     
    Last edited: Apr 11, 2018
  8. Apr 11, 2018 #8

    planebuilder

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    I was somewhat involved (minor) in the implementation of explosafe in aircraft tanks when it first came out, decades ago. It looked promising, but one unforeseen scenario was that condensation in the tank would hang up in the matrix, when you took a fuel sample, it was clean. When you taxied out to the runway, and hit a small bump or vibration, the water droplets shook free and accumulated at the lowest point, just in time for climb out! Would the foam hold water too?
     
  9. Apr 11, 2018 #9

    Beej

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    I installed this, too. The reset trigger is within reach, and if it trips due to a hard landing, a red LED lets me know. the one I used is used in Ford gas tanks.
     
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  10. Apr 11, 2018 #10

    bf92

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    My "Amanda Switch" is a relay that shuts off the smoke pump if the oil pressure drops below 20psi. I had to install a by-pass switch to run the pump when I wanted to pump out the oil tank in the hangar.

    Danny
     
  11. Apr 11, 2018 #11

    clay

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    All,

    Seems the current design thinking is internal....I like the fuel shut off valve....the issue is design from the beginning. As to apples and Oranges....try not think so literal...Many of the counterarguments were the same arguments used in 1960-1969. F! ...when budgets were much smaller...when the sponsors did not want to spend the money for track improvements and car design improvements....when they started to loose the sport... they changed....lets get ahead of that by trying some external solutions, in addition, to contain an explosion, vice JUST focusing on not starting an explosion. Seems advanced composites would help in weight and balance....a layered solution of material designed to fail progressively....the accidents we are talking about would require a rebuild anyway in most all cases....if we can stop fires, the pilot has a fighting chance...
     
  12. Apr 11, 2018 #12

    clay

    clay

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    If we have cell containment....we don't worry about materials of any kind inside the tank....bladders, foam what have you....in racing bladders are the tank...and the tank is the protection.....so maybe we can use the tank as a tank and add some external designs?
     
  13. Apr 11, 2018 #13

    PittsDriver68

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    The first problem is that there are almost zero new designs. And if the cost-benefit spreadsheet really showed significant saving of lives, the FAA would add a requirement to Part 23. That they have not speaks volumes.

    The airplanes that we talk about in this forum are surprisingly crashworthy. Steel tube structures can absorb as stunning amount of energy as they fail. And our fuel tanks are inside those structures.

    The example of the crashworthiness of our airplanes that I repeat comes from a Reno incident. A Mong came around the start pylon going for a qualification lap. Wagged to signal that he wanted to be timed, then hit some turbulence going full tilt boogie. Started porpoising and hit the desert floor going as fast as the airplane could go. Little bits of colored airplane went everywhere. All of us spectators assumed the pilot was toast. Lifeflight cranked up and flew over, landed, and shut down. We all thought that the pilot was toast. Eventually Lifeflight cranked up and headed towards Reno. We all felt bad for the pilot. Flying started up again. Well, 40 minutes later flying stopped and there were folks out where the biplane had crashed. Announcer came on the PA system to report that flying was taking a break for a few minutes. Why? They were looking for one of the crash pilot's shoes. He was down at Reno General with a broken collarbone and bruises, and somewhere he had lost one shoe. So the race staff was looking for his shoe. Now all of us who saw that airplane die looked at each other in astonishment. After a crash that bad this guy was concerned about losing a shoe?! But that little airplane took that high speed hit and as it came apart the only serious injury it left the pilot with was a broken collarbone. That says a lot about how tough the biplanes are.

    And foam does hold water, which is a big problem in aviation fuel tanks. If that was the solution, all of the jets would have foam in their tanks. But jet fuel grows bacteria and foam would really turn that into a problem. So we see some jets now put inert gas into fuel tanks as they empty. Not a viable solution for the airplanes that we talk about here.

    The Amanda accident is the only tragedy in my memory where fire was the immediate cause of death of an airplane occupant after a survivable crash. And unfortunately the harness was the major factor. If she had not been secured to the seat in the manner that she was she would have scrambled out and be alive today. We just saw a similar situation with the helicopter that went into NY harbor last week. In the totality of your safety analysis you have to look at the big picture and every part of that picture. Focusing on just one detail does not lead you to the best answer (yes I have been involved in Failure Modes and Effects Analysis - FMEA).

    Aviation always will be a risk management exercise.

    Wes
     
  14. Apr 11, 2018 #14

    clay

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    Fighting chance for pilot...not causation of an accident...is what we are seeking. Attached is a bladder focused discussion...not a huge fan...I consider foams similar to bladders....HOWEVER....it yields some interesting methodologies' to consider in item 3 and on.....worthy of design consideration.

    View attachment DS526 Replacing a Vintage Bladder Tank Guide.pdf
     
  15. Apr 11, 2018 #15

    lanceav8r

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    This isn’t a retrofit possibility but the design of my Diamond DA40 fuel system seems to prevent post-crash fires. The aluminum fuel tank is between two full size carbon spars. I don’t think there has been a single post-crash fire.
     
  16. Apr 11, 2018 #16

    rvsuper8

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    Wes very true. There have been other 'potential' cases like Eddie Andreini Travis airshow where there was at least a possibility that this MAY have helped him. Seconds of additional safety can make all the difference. Also of note in his case on this topic, his engine ran for quite a while after impact. This puts Danny's oil pressure switch at risk in his particular case. Not saying his choice is bad at all! Each has his own reasons and analysis.
    This switch was just one simple and effective way to solve one potential problem in our use case and environment that we felt was worthy of our attention.

    From an access the button point of view, we decided to NOT make it accessible. It is not a safety of flight issue on a trip and we did not want pilots troubleshooting trivial issues in the low level aerobatic environment. Many a pilot as you all know, can take a non issue, and turn it into one very quickly, trying to troubleshoot an otherwise trivial problem that is better left dealt with on the ground. There are arguments to be made on both sides of this of course. This switch was installed on both my S1's within a week of purchase.

    Cost, risk assessment, ease of implementation, complexity, failure modes, and usability are important areas to address always. Its a learning process.

    Survivability is a key area of focus for folks who do this for a living. Helmets (which we mandated after Buck Roetmans accident after seeing his helmet cracked badly), fire retarding flight suits and the like are just a few of the additional items we looked at and required over time.
    "Just give me a fighting chance!"

    Mike
     
  17. Apr 11, 2018 #17

    clay

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    Now that is interesting...worthy of further research.
     
  18. Apr 11, 2018 #18

    clay

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    "Just give me a fighting chance!" - exactly....don't discount regular pilots....accidents happen and we are not trained at below minimums.....a fighting chance is more important than ever. NO fire = More Time...for everyone including safety support incoming.
     
  19. Apr 11, 2018 #19

    clay

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    the...all foam will disintegrate....on race cars the foam is changed out every 2-3 years or so.....they are not left indefinitely.

    As to design...a bladder would work to keep the tank from penetration (1/4 or 3/8 rubber) and a technique race motorcycles use is taking a 1 in wide strip of corrugated aluminum ( about the thickness of kitchen aluminum foil) and roll the strips up into a bunch of individual cylinders and then fill the whole tank up with these cylinders....all of this to handle sloshing....still trying to figure out the flop tube issue.
     
  20. Apr 11, 2018 #20

    PittsDriver68

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    For what its worth, a number of airplanes use bladders. It appears that there is a market for replacing bladders with tanks and a couple of companies make money doing that. Bladders have their own problems.

    There is no free lunch in aviation. Discussion is healthy. Look at an aircraft as a system that is designed to meet performance requirements, where failures and catastophic events are prioritized, with engineering trade-offs made based on performance vs cost and risk vs reward. If you do that you will see why we have the airplanes that we have.

    The probability of crashing is low if the pilot does his or her part. The probability of crashing and then having a fire is even lower. Adding 10% to an aircraft's weight to address a very unlikely event is undesirable. Same for reducing the fuel capacity 10%.

    Real safety may mean never leaving the ground.

    Best advice - don't crash.

    Best of luck,

    Wes
     
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