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I’ve seen a bunch of mangled auto parts in my day, but this is the first time I’ve seen a broken crank from an aircraft.  Though it must happen in the air about as often as it happens on the ground, when one of these shears in the air it must be a show-stopper.

If you bug Chuck even a little he’ll probably be glad to tell you about his first solo flight where he lost his engine — from that and all the other stories I hear about single-engine-craft motors conking out, I must say it sounds like it happens entirely too much for my taste.  I’m all about working on any motor, and fixing the Stinson that this came out of sounds fun as well, but I think I’ll have to sissy out on the test flights after it’s fixed.

Statistically I know that’s stupid to say. I’ll hop on any motorcycle after fixing it, and I’m plenty aware that they’re much more dangerous than aircraft — more people are killed on them each day than in planes. Perhaps I’ve seen too many disaster movies.  Regardless, nice pic of the crank, Beano!

Toolmonger Photo Pool [Flickr]


15 Responses to Flickr Pool: Sheared Crank

  1. Stacy says:

    According to the Hurt Report, vehicle (motorcycle) failure accounted for less than 3% of these motorcycle accidents, and most of those were single vehicle accidents where control was lost due to a puncture flat.

    A mechanical failure on your bike should be the very least of your worries.

  2. Tim C says:

    I’m with you Sean. Mechanical failure on the ground doesn’t give you much time to think about the end result. In the air there would be a little too much time to contemplate my inevitable demise. I’d prefer to be the guy whose obit reads, “He never knew what hit him!”

  3. jeff says:

    On a cycle, it is way easier to gear up, leave the booze for after the ride, and ride within my abilities. Even if I get a flat, I have a lot of faith in my protective gear. I don’t mind flying but I feel way safer on my motard.

  4. beano_t says:

    Show stopper indeed. I would say though, that I have practiced “engine out” situations so many times I know the checklist in my sleep. That being said without the engine I can put that plane into a field with little or no damage no doubt in my mind but Stacy is right.

    More than the flat tire, I worry about the other driver. Many times with the plane I have someone directing traffic in real time. Take that ONSTAR.

    Of course you never know, you could get hit by lighting while walking without doing anything at all. I guess do what makes you happy because you never know.

  5. Rob says:

    I’m a pilot and this is a very rare failure. Aircraft engines used in certified aircraft (Cessnas, Pipers, Stinsons, etc) are designed to be reliable, their design has to be certified by the government, they are regularly inspected and overhauled according to strict rules, and almost all the maintenance on them has to be done by licensed mechanics.

    When these aircraft engines do fail, it is typically the pilot’s fault because they’ve done something like run out of gas or they didn’t apply carburetor heat in conditions that called for it.

    Keep in mind that these rules apply to engines used in certified aircraft. Homebuilt/experimental /light sport/ultralight aircraft often use engines that don’t meet such high standards for design and maintenance, but even they are usually pretty reliable.

    One last thing, even though it is very rare, pilots are trained to anticipate an engine failure at any time. You’re always trying to think ahead about where you would put the aircraft down if the engine(s) were to suddenly stop working. This is especially important when taking off or landing, which is when engine failures are most likely to occur.

  6. Chris says:

    Mechanical failure accounts for something like 10% or less of all aircraft accidents. I don’t think there are any studies on specific causes of the mechanical failures themselves, but the ones I can think of off the top of my head where a probable cause was determined beyond “the failure of the crankshaft/connecting rod/cylinder stud/piston/valve/etc. for undetermined reasons” were all related to bad batches of metal from which the cranks were originally forged.

    Rob, don’t confuse “mechanical failure” with fuel starvation or carburetor icing. They are very different animals, and as you point out, the latter two can usually be controlled by the pilot. Mechanical failures like this usually can’t be controlled by the pilot (or the IA who signed off the last annual). Metallurgical problems aren’t usually found until something fails catastrophically, and you just hope you can get a good post-mortem at that point.


  7. Stan says:

    Many years ago when I was stationed in Italy, I had a Fiat that broke it’s crank almost perfectly on the output to the tranny. It was so smooth of a break the engine would still run with just a slight tapping noise. The mechanic I took it too at first thought the clutch went out.


  8. bobk says:

    I also am a pilot and would expand on Rob’s statements. One thing to add is that IF the engine quits rotating the propeller, the aircraft does not stop and simply fall out of the sky as shown in most cartoons. Instead, it simply becomes a glider. Not a very good glider and indeed, in some notable designs, a particularly bad glider. But it does give time to make some decisions and preparations.

    Example: I own and fly a Piper Cherokee which in pilot’s vernacular is a “lead sled”, putting it somewhere in the “bad” end of the good-to-bad improvised glider scale. But using its numbers, here is what happens. I am generally cruising at 6.5k/7.5k ft above ground here in the midwest. Whith the engine out, my best glide speed is 80 mph, and I lose approx. 1k ft per minute at that speed (lead sled, remember?). I probably do better than that but better to overestimate that number than underestimate.

    Using the above numbers and my mind working at warp speed, I know that I have somewhere around 6 1/2 & 7 1/2 minutes, and somewhere around 8.6 & 9.75 miles to find someplace to land. At the same time, I am hitting the NRST(nearest) button on the GPS (thank god for GPS) to find the nearest airports. Assuming that an appropriate airport is in range, I am going to declare an emergency and state that I will attempt a dead stick landing at that airport. Then I will start working the checklist to attempt to restart the engine.

    If no airport options exist within comfortable gliding range, I’m looking for a reasonably flat, open field. Why not a road? Well, forgetting the moving obstacles known as “cars”, there are other problems, powerlines and associated poles, traffic signs, over/underpasses, etc to run into. Not fun.

    Finally, to emphasize what Rob has already said about pilots being trained to anticipate an engine failure, all of the above is, to this point, strictly an academic exercise for me. In my 20 years of flying, I have never had an engine failure. But it is one of the many things that I constantly consider while flying.


  9. Shopmonger says:

    Rob Says:

    March 17th, 2009 at 3:38 pm

    Rob, I am sorry to inform you but all engined are deisnged not to fail, but the reality of it is that ALL MACHINES FAIL….. But i will admit the more maint. done and the better quality parts used the less likely they are to fail…

    But I have seen a ton of engines fail…….I love the “Investigation part” after to determine the problem….

  10. Robert H says:

    You know what can really mess up a crank? When the prop strikes a solid object- like the ground.

  11. Zathrus says:

    So you’d rather take a motorcycle or car than an airplane?

    Hrm… one is a vehicle that is inspected extensively before every use, has regular maintenance and repair, has to meet incredibly strict safety standards, and requires an operator to have hundreds or thousands of hours of training before being licensed. Oh, and even then the next nearest vehicle isn’t allowed to come within a couple miles during normal operation.

    The other might be inspected once a year or so, has regular maintenance ignored most of the time, is repaired only after a problem has surfaced, requires no training to be licensed, and is regularly only a few feet from other vehicles that regularly exceed 50 mph (or well over 100 mph if you consider oncoming traffic).

    The only difference is the illusion of who’s in control.

    And no, I’m not a pilot… but far too few people practice defensive driving to think that they’re actually in control of the situation in their car or motorcycle (to be fair; I see very few motorcyclists that aren’t defensive drivers… those that aren’t are generally on crotch rockets).

  12. Patrick says:

    In defense of the car/motorcyclists – reading that Freakonomics book a few months ago, the author used the old myth that “a plane is safer than a car” as an example in misused statistics. Yes, he said, less people die on planes every year than in cars and motorcycles. But then, most people only fly for 10 – 20 hrs a year. We drive and ride for thousand more hours and thousand more miles. Average out deaths/seat time in the respective vehicles…and you find out that planes are only marginally safer, or not safe at all. Basically, if you flew with the same regularity we drive, sooner or later you have an accident. Which might be why we lost Buddy Holly, Patsy, Johnny Horton, John Denver, etc. etc. so early.

  13. Patrick says:

    And I’m diggin’ the number of small-engine pilots reading this blog. Awesome.

  14. jeff says:

    @Zathrus I’m betting that a fair bit of the audience on this site would beg to differ with you about the upkeep of their wheeled vehicles.

  15. Chris says:

    @Patrick: that’s not *really* a fair argument. Here’s why.

    Most of the “flying is safer than driving” arguments are centered on airline travel, and there’s absolutely no question that on the basis of passenger-miles travelled, flying commercially is VASTLY safer than riding in/driving a car.

    Oh, but, you argue, those are aircraft operated by professional pilots, and we’re comparing that to cars driven by a bunch of amateurs (literally). Sure, but again, when you consider total miles travelled, even when you factor in non-commercial aviation, the safety record is still far superior *per distance travelled* than it is on our roads.

    I’m not sure what seat time has to do with this, but even if you look at it that way, airline travel is still far safer than land-based vehicles of any sort. (We’re talking about a safety record that’s something like three or more orders of magnitude better than that of passenger vehicles.) In terms of accidents per hours flown, the accident record even for non-commercial aviation is still very good. It’s very difficult to compare to cars, however, because there’s no good data on exactly how much *time* people spend driving. Determining total miles driven is easy, but determining time spent covering those miles is much more difficult. (It’s easy in airplanes for a host of reasons, primarily because there’s a paper trail with all airline flights and most smaller aircraft use an hour-meter to determine maintenance schedules.)

    You could make a pretty good argument, too, that part of the appeal of aircraft relative to other forms of transportation is that they minimise the time spent en route, and therefore, by reducing the time you’re exposed to risk, reduce the risk itself. Excluding all other factors, would you rather get from point A to point B by spending two hours in an airplane or eight in a car?

    Back to specific examples that you quoted there…I’m most familiar with Buddy Holly and John Denver of those four. Buddy Holly (and Richie Valens and the Big Bopper) was a passenger on a flight that would never take place now due to various changes in laws governing charter flights. Furthermore, the pilot on that flight was relatively inexperienced, even by the more relaxed standards of the day. John Denver’s death was eminently preventable, too — he was a fairly experienced pilot, but not in the airplane in which he died, and that airplane, which was not a certificated design, had been modified from its original design in a way that may have directly contributed to the crash.

    The Freakonomics author and I do agree on one thing, though: it’s time to stop trying to describe general aviation flying as “safe”. Perhaps “less risky than activity X” would be a better way to say it. I wish I could remember who wrote the article (or what magazine it was in) that I read recently about this. The level of risk assumed by passengers getting into the typical GA aircraft is far higher than the level of risk assumed by airline passengers, and it’s not fair to them (or us as pilots) to try to pretend the level of risk is the same.


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