Ever fly with plane overloaded? Experiences?

Discussion in 'Lessons Learned' started by LongRoadBob, Apr 30, 2017.

  1. LongRoadBob

    LongRoadBob Line Up and Wait

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    Just wanted to say, so far many responses were just what I was hoping to hear about, learn.
    Since one should never exceed the limits, some people seem to think "why ask about it then" but reading that the elevators might not have the "authority" one is used to, and other effects is one thing but I "get it" a lot more when reading of experiences with this.

    And I'm also thinking about Density altitude, or possibly being over weight, or balance because of mistakes.
    I'm not sure everyone reports their actual weight, or one could have missed something, made a mistake in calculations.

    So I think it is good to hear of experiences in case.

    Thanks all for the interesting responses!
     
  2. genna

    genna Line Up and Wait

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    For N, perhaps. For P(30deg flaps standard) model that is not the case. Standard P is 2400lb max gross, 180 conversion(on CAP planes here) is 2550(same as S). As far as I know, there are no structural changes. Just bigger engine... Useful load stayed the same as well

    What's the 180hp N's max gross?
     
  3. MAKG1

    MAKG1 Touchdown! Greaser!

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    2550 with the extra STC. It's a big change, and usually makes for useful load over 1000 lb. Very much worth losing 10 deg flaps.
     
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  4. genna

    genna Line Up and Wait

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    it is. Sounds like extra HP is pretty much the only reason for 2400 to 2550 lb change.
     
  5. MAKG1

    MAKG1 Touchdown! Greaser!

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    I seem to recall an STC that raises max gross weight by adjusting some of the limitations. There should be copies of all the STCs in the AIF. Most CAP planes have several (E.g., the DF can, some of the intercom systems, etc.).
     
  6. kgruber

    kgruber En-Route

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    I was at Aerocet one day and watched Tom Hamilton design the front landing gear for the then new Aerocet Amphibian. The test to failure was completely computer generated. It would fail, and then Tom would add a little more metal, and try again.
     
  7. Stewartb

    Stewartb En-Route

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    Wing structure. The best example of a gross weight mod and wing structure that I know is the Wing X wind extensions on a Cessna 180. With no other structural mods the wings are extended and the gross weight goes from 2550 or 2650 to 2950 even with added leverage on that old wing structure. My own 180 GWT mod included a tail carry-through doubler and increased gross from 2800 to 3190. And it's seen 3190 a lot. No horsepower increases required for either mod.
     
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  8. genna

    genna Line Up and Wait

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    You are right, there is a separate STC that ups the GW from 2400 to 2550 on P. I can't find the details of what's involved in it, but it seems to be just paper STC. The 180 conversion(separate STC) can be done without this STC and GW increase. I stand corrected.

    http://airplains.com/useful-load#cessna-172-m-n-p
     
  9. Checkout_my_Six

    Checkout_my_Six Final Approach

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    As you can see there are many factors that affect a gross weight limitation.....structural is but one....climb performance is another.

    google 14CFR 23 weight limit and you'll find all kinds of stuff.
     
  10. Tantalum

    Tantalum Cleared for Takeoff

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    Makes you appreciate how overbuilt the original structure was, and also to @Checkout_my_Six point that there is a lot more at play here... power and structural loads are but one only a part of the many items at play
     
  11. SkyDog58

    SkyDog58 Final Approach

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    Yeah, but decimals can decimate.

    :D
     
  12. Stewartb

    Stewartb En-Route

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    The shape of a 172 wing is the same as a 182, 180, and 185. Speed and weight limits are mostly determined by tail and power. Structures aren't very different, either.
     
  13. danhagan

    danhagan Cleared for Takeoff

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    I've been at MTOW in the Tiger a couple of times. In the C-152 during PPL years ago where I live, ALL departures were calculated to be EXACTLY 6 pounds over MTOW (instructor required a W&B for every flight). Max fuel with two of us was about 14 gallons. Fuel burn is supposed to be 6 GPH, but several of the 152's were sparrowhawk conversions and were burning more like 7-7.5 GPH. The extra couple of pounds were supposed to be "shed" during startup, taxi and run-up (about a gallon) trying to be EXACTLY AT MTOW on departure after start/taxi/run-up. Taking off in the desert mid day in my area, 100* was always interesting:confused:
     
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  14. Tantalum

    Tantalum Cleared for Takeoff

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    That's awesome. More people should do that. I plot a W&B for every flight as well, even if it is just me in the plane. It is easy enough to do in Foreflight and I think it's good practice to make that a standard part of a good preflight, including calculating take off and climb performance. If the book says I should use up half the runway for take off, and I'm not seeing the expected performance I know to abort rather than just hope for the best

    If more people did that and had made it part of habitual preflight I'm sure we'd see less accidents tied to W&B related items
     
  15. danhagan

    danhagan Cleared for Takeoff

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    That's good practice, especially if you change planes a lot. I've flown the Tiger in the avatar for 6 years now and about 600 hours. Usually solo. Max weight with max fuel is 651 lbs, not more than 120 in the cargo bay and not more than 330 lbs behind the front seats puts me in CG at all times.
     
  16. Tantalum

    Tantalum Cleared for Takeoff

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    Thanks. The POA folks here will start to realize, if they haven't already, that I have a very "if the worst thing happens, how can I mitigate that?" <- in flying the worst thing is almost always going to be "I crash" and mitigating that is foremost "I want to live" and secondary "how can I limit blowback after the fact" <- the W&B thing seems to achieve both of those

    Reading the NTSB articles, and almost always the ones in Flying Mag, they seem to draw attention to "witnesses say the accident pilot did not prepare a W&B that day for his flight with 4 people, a dog, and a box of tools in the Cherokee 140 on the 100* day in Denver"
     
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  17. asicer

    asicer Pattern Altitude

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    I do change planes a lot but I'm not that extreme. If solo, I run WB once and keep it on file somewhere. The things that trigger a new WB for me are:
    1. Something about the plane is different
    2. Another human on board
    3. Loading something that takes more than one hand to lift
     
  18. denverpilot

    denverpilot Taxi to Parking

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    I think I saw that dude loading up once, from the upstairs windows above Denver Jet Center at the Perfect Landing restaurant. LOL.

    No kidding. I've seen some incredible amounts of crap being loaded into aircraft that shouldn't be carrying that much stuff from those windows, while enjoying a burrito or burger.
     
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  19. Stewartb

    Stewartb En-Route

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    With smart phone W&B apps there's little excuse not to become familiar with your loads and balances. I've had my plane long enough that I know how to load it to maximize the performance I want that day. A little aft makes the plane faster. A little forward helps it work shorter. Do I do a W&B for every flight? Oh hell no. I won't bother with that until I start approaching the limits of gross or CG, and that isn't the norm for my average flights these days.
     
  20. Tantalum

    Tantalum Cleared for Takeoff

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    ..and that definitely makes sense if you own your plane and are very familiar with it. But with the club planes and having a few different Skyhawks, Archers, and even SR20s to select from I find it to be good practice, at least for me. I obviously know that with me and one pax I'll be well within limits, but the extra calculation from the POH to check take off distance etc just gives me that much more familiarity with the plane, especially on very hot or cold days so I can expect some different performance

    Maybe I also spent too much time in my youth on MSFS plugging in weights to FMCs, etc., and it became habit forming from there...
     
  21. Tantalum

    Tantalum Cleared for Takeoff

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    By the way, how hard would it be to put scales in the wheels and a little computer algorithm to calculate these things for you and have it talk to the Avidyne, G1000, etc. I know the immediate response will be "weight, more things to break, complexity, costs, insurance, etc." but I mean, think about how complex the other systems on a plane are. Putting a weight sensor by each wheel surely would fall on the lower end of the complexity spectrum??
     
  22. gasfiltered

    gasfiltered Pre-takeoff checklist

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    Could someone explain the "Alaska 15%" rule? I know there is or was an exception to the FAR which allows commercial operators in AK to operate at 15% over gross, but I never understood the details. I think it's germane to the structural v. performance debate going on in this thread. That doesn't sound like much at first but 15% of a 3100lb 182 is 465lbs; quite an extra load.
     
  23. Mtns2Skies

    Mtns2Skies Super Moderator Management Council Member PoA Supporter

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    Hmm that's a good thought! The only minor issue I can see with it it that tricycle gear planes sit at varying levels of nose up attitude which the sensors would read as more weight on the main wheels than is true for level flight. This probably wouldn't amount to THAT big of a difference though.
     
  24. Clark1961

    Clark1961 Touchdown! Greaser!

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    SMDH. Young engineers....

    I once had one tell me the load on a mast was some multiple of a hook load and that the multiple was much greater than one. We were discussing multi-part hoists. I seriously asked him if he believed that the crane pulled down harder than it pulled up and the earnest response was yes....what can ya do?
     
  25. Mtns2Skies

    Mtns2Skies Super Moderator Management Council Member PoA Supporter

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    Well correct me if I'm wrong but you'd take the (lets assume 5 deg nose-up) sin(5) = 0.087 and we see that there is an extra vector on the main gear increasing the magnitude on the main gear(due to the X component) and decreasing it on the nose gear. What you don't have in the air is the normal force the nose wheel strut exerts upwards which of course doesn't change the weight of the aircraft, but shifts the angle thus putting more weight MAGNITUDE on the rear wheels. So the CoG wouldn't actually be changing but the perceived weights on the sensors would differ.
    [​IMG]
    :dunno:
     
    Last edited: May 5, 2017
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  26. Stewartb

    Stewartb En-Route

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    121 and 135 operations only. Supposed to allow useful payloads with full fuel for long flights, so obviously the overweight condition corrects itself along the route. It isn't an arbitrary choice of the operator. The FAA has to approve it.

    https://aviation.stackexchange.com/questions/202/is-it-legal-to-overload-a-plane-in-alaska
     
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  27. MAKG1

    MAKG1 Touchdown! Greaser!

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    Considering Skyhawks can't even manage a dirt simple fuel level gauge, do you really want to bet your butt on a calibrated spring that will read overweight permanently the first time some 5 hour student plops a landing?

    Such a device will need periodic inspections and adjustments equivalent to weighing the aircraft at every 100-hour.
     
  28. Mtns2Skies

    Mtns2Skies Super Moderator Management Council Member PoA Supporter

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    You could place strain gauges on spring steel gear. Thus using the gear as the calibrated spring.
     
  29. MAKG1

    MAKG1 Touchdown! Greaser!

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    And it would function just as reliably as the Cessna flap indicator.

    Just because you can get "an" answer doesn't mean it's the correct answer. W&B can be touchy.
     
  30. Clark1961

    Clark1961 Touchdown! Greaser!

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    See what I mean? The new ones go into analysis (and that analysis is perfect by god!) without stepping back and asking what is really happening here. Yes, we spend years training them to solve equations that we give them. We teach them to jump into analysis. We don't teach them to look at the big picture. There are reasons for this and please feel free to discuss.

    In this case the scales would have to be on all three wheels and since they are free to roll there would only be load in one direction. Angles will not matter if the sensors are at the axles.
     
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  31. Tantalum

    Tantalum Cleared for Takeoff

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    Reminds me of the cartoons we're they pull on the locked door using the door as leverage on itself

    I never got why the fuel gauges on planes were some enigmatic entity. The fuel gauge on my 5 gallon tank from Walmart is more accurate
     
  32. Mtns2Skies

    Mtns2Skies Super Moderator Management Council Member PoA Supporter

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    Pretty sure I'm still right: L=10m
    IMG_20170505_105932232.jpg
     
  33. Clark1961

    Clark1961 Touchdown! Greaser!

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    See what I mean? They are right by god!
     
  34. mondtster

    mondtster Pattern Altitude

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    I'm curious, how much experience do you have working with strain gauges?
     
  35. Mtns2Skies

    Mtns2Skies Super Moderator Management Council Member PoA Supporter

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    Experiments in school and a few times at work measuring deflection of a slider crank.

    Surely one could find deflection of the (spring steel) landing gear based upon the strain gauge and then translate that into a force. (Castiglianos thm)

    ... Is this incorrect?
     
    Last edited: May 5, 2017
  36. mondtster

    mondtster Pattern Altitude

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    You're not incorrect, I'd just say it is impractical and not durable for a production environment. How involved were you in the laying of the gauges, calibration and data collection? Do you believe the data you generated is accurate?

    There are lots of ways to screw this up. Then there would be about zero chance of it ever working again after a mechanic works on it for any length of time, because the number of mechanics that understand strain gauges is about nil.
     
  37. Mtns2Skies

    Mtns2Skies Super Moderator Management Council Member PoA Supporter

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    Very involved with collection and calibration. Not with laying the gauge. All times I've used them were not for sustained purposes and were removed after we had our data. Lots of noise and low signal, so I had to put a large gain on it and run it through a high pass filter and a few others. I believe the data was accurate within 2% which was good enough for my applications.
     
  38. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    Bruce, it doesn't look like the NTSB has reached a conclusion yet... But it doesn't seem to me like a 414 being 271 pounds over gross is enough to cause it to fall out of the sky without an engine failure at a critical time? Or do you think it was the aft CG (also a bigger problem with a failed engine)? They do seem to indicate that the props were both turning at impact and neither was feathered.
     
  39. MAKG1

    MAKG1 Touchdown! Greaser!

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    2% is a nearly 50 lb error on a 172.

    Remember, excess power available to climb is NOT linear in gross weight.

    You can do a lot better with a scale and a calculation.
     
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  40. Clark1961

    Clark1961 Touchdown! Greaser!

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    I've used strain gauges in an industrial environment with a rather carefully controlled installation and calibration. We used them for fluid pressure measurement in lieu of crystal gauges. Any time a weight measurement is needed we use hydraulic load cells.

    Anyway for the whole point of this exercise the measurement was spec'd at the wheels so no trig involved.