Weight and Balance PA28150 Cherokee

Discussion in 'Maintenance Bay' started by JoesPiper, Mar 17, 2019.

  1. JoesPiper

    JoesPiper Filing Flight Plan

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    Who has their weights for each main? Looking for comparisons. (yes, there will be a wide range I'm sure)
     
  2. AKBill

    AKBill Pattern Altitude

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    I've got the numbers for a Beech Sport w/full fuel...:rolleyes:
    Nose 523lb
    Left 669
    Right 657
    :D
     
  3. JoesPiper

    JoesPiper Filing Flight Plan

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    That spread not so bad. Looking for more.
     
  4. Timbeck2

    Timbeck2 Final Approach

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    Joe, what is the spread between your mains? This is the second thread you've asked the question, now I'm curious.
     
  5. AKBill

    AKBill Pattern Altitude

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    Not sure meaning of the spread? I'm curious as well.
     
  6. Timbeck2

    Timbeck2 Final Approach

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    I'm guessing he means the weight difference in the two.
     
  7. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    Difference in weight between the two.
     
  8. AKBill

    AKBill Pattern Altitude

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    That's what I thought. So my spread is 12 pounds. Must be the weights to balance the wheels...:rolleyes:

    Maybe more paint on one wing or the landing light and pito tube..:)
     
  9. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    Or the six-pack of instruments and other assorted stuff mounted on the left side of the panel.
     
  10. murphey

    murphey Final Approach PoA Supporter

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    why? why is it relevant? and how do you measure weight on dfferent wheels?
     
  11. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    With a scale under that wheel?
     
  12. murphey

    murphey Final Approach PoA Supporter

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    No, really, what is the benefit of knowing weight at each wheel?
     
  13. Ravioli

    Ravioli Final Approach PoA Supporter

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    You'll need a henweigh to figure out the spread.

    What's a henweigh? Usually about 5 pounds. :) :)
     
  14. Ravioli

    Ravioli Final Approach PoA Supporter

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    For serious conversation, knowing the weight at the mains and the nose or tail wheel is critical to W&B. As far as left main vs right main I'm unaware of a reason.
     
  15. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    Well, you can’t know the total weight of the aircraft without knowing the weight at each wheel.

    Otherwise, I don’t understand the question.
     
  16. AKBill

    AKBill Pattern Altitude

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    :blueplane:
    :yeahthat:
     
  17. Timbeck2

    Timbeck2 Final Approach

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    I think Joe was just curious about the difference in the weights of the main wheels. It really doesn't matter but I'd be curious too if say my left main weighed X and my right main weighed X+ 50. I'd be wondering why so much heavier on the right side. Since the mains are at the same station, they are added up together. That measurement plus the weight of the nose gives the total weight of the plane. You need each measurement to determine the exact CG for weight and balance calculations.
     
  18. AKBill

    AKBill Pattern Altitude

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    I'm picking up what you are putting down. In my case 12 pound difference between mains. Could have been the fuel load, as I went with full tanks when I weighed it. Maybe, maybe not. I think the empty weight of the Sport is 50 pounds heaver that the original W&B from Beechcraft.

    I have removed and added parts over the years. Owned for the Sport since 1996, it's a 1974 model. Heck I have gained 40 pounds since 1996..:( For the Beech there is a specific procedure to follow. I'm good with my numbers but I would like to get picky and find were the 50 difference is.
     
  19. JoesPiper

    JoesPiper Filing Flight Plan

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    Ok! First off, I've been at this airplane stuff as an A&P/IA for 40 years!- no kidding. yep, so when I see something off it drives me nuts. I wanted to research others within my week break between weighing) For example, back in 05, I weighed my craft (73 PA28150 Cruiser with Piper Air (www.joespiper.com) and the mains were very close - 5 lb spread. Over the years I have removed and added various equipment and accessories. I also repainted the craft (colors only) recently, added ADS-B (978 in/out wifi), PFS exhaust,new Skytech started (huge weight savings), removed AC air compressor and bracket (26 lbs off the nose). Total 35 lbs off nose.
    Time to reweigh airplane. Mind now, I am using digital scales to 1/10th % tolerance (extremely accurate with indicated percentage weights as well - all percentages must equal 100%). Drained tanks empty (mandatory), set the plane up, removed tail satnd and weighed it - 30 Lb spread between mains (Lft - 539, Rt - 509, Nose - 402: (rocked wings for stable, same - WTF?
    Why is spread important - roll balance with equal fuel each tank. You ATP people know this. Anyhoo, I reweighed - same thing. So, took a break, following week. Removed head sets, and quart of oil from left seat (6 lbs). Reset scales - zero weight, rocked wings to equalize struts EQUAL length (key), and also set prop to vertical position (key) - WALA! Actually, opening the door (swinging it) has an affect on the weights as well, but we fly with door closed. So, with the craft set aligned laterally and longitudinally ( my mistake - no brainer / happens!) and refilling tires all to 25 psig (important) the weights came out as they should Nose - 396, Rt - 517, Lft - 528 (12 lb spread). I can now sign off new weight and balance with annual. I must have been having a bad day that initial weigh day. That's why we do things over and over until its right and not until then. That is also why I am very concerned about the FAA wanting to change training rules be it pilot or mechanic to skip corners to please business for profits - its killing people (so far recent 2 Boeing 737's)
    Answered my question, hope it answers yours :) All about the setup or in flight - sterile cockpit and checklists. On the ground you get a second chance, in the air, might be a flip of the coin!
     
  20. murphey

    murphey Final Approach PoA Supporter

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    That’s what I didn’t understand...thanks.
     
  21. Bell206

    Bell206 Cleared for Takeoff

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    FYI: it's not so much the weight at each wheel but the weight at each reference point which is dependent on the type of WB equipment used. Some systems and/or aircraft procedures measure at the jackpoints. And some use 4 load cells vs the normal 3 used.

    As to the difference between left and right readings there is an A-Z list of possible reasons. Regardless of the weight difference, it's the total final weight and calculation of CG that matters. However, some aircraft can be sensitive to lateral CG changes so any difference will be dealt with via the OEM empty weight charts/calculations and not the raw weight readings at the load scales.
     
  22. JoesPiper

    JoesPiper Filing Flight Plan

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    Weight difference is huge and does make a difference. Basing your weight off a piece of paper written 40 years ago is a NOT. You always want to know why there is a massive difference between wings or mains. I know of No pilot that doesn't and NO mechanic that would refuse to also.
    Calculating CG is one thing (pitching on lateral and aft weight), but longitudinal differences are huge as well - rough weather, mountain drafts etc.
    30 lbs dif may not be so much, but other aircraft their difference go unlooked. 30 lbs on a small aircraft is huge. Also, we are not talking gross weight here - that's a no brainer. Nice response but a little off.
     
  23. Bell206

    Bell206 Cleared for Takeoff

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    And neither am I. I believe the original question is dealing with empty weight not loading weight values. As such the pilot/owner is not involved in calculating the empty weight/CG only a AP. But I'm curious, how do you know an aircraft is out of the lateral CG limits by only looking at 2 of the 3 weighing point values without further calculations?
     
    Last edited: Mar 20, 2019
  24. JoesPiper

    JoesPiper Filing Flight Plan

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  25. JoesPiper

    JoesPiper Filing Flight Plan

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    Lets assume there is no factory data on an aircraft, you wouldn't. That is why having the very first weigh at birth gives you an idea. If I did have a real 30 lb spread, the airplane will fly but I might have to consider a 5 gallon tank difference. Most small aircraft are usually within 15 lb spread or less and the less is always better. Lets say a bird builds a nest in a wing full of mud and other crap ( seen it) which adds a lot of weight. When flying, that weight would be felt as a slight off roll causing a slight slip correction ( more drag, less speed) which would be cuase for concern as an example. All mechanics learn in school is CG
    ( pitch) and for good cause. AFt CG is extremely dangerous because of stalls. All pilots is CG because of aft stall due to too much baggage weight which have killed many people, but never longitudinal balance. Weird huh! The things that death teaches you.
     
  26. Bell206

    Bell206 Cleared for Takeoff

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    Not quite. Don't follow your narrative. Every aircraft is required to have "factory data", i.e., empty weight/CG report, at the time it rolls off the line and receives its original AWC. That "data" in turn must be updated as needed which is a requirement for the airworthiness of the aircraft.

    But as I stated earlier, intermixing empty weight issues with "baggage weight" issues is comparing apples to oranges. Can't really add any more to the discussion.
     
    Last edited: Mar 20, 2019