Flaps definitions in theory vs. reality

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by geosnooker2000, Jul 16, 2019.

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  1. Jul 17, 2019 #21

    Pops

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    I do not like electric flaps on a small airplane. Electric flaps on a Cessna 150/172 was a mistake. Marketing ? , can't think of any other good reason.
     
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  2. Jul 18, 2019 #22

    Dan Thomas

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    Marketing, mostly. Buyers wanted little airliners, with power-everything. And more women were flying, and some of them had diffculty extending the flaps. The 150's flaps were huge, nearly as big as a 172's.
     
  3. Jul 18, 2019 #23

    Dan Thomas

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    We had one that did that, and it happened a long way from home so cost a lot to repair. The wing had to come off for rebuilding, it did that much damage. I didn't see the damaged components so I wasn't aware of the roller problem until the Service Bulletin came out. Took the flaps off all the Cessnas and found some with the damage happening. Spent the money to install the stainless washers and the McFarlane kits for the inboard aft roller; Cessna didn't have those parts for a LONG time. Our 2006 172 didn't even have the washers and roller kits installed; what were they thinking? 11 years after that SB came out and they still weren't installing the upgraded parts in their new airplanes!
     
  4. Jul 18, 2019 #24

    Pops

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    Have owned 3 straight tail C-172 with mechanical flaps and one of the first things I would do was to replace ALL the cables in the airplane. Amazing what you can find.
     
  5. Jul 18, 2019 #25

    Dan Thomas

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    Exactly. Buyers and owners think that since the airplane only has low hours on it, the systems will all be good. And yet I have replaced a bunch of cables in an 1100-hour 180 that sat on floats in an open hangar most of its life, with the wind blowing through. Even with the control lock in there's still a little control surface movement, and the cables are moving across pulleys and fairleads and they wear. The pulley bearing grease hardens and they stop turning, and chafe the cable. Stainless cables are used in floatplanes and they wear about four times faster than galvanized cables. In that 2006 172 the cables were stainless, as are all Cessna's restart airrplanes, and at 600 hours the aileron cables were shot where they passed over a rub strip to clear the autopilot aileron servo in the right wing.

    FWND Cables 007.jpg FWND Cables 002.jpg
     
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  6. Jul 18, 2019 #26

    Victor Bravo

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    Cessna manual flaps are still cable operated, and you can still get an asymmetrical roll if one cable breaks.
     
  7. Jul 19, 2019 #27

    Dan Thomas

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    You can get an assymetrical roll with electric flaps, too. The motor is in the right wing (left wing in a 210) and cables connect the left bellcrank with the right, and the motor operates one bellcrank. That means that one flap is directly operated by the motor and the other by two cables. If the cable-operated flap suffers a down-cable break when the flaps are down, nasty things happen. The 150/172/182/206 had 3/32" cables for the flaps up until production ceased in 1986; when they restarted in '96 those cables were 1/8", maybe because some failures happened after mechanics didn't bother opening the headliner to check the cables, and extra cable is more forgiving of such neglect. For a time, anyway. Neglect (or, more properly, negligence) eventually has its price.
     
  8. Jul 19, 2019 #28

    Dan Thomas

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    He needs another inspector.

    Cessna's riveting is seldom perfect, but the airplanes don't fall apart because of it. Some other stuff, though, is inexcuseable. The Cessna 20 has an AD against the wings, forcing a check of the lower skins along the spar for a couple of feet from the root outward, and of the lower spar caps inside the wing. Cracks have been found in some airplanes, notably those with higher airframe times and those operated in harsher conditions such as pipeline patrol (low level turbulence). The one I worked on (a 1970s model) had not had its spar cap rivet holes deburred, and under some rivets was pinched the little aluminum disc that often pops out as the drill breaks through, proving that no deburring had taken place between drilling and assembly of the wing. They hadn't even torn the little disc off. Deburring, of course, is to remove the rough edge that creates stress risers that can lead to cracking. I also found some nicks in the spar caps due to rough handling in the factory. Another no-no. Your friend's DAR would have instantly shut Cessna down for that.
     
  9. Jul 19, 2019 #29

    pictsidhe

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    This thread has transitioned nicely from theoretical to practical. I'm riveted!
     
  10. Jul 19, 2019 #30

    TFF

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    I would send pictures to a EAA tech rep and ask. A DAR can say no, but there is no rule that says it can’t be inspected by a different one. They will pay special attention to the cause of failure, but if the other says good. It’s good.

    You can also force the FSDO to inspect. You might be starting a land war in Asia, but they do have to come out if you are persistent with the rules. When the company I work for had a pt 135 for one of the helicopters, The FAA had to go to Alaska to find a qualified check airman and fly him to Tennessee every year. In the end after ten years, that did turn into a land war. We did turn in our 135 because of undue pressure , and in the end they looked like asses and it got around that they were a little more heavy handed than was fair. If he is really going to have to scrap the wings, burn some of your tax money and make them come out.
     
  11. Jul 19, 2019 #31

    Pops

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    The DAR turned the wings in to the FAA as rejected. FSDO says its all up to the DAR and they can do nothing. Also told him that he can't go to another DAR since it was turned down and not allowed to go DAR shopping.(BULL). He talked to EAA, all they would say was the DAR program was great, didn't seem to want to hear anything negative about it, no help. The AOPA would at least listen to the problem. Has had 3 other IA's look at the rivets, all says they see no reason for rejection.
    Builder is ready to junk the wings and quit flying. Says he has has enough.
    We have come a long ways baby. (And not for the good).
     
  12. Jul 19, 2019 #32

    Victor Bravo

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    Well this comment actually gets into an area that I am fairly familiar with, but since I manufacture a commercial product that is directly related to this subject I will have to watch my P's and Q's. Modedrators feel free to let me know if I need to shut up and walk away so as to not be self-serving..

    Cessna made the choice to use manual flaps because it was simpler and better and less things to go wrong. They also bought a parking brake mechanism from a 1950's Buick or Packard or something, for three dollars or so, which worked prfectly well. Then they mounted this mechanicm in the airplane, in a place that was convenient for Cessna (to run the cables and pulleys), but it was not convenient for the pilot at all.

    Back then you were lucky to get a lap belt, nobody even thought about shoulder harnesses. So you had plenty of room to reach down to the floor next to your ankles and grab the Cessna flap handle.

    When some pilots complained that they couldn't reach the flap handle because they were short, or after people stated using shoulder harnesses, Cessna took the easy way and put in an electric switch.

    But several thousand Cessnas were built with manual flaps. Is you have a shoulder harness you have to remove or loosen it to reach the flaps. No matter whether you have a fixed shoulder harness, a modern "inertia reel" harness, or no harness, you have to lean forward and down, taking your eyes off whatever you were doing.

    Cessna's electric swithc solves all of thoe problems, but it makes the flaps much slower and less "manly". It was done for ease of access and to address complaints.
     
  13. Jul 19, 2019 #33

    Pops

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    Being manly has nothing to do with it. Electric flaps are to slow at times, to fast at times and more parts to go wrong. Simple is good. I agree you need a reel on the shoulder harness so the pilot can reach the flap handle. If you have to look down to find the flap handle, you are unfamiliar with the aircraft.
    I do like your product and it fills a need.
    Cessna made another change that I always thought was going in the wrong direction besides the rear windows. The change of not having 40 degs of flaps. I fly in the mountains and the 40 degrees of flaps are needed most of the time. Even 40 degs and a hard slip. I know the book says not to slip when using 40 degs. No big deal, the nose will drop a few degrees as one side of the stab and elevator get blanked out. Easy to raise and lower the nose with the rudder in a slip with 40 deg of flap. Had lots of time in 30 deg flap c-172's and I'm always reaching for another notch of flaps that I don't have.

    Cessna also used GM truck door handles on the straight tail models and Ford voltage Regulators. Piper used VW door handles on the Cherokees. Same a buck where you can.
     
    Last edited: Jul 19, 2019
  14. Jul 19, 2019 #34

    Jerry Lytle

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    Cessna had little problem with keying. Almost any Chevy key fit the doors and ignitian switch. I wanted to try out a C175, the broker said he didn't have a key for it but if I had a Chevy key it would work and gave me the go-a-head for a couple of times around the field. I used my PU key in my 170 for 1000 hours. I wonder how much a Cessna key would have cost.
     
  15. Jul 19, 2019 #35

    Hot Wings

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    Unless there is a serial number on the wings that has been recorded somewhere I'd say your friend has been real quick at building a second set of wings. ;);)
     
  16. Jul 19, 2019 #36

    Pops

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    I told my friend that even if he bought a set of quick build wings from the factory, I believe the DAR would turn it down.
     
  17. Jul 19, 2019 #37

    geosnooker2000

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    What happened to Pops' post that you quoted here in this post? It's gone...
     
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  18. Jul 19, 2019 #38

    Pops

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    I'm bad about posting off topic and been trying to do better and I deleted my post then after deleting it, people started posting about it.
    Just trying to stay more on topic.
    I want to THANK EVERYONE for putting up with me. When someone says something that reminds me of something else, I go chasing that rabbit.

    Sure are a great bunch of people on this site. Thank You very much for being who you are.
     
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  19. Jul 20, 2019 #39

    Dan Thomas

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    We're just a couple of old guys that start reminiscing. The young guys that complain about thread creep have their turn coming....
     
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  20. Jul 20, 2019 #40

    Pops

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    Isn't that the truth :)
     
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