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  • #31
    Originally posted by skywagon View Post
    Cary, it has to do with passing certain flight test requirements which are too extensive to go into here. Mike is correct. Balked landings is one of the tests part of which is a trim condition and certain control pressures encountered in the process. It's not nanny state as much as it may sound like it. I'm not sure just what was changed at the serial number when they went from 40 to 30 flaps, there could have been an increased horsepower at that time or a gross weight change. It could be a combination of any number of things. Those 172s which go back and forth between floats and wheels and are limited to 30 are supposed to have a stop installed to prevent the flaps from exceeding 30. This may have been overlooked in some cases.
    That may be so, but it seems like an unnecessary over-protection for insufficient pilot performance. Think about this: if Mike is correct that a major part of the reason had to do with the fact that at 40 degrees of flap, a go-around would be difficult because the flaps would provide too much drag, a 160hp or 150hp or 145hp 172 isn't going to have any ability to climb with just 30 hanging out, either. A 180hp 172 can just barely maintain altitude with 40 and has an extraordinarily anemic climb rate with 30. With every one of them, the only successful go around method is full throttle, milk the flaps to 20, and as it gains speed, milk them on up 10 at a time, meanwhile keeping the nose down with forward yoke and retrimming to relieve the pressure on the yoke, just like the earlier manuals and later POHs say to do.

    But like Mike also says, by limiting the flaps to 30, that's one more tool removed from the toolbox. That tool, 40 flaps, is one of the reasons I looked for an older 172 when I bought my P172D. There are times when I choose to use only 30, and when there's a strong crosswind I'll use less or even none, but most of the time I use 40. I'm no extraordinary pilot, but I've never had any trouble with the several go arounds that I've done over the years with 40 hanging out, whether with my airplane, the 150s I learned to fly in, other earlier 172s, various earlier 182s, or any other airplane.

    So yeah, there are undoubtedly reasons for the flap limit that we don't have any idea about, but the question is, are those reasons good enough to justify the loss of the tool? Or was it just a decision made by some functionaries at Cessna or the FAA that they thought was a good idea without any empirical evidence to back it?

    Cary
    I have slipped the surly bonds of Earth...put out my hand, and touched the face of God. J.G. Magee Jr.

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    • #32
      Originally posted by skywagon View Post
      Cary, it has to do with passing certain flight test requirements which are too extensive to go into here. Mike is correct. Balked landings is one of the tests part of which is a trim condition and certain control pressures encountered in the process. It's not nanny state as much as it may sound like it..........
      Originally posted by cary View Post
      That may be so, but it seems like an unnecessary over-protection for insufficient pilot performance. ..........................
      Cary
      Cary,
      As I stated above, this topic is too extensive to go into here. Mike has a silver tongue and is more capable of explaining the issue than I. A 172 is a CAR 3 airplane and the following is intended for FAR 23 airplanes. The requirements are similar. The following documents are just a portion of the guidance for certifying an airplane. I present them here for you in the interest of saving time. I suggest that you review them and the requirements to which they refer. Perhaps you will then begin to understand. Believe me I do understand your concern. What on the surface appears to be an innocuous question, does turn into a can of worms.

      http://www.faa.gov/regulations_polic...mentID/1019689
      http://www.faa.gov/regulations_polic...mentID/1019681
      http://www.faa.gov/regulations_polic...mentID/1019676
      http://www.faa.gov/regulations_polic...cumentID/22302
      http://www.faa.gov/regulations_polic...cumentID/22315

      Comment


      • #33
        Originally posted by skywagon View Post
        Those 172s which go back and forth between floats and wheels and are limited to 30 are supposed to have a stop installed to prevent the flaps from exceeding 30. This may have been overlooked in some cases.
        I flew a 206 F for several years that went from wheels to floats, and on those floats, the flap deflection was limited to 30 degrees, though on wheels, the plane was approved with 40. The mechanics wanted to limit flap travel to 30, but I argued successfully to simply put a bar across the slot for the flap lever, which limited the switch travel to the 30 degree mark. The bar could then be removed when the plane went to wheels. There were a couple summers when everyone failed to remember to put that little bar across the flap handle slot......and I never bothered to bring it up.

        That 30 degree limitation was specified because the airplane was on Wipline 4000 straight floats. I never found it particularly challenging to perform a heavy balked landing, even with those floats hanging out there, and I did practice those with forty flaps. That said, I didn't try that in worst case scenario.....Consider what that might be like in Australia on a hot day.....

        As Pete notes, there are many things that go into these certification limitations. And, one of the things that many pilots fail to understand is the breadth of testing that an airplane must complete for certification. Another example was with that same 206 on those big Wip floats: extensions were required to be installed on the cowl flaps. With those extensions, the cowl flaps could never completely close, and with the cowl flaps full open, they were REALLY open. And, believe me, those extensions were definitely necessary for engine health. Lots of drag, and slow climbs make for lots of engine heat. At least one spring the mechanics failed to install those extensions, and I wanted them installed. The guy turning wrenches thought those extensions were a "nanny state" kind of issue. They weren't and they got installed.

        Also, bear in mind that these things have to meet certification standards in "worst case" conditions....like REALLY hot weather and high D.A.

        A balked landing in a heavy 172 on a hot day and high DA can be a handful, regardless of flap settings. Fortunately, we rarely land our airplane at gross weight, so balked landings at gross are pretty unlikely, but.....

        If you want an interesting example, take a look at this video: https://www.youtube.com/watch?v=qc_v6tXsv6g While this is a transport category aircraft, which must meet much higher standards than our aircraft, this video illustrates some of the issues most of us wouldn't normally think about in the certification program. But, you can imagine a scenario where this might happen, and lighting your plane on fire as a result could be disastrous.

        Mike
        Last edited by mvivion; 04-19-2015, 09:48 PM.

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        • #34
          Originally posted by skywagon View Post
          Cary,
          As I stated above, this topic is too extensive to go into here. Mike has a silver tongue and is more capable of explaining the issue than I. A 172 is a CAR 3 airplane and the following is intended for FAR 23 airplanes. The requirements are similar. The following documents are just a portion of the guidance for certifying an airplane. I present them here for you in the interest of saving time. I suggest that you review them and the requirements to which they refer. Perhaps you will then begin to understand. Believe me I do understand your concern. What on the surface appears to be an innocuous question, does turn into a can of worms.

          http://www.faa.gov/regulations_polic...mentID/1019689
          http://www.faa.gov/regulations_polic...mentID/1019681
          http://www.faa.gov/regulations_polic...mentID/1019676
          http://www.faa.gov/regulations_polic...cumentID/22302
          http://www.faa.gov/regulations_polic...cumentID/22315
          Well, much to my consternation, I actually read those portions of each of your cites regarding flaps. Although it's more implied than stated, I conclude that these appear to be the justifications for limiting flap travel:
          • In the event of a go around with landing trim, the "push" to keep the nose down before retrimming must be no more than 60 lbs.
          • In the event of a disconnect between the flaps resulting in asymmetrical deployment, the airplane must remain fully controllable in spite of one flap being fully retracted and the other being fully deployed.
          • In the event of a go around, the airplane must be able to fly level with full power and flaps fully deployed.


          I'm sure I missed stuff, but those were the big ones I saw. All those are good reasons--and yet I still maintain that all those concerns are dwarfed by inadequate pilot performance. Whether it's the little airplanes that you and I fly or the big iron, mechanical failures appear to be a very small piece of the cause of LOC accidents--the biggest piece is still inadequate pilot performance--some form of pilot error.

          Like many of us, I'm a devotee of reading NTSB reports, and although I don't keep track precisely, it appears that the vast majority of mechanical defects are engine related, and very few are airframe related--airframes don't seem to break very often.

          I don't know whether the pilot performance problems are training related or are simply human factor issues that training can't fix. I don't have the answers, and it doesn't seem as if others do, either--but limiting the mechanical performance characteristics of the airframes doesn't seem to be the answer. In my view, FWIW, taking away such tools is counter-productive as long as we have engines that occasionally fail. When my engine threw a rod and I landed in a field 11 years ago, I was really glad that I had those 40 flaps. I'd hate to see a report that said the pilot did everything right, but that his airplane didn't have the capability to do what he asked it to do, because of some overly restrictive AC or reg which ham-stringed its performance.

          It's been a fun discussion.

          Cary
          I have slipped the surly bonds of Earth...put out my hand, and touched the face of God. J.G. Magee Jr.

          Comment


          • #35
            Yes Cary, This has been a fun and educational discussion. There is one thing, which has not been mentioned here, that I have not seen in print. That is that the PTS for a Private pilot are "minimum acceptable standards". This means than a person who only barely meets the minimum standards must be able to handle any of the airplanes for which his certificate qualifies him. It is clear from this discussion that neither you nor Mike nor I are one of those individuals. The airplane is certified in a manner that allows that individual to be able to fly safely. The three of us could easily handle a 172 or 206 on floats with 40 degrees of flaps. However it is the opinion of the FAA certification test pilot that the average minimum pilot could not. Thereby the limitation.

            Once upon a time I was demonstrating cross wind take off and landings in a float plane for a FAA certification test pilot. He refused to accept the demonstrated cross wind component because he felt that I was better than the pilot who only meets the minimum standards. He arbitrarily reduced the certified cross wind limitation. I didn't agree with him but, he was signing off the airplane. Actually had this not been a certification test demonstration, I would have landed into the wind.
            Last edited by skywagon; 04-20-2015, 08:20 AM.

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            • #36
              Correct me if I'm wrong here but the "Maximum demonstrated crosswind component" isn't a true limitation like VNE.

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              • #37
                You are correct. It was a square which the FAA test pilot was required to fill.

                Comment


                • #38
                  Originally posted by skywagon View Post
                  Yes Cary, This has been a fun and educational discussion. There is one thing, which has not been mentioned here, that I have not seen in print. That is that the PTS for a Private pilot are "minimum acceptable standards". This means than a person who only barely meets the minimum standards must be able to handle any of the airplanes for which his certificate qualifies him. It is clear from this discussion that neither you nor Mike nor I are one of those individuals. The airplane is certified in a manner that allows that individual to be able to fly safely. The three of us could easily handle a 172 or 206 on floats with 40 degrees of flaps. However it is the opinion of the FAA certification test pilot that the average minimum pilot could not. Thereby the limitation.

                  Once upon a time I was demonstrating cross wind take off and landings in a float plane for a FAA certification test pilot. He refused to accept the demonstrated cross wind component because he felt that I was better than the pilot who only meets the minimum standards. He arbitrarily reduced the certified cross wind limitation. I didn't agree with him but, he was signing off the airplane. Actually had this not been a certification test demonstration, I would have landed into the wind.
                  I don't think I'd put me in the same league as you or Mike on floats--my total of less than 10 hours on floats hardly qualifies me! On land, yeah, I'm reasonably competent, especially in a 172, less so in a 206. That brings up the old joke about docs: "What do you call a doctor who gets a 100% on his final tests? Doctor. What do you call a doctor who only gets 70% on his final tests? Doctor." Although most pilots rate themselves as above average, it's a fact that that's impossible--many are barely average, and unfortunately there are some who are less than average but still minimally passed their checkrides. We all know some of them.

                  Cary
                  I have slipped the surly bonds of Earth...put out my hand, and touched the face of God. J.G. Magee Jr.

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                  • #39
                    Just because you have only about 10 hours on floats does not mean that you don't understand. By being open minded and engaging us in this discussion you have shown that you are open to being a safe pilot. It is always a good idea to learn from another's mistakes rather than your own.

                    Comment


                    • #40
                      Originally posted by skywagon View Post
                      Just because you have only about 10 hours on floats does not mean that you don't understand. By being open minded and engaging us in this discussion you have shown that you are open to being a safe pilot. It is always a good idea to learn from another's mistakes rather than your own.
                      Yeah, even after flying for better than 42 years, I'm sure I won't live long enough to make all the mistakes on my own. I've sure made my share, though.

                      Cary
                      I have slipped the surly bonds of Earth...put out my hand, and touched the face of God. J.G. Magee Jr.

                      Comment


                      • #41
                        I fly a 185 on EDO 2790 amphibs. On heavy takeoffs when it is difficult to get on the step I use a bush pilot flap technique: Takeoff power with 20 degrees of flaps, accelerate close to getting on the step, bring the flaps up. The airplane will accelerate rapidly to step speed, stay on the step until flying speed, pop the flaps to 20-30 degrees/increase pitch without digging in tails of floats and the airplane will jump out of the water. Fly at zero climb angle as speed increases, milk the flaps down to 20-10-0, climb at normal speed. I have wing and tail VGs that enable flying at very low speed. With minimum head wind or glassy water you have to pop the flaps to get one float our of the water, bring the flaps up to accelerate to flying speed, pop the flaps again to 20-30 degress to get out of the water.

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                        • #42
                          The Horton STOL kit on my Cessna's wings changed the best "float" flap setting from 10 degrees to 15 degrees. It works OK in aircraft with electric flaps. Plus I pained marks out on the wings to see when the flaps are in the best place.

                          As a Float CFI I have experiments with various flap popping methods with clients. in numerous types of aircraft. While it often works in controlled circumstances, there are the occasional BOO-BOOs which create a longer take-off or worse take-off run. One time in a C-185 the client let the flap handle slip out of his hands during a stressful take-off. Somehow or another the latching button stayed in and his flap handle dropped to the floor when we were too slow for that to be a good thing.
                          Dragonfly Aero
                          Seaplane Instruction
                          Homer, Alaska

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