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AR-1 N923DJ Texas 15-12-18

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  • #16
    As always Jeffery; a well thought out and well written response.

    I certainly agree with landing on the mains and using the rotor to slow the aircraft.

    The practical test standards are a way to quantify the skill of a pilot and I mentioned them because the approach to land is the only time the airspeed is plus or minus five knots. Someone felt airspeed on approach was important.
    Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

    Comment


    • #17
      Originally posted by fara View Post
      It was simple pilot error brought on by sudden unexpected wind shear and sink and gyro ran out f energy high off the runway and sunk down hard.
      I am trying to understand this better... by "wind shear and sink" are we talking about an unexpected downdraft? If so, how does that leave one high and slow above the runway?

      Comment


      • #18
        Thanks to all my well wishers regarding this accident.

        Here's the report that I submitted to the FAA verbatim:

        While practicing autorotations on the grass runway 35 at Chambers County (T00), during the third landing, I experienced a sudden loss of lift during the flare due to a possible strong wind shear, resulting in a vertical drop of about four feet. I immediately attempted recovery with full power, but was unable to prevent a hard landing during the go-round which caused the propeller to strike the bottom keel. The aircraft bounced to the left initially, the rotors impacted the ground, and the detachable mast sheared at the junction and twisted off, held in place with the control rods. The aircraft came to rest on the mast junction on its right side, and I evacuated the aircraft immediately and called for help.

        Major damage caused was to the three propeller blades which sheared at the hub, mast sheared/bent at the detachable junction, and both rotor blades gouged and bent.



        It is interesting to note how someone has posted that the gyro ran out of energy high off the runway. This is pure speculation, and that is the reason I am not seen on this forum anymore. What does one tell the pilot that crashes during a microburst, caught on the wrong side of the shear, pilot error????



        As you may note in my report, the sink was quite sudden and unexpected and full power was applied, but it did not prevent the hard touch down.

        I have even experienced unexpected tail winds occasionally at Anahuac when the wind direction changes suddenly. For those that feel this cannot happen, please go through some of the old threads and posts by Birdy, where he explains some interesting and unexpected phenomena regarding wind shear at low altitudes.

        I hope this answers the queries, and I am thankful and blessed to have walked away from this one. Moral of the story is that one should always be prepared for the unexpected.

        As an instructor, what I teach students is that it is not so much as the situation itself, but how one deals with a situation. In this situation, all that I could do was open full power to try and arrest the sink. Sometimes, it just may not be enough power under the circumstances. But any landing you can walk away from is a good one, as the saying goes.

        Happy landings and Merry Christmas!



        Antony Thomas
        “Learning without thought is labor lost; and thought without learning is perilous”
        ― Confucius

        Comment


        • #19
          I'm a bit confused by the notion of "practicing autorotations" (a gyroplane is always in autorotation whenever it is airborne, with the rotor driven by airflow, whether in cruise, climb, or descent, excepting only highly unusual situations such as jump take-offs). In the helicopter world, the term is used for that brief period when the airflow is reversed from normal powered flight during an emergency, but a gyro just glides without any airflow reversal through the rotor, so the term is inapt. Did you mean simulated power-out landings?

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          • #20
            Thank you for the information Antony.

            It is nice to know more about what happened when such an experienced pilot has a mishap.

            I have no doubt the same thing could happen to me.

            I have seen wind shears on approach close to twenty knots at Santa Maria and San Luis Obispo with no reported gusts on the ATIS.

            I hope you are back up again flying and teaching soon.
            Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

            Comment


            • #21
              Wasp, yes, of course. Just an old habit of saying it from helicoptering days.

              Vance, thank you for your encouragement and support. I appreciate it very much.
              Antony Thomas
              “Learning without thought is labor lost; and thought without learning is perilous”
              ― Confucius

              Comment


              • #22
                It is interesting to note how someone has posted that the gyro ran out of energy high off the runway. This is pure speculation, and that is the reason I am not seen on this forum anymore.
                thomasant, that "someone" was fara in his post #3. He spoke with you, so his reported details didn't come across like "pure speculation". I merely quoted what he posted:

                I talked to the pilot. In fact he called me. . . . It was simple pilot error brought on by sudden unexpected wind shear and sink and gyro ran out [o]f energy high off the runway and sunk down hard.
                As with WaspAir, your "practicing autorotations" also caught my eye. Did you mean engine-idle landings?
                What was wind direction and strength? Any gusting?
                What was your estimated AS and GS when you "
                experienced a sudden loss of lift during the flare due to a possible strong wind shear, resulting in a vertical drop of about four feet"?
                Do you normally begin your flares at 4 feet?

                Thanks for posting with such candor, so we all can learn from what happened.



                _____________
                Along the grass runway here in Anahuac, there is a large patch of tall trees. With the wind direction coming from the West that day, there very well could have been some rotor coming off of the trees.
                Interesting, AirCommandPilot, thanks.
                Here's an overhead view of T00, and grass Runway 35.


                Click image for larger version  Name:	T00.png Views:	1 Size:	96.7 KB ID:	1140974




                __________
                So I would still advocate slightly higher approach speed during gusty conditions, to decrease the risk of drop ins from up high during approach, and then a more nuanced adjustment of pitch as necessary during the roundout and on touchdown.
                Yes, loftus, I generally agree; such was also my point here, and in previous thread (although bizarrely uncomprehended by one in particular).
                A moderate groundspeed is a form of turbulence insurance, which you can cash in if unused for wind shear by simply bleeding off the energy in your flare.


                All landings -- even the greasers -- must absorb some degree of vertical energy.
                During turbulent landing conditions, I don't roundout at 15-20' and I certainly don't attempt a vertical descent.
                Rather, I prefer to quickly get to about 2' off the runway with about 10-15mph groundspeed.
                Although Vance terms this as "
                counterproductive" I disagree, as from there any microburst or wind shear or rotor or gust has much less potential effect.

                For example, if I'm dropped or slammed in from only 2', my moderate forward motion reduces the impact angle from something near 90° to something like 45° or less,
                yet 10-15mph GS is not so fast that it poses a touchdown danger even in a rigid geared RAF. (NOTE: I do not advocate normally touching down at 10-15mph in nonturbulent conditions.)

                None of this is to meant to comment on or criticize thomasant's actions that day.

                Regards,
                Kolibri
                PP - ASEL complex (C172RG, Piper 180, C206, RV-7A), SP - Gyro (Calidus, RAF, Sport Copter II, M912), soloed in gliders

                "
                When an honest but mistaken man learns of his error, he either ceases to be mistaken -- or he ceases to be honest."

                Comment


                • #23
                  Yes, I spoke with Fara after the accident, mainly to commend him on the split mast. I even sent him the email of the statement given to the FAA. So I am surprised that he came to his own conclusions regarding what I experienced. Anyway, you all have the details now. So I'm pretty much done with this thread. Stay safe my friends.
                  Antony Thomas
                  “Learning without thought is labor lost; and thought without learning is perilous”
                  ― Confucius

                  Comment


                  • #24
                    Stay safe? How could we do that?
                    You're Instrument Helo rated, as well as a Gyro CFI. You've some 3,400+ hours in rotorcraft.

                    I cordially ask that you make this an instructional example for us.
                    In retrospect, would you have done anything differently that day?
                    What can we learn from that day?

                    If nothing, then you leave us with the impression that sudden wind shear is an unrecoverable bane during gyro landings.
                    That your crash has nothing to teach us but that "sh*t happens".

                    Personally speaking, I cannot accept that.

                    Thank you,
                    Kolibri


                    PP - ASEL complex (C172RG, Piper 180, C206, RV-7A), SP - Gyro (Calidus, RAF, Sport Copter II, M912), soloed in gliders

                    "
                    When an honest but mistaken man learns of his error, he either ceases to be mistaken -- or he ceases to be honest."

                    Comment


                    • #25
                      I've seen several mentions of "microbursts" in this thread and would like to add a comment on that topic. One should never let the "micro" part of that word give the impression that such an event is not a big deal, or that it should be thought of as survivable. I was the first responder at an incident, in which I saw a friend approach our airport in his sailplane when he appeared to be swatted like a fly, slammed down to the ground as if a giant hand simply smashed him from 100 feet to the ground in an instant despite 85 knots of airspeed and a 40:1 glide ratio. He suffered major, serious injuries, and the aircraft (a beautiful, strong, kevlar/carbon/fiberglass +6 g to -4g capable ship many times stronger than any gyro you can imagine) was destroyed. No general aviation aircraft has much chance of surviving a true microburst; adding a few knots before the encounter or powering up during it won't do it. Even fast airliners with massive turbine thrust at their disposal are still at risk of being unable to power out (see Delta Flt 191). In a gyro, your only hope is avoidance.

                      That's not to say that windshear or a healthy downdraft is unlikely, can't be anticipated or shouldn't be prepared for. Just realize that a real microburst is a different and much more terrifying beast. They have been known to flatten a whole stand of trees.

                      Comment


                      • #26
                        Thanks WaspAir, distinction noted. Not an actual microburst at T00 that day.
                        What seems to have happened to N923DJ was more like wind shear or a rotor over the trees just west of Runway 35.

                        Thoughts/comments on the gyro handling of wind shear are invited. Let's all learn what we can from this.


                        PP - ASEL complex (C172RG, Piper 180, C206, RV-7A), SP - Gyro (Calidus, RAF, Sport Copter II, M912), soloed in gliders

                        "
                        When an honest but mistaken man learns of his error, he either ceases to be mistaken -- or he ceases to be honest."

                        Comment


                        • #27
                          Thanks for elucidating this Wasp. Your insight is always great.

                          Kolibri, since you wish to use this as a learning example, I'll try and explain it this way. What I have seen during short finals is that sometimes the air speed is dropped inadvertently, which can happen during gusts, and also with power changes. The sudden sink in a gust is quite noticeable and the initial tendency is to push the nose down to increase airspeed if the speed had reduced. This is when the ROD increases quite rapidly. Of course, there is still enough height to prepare for the flare. However, in many instances if the rate of sink seems uncomfortable for me, I have the student initiate a go round. So IMHO, the air speed is a critical factor in a landing till the flare.

                          Now what happens when there is a possible reversal of airflow like in a wind shear or sudden gust? the lift component can change perceptibly and the only way out if in the process of flaring is to open some power and either cushion the landing, or go around. So the use of available power is critical. Again it depends. If the aircraft is heavy, the power may not suffice. If the shear is quite strong, the power may not be enough and the climb out can be sluggish.

                          What could I have done differently? I really don't know. The only action I could take in the situation was to open full throttle. The fact that all three prop blades sheared at the hub usually is a sign that the engine was revving high.

                          This type of event is rare and if one is able to power out, all is well. Otherwise, a simplistic explanation is called Pilot Error, where the pilot screwed up the landing.
                          Antony Thomas
                          “Learning without thought is labor lost; and thought without learning is perilous”
                          ― Confucius

                          Comment


                          • #28
                            Thanks thomasant for bearing with this thread for a bit.
                            I agree with you that
                            "air speed is a critical factor in a landing till the flare".
                            During your previous two landings, had you noticed any crosswind, gusts, or rotors?

                            From where you were, adding full power was clearly your only option, which you did. I'm sorry that it didn't save things.
                            I assume that you were at idle rpm, which added some lag time to realizing full thrust.

                            What was your estimated GS when you encountered the wind shear?

                            The prop strike seems a bit of a mystery.
                            What bent or broke upon initial impact? The keel boom? Mast? Motor mounts?

                            Had the prop not sheared away, and you had thrust command, would it have made any difference?
                            I.e., could you have regained air after the first bounce?

                            Thanks for these details,
                            Kolibri
                            PP - ASEL complex (C172RG, Piper 180, C206, RV-7A), SP - Gyro (Calidus, RAF, Sport Copter II, M912), soloed in gliders

                            "
                            When an honest but mistaken man learns of his error, he either ceases to be mistaken -- or he ceases to be honest."

                            Comment


                            • #29
                              Kolibri, I appreciate your interest in this accident and if it helps, I will describe things in a little more detail.

                              Being close to the coast, the winds at Anahuac can get strong and gusty. Normally that is not an issue during landings in the AR1 due to the high inertia rotors. I was practicing simulated power off accuracy landings across the RW, into the wind direction, which is possible and advocated. I've done this many times and it is a non event. Both previous landings were just fine.

                              During the third landing, my recollection is that things were fine till I was about four or five feet and yes, at idle RPM. Ground speed was normal, around 10 mph. In this situation, I felt like I was pulled down to the ground at a faster than normal rate. I opened full power. When powering out, normally it responds without problem and one can feel the climb sensation. Things happened very fast and instantaneously. I knew instinctively that I was going to touch down. When I felt the impact, which was significant, I heard the engine go quiet and I instinctively knew that the prop had stopped. There was the sound that I heard, probably of the prop striking, and I knew then that I was toast. I actually closed my eyes and felt the rotors impact and when I opened them again, I was tipped over to the right side.

                              The ground was a bit soft, and that helped dissipate some of the energy. The mast bent completely at the detachable junction and that actually saved me, as the aircraft did not completely roll over.

                              Regarding the question of going round without the prop shearing, yes I believe that I would have been able to go round even if it had bounced slightly. I have done this several times and also during instruction. As I said before, during landing, one needs to be always prepared to go round with power. The rest will depend on how the machine responds and any lag.

                              Of course, what Wasp described is a possibility when we fly and is quite rare, but it can happen.

                              I recollect the time when I was T boned in the car several years ago. A vehicle that was stopped at a stop sign started moving onto the road on which I was driving, which was through traffic. It was dark and I was driving at around 45 mph. I saw the stopped vehicle at the stop sign and as I approached almost abeam, the car darted forward. I swerved instinctively to the right to avoid being hit, but she caught me at the left rear wheel and I was facing oncoming traffic from the opposite direction. I swerved right and I felt my car begin to flip over. That is the period of time when there is nothing else one can do. As I flipped, there was a safety sign on the right side of the road that caught me and arrested my roll, and I came to rest on the right side of the road facing the opposite direction, but on all four wheels straddled across a ditch on the side, with the sign beneath.

                              Moral of the story is that we cannot avoid or prevent certain situations. In such instances, what can determine the outcome is the initial corrective actions when things go wrong. Sometimes we are still here for a reason, while many others are not so fortunate.
                              Antony Thomas
                              “Learning without thought is labor lost; and thought without learning is perilous”
                              ― Confucius

                              Comment


                              • #30
                                m
                                Originally posted by thomasant View Post
                                Thanks for elucidating this Wasp. Your insight is always great.

                                Kolibri, since you wish to use this as a learning example, I'll try and explain it this way. What I have seen during short finals is that sometimes the air speed is dropped inadvertently, which can happen during gusts, and also with power changes. The sudden sink in a gust is quite noticeable and the initial tendency is to push the nose down to increase airspeed if the speed had reduced. This is when the ROD increases quite rapidly. Of course, there is still enough height to prepare for the flare. However, in many instances if the rate of sink seems uncomfortable for me, I have the student initiate a go round. So IMHO, the air speed is a critical factor in a landing till the flare.

                                Now what happens when there is a possible reversal of airflow like in a wind shear or sudden gust? the lift component can change perceptibly and the only way out if in the process of flaring is to open some power and either cushion the landing, or go around. So the use of available power is critical. Again it depends. If the aircraft is heavy, the power may not suffice. If the shear is quite strong, the power may not be enough and the climb out can be sluggish.

                                What could I have done differently? I really don't know. The only action I could take in the situation was to open full throttle. The fact that all three prop blades sheared at the hub usually is a sign that the engine was revving high.

                                This type of event is rare and if one is able to power out, all is well. Otherwise, a simplistic explanation is called Pilot Error, where the pilot screwed up the landing.
                                Thank you very much for coming on and explaining everything in detail. As I said in my posts it was all speculation in the absence of first person reporting, and thankfully you walked away, so you are able to do so. My questions respectfully are - where there any signs in terms of wind conditions that could have warned you that a gust like this was likely?
                                Have a wonderful Christmas and safe 2019.

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