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  1. Username Protected
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       #1  

    ‘The Phenom Shuffle’?

    I am new to the aircraft.
    I have found in the few hours of flying one plane that no matter how gentle I am on the brakes, the plane wants to go left or right….and then, of course, it starts the ‘left, right’, ‘left, right’ shuffle….However, every once in a while, it seems to want to not do the shuffle.
    I am sure it’s the pilot, but I have just as many hours in another 100 plane, and I don’t have the shuffle problem with that aircraft…not once!
    Any advice from the high time gurus and instructors would be appreciated.
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    #2  
    What version of BCU does yours vs the other aircraft have?

    BCU-8 is reported to have a lot less Pilot Induced Oscillations.
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       #3  
    Quote Originally Posted by (Username Protected) View Post
    What version of BCU does yours vs the other aircraft have?

    BCU-8 is reported to have a lot less Pilot Induced Oscillations.
    Thanks (Username Protected)
    BCU 8.0 is installed.
  4. Username Protected
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    #4  
    (Username Protected), are your brake assemblies dash 1 series, dash 3 series, or one of each?
  5. Username Protected
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       #5  
    Quote Originally Posted by (Username Protected) View Post
    (Username Protected), are your brake assemblies dash 1 series, dash 3 series, or one of each?
    (Username Protected),
    I don’t know. Where would I look for that info? Go through the aircraft logs?
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    #6  
    Do you use CAMP for maintenance tracking?
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    #7  
    Can I offer a small piece of advice with the brakes?

    Do not modulate or change pressure too much with your feet/toes, if it starts pulling to one side, use the heel of your foot to steer the aircraft whilst applying consistent braking. You should find it massively eases the issue.

    Too many pilots treat the Phenom like other types and try to steer it on a runway just using the brakes.
  8. Username Protected
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       #8  
    Quote Originally Posted by (Username Protected) View Post
    Do you use CAMP for maintenance tracking?
    Yes- Will ask them Thanks
  9. Username Protected
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    #9  
    (Username Protected),
    I had BCU-06 and went to -07, which like others, found to be worse. BCU-08 added a pause in the braking which was frightening the first time, we sent it back to find the second -08 unit behaved the same way. What I find works is don't rush to maximum brakes, ease into it and use a significant forward yoke pressure. This reduces the lift, puts more weight on wheels and more pressure on the nose wheel to help the plane track true. I brought this technique up at the EJOA conference when they had the presentation from the certification folks. They said the engineers don't believe it has much impact (though it's in the manual to use forward pressure) and they said the test flight engineers all insist it works. I find this technique the plane tracks well and stops in the numbers.
    BTW, Only four of us made it to that presentation that was tagged on at EJOA conference and by far the best presentation.
  10. Username Protected
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    #10  
    I've found there are two ways to minimize the lateral pilot induced oscillations:

    1) As (Username Protected) says, footwork is critical. I find pilots who land with heels on the floor, and then "slide" their feet up on the roll-out are by far the most likely to be applying differential brake inadvertently, which makes the oscillations worsen. Practice landing with heels on the rudder, toes pulled back off the brakes. Not only does it reinforce that the brakes can be controlled independently of the rudder pedals, you don't have that second of transition where directional control is poor or nil.

    2) Just as important is aileron into the wind after touchdown. When pilots neutralize the controls after touchdown in a crosswind I've found it to be a consistent trigger for oscillations. You now have one wing ("upwind wing") producing more lift, and especially in pre-E/ EV P100's this means that wheel has lower friction with the surface, and less braking effectiveness. So even with evenly applied brakes, the plane will pull slightly downwind (against weather-vaning) when the brakes are applied. This sets off the oscillation, which the pilot often then exacerbates.

    If you find you are getting the "shuffle" after touchdown, try increasing the aileron into the wind after the mains touch down. Remember as the plane slows you need more control deflection to effect the same force, so in a good crosswind you should end up with the yoke jamming into your leg as you near taxi speed.
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       #11  
    Quote Originally Posted by (Username Protected) View Post
    (Username Protected), are your brake assemblies dash 1 series, dash 3 series, or one of each?
    Hi Larry
    Thanks for your time last week and the idea to check the brake assembly model.
    Both are Dash-3. However, on was replaced 40 hours go, the other maybe 200hrs.
    I think (Username Protected)’s point is well taken and makes sense, both from the standpoint of foot position and correct control input after landing for crosswind correction, if needed.
    Appreciate everyone’s input.
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       #12  
    Quote Originally Posted by (Username Protected) View Post
    I've found there are two ways to minimize the lateral pilot induced oscillations:

    1) As (Username Protected) says, footwork is critical. I find pilots who land with heels on the floor, and then "slide" their feet up on the roll-out are by far the most likely to be applying differential brake inadvertently, which makes the oscillations worsen. Practice landing with heels on the rudder, toes pulled back off the brakes. Not only does it reinforce that the brakes can be controlled independently of the rudder pedals, you don't have that second of transition where directional control is poor or nil.

    2) Just as important is aileron into the wind after touchdown. When pilots neutralize the controls after touchdown in a crosswind I've found it to be a consistent trigger for oscillations. You now have one wing ("upwind wing") producing more lift, and especially in pre-E/ EV P100's this means that wheel has lower friction with the surface, and less braking effectiveness. So even with evenly applied brakes, the plane will pull slightly downwind (against weather-vaning) when the brakes are applied. This sets off the oscillation, which the pilot often then exacerbates.

    If you find you are getting the "shuffle" after touchdown, try increasing the aileron into the wind after the mains touch down. Remember as the plane slows you need more control deflection to effect the same force, so in a good crosswind you should end up with the yoke jamming into your leg as you near taxi speed.
    (Username Protected)
    whats your thoughts on pushing forward on the yoke after mains touch down?
    EMB seems to recommend that but I have had other instructors say not to do that, but neither to keep the nose wheel from touching down.
    One would think that pushing forward on the yoke would move the CG forward and reduce the mass effect on mains, reducing braking effectiveness?
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    #13  
    (Username Protected)-

    You certainly want to lower the nose quickly, definitely do not hold aft pressure in a misguided attempt at "aerodynamic braking".

    I haven't seen guidance to actually push the yoke forward in the SOPs, though- the comments run more to:

    "Lower nose wheel immediately to the runway. It will decrease lift and will increase main gear loading."
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    #14  
    I know you asked (Username Protected)l, but I’ll add a bit more…
    It does move the CG forward slightly as well as reducing lift, both of which are helpful. When I researched it, there was a lot data on airliners on how it works and “air braking” doesn’t. For very light aircraft, it’s not recommended because the CG is already very far forward with piston engine and for stability so pulling back on the yoke is a better choice. Consider the the light weight on nose in the phenom. With no one in the airplane, it only takes about 12 ft/lbs to turn the nose wheel. So while you’re slightly moving CG forward, you are putting more weight on the nose wheel which does two things, it puts a bigger patch of rubber on the road and more pressure between the tire and the ground. Reducing lift, effectively increases the weight on the main wheels which improves braking. A lot of pilots notice that braking in the first 1,000 ft is relatively poor vs. the second 1,000 ft. The reason is that the effective weight on wheels is increasing as a square function as the speed and lift is reduced.
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    #15  
    I was having the same problem. A wise mentor of mine suggested that I was probably unknowingly pressing down harder with my "dominant foot" . As I am left handed, I subsequently started landing with what I felt was only my right foot ( it isn't) and my landings immediately improved. Hope that helps
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    #16  
    Do not push the nose down after landing.

    Please note the recent revision to the manuals - SOPM 4-00 Page 68 which advises pitch neutral only, as pitch forward WILL REDUCE braking efficiency.
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    #17  
    Quote Originally Posted by (Username Protected) View Post
    Do not push the nose down after landing.

    Please note the recent revision to the manuals - SOPM 4-00 Page 68 which advises pitch neutral only, as pitch forward WILL REDUCE braking efficiency.
    This latest comment in 100% spot on.
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    #18  
    (Username Protected)’s response is the correct method 100%
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    #19  
    What a hot topic! My thoughts:

    Don’t push the nose down, my guess is the pilots who felt this was affective, we’re following the Embraer recommendation of smash the plane on the runway without breaking your attitude. Doing this you always touch down overspeeding and the nose down will help to keep the plane down. If you land properly and not how they teach, follow a proper profile, do break the profile with appropriate flare, touch down, then aft on the control, will stop faster and have more control when all 3 points touch down.

    I found the oscillating brakes to happen on contamination most of the time, but as they say, if you trust it, it will balance out. Land centre, keep direction neutral, apply brakes together (with your mind) and HOLD. You will not experience the issue if using this method.

    Cheers and fly safe!
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    #20  
    I know there are different opinions on this but the part I don't follow is the "over speeding". If you follow the EMB recommendation, Vref over the fence and idle power, you will be slowing down well below Vref by the time the wheels hit the ground, especially if there is a strong headwind, where you may actually get the first "stall" warning.
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    #21  
    Embraer teaches Vref to the ground, meaning at your touchdown, your aircraft is at the 1.3 Vso speed, therefore overspeeding based on speed keeping your lift vector valid at that touchdown speed.

    They really should teach Vref until aimpoint and allow the aircraft to settle rather than fly it onto the runway. When touching down at the speed they teach, your aircraft is and still wants to lift. Your landing distance does not increase as well since the energy to bleed off in the higher speed vs the distance spent touching down properly is relatively the same.

    Let me know if you have any feedback!
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    #22  
    (Username Protected), you are incorrect about what we teach! Just to clarify IAW POH 3-45-20,

    The landing performance data in this manual is based on the following procedures and conditions:
    - Steady three degree angle approach at VREF in landing configuration;
    - VREF airspeed maintained at runway threshold;
    - Idle thrust established at runway threshold;
    - Attitude maintained until MLG touchdown;
    - Maximum braking applied immediately after MLG touchdown;
    - Antiskid system operative


    Therefore, as per CS-25 Perf A certification, the aircraft is placed to IDLE thrust at 50ft (Runway Threshold), with VREF maintained to that point. You do not continue "overspeeding", there is an anticipated speed bleed maintaining the 3 degrees to MLG touchdown. This is the very definition of a parametric landing.

    If the correct technique is followed, then any "flare" or "settling" onto the runway will increase the distance. Just a 3 sec flare dealing touchdown will increase landing distance by 18%.

    I'm realistic that we all want a smooth landing for our boss(es) in the back, but therefore add a sensible factor.

    As a note, distance effects for Embraer aircraft:

    VREF + 5 = 10% increased in the required ULD.
    5KT TW = 10% increased in the required ULD.
    3 sec Touchdown delay = 18% increased in the required ULD.

    (All three together are around a 36% increase in the required ULD!)

    If you want book numbers, fly book technique.
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    #23  
    Thank you for your reply, but what you have written indeed supports what I’m saying.

    Should be noted, threshold and touchdown point are not the same.

    Flare can be done between threshold and touchdown point to not give 18% increase as you suggest, and the 3 second concern is from touchdown point with ULD being increased. If an appropriate procedure is conducted, there should not be a 3 second delay, just the same as if the current procedure is conducted book numbers will remain valid.

    If flare is conducted between threshold and touchdown point, aircraft touches down with appropriate speed, then if the Vref is achieved at touch down point it’s above flying speed, and a factor of things play in this scenario, including the questions raised of braking recognition, effectiveness, and control wheel procedures and why pushing forward seems to have “worked”. There is no argument there.

    Not trying to be smart here, but I’m speaking from experience, comparisons, have demonstrated to course instructors the result, however the consensus stays the same with instructors that this doesn’t make sense but it’s what we are to teach. Book numbers are being maintained minus Vref at touchdown point in the method I’ve described. Anyone that’s landed with max landing weight with the procedure set forth will tell you it’s not safe to touch down at Vref and attitude that’s mentioned in the book, especially when there is no interpolation and everything is to be rounded higher.

    Then again, nothing in the book says after takeoff you have to rotate to almost 20 degrees as the procedure not to overspeed your flaps etc.

    Just because it’s in the book, doesn’t make it valid, the best, correct, or unchangeable for the future.

    I’d be happy to share more with Embraer pilots, can support my points based on my experience level on the Phenom 300 having at least 2500+ landings in it… not to mention not having to change the tires more frequently which are not available ever

    Please do let me know your feedback as I appreciate the open dialogue and discussions.
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    #24  
    (Username Protected),

    Your original post said:

    "Embraer teaches Vref to the ground, meaning at your touchdown, your aircraft is at the 1.3 Vso speed, therefore overspeeding based on speed keeping your lift vector valid at that touchdown speed."

    That is not correct. I am aware of the difference between touchdown point and the threshold. VREF to touchdown point is not correct. VREF to threshold and throttles to idle, maintaining the same attitude to MLG touchdown. It does not support what you have said. It may not make sense to you, but that is what the numbers are certified on, and what is expected as the correct technique.

    Flare between threshold point and touchdown point following the Embraer assumptions at three degrees, means you are destabilising an approach to give it a much steeper descent rate, to then require more flare, resulting in greater potential of speed bleed off towards VSO. Pushing forward on the controls has already been shown to be ineffective and incorrect.

    The book is approved with a certain technique, sadly, whether we like it or not.

    The main thing is make sure that any performance is appropriately adjusted for any deviation away from procedures published (that ultimately give the numbers that are being used).

    The instructors teach the way they do because that is what they are required to do following the manuals we are all meant to operate to. What you do personally is your choice, but please be careful in the advice you give. Not everyone out there has 2500+ landing like you.
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    #25  
    Let’s go one more time. I don’t argue that the book holds what’s certified..

    As we have seen in the past, the book can be wrong and gets updated #boeing. I think as a demo pilot, you should share techniques and understandings that came about during operation of the aircraft in the past 13/14 years. There are ways to achieve the same results as certification with minor tweaks, and update the book to whatever it needs to be.
    To clarify, I should have said the book says to keep Vref attitude until touchdown, regardless of the power setting going to idle.

    Speaking of safety, and not smooth landings for the back, imagine this scenario: landing on an approach speed of Vref, at max landing weight, on a 3.5 degree slope, you go to throttle idle after threshold is achieved, and you hit the ground very hard due to the technique that’s certified in the book.

    The book should be reviewed for that last phase of flight as the concept does not work for when too light or too heavy, and the technique puts pilots in a bad position with ground contact, and braking action.

    Embraer should add 3 different methods for landing it seems. NOT arguing what’s in the book, arguing what SHOULD be.

    I suggest the method of power idle after threshold and control the plane rather than maintain the degree the book says. That’s my advice to anyone on their first landing. It would be great to see Embraer staff pilots across the world report these things back operationally and not wait for bad results first. how many people have had hard landings or runway issues solely from the current published method?

    Anyway, as I said, wasn’t trying to be smart, but the fact is that Embraer has done some things to support some certification goals which should be reconsidered. As a final thought, my advice to pilots is clear that I don’t support the current method to get book numbers as it puts other things in jeopardy. Keep it safe and practice other methods as you learn IF not affected by very short runways or other airport/performance factors.

    I hope in 5 more years this portion of the POH/AFM gets updated, and I hope to have contributed to it.
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    #26  
    Now that I agree with (Username Protected).

    I'm particular about what is said regarding the product due to some of the things which I see taught which are deeply incorrect. Also because this is written down and not discussed face to face where things can be clarified much more simply.

    We have not received any hard landing as a result of the technique....the aircraft was built and certified for it. It may not be comfortable, but it is what was certified for every day of its life.

    Like you I would love to see alternative techniques, however I do not see Embraer running a whole new testing programme to achieve it, unless the authorities insist upon it.

    Thankfully as with most professional pilots such as yourself, common sense prevails.

    All feedback is shared with the Embraer Team, I can assure you of that. But I also know (sometime sadly) what they will and won't invest in!

    This is also why we have gone with the operational landing data, to go someway to giving new data which is realistic and reliable. The numbers are bigger, but they are also far more accurate for the appropriate RWYCC.

    I'm grateful for the conversation and feedback. As a demo pilot, unless its a short runway, we all very much use a flare!
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    #27  
    This has been a great discussion. I reached out to (Username Protected), who has been wealth of knowledge and practical experience to jump on the post. Be on the lookout.
    (Username Protected)
    p.s. and if you haven't met or trained with (Username Protected), please come to the next PP.Org event in Boston
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    #28  
    Great discussion and both (Username Protected) and (Username Protected) are correct. (Username Protected) is giving practical technique which is not the book nor what EMBRAER teaches and (Username Protected) is quoting the book. By the book, the aircraft will touchdown at slower than Vref, but that is very hard to achieve in reality. I see hundreds of pilots a year through training and checkrides and almost no one arrives over the threshold exactly on Vref as the book distances would require. Therefore their actual touchdown speeds are closer to Vref (as (Username Protected) indicates) which will increase the book landing distances (as (Username Protected) indicates).

    The bot(Username Protected) line here is the POH unfactored landing distances were meant for certification purposes in a very perfectly controlled test environment and are not realistic to use for everyday and every pilot's use. You should be factoring the unfactored landing distances based on your individual landing style and I have found that is anywhere from 1.15 to 1.6 times the unfactored landing distance. Personally, my landings require a 1.3 factor for a comfortable landing. The new chapter in your POH performance section titled “Operational Landing Distance” has adjusted all the landing distances (even dry) for more realistic pilot technique (based on AC25.32) and contaminations. Comparing this new Operational Landing data with NTSB runway overrun accident data with actual Phenom deceleration rates demonstrates that this new data is more realistic. The new data still assumes maximum breaking so they still may need to be adjusted for less than maximum breaking. Also, I recommend to always add the Vref + 5 knot landing distance adjustment when computing your landing distance with this new table. It’s just reality.

    If you want more detail, you can watch the PhenomPilots.org webinar I did on Runway Overruns.
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    #29  
    (Username Protected), as always fantastic explanation. Appreciate your contribution.
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    #30  
    This. An experienced pilot will let up/increase pressure one side or the other if he feels the aircraft starting to drift. In the Phenom you have to resist the impulse. Apply equal toe pressure on both brakes and steer with the heels for directional control.

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