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Thread: Pushing down on the Elevator

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    Mtns2Skies's Avatar
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    Pushing down on the Elevator

    I have heard both sides to this, Is pushing down on the horizontal stab an acceptable method to moving an aircraft? I have seen CFI's do it and I have had CFI's tell me not to do it. Obviously only pushing on the inboard bit... but is this advisable or does it cause damage? (Tricycle gear only)
    Last edited by Mtns2Skies; 04-22-2013 at 08:33 AM.

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    I don't know for sure, and I haven't read anywhere in any plane manual about this, like you do read prohibitions against moving one by pushing on the prop spinner. It doesn't look like the best practice, better to get a bar to attach to the nosewheel to move it.
    I have often seen CFIs move a small Cessna by pushing down on the tail to raise the nosewheel off the ground so they can pivot the plane around. I think I have also seen gliders moved by pushing down on the nose to raise the tail wheel off the ground.

    But if you think about it, it probably doesn't really do harm, we don't see airplanes crashing very often because the hor stab fell off after being moved like this.
    Think about it, a standard Cessna 152 is built to stand 3.8 gs, I believe, some planes like some Beechs more than that, not counting acro or military planes.

    So the stab can stand 3.8 gs, and when you push down you are not applying anywhere near that, maybe a 200 lbs man might push down 60 lbs. of force. You are not having Shaq jump up and down on the stab.
    Last edited by Bill Greenwood; 04-22-2013 at 09:32 AM.

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    Any time I push down in the back, it's on the stabilizer, not the elevator. With that said, I had to do that only once to get the nose out of mud. If you do push down, lift the nose only as far as you need it, usually only an inch.

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    From day one, my instructors taught me to push down on the dorsal fin only(for 150/152 & 172), never the stab. I haven't been concerned about this technique for years as the 182 I fly has retractable handles at the rear.

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    Mtns2Skies's Avatar
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    Quote Originally Posted by Floatsflyer View Post
    ...the 182 I fly has retractable handles at the rear.
    First off... that is REALLY cool!

    Second I was purely curious because I have gotten so much conflicting information on this... but it doesn't matter that much to me. The planes I fly have the wheel in the correct place, In back!

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    The preferred method on a Cessna is to push down on the fuselage. That said, pilots have been pushing down on the inboard end of the horizontal stab for years. It is best to push on the rivet line for the rib and the forward spar.

    The engineers know that pilots push the airplanes around in that way. Ground handling loads are part of the design calculations. That said, most older Cessna's, particularly 182's, 180's, and 185's wind up with broken inboard nose ribs in the horizontal stab. When a smart mechanic does the repair, he or she beefs it up a little. But that only happens if there is a reason to take the skin off. Mine got beefed up when I got some hail damage and had the horizontal stab reskinned.

    The retractable handles for pushing the airplane around are a great idea and good investment.

    Best of luck,

    Wes
    N6234A

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    Quote Originally Posted by Mtns2Skies View Post
    I have heard both sides to this, Is pushing down on the horizontal stab an acceptable method to moving an aircraft? I have seen CFI's do it and I have had CFI's tell me not to do it. Obviously only pushing on the inboard bit... but is this advisable or does it cause damage? (Tricycle gear only)
    A CFI probably isn't the best resource.....


    Ref: Cessna Mandatory Service Bulletin No. SEB94-8 released April 29, 1994.

    "NOTE: Improper ground handling can cause cracking and deformation of the horizontal stabilizer structure. It is recommended that a tow/steering bar be used whenever the airplane is to be manually positioned on the ground. Do not steer the airplane by pushing down on the horizontal stabilizer.

    In addition, the Cessna service manual for 100-200 series airplanes states: “Caution: do not push on control surfaces or outboard empennage surfaces.” (that means in any direction)

    Cessna's S.E. safety initiative re-emphasizes not to weight, push or lift on the horizontal stab. One engineer at Cessna said the majority of field report cracks were traced to pushing down on the stab.



    Not sure how to make it any clearer.

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    It is also very important to note that these airplanes were never designed to be in service for 40-60 years. They were originally designed to be flown by the owner for seven or eight years, and then traded in for a new one just like a car. THAT is why most airplanes do not have nearly enough inspection access panels, and why it is so difficult to do anything other than short-term routine maintenance. The original designers of Cessna, Piper, and other types of aircraft would be turning in their graves if they knew their airplanes would stillbe out there flogging along 50 years afterward. They would have made many many different decisions, and put in much more access panels, and done a lot more corrosion protection.

    There is also the simple fact that you are asking a 30 or 50 year old airplane to protect you, protect your family, and give you a safe flying machine. Anything you do that risks un-necessary damage is just not smart. When was the last time the stabilizer has been off of that aircraft for inspection? Chances are, it has never been off since it left the factory at Wichita. Even when wings are removed, many times the tails stay on.

    IMHO Pushing down on the stabilizer spar at the root with 50 or 80 pounds of force is reasonably harmless. Yes it was designed for a lot more force than that. But pushing down on the unsupported leading edge of the stabilizer forward of the spar is just stupid, it damages the airplane, and is an immediate indication of someone who should really not be around an airplane.

    Anyone who lifts or pushes a light airplane around by the spiinner is an idiot, and should be taken out behind the hangar and beaten. I have personally had a spinner come off in flight, it took off part of a propeller blade, and I had to shut the engine off inflight to avoid having it fall off of the airplane. NEVER put any force on the spinner! It is designed to be loaded only very lightly, and any misalignment or stretching can cause a vibration that WILL get serious very soon.
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    Well said, Victor Bravo!

    My instructor used the centerline of the fuselage just forward of the tail fin to move a C-150 around in tight circumstances. He pointed out that the leading edge of the horizontal stabilizer should not be used and that Cessna had some advisories regarding tail inspections on some models. We always checked-out the rivets and general condition of the skins on the horizontal stab. That pre-flight inspection has stayed with me to this day. As for the spinner, if you take a look at how they are attached and what they're made of, you can see that using them to push anything more that air would be a mistake.

    Joe

  10. #10
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    Yes, on a 150 and even a 172, it's easy to stand with your back to the horizontal stab and put your arm over the top of the fuselage tube with one hand on the the root of each horizontal stab and press uniformly down centered on your armpit enough to lift the nose and turn the aircraft. Once the aircraft is pointed in the right direction, I push on more solid parts (the wing struts).

    On the Navion, I put my foot on the little skid piece that guards the rear tiedown ring enough to lift the nose (it's a lot heavier than a 152). You can then sort of hop the plane around with the nose gear off the ground.

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