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![]() The article below is printed (in its entirety) in the current issue of AOPA Pilot magazine. In it, Rod Machado mentions the controls being "mechanically sticky." It has been my experience, that the bar attached to the control yoke which goes through a bushing in the control panel often binds as it moves fore and aft through its entire range of travel as it might during a landing flare. This stickiness can cause an unexpected balloon leading to pilot induced oscillations. As part of the Piper PA28 annual inspection lubricating the bar attached to the control yoke with engine oils is mentioned. I have found that this lubrication is often overlooked, and most rental aircraft suffer to a greater of lesser extent from sticky elevator controls as a result. Has anyone else experienced this? -------------------------------------------------------------------- http://www.aopa.org/members/files/pi.../ltol0509.html License to Learn Arms control: A case for the two-handed flare BY ROD MACHADO (From AOPA Pilot, September 2005.) .... The truth is that humans, like cats, find it harder to hold onto things as they age. A hood, however, isn't one of those things. Instead, we often struggle to sustain a grip on the ideas we once held in our youth. For me, this involved believing that it was never proper to flare an airplane with both hands on the yoke. Unlike my cat, I hope, you will at least consider the following discourse without stomping off in a huff and refusing to speak to me for days, or longer. Why would anyone want to flare an airplane with two hands on a typical "wheel type" yoke instead of keeping one hand on the throttle? Ask a handyman and often he'll profess that it gives him better control of the landing flare, allowing a much smoother touchdown. There's a good reason for this, too. Let's call it the Big Bang theory. In Westerns, you always see the hero shooting from the hip, with one hand. In reality, police officers are taught to fire a gun with two hands on the weapon. Why? It provides improved control and precision, and enhances the chances of hitting what they're aiming at. These are all things I think most pilots would be happy to have on their side when shooting for smoother, more controlled contact with the runway. Biomechanically, it's simply easier to apply precise changes in elevator control pressure when you dedicate additional strength and more nerve endings to manipulating the control yoke. Two hands also provide better leverage. This is why many pilots opt to place both hands on the yoke during steep turns. Using two hands also can help overcome any binds or crimps in the yoke's gearing mechanism, a common issue in older airplanes. It's very important to understand that I'm speaking of using two hands only in the flare (not the roundout), and only when the engine is at flight idle and certainly not when the airplane is more than a foot or so above the runway. The fact is that some folks like to flare with two hands. Fine. Given this preference, is there any risk that might outweigh the benefit of more precise elevator control when one hand is moved to the throttle and power applied during the flare? Let's see. As a young CFI, I was adamant about my primary students keeping one hand on the yoke and the other on the throttle during the landing flare. I still am. This is simply good practice, given that students may not have enough practical experience to locate the throttle by feel or spatial memory. On the other hand, I also insisted (long ago) that my advanced students do the same. Most willingly complied, but a few seemed quite insistent about using two hands to flare. When I recall the wholesome and playful discussions inspired by my request, the phrase "over my dead body" vaguely comes to mind (a response that, at the time, seemed more prescient than playful). It turned out that many of the people preferring a two-handed flare flew larger single-engine airplanes such as the Cessna 210 and Piper Cherokee Six. The handy use of two hands for the flare helped these pilots manipulate elevators (yokes) with greater precision in pitch control for any number of good reasons. Most likely, the controls were aerodynamically heavy, mechanically sticky, or the pilot's seating position provided for insufficient leverage on the yoke. Unfortunately, as a young instructor I was sure that the only way to fly an airplane was to do it the way I was taught, which didn't involve having two hands on the wheel. For those students refusing assimilation, I often swung the unforgiving blade of knowledge to untether them from the notion that a two-handed flare was a safe practice. "What would happen during the flare if you encountered a gust, or heaven forbid, wingtip vortices, and had to apply power immediately?" I asked, rattling my mighty saber. ... |
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![]() "Larry Dighera" wrote in message ... The article below is printed (in its entirety) in the current issue of AOPA Pilot magazine. In it, Rod Machado mentions the controls being "mechanically sticky." It has been my experience, that the bar attached to the control yoke which goes through a bushing in the control panel often binds as it moves fore and aft through its entire range of travel as it might during a landing flare. This stickiness can cause an unexpected balloon leading to pilot induced oscillations. As part of the Piper PA28 annual inspection lubricating the bar attached to the control yoke with engine oils is mentioned. I have found that this lubrication is often overlooked, and most rental aircraft suffer to a greater of lesser extent from sticky elevator controls as a result. Has anyone else experienced this? Me too. I have used the two handed flare for as long as I can remember and had a number of arguments with instructors about it. My other problem is that my body proportions are a bit out. When I buy a suit, the pants need to be just a tad short of "regular", but the jacket has to be "long". This means my legs need the seat forward for the feet on the pedals but my arms need the seat back as I have plenty of reach. So what we do is for take off and landing the seat is forward and for cruising its well back. When it comes to landing, I just don't get the right leverage from my left arm alone for the round out and flare so I use a combination of both hands and a bit of up trim just to lighten the load and make the it more comfortable. This is especially important with a sticky Pa 28 column and there are not many Pa28s which don't get a bit sticky at some time or other. cb |
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In article ,
Larry Dighera wrote: The article below is printed (in its entirety) in the current issue of AOPA Pilot magazine. In it, Rod Machado mentions the controls being "mechanically sticky." I read this article also, and couldn't believe that he would recommend a two-handed flare. My experience is that folks tend to over-control with two hands on the yoke, and if the airplane is properly trimmed, two hands shouldn't be required in most cases. Two hands on the yoke also means zero hands on the throttle, and if you need power in a hurry you will not be properly positioned. As part of the Piper PA28 annual inspection lubricating the bar attached to the control yoke with engine oils is mentioned. I have found that this lubrication is often overlooked, and most rental aircraft suffer to a greater of lesser extent from sticky elevator controls as a result. I believe that Piper used different types of bushings depending on model year, but I have never heard of "engine oil" being recommended as a lubricant on the tubes. Maybe on the control chain, but not on the tubes. I use silicone spray on the tubes, and have occasionally used DC4. My yokes do not stick. However, it's obvious that someone in the past has used a petrol-based lube, because it's all over the bushings and I can't get rid of it, and it makes a mess of the tubes in short order. I would not recommend a petrol-based lube on the tubes. I believe that Piper recommends Parker O-Ring lube in most cases. JKG |
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I use silicone spray on the tubes, and have occasionally used DC4. My
yokes do not stick. However, it's obvious that someone in the past has used a petrol-based lube, because it's all over the bushings and I can't get rid of it, and it makes a mess of the tubes in short order. I would not recommend a petrol-based lube on the tubes. I believe that Piper recommends Parker O-Ring lube in most cases. Me, too. Silicone spray is the way to go. We apply it at least monthly, for that oh-so-smooth flare at the end... :-) And don't feel bad about someone using engine oil on your yoke shafts -- at least it wasn't graphite. That's what some genius used on ours, and -- three years after buying the plane -- we're STILL getting that awful black crap on a rag every time we lube the shafts with silicone spray. -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" |
#5
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I used the teflon-based stuff that I also use on my bicycle chain.
Works beautifully. |
#6
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This topic has come up before. Bottom line is that it is important to
keep one's control mechanisms well lubed. I use teflon-bearing lube on my yoke shafts also. David Johnson |
#7
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In article ZAFZe.367234$_o.200869@attbi_s71,
"Jay Honeck" wrote: And don't feel bad about someone using engine oil on your yoke shafts -- at least it wasn't graphite. That's what some genius used on ours, and -- three years after buying the plane -- we're STILL getting that awful black crap on a rag every time we lube the shafts with silicone spray. Others have suggested Teflon spray, and that may work better--last longer--but DC4 works better than silicone spray, though it is "more messy." In any case, any of this stuff should prevent the yokes from sticking. I'm always amazed at how often I hear the "sticky yoke" complaint, and how the solution seems to be to modify your flying behavior to work around it--doesn't seem logical to me. I'm not sure what the previous owner(s) of our airplane used, but I also have a nice collection of black gunk accumulate on the tubes. I suspect that the tubes have been hit with just about everything over the years. I suppose the only way to "fix" the problem is to pull the tubes and bushings and clean them out. JKG |
#8
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Larry Dighera wrote:
As part of the Piper PA28 annual inspection lubricating the bar attached to the control yoke with engine oils is mentioned. Beeswax works very well and does not run off. There's also a liquid Teflon coating available at Lowes. Apply it and let it dry. Even a light coat of wheel bearing grease works better than oil. Less likely to leave a mess. Has anyone else experienced this? The shafts on the Maule had to be lubricated every few hundred hours. George Patterson Give a person a fish and you feed him for a day; teach a person to use the Internet and he won't bother you for weeks. |
#9
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Molybdenum disulfide used to be touted as the acme of lubricants. I
don';t hear it mentioned here. What happened to it? Don |
#10
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Don Tuite wrote:
Molybdenum disulfide used to be touted as the acme of lubricants. I don';t hear it mentioned here. What happened to it? IIRC, that's one variant of wheel bearing grease. George Patterson Give a person a fish and you feed him for a day; teach a person to use the Internet and he won't bother you for weeks. |
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