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Post by cole505 on Mar 25, 2022 3:58:36 GMT
Hi All,
I was wondering if anyone knows or has seen the allowable movement specifications on the Stabilator trim tab. I have about a 1/16 inch movement of the trim tab hinges while doing my preflight with the stabilator at rest in the down position. The airplane seems to have a slight up and down pitch in straight and level flight No autopilot engaged. I did replace the the Stabilator bolts as the ones installed were to short and the bearing was riding directly on the bolt thread rather on the shoulder or un-threaded part of the bolt.
I am thinking maybe they installed the wrong size hinge pins giving the trim tab that slight 1/16 play…… Any way feel free to chime in your Ideas and thoughts are most welcome 🤗
Ray & Lucy 👍🏻😊✈️🇺🇸✅
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Post by nohippychicks on May 6, 2022 3:19:57 GMT
Ray & Lucy,
I'm pretty sure you're not going to find guidance in the AMM; if you do, I'd like to know where you found it.
Without manufacturer instruction, we're left to FAA guidance which says that if your tab is 20% or less of the span of the control surface (which I'm pretty sure yours is) that you're allowed 2% of the tab's chord worth of movement. I can't find the actual reference for that, but I know it was a question I got very familiar with before taking my IA exam. Reference not being provided, take all of this with a grain of salt but Google will back me up here.
That's about as much help as I can give.
How did you measure the free play?
If it means anything, when I measure free play, I've got a steel bar all taped up to prevent paint damage. I'll use speed tape to stick that to the primary control surface and then attach a magnetic fixture to that, stick a dial indicator in the end and use either manufacturer or Cessna guidance as to where to put the probe of the dial indicator and push/pull with a calibrated "Fish scale."
If there's no guidance as to where to put the probe of the indicator, I'll use Cessna's guidance which is, off the top of my head, .25" forward of the trailing edge and in the center of the span of the tab; then apply 3 lbs of pressure up, then 5 lbs and a reading of both of those, then 3 lbs of pressure down, then 5 lbs and more readings. Add math to that and you get an average that's pretty good at telling you what your free play is.
If you were just grabbing the tab and giving it a shake, the good news is that way seems to give some pretty rowdy readings, so there may be no problem there.
Have you had a decent mechanic give you a second opinion?
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Post by Ed Midgley on May 6, 2022 12:13:34 GMT
The up and down pitch change is normal. I believe it’s called a Frugoid (sic). The autopilot does a good job of handling it but, it’s easy to chase it while hand flying.
One of my hinge pins has always had some play. I’ve pulled the pin and it doesn’t show any signs of wear. I think some of the loops are just made oversized. In 1100 hrs it hasn’t changed any.
Ed
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Post by ronin5573 on May 6, 2022 14:04:48 GMT
The up and down pitch change is normal. I believe it’s called a Frugoid (sic). The autopilot does a good job of handling it but, it’s easy to chase it while hand flying. One of my hinge pins has always had some play. I’ve pulled the pin and it doesn’t show any signs of wear. I think some of the loops are just made oversized. In 1100 hrs it hasn’t changed any. Ed I have also noticed that oscillation. Seems to only happed at higher speeds. |
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Post by cole505 on May 6, 2022 15:29:16 GMT
Ray & Lucy, I'm pretty sure you're not going to find guidance in the AMM; if you do, I'd like to know where you found it. Without manufacturer instruction, we're left to FAA guidance which says that if your tab is 20% or less of the span of the control surface (which I'm pretty sure yours is) that you're allowed 2% of the tab's chord worth of movement. I can't find the actual reference for that, but I know it was a question I got very familiar with before taking my IA exam. Reference not being provided, take all of this with a grain of salt but Google will back me up here. That's about as much help as I can give. How did you measure the free play? If it means anything, when I measure free play, I've got a steel bar all taped up to prevent paint damage. I'll use speed tape to stick that to the primary control surface and then attach a magnetic fixture to that, stick a dial indicator in the end and use either manufacturer or Cessna guidance as to where to put the probe of the dial indicator and push/pull with a calibrated "Fish scale." If there's no guidance as to where to put the probe of the indicator, I'll use Cessna's guidance which is, off the top of my head, .25" forward of the trailing edge and in the center of the span of the tab; then apply 3 lbs of pressure up, then 5 lbs and a reading of both of those, then 3 lbs of pressure down, then 5 lbs and more readings. Add math to that and you get an average that's pretty good at telling you what your free play is. If you were just grabbing the tab and giving it a shake, the good news is that way seems to give some pretty rowdy readings, so there may be no problem there. Have you had a decent mechanic give you a second opinion? Hi Nohippychicks, I really appreciate your Input! I went thought pretty much everything you stated. Just Completed LSRM-A training and my Hanger Neigbor is an A&P, I even spoke with Josh at Tecnam……. I got the exact measurements for the hinge pin and hinges…… I have concluded as Ed also stated there is going to be a tiny amount of play. Do you own the P-2008 I am trying to get a consensus of what other owners are finding on they’re trim tabs….. Ray & Lucy ✈️👍🏻✅🇺🇸😊 |
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Post by cole505 on May 6, 2022 15:37:47 GMT
The up and down pitch change is normal. I believe it’s called a Frugoid (sic). The autopilot does a good job of handling it but, it’s easy to chase it while hand flying. One of my hinge pins has always had some play. I’ve pulled the pin and it doesn’t show any signs of wear. I think some of the loops are just made oversized. In 1100 hrs it hasn’t changed any. Ed I have also noticed that oscillation. Seems to only happed at higher speeds. Hi Ed, Thanks for your input! I have concluded pretty much everything your have stated. I am hoping to get a few more P-2008 owners to chime In. Also see my previous comment I always value your opinion an over the years you have been a tremendous help with some Issues and its always very much appreciated! May I ask how your windshield change is going ? Very curious about how your Install is going or has went ? I hope I never need to change mine, but if I ever do I will be buying one of yours! Ray & Lucy ✈️👍🏻✅🇺🇸😊 |
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Post by Ed Midgley on May 6, 2022 23:30:21 GMT
The Polycarbonate windshield isn’t done yet. I’ll probably get it in the next month.
You definitely will be hearing from me when I get ready for the install.
Ed
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Post by nohippychicks on May 8, 2022 23:00:33 GMT
I really appreciate your Input! I went thought pretty much everything you stated. Just Completed LSRM-A training and my Hanger Neigbor is an A&P, I even spoke with Josh at Tecnam……. I got the exact measurements for the hinge pin and hinges…… I have concluded as Ed also stated there is going to be a tiny amount of play. Do you own the P-2008 I am trying to get a consensus of what other owners are finding on they’re trim tabs….. Ray & Lucy ✈️👍🏻✅🇺🇸😊 Ray & Lucy,
I don't own one, but I do maintain a fleet consisting of several 2008s, 2010s, a couple 2006s and a few other goodies tossed in for good measure. Out of all of our aircraft, at least one with fewer than 300 hours, if I could walk you around the hangar I would be able show you some slop/play in all of them.
When Josh and your neighbor gave you your measurements, are you saying they were consistent with what you measured?
I've worked on a lot of different aircraft and, even brand new, it's my experience that every joint will have SOME play from wheel bearings to door hold open rods. The way play is removed, if it is critical, is with some sort of preload applied.
Just out of curiosity, are you wondering if your AC is in airworthy shape or is this just an observation you've made?
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Post by cole505 on May 9, 2022 5:07:15 GMT
Hi NOHIPPYCHICKS,
I appreciate your Inputs! Sounds like your pretty darn experienced on the P-2008. Yes, shoot some pictures of your hanger that would be great! I emailed Tecnam they provided the exact specifications on the hinge and the hinge pin. From what I have found out so far is that some do have a tiny amount of play. Ed another Tecnam owner has 1100 hours on his airplane. And has pulled the pin and measured the wear on the pin and checked the hinges, no change from when the airplane was new. And he stated that he does have a little play.
There is no doubt the airplane is airworthy, I just feel better knowing across the board I have covered all my bases. I am and old F-16 Mechanic and I just completed SLRM-A school at Rainbow aviation. I really like to have all information and experiences from other pilots, & Mechanics as I can 😊
Glad to have your with us! I am sure you have read a few of our post. We have had this forum for quite a few years 😊 a great bunch of Pilots and mechanics. As pilots we get to know our airplanes and the little quirks that go with them! Who better would understand how to fix them and really notice even the smallest change or noise ect………… look forward to your to reading more of your posts!
Ray & Lucy ✅✈️👍🏻🇺🇸😊
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Post by nohippychicks on May 14, 2022 13:24:13 GMT
Ray and Lucy,
I feel like going a little off track in this thread isn't a terrible thing, so let's have at it!
I love, Love, LOVE seeing an owner taking an interest in knowing as much a possible about their planes! I bet you have some interesting experience working on F-16s! I'm glad that you went through that course at Rainbow too. Anything in particular you found useful during that course or was it mostly checking blocks so you can get that certification?
An owner getting that hands on is rare in my experience and I love to see people on this forum getting handsy with what they own. Tecnams of any model seem to be really rare, at least CONUS, and I never expected there to be an entire forum just dedicated to this manufacturer; some of the posts here have been pretty fun to read.
Would you mind copying and pasting that E-mail from Tecnam? Maybe in a dedicated thread, as that will probably be information everyone would love to know. I'm curious about how Tecnam interacts with owners and how forthcoming they are with information. My experience with them is that they are happy to give information, but don't seem to update their manuals to contain that very same information that should have been there in the first place.
I do have a decent amount of experience working on the '08s but I mostly focus on the 2010 airframe. I like them both very much and it's been a fun time seeing the differences between things like how they decided to attach seats to rails in their different models (does anyone actually LIKE the seat adjustment setup on an 2008??) as well as the differences from more conventional manufacturers like Cessna and Piper. I've learned Tecnam REALLY loves blind rivets and using odd sizes of hardware.
Thanks for taking the time to respond to all of this!
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