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  #1  
Old 06-06-2019, 11:53 AM
Bubblehead's Avatar
Bubblehead Bubblehead is offline
 
Join Date: Jul 2007
Location: Keller, TX
Posts: 1,553
Default Manual Trim Issue

Yesterday when approaching to land I pulled power back and started running my manual trim nose up to trim for approach speed but I never got the speed change I expected. I ran it all the way out and had to hold back pressure for the landing. I was ready to do a go around if needed but the landing worked out fine. I wish I had left the trim tab where it was so I could look at it after landing but I did not.

After parking the plane I got a little help from a local mechanic and we cycled the trim full up to full down and then did it with a little pressure on the tab and everything worked fine.

The mechanic mentioned that some manual trim systems include a clutch in them that can slip so that the pilot thinks he is moving the trim tab but is just turning the knob. He does not know RVs.

Hence my posting to the forum. Has anyone else had a similar experience?

BTW I am in Talkeetna, AK today. Am doing my bucket list flying vacation from Texas through Alberta, BC, the Yukon and into Alaska. Very interesting, tremendously beautiful, but with challenging weather. Definitely not Texas "severe clear" flying.
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RV-8 180 hp IO-360 N247TD with 10" SkyView!

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  #2  
Old 06-06-2019, 12:52 PM
noelf noelf is offline
 
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Location: Solomons, MD.
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Default

What was your gross landing weight and CG?
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  #3  
Old 06-06-2019, 12:53 PM
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Bubblehead Bubblehead is offline
 
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Default

More info - I was the only person in the plane, I had about 30 lbs in the front baggage compartment and nothing in the back. ForeFlight wt and bal showed I was still in the envelope but on the nose-heavy side. Maybe I just don't have enough trim authority at fwd cgs and need to move stuff behind the back seat.
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RV-8 180 hp IO-360 N247TD with 10" SkyView!

VAF Donations Made 8/2019 and 12/2019
"Cum omni alio deficiente, ludere mortuis."
(When all else fails, play dead.)
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  #4  
Old 06-06-2019, 12:59 PM
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Bubblehead Bubblehead is offline
 
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Quote:
Originally Posted by noelf View Post
What was your gross landing weight and CG?
about 1405 lbs and 79.9 in
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RV-8 180 hp IO-360 N247TD with 10" SkyView!

VAF Donations Made 8/2019 and 12/2019
"Cum omni alio deficiente, ludere mortuis."
(When all else fails, play dead.)
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  #5  
Old 06-06-2019, 01:49 PM
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fl-mike fl-mike is offline
 
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Default

no clutch on the RV manual trim system.
you probably just ran out of trim. Not uncommon with forward CG 8's.
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  #6  
Old 06-06-2019, 02:36 PM
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Bubblehead Bubblehead is offline
 
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Location: Keller, TX
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Thanks Mike. The more I think about it the more I think you are right. I rarely fly without traveling bags and stuff in the back, or a passenger, and on this trip I have extra tie-down material in the front baggage compartment. I am within the cg envelope but ran out of trim.

BTW I now have 998.8 hrs flying this RV and tomorrow will go over the 1000 hours mark. The plane has more - I am the 4th owner and have had it for 11 years.
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RV-8 180 hp IO-360 N247TD with 10" SkyView!

VAF Donations Made 8/2019 and 12/2019
"Cum omni alio deficiente, ludere mortuis."
(When all else fails, play dead.)
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  #7  
Old 06-06-2019, 04:34 PM
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Tankerpilot75 Tankerpilot75 is offline
 
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Location: Oklahoma City, OK
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Look at the base of your trim control knob. There is a nut on the cable housing that screws to the base of the trim control knob. Make sure it?s tight. Before I converted from manual trim to electric trim I had that cable nut become loose and then off the trim control knob (twice). If it happens in flight you?ve got your hands full of aircraft, but it?s still controllable. However, it?s feels strange to release stick pressures to land.

Had that happen which is one of the reasons I converted to electric trim. I love my electric trim system!
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  #8  
Old 06-06-2019, 04:42 PM
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BruceEicher BruceEicher is offline
 
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Location: Wilsonville/Aurora KUAO Oregon
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Solo I always put my tiedowns, oil, tools and any luggage in the back for better CG. In your configuration I would run out of trim but my knob will stop turning.
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  #9  
Old 06-07-2019, 01:16 AM
Yen Yen is offline
 
Join Date: May 2010
Location: Benaraby Queensland. Australia
Posts: 223
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You will get better fuel economy with the G of G aft, rather than forward. The only reason to have weight forward is if you are getting too close to the aft C of G.
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  #10  
Old 06-07-2019, 09:25 AM
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Bubblehead Bubblehead is offline
 
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Location: Keller, TX
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I gave this a lot of thought and I am sure the problem is that I had nothing in the back and more than normal stuff (tie down, oil, some tools) in the front. I appreciate all the information. It is very rare for me to be solo in the plane without luggage etc. in the back that I guess I never had the cg that far forward!.

TankerPilot 75 - I will check that nut too.
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RV-8 180 hp IO-360 N247TD with 10" SkyView!

VAF Donations Made 8/2019 and 12/2019
"Cum omni alio deficiente, ludere mortuis."
(When all else fails, play dead.)
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