As it stands now - the mass balance arm top or bottom dont come anywhere near the stops - so thats not the issue - what else can I look at?
What I dont understand is that I originally check this before first flight an we were getting bout 14 deg up and on rechecking this weekend I barely got 9 deg up.
On Mon, 18 Mar 2024 15:00:39 +0000, Bud Yerly <budyerly@msn.com> wrote: Tony,
If our stab mechanism is hitting the mechanical mass balance limits at the mass balance arm and you are sure the pitch tube MW bearings are clear on the pitch torque tube (CS10) in the wing center and there is not mechanical binding there, look at the following:
It is quite easy technically to adjust the incidence of the stabilator by changing the stabilator balance weight upper and lower mass balance stops.
Hopefully you have done the Mod 70, but even if you haven't, it's straight forward. (Mod 70 and or the cable sway supports with original TP18 fittings can still can be adjusted easily).
You are essentially looking to have +13,-5 or a minimum of +12,-4 degrees of trailing edge travel so 16-18 degrees total from full up to down.
Simply carve the upper and lower slots to get the total travel plus the bump stop rubber and reinstall the bump stop rubbers and recheck.
I have an archived a document somewhere, but the main issue is the uncomfortable access if the viewing/inspection plates are small.
I see this all the time on prebuy inspections and it can be an 2-8 hour exercise but it is worth it to get the stab incidence right.
The amount to actually relieve the current stops starts with measurement of course.
I personally pull off the installed upper rubber stop (as many builders fail to adjust for the bump stop thickness) on the top and sometimes the bottom to make my adjustment but always measure and look first. In some cases a large upper stop has been made that has about 20mm between the wood cutout and the fuselage inside top surface. Remove the rubber bump and Demel out the arc to suit your stab throw needs to increase the TE down (mass balance hitting the top stop). Some have the upper mass balance stop nearly at the upper skin so you have the lower limit to move only. In your case with only needing a degree, pull the top rubber stop off and see if you can relieve that a bit, then reinstall your rubber bumper and install a stick between the lower stop and the weight to hold the stop firmly until it dries. To make it pretty, get the arc set by using a thin metal strip bent to a pleasing arc while holding the mass balance firmly to the stop limit.
If you have a nose down of -4 degrees and just need a bit on the up stop limit, the rubber bolted wood dowel normally can be changed. This can be changed by simply moving the lower stop down a bit (filling and redrilling) or if clearances are an issue with the stab push pull tube, 3D printing a smaller cylinder or by center drilling a smaller wood dowel and fitting a rubber hose sized properly to get more trailing edge up to suite your throw needs.
Once the total throw is as you desire (normally 17 degrees (+13,-4)) but you cut or modified both the upper and lower stops, there is little chance that the new top and bottom stops are perfect, so one must remove the stabs (for ease of access) and "simply" remove the TP18 adjustment body bolts and adjust the mass balance arm and reassemble as necessary to get the stab mechanical stops up front to clear nicely. That is time and patience consuming to get the desired +13 to -5 hence, 17 degrees may be a better option. And this is where the time and patience grows thin. Suck it up and make a pin to replace the bolt to make adjustments of the TP18C easier. Then reinstall the bolt while forcing the pin you made and bolt it up. Carefully and patiently readjust the full down limit to -4 degrees to -5 degrees so the pitch tube doesn't bind on the torque tube (full forward stick also not hitting the panel). If the controls were built per the manual, you now should only have the trailing edge up or stick aft issue to get adjusted. Again, if the torque tube arms in the center tunnel don't hit the limit at the roll tube arm CS08. If you have issues with the original build in this clearance, much adjusting will be necessary to allow the stick movement, pushrods, arms and torque tube to work properly. Then you have the issues of push rod adjustment and perhaps even stab push tube lengthening to contend with. I've done them all and it can try ones patience but it is worth it in the end.
To be honest, if you have a weight and balance near 60 per the manual, +12-4 stab travel is quite acceptable. If it is a nose heavy or tail heavy beast, then go for full travel.
If you notice the left and right stab incidence is noticeably different then a bit of extra work will make all that work out also, see pdf attached.
Whatever you do, the mechanical bolts and metal fittings can't bind at the cockpit module linkages. If you can adjust only one stop, life is good. If you must adjust both, and then find the limit is with the pitch tube hitting the mechanical limits. Life will suck a bit. Then we must adjust the stick travel and limits to just clear and then go back to the stab stop limits and continue aft until all is well.
I've only had two cups of coffee, so email back if you need more clarification Tony.
Best Regards,
Bud Yerly
From: owner-europa-list-server@matronics.com <owner-europa-list-server@matronics.com> on behalf of tonyvaccarella <tony@weimagine.com.au>Sent: Monday, March 18, 2024 8:46 AMTo: europa-list@matronics.com <europa-list@matronics.com>Subject: Europa-List: Trailing edge elevator deflection issue