The International Cessna 170 Association

Hi Steve and Jim, I want to thank you both for setting me straight. The light bulb has just illuminated on where I was making my mistake. I guess I was interpreting the weight that was listed for each control surface as the weight to be used on the balance beam. Now, I know that weight is the weight of the actual lead weight in each control surface. So now I'll be using an exact one-pound weight on my balance beam and from there will make my adjustments, if needed. I was really dreading the thought of dismantling my rudder. It has been so long, I can't remember the last time I balanced a control surface and I was misinterpreting this limits page in SNL 86-44. Can't thank you guys enough for giving me the proper point of view.

Been there too! Try to balance your balance beam as best as possible prior to determining you Flt control surface balance to again reduce errors, I don't think you have to be perfect as our airplanes (other than the RED ones) are sub high performance, but that could just be my attitude.

I recently checked my rudder balance. It is seriously underbalanced at 42.5 in-lbs. To get it in within limits I would need to add 1.6 lbs. at 9.5"! The previous owner was a used car dealer who must have got a bulk discount on Bondo. There are two 6"X6" doublers just under the nav light, one on each skin with some evidence of body filler on the repair. So I'll be replacing at least the bottom rudder skins. My question, for those who have balanced control surfaces is how much of an allowance should one give for the paint that will be added on the control surfaces? In other words, if I balance an unpainted aileron, elevator, or rudder, and I find that unpainted the control needs say 5 ounces of lead, how much additional weight should be added so that, once painted, the control is still in balance?

Gary, wouldn’t that be influenced by how much paint you intend to apply? (I.E., just a stripe..?? or the entire rudder surfaces..?) Also if the balanced-weight has a “range” of value…then balancing it using the middle of the range should allow you some variance…heh..??

I’d balance it close to the 23 in-lb end of the spec to give the painters the most weight to work with. That’s my plan with my out-of-balance rudder.

n2582d wrote: ↑Wed Nov 01, 2023 1:33 am I recently checked my rudder balance. It is seriously underbalanced at 42.5 in-lbs. To get it in within limits I would need to add 1.6 lbs. at 9.5"! The previous owner was a used car dealer who must have got a bulk discount on Bondo. There are two 6"X6" doublers just under the nav light, one on each skin with some evidence of body filler on the repair. So I'll be replacing at least the bottom rudder skins. My question, for those who have balanced control surfaces is how much of an allowance should one give for the paint that will be added on the control surfaces? In other words, if I balance an unpainted aileron, elevator, or rudder, and I find that unpainted the control needs say 5 ounces of lead, how much additional weight should be added so that, once painted, the control is still in balance?

I’m probably misunderstanding this, but recalling painting a fleet of airplanes (not Cessnas) many years ago, we removed all flight controls and inspected/repaired as necessary before sending to paint shop. All were balanced after painting and prior to re-installation on the repainted ship. If a control was either too damaged or worn beyond limits, it was rejected. Isn’t that still standard practice?

Correct, Harlow…. the balance should be performed (or at least checked) after paint.

(Dead give-away <it was likely not properly accomplished>: the attach hardware is also painted and without tool marks.)

Yes, controls are balanced after paint and before installation. However, it is smart to check them after stripping and before paint to identify major discrepancies before applying a fresh coat of paint, especially in the case of 170 elevators and rudders where significant disassembly is required to adjust the balance weight. In the case of the rudder mentioned earlier, I would balance it as leading edge heavy as possible prior to paint so it winds up somewhere in the middle of the range.

cessnut wrote: ↑Tue Nov 07, 2023 12:43 pm Yes, controls are balanced after paint and before installation. However, it is smart to check them after stripping and before paint to identify major discrepancies before applying a fresh coat of paint, especially in the case of 170 elevators and rudders where significant disassembly is required to adjust the balance weight.

You took the words right out of my mouth. It's one thing to add or remove some weight to an aileron but a nasty surprise to find, after painting, that the rudder or elevator balance is not within spec.

How many of you that have added a uAvionix tailBeacon have balanced your rudder after installation?I calculate, in order to maintain the balance in the same position as when original nav light was installed, it would require 6 oz. of lead at the balance weight. Edit: The above calculation is for the 140 gram uAvionix tailBeaconX, not the 80 gram tailBeacon.

cessnut wrote: ↑Tue Nov 07, 2023 12:43 pm In the case of the rudder mentioned earlier, I would balance it as leading edge heavy as possible prior to paint so it winds up somewhere in the middle of the range.

DaveF wrote: ↑Mon Nov 06, 2023 5:00 am I’d balance it close to the 23 in-lb end of the spec to give the painters the most weight to work with.

Thanks Cessnut and Dave, that makes sense.

The FAQs published by uAvionix of this device include the comment: “ tailBeacon weighs 80grams/2.9oz/0.176lbs including 6″ of 22AWG. The rebalancing of the rudder will depend on the weight difference between the existing light and the tailBeacon. In many cases, the weight difference is less than 0.5oz” (One might notice that Tailbeacon and Tailbeacon-X have different specified weights)

This does not account for the relative differences in “arm” from the pivot-point of the rudder. (One cannot simply add any particular off-set weight to the counter-balance. This issue may also be of interest to those who substitute L.E.D. Nav-lamps for incandescents on their flight controls.)

uAvionix Installation Instructions: While perusing these documents I did not notice any approval-basis of the Instructions themselves. uAvionix instructions (rather quietly) do include the comment that the installation must be “in accordance with AC 43.13, 2B, Ch. 1” ….I suppose that’s one sly way to deal with responsibility.

(While this Thread-Topic was originally “Elevator Balance”… I hope no one installs their Tailbeacon on the elevator.)

George,
My mistake was not noting the difference between the uAvionix tailBeacon and their tailBeaconX. It was the tailBeaconX, at 140 grams, that I was using for my calculations in the above post. I weighed my nav light, together with the wire in the rudder and the two mounting screws, at 81 grams — nearly identical with the uAvionix tailBeacon.

Help, how do you add weight to the rudder horn? What is the best procedure? I installed new lower skins and i'm 10 oz short of balance.