Whelen LED tail strobe, rudder rebalance?

[bmcconnaha]

Hi guys and gals.  I put a whelen Orion LED tail strobe on my 1990 M20J.  I’ve seen several folks mention rebalancing the rudder when installing tailbeacons for ADS-B compliance, and it got me thinking...Did anyone weight the outgoing parts? I can’t find my model number that I had on their previously to find the weight on whelens website.  I believe it’s only a .02lbs diff, and I won’t worry about the rebalance if that’s the case, but i want to confirm that.  

[carusoam]

I believe pics and weight have been done around here...

Somewhere....

Fuzzy memory says they look very different from each other....

Find @OSUAV8TER he is our Whelen guy... he may be able to point you in the right direction...

Best regards,

-a-

[larrynimmo]

I changed out my tail beacon and I didn’t even think of rebalancing the rudder.  The weight between the old and the new was reasonably close.

the rudder performs exactly the same as it did before

[OSUAV8TER]

I think you'll be okay but for some model aircraft such as Barons and some Twin Cessnas, you have to rebalance the rudder because the beacon light on the top is part of the total weight and balance for that control surface. For example, I sell a LED beacon light for Barons that weighs exactly the same as the old light to make the swap easier. 

[bmcconnaha]

1 hour ago, OSUAV8TER said:

I think you'll be okay but for some model aircraft such as Barons and some Twin Cessnas, you have to rebalance the rudder because the beacon light on the top is part of the total weight and balance for that control surface. For example, I sell a LED beacon light for Barons that weighs exactly the same as the old light to make the swap easier. 

Do you have the weight difference between the two? The light Is on a control surface and therefore part of the balance I believe.  

[bmcconnaha]

5 hours ago, larrynimmo said:

I changed out my tail beacon and I didn’t even think of rebalancing the rudder.  The weight between the old and the new was reasonably close.

the rudder performs exactly the same as it did before

Well... they want you to balance the control surfaces after paint, so It doesn’t sound like it takes much weight to change the balance.  I have the 2900 gross and the balance on the rudder is a narrower envelope.  As far as the rudder working the same, yes they will, until they don’t.  Flutter isn’t anything to mess with.  I’d like to push the nose over in a descent and not worry too much about it.  

[OSUAV8TER]

47 minutes ago, bmcconnaha said:

Do you have the weight difference between the two? The light Is on a control surface and therefore part of the balance I believe.  

I was looking at the Orion 500 paperwork and it did not have a weight but I can find out. What light did you remove? 

[EricJ]

Control surface balancing is done with ounces, so small differences in weight can affect the proper balancing of the particular surface.   That's why it's checked during repaint.

How much difference it makes on a Mooney rudder is a good question.   One change required for the increased gross weight mod is to change the rudder balance weight, so it must not be considered an inconsequential thing.

 

[bmcconnaha]

32 minutes ago, OSUAV8TER said:

I was looking at the Orion 500 paperwork and it did not have a weight but I can find out. What light did you remove? 

I wish I knew lol.  That’s what I can’t find.  I think I saw the Orion weighing in at .3

[bmcconnaha]

14 minutes ago, EricJ said:

Control surface balancing is done with ounces, so small differences in weight can affect the proper balancing of the particular surface.   That's why it's checked during repaint.

How much difference it makes on a Mooney rudder is a good question.   One change required for the increased gross weight mod is to change the rudder balance weight, so it must not be considered an inconsequential thing.

 

Yep.  And mine has the GW increase, and it has quite a bit of weight on top now.  I should have weighed the stuff I pulled off.  I know that now.  

[OSUAV8TER]

5 hours ago, bmcconnaha said:

I wish I knew lol.  That’s what I can’t find.  I think I saw the Orion weighing in at .3

Snap a photo, we can usually identify it that way.

[AerostarDriver]

I have stopped short of doing my Orion 500 until I can get to the bottom of this on my Aerostar E. My concern has a lot to do with the additional moment arm that the stinger adds on weight the rudder. The Orion 500 weighs significantly more then the light it is replacing. The only mention within the STC and Install instructions to balancing is the eligibility notes on the STC marking certain aircraft as requiring proper balancing of which the M20 series is not technically listed.

[bmcconnaha]

2 hours ago, OSUAV8TER said:

Snap a photo, we can usually identify it that way.

I’ll see if I can round it up tomorrow...

[PT20J]

Is this one of those things where you already know the right answer?

[bmcconnaha]

2 hours ago, PT20J said:

Is this one of those things where you already know the right answer?

 I’m asking if anyone weighed their outgoing parts, as I stated.    I didn’t, and if the weight is much different, I’ll rebalance. I can’t verify the strobe model I had.  The parts manual lists the part number, but I can’t find that anywhere in a whelen part.  I’ve seen several Whelen models listed at .28lbs. But if you’re asking if I know the answer, sure.  I’d rebalance if the Orion weighs more.  That’s what I don’t know.  If I knew the weights, there would be no need for the post.  The other factor is finding someone to balance it, and the service centers near me are several hours away by air.   

[PT20J]

1 hour ago, bmcconnaha said:

 I’m asking if anyone weighed their outgoing parts, as I stated.    I didn’t, and if the weight is much different, I’ll rebalance. I can’t verify the strobe model I had.  The parts manual lists the part number, but I can’t find that anywhere in a whelen part.  I’ve seen several Whelen models listed at .28lbs. But if you’re asking if I know the answer, sure.  I’d rebalance if the Orion weighs more.  That’s what I don’t know.  If I knew the weights, there would be no need for the post.  The other factor is finding someone to balance it, and the service centers near me are several hours away by air.   

My point was that the service manual is pretty explicit about this. Any A&P can do it.

 

 

[bmcconnaha]

10 minutes ago, PT20J said:

My point was that the service manual is pretty explicit about this. Any A&P can do it.

 

 

I missed that in the service manual.  Guess it’s settled.  It should be balanced.  Wish my a&p had mentioned it when he installed them.  

[OSUAV8TER]

11 hours ago, bmcconnaha said:

I’ll see if I can round it up tomorrow...

Cool. The fastest way to reach me is to email me at gallagheraviationllc@gmail.com. I check in here about once a day. 

[Missile=Awesome]

If I am to believe that .3 ounces in the bottom center is a significant issue than I need to re-think the Mooney design.  Ragged edge?  Really?  Flutter?  Really?  REALLY?  Umm k.  Holding my breath while this critical engineering analysis plays out...

[1980Mooney]

On 11/8/2020 at 11:36 AM, bmcconnaha said:

Yep.  And mine has the GW increase, and it has quite a bit of weight on top now.  I should have weighed the stuff I pulled off.  I know that now.  

There is a lot of focus on the weight of the actual light bulb module in the tip of the rudder but I assume that you removed the old Whelen strobe power supply when you upgraded to LED.  Doesn't that weigh about 2 lbs and is located somewhere in the tail at 150-180 inches of arm?  If so that seems like a material change to your W&B which needs to be modified and signed by an A&P or avionics shop.

Edited November 9, 2020 by 1980Mooney

[Gatlin Gun]

This is probably not as helpful as you want, but this year I had all lights and wires replaced with LED Whelens and it was definitely less weight...not more.

[bmcconnaha]

9 hours ago, 1980Mooney said:

There is a lot of focus on the weight of the actual light bulb module in the tip of the rudder but I assume that you removed the old Whelen strobe power supply when you upgraded to LED.  Doesn't that weigh about 2 lbs and is located somewhere in the tail at 150-180 inches of arm?  If so that seems like a material change to your W&B which needs to be modified and signed by an A&P or avionics shop.

We’re talking about a control surface rebalance, not a w&b change.  That’s complete.  

[bmcconnaha]

10 hours ago, Missile=Awesome said:

If I am to believe that .3 ounces in the bottom center is a significant issue than I need to re-think the Mooney design.  Ragged edge?  Really?  Flutter?  Really?  REALLY?  Umm k.  Holding my breath while this critical engineering analysis plays out...

The weight of the new strobe is .3 lbs, not .3 ounces.  What I don’t know is what was the weight of the previous strobe tube assembly.  Funny to hear both sides of this, a former engineer at mooney says it absolutely needs a rebalance when talking about the tail beacon adsb solution on another forum.   Some people say it doesn’t. The rudder balance required a check with the increase in gross to 2900, would be nice to see the engineering data behind why they wanted it checked to increase the gross.  As for the “ragged edge”, maybe I missed something.  I remember reading (dont quote me) that mooney test flights had flutter at like 240kias, but I could be wrong, just something that stuck in my memory for whatever reason.  Doesn’t seem very close to the ragged edge to me, but we are talking a few hours for a rudder balance, not 20, so it’s not a big deal to have checked.

On a separate note, Whelen finally got back to me.  They believe I had an A625 strobe assembly, and the weight is very close.  I’ll probably worry about the balance when I paint it.  On the other hand, they did point out that the Orion 500 isn’t stcd for the J, and I would need to do “an alternate means of compliance”.  Not familiar with what that means.  My a&p review the docs and installed them with just a logbook entry. 

[Missile=Awesome]

11 hours ago, bmcconnaha said:

The weight of the new strobe is .3 lbs, not .3 ounces.  What I don’t know is what was the weight of the previous strobe tube assembly.  Funny to hear both sides of this, a former engineer at mooney says it absolutely needs a rebalance when talking about the tail beacon adsb solution on another forum.   Some people say it doesn’t. The rudder balance required a check with the increase in gross to 2900, would be nice to see the engineering data behind why they wanted it checked to increase the gross.  As for the “ragged edge”, maybe I missed something.  I remember reading (dont quote me) that mooney test flights had flutter at like 240kias, but I could be wrong, just something that stuck in my memory for whatever reason.  Doesn’t seem very close to the ragged edge to me, but we are talking a few hours for a rudder balance, not 20, so it’s not a big deal to have checked.

On a separate note, Whelen finally got back to me.  They believe I had an A625 strobe assembly, and the weight is very close.  I’ll probably worry about the balance when I paint it.  On the other hand, they did point out that the Orion 500 isn’t stcd for the J, and I would need to do “an alternate means of compliance”.  Not familiar with what that means.  My a&p review the docs and installed them with just a logbook entry. 

You keep the focus on this important issue.  I look forward to hearing about the resolution.  Meanwhile I will try not to blow through my VNE and come fluttering down from the heavens. 

[carusoam]

For additional info on balancing flight controls...

There is a procedure for that in the maintenance manuals...

It is something that gets checked when the control surfaces get painted...

There isn’t much leeway for the extra weight of a second coat of paint...

Sometimes the weight of paint makes it difficult to balance properly...

The procedures as they are written qualify as ‘sucky’...

See if @jetdriven has any insight to rudder balance after adding/subtracting weight of a tail strobe...

You definitely want to follow the proper balance procedure, to avoid a vibrating rudder....

 

PP thoughts only, not a mechanic...

Best regards,

-a-