Rudder skin Repair

[1980Mooney]

A question for those with IA knowledge out there.  There seems to be a lot of different opinions on the "acceptable" way to repair a rudder skin.  Is it possible for an IA in the future to declare a modification or repair previously signed off by a different IA as "Airworthy" at the time of the repair/mod to be "unairworthy" today? (i.e. declaring that it should have never been approved)

[EricJ]

52 minutes ago, 1980Mooney said:

A question for those with IA knowledge out there.  There seems to be a lot of different opinions on the "acceptable" way to repair a rudder skin.  Is it possible for an IA in the future to declare a modification or repair previously signed off by a different IA as "Airworthy" at the time of the repair/mod to be "unairworthy" today? (i.e. declaring that it should have never been approved)

Happens all the time.    Another common instance is an IA disapproving parts that were previously installed as 'not approved', which is why the VARMA program was created, so that an owner can have an actuall letter from the FAA saying it is okay.

[Grant_Waite]

6 hours ago, Fly Boomer said:

Were you able to acquire a new servo, or get the old one rebuilt?

Actually the previous owner had bought a servo a couple months before I bought it so he gave it to me. I’ve just had it sitting at home. I had a highly qualified avionics guy from Sarasota avionics come to me and he diagnosed what made it stopped working in the first place. The in line fuse had blown, from what I’m not sure but most likely because one of the wires was frayed almost in half. Not long before he came I was just using a 12v battery to move the old servo to test it and it shit the bed after a time or 2. The gears inside had all been stripped. See picture attached of the new servo. Old one is identical inside.

[EricJ]

That's one high-tech jack screw right there. 

 

[Grant_Waite]

10 hours ago, EricJ said:

That's one high-tech jack screw right there. 

 

Yeah it’s not the most confident inspiring design by any means. But when it worked it worked. 

[A64Pilot]

Many Experimental’s use Model airplane Servos for Autopilot and or trim

[Slick Nick]

13 hours ago, Grant_Waite said:

Yeah it’s not the most confident inspiring design by any means. But when it worked it worked. 

...Until it didn't.

[Grant_Waite]

4 hours ago, Slick Nick said:

...Until it didn't.

Kinda crazy they still sell them for 2500 bucks. 

[cliffy]

Please report back if you recheck the rudder balance and how it turned out.

[A64Pilot]

2 hours ago, cliffy said:

Please report back if you recheck the rudder balance and how it turned out.

IF it were rebalanced when the servo was installed it should be a little nose heavy, which is conservative for flutter

[PT20J]

I believe that the M20J SMM specifies control surfaces to be balanced trailing edge heavy. 

[N201MKTurbo]

7 hours ago, PT20J said:

I believe that the M20J SMM specifies control surfaces to be balanced trailing edge heavy. 

So, for the rudder, is that the left or right trailing edge?

[cliffy]

Mooney refers to "underbalance" as trailing edge heavy  In the case of the J  it shows in the manual 17.4 to 20.8 ounces at a point of  12.87 inches aft of the hinge line. BEAWARE THE WEIGHT AND THE DISTANCE VARY BY MODEL AND S/N !

Its very specific and detailed in the manual. 

AND its for PAINTED surfaces only. 

We have a 3.4  oz. spread or window for balance on this model.

This is taken from the M20 Service and Maintenance manual Rev D 8/1/81

[Slick Nick]

I've always wondered, how is balance changed? By using weights on the horn? Are they interchangeable, or is the practice to modify the existing weights somehow?