M20K left roll tendency

[Airways]

This is a continuation of a similar topic in the Bravo-section, but that one seems dead. 
 

My M20K has a tendency to start and continue a left roll when I let go of the yoke. The yoke stays centered and I have the impression that the ailerons are pretty flush with the wings. 
 

The left turn can be prevented with a little right rudder, so I’m looking at the rudder-aileron interconnect.  Of course a little right rudder makes for a little skid. 
 

Is this fixable ?

 

 

 

[RJBrown]

This Mooney required pressure to hold straight. Last cover on the bottom of the right wing caused a pull. I guess it just wasn’t installed properly.

[Airways]

Interesting ! Was the cover like this due to aerodynamic forces or was it really installed like that ?

 

My plane started to misbehave after an extensive annual...

[RJBrown]

I assume the screws were loose or partially forgotten by a prior service person. My friend just bought it last December. He did not have a prebuy. Front edge had no screws by the time I saw it. It was bent down and catching air.
The owner stores it in my hangar. Since I have permission to fly it he let me know it required left pressure to fly straight. 

 

[A64Pilot]

Any Certified aircraft can have a low wing lifted by the rudder, it’s the reason many aircraft have aileron to rudder interconnects, so check the interconnect but I’d be surprised if that’s it.

‘Once your sure fuel is balanced etc. you’ll most likely end up tweaking the trailing edge of an aileron, I’ve not read it, but I’m sure it’s in the manual.

But if i cruise the ball is centered the odds of it being rudder are small

[EricJ]

Also check the flap rigging.   If the flaps are not right, especially with some asymmetry, it can cause the roll as well.

 

[PT20J]

Shoptalk - rigging.pdf

[MarkD34M]

I just got out of annual also and had a similar situation. The shop put chafe tape on the flaps and when they were retracted, the tape held the one flap off by a very small amount. I removed it and it flew straight as an arrow. Maybe confirm the flaps are fully retracted in flight. 

[Ragsf15e]

I’d hate to start a civil war on here, but after my annual at Top Gun several years ago they straightened all the rigging.  On the test flight it rolled pretty hard. Tom R. Used duckbill pliers to very slightly bend the aft edge of one aileron (unnoticeable).  She’s flown straight ever since.  I don’t think we’ll find that in the manual, but they had already rigged the airplane first.

Edit: it is in the manual!  Top Gun definitely knows Mooney!

Edited April 15, 2021 by Ragsf15e

[PT20J]

51 minutes ago, MarkD34M said:

I just got out of annual also and had a similar situation. The shop put chafe tape on the flaps and when they were retracted, the tape held the one flap off by a very small amount. I removed it and it flew straight as an arrow. Maybe confirm the flaps are fully retracted in flight. 

Hard to tell without seeing it, but a common problem with Mooneys is that that small gap where the wing trailing edge meets the top leading edge of the flaps is too tight allowing rubbing of the flap leading edge attachment rivet heads against the wing. I have seen a number of airplanes with the rivet head half worn through! The shop may have applied the tape to fix this. But any reasonable thickness tape should not deflect the flaps significantly. Don Maxwell fixes the problem by lowering the flaps slightly and putting a wood shim over the flap and using a stiff putty knife placed between the wood shim and the wing skin to flex the wing skin upwards slightly to increase the gap enough so that the flaps don't rub

Skip.

[PT20J]

16 minutes ago, Ragsf15e said:

I’d hate to start a civil war on here, but after my annual at Top Gun several years ago they straightened all the rigging.  On the test flight it rolled pretty hard. Tom R. Used duckbill pliers to very slightly bend the aft edge of one aileron (unnoticeable).  She’s flown straight ever since.  I don’t think we’ll find that in the manual, but they had already rigged the airplane first.

Actually, that procedure is well documented in the service and maintenance manual. Trailing edges can be bent down slightly but not up. This is the last step after the rigging has been verified. And you are correct -- it doesn't take much. 

Skip

[carusoam]

It only takes a small amount of force to start a roll...

 

When everything is balanced and working properly...

A solo pilot can use weight shifting to follow the magenta line... on a smooth day...

 

So... expect that a solo pilot is always sitting on the left side... does the same occur when a SIC is aboard?

It is possible that the leveling force can be determined by the amount of fuel offset needed to balance things out...

 

There have been some cases of odd amounts of weight left in the wing tips of some planes... like expansion tanks...

PP thoughts only, my M20C wasn’t special, but it would follow the magenta line using weight shifting inside the cabin... 

 

Visiting an MSC with travel boards could be  great way to start...

Best regards,

-a-

 

[Airways]

I performed the wing level test ( as mentioned in @PT20J’s document) about 1,5 years ago and it flew perfectly straight, even after 10’’.

I did however have a passenger in the RH seat when I did this.  In the meantime I had an avionics upgrade (lost some weight) and an annual.

it is weird how the behaviour of the plane has changed in so little time.  No signs of hangar rash...  But I’ll have a closer look at the flaps and the underside of the wing.

[FlyingDude]

7 hours ago, carusoam said:

There have been some cases of odd amounts of weight left in the wing tips of some planes... like expansion tanks...

Could you explain more? Thanks

[FlyingDude]

4 hours ago, Airways said:

had an avionics upgrade

Avionics are almost on the longitudinal axis. The roll moment induced by their removal would be minimal, methinks. 

 

When I'm alone, I try to keep 10 gallons more on the right tank than left. The 60 lbs seem to balance my 78kg. 

[Airways]

11 minutes ago, FlyingDude said:

When I'm alone, I try to keep 10 gallons more on the right tank than left. The 60 lbs seem to balance my 78kg.

Do you think it makes that much of a difference on the handling ?  I’d think the POH would mention a max. difference between left and right tank.  If I remember correctly then Cirrus has a 8 gal max differential.

 

But it is an interesting perspective.  I’m gonna fly with a passenger next time & see what happens...

[FlyingDude]

I have extended tanks, they have some fuel even when the mains are 1/3 full. The center of the tanks is about 1.5-2m from the longitudinal axis. My Johnson is about 40cm from the plane's johnson. To balance my weight, the counter weight needs to be 40/150, or 40/200= 20%-25% of my weight. That's about 16-20kg, which is 40-50lbs.

Next time lean towards the right or fly from right seat or engage autopilot and change seats...

[FlyingDude]

42 minutes ago, Airways said:

Cirrus has a 8 gal max differential

When I got the plane, I flew once with 30 gallons on left wing (full minus about an hour) and empty right wing, because the poh says to fly 1 hr on one tank then switch and deplete the other tank and then use the first tank (when starting on both full tanks). Landing was tricky. I had to come in at 80 kts and land at 70 as opposed to my usual 70 on final and 65 over threshold. Aileron deflection about 1/3 and shit tons of rudder. Of course I conducted this experiment on a calm day... 

I don't want to repeat that landing as standard practice...

[A64Pilot]

9 hours ago, carusoam said:

It only takes a small amount of force to start a roll...

 

When everything is balanced and working properly...

A solo pilot can use weight shifting to follow the magenta line... on a smooth day...

 

So... expect that a solo pilot is always sitting on the left side... does the same occur when a SIC is aboard?

It is possible that the leveling force can be determined by the amount of fuel offset needed to balance things out...

 

There have been some cases of odd amounts of weight left in the wing tips of some planes... like expansion tanks...

PP thoughts only, my M20C wasn’t special, but it would follow the magenta line using weight shifting inside the cabin... 

 

Visiting an MSC with travel boards could be  great way to start...

Best regards,

-a-

 

Need to fly my C-140, fly with the windows open, sticking an arm out will almost put it in a standard rate turn.

Ref anti chafe tape, I use this as even putting it on both sides won’t require different lengths of Camlocs etc. I believe it’s 1/2 of a thousands thick yes, that’s .0005 

https://www.aircraftspruce.com/catalog/cspages/tefloncoatedtape.php

I believe that’s thinner than paper on average?

 

 

 

Edited April 15, 2021 by A64Pilot

[Airways]

4 hours ago, FlyingDude said:

Next time lean towards the right or fly from right seat or engage autopilot and change seats...

Yes, seems like an interesting experiment. TGI(almost)F !

[Hank]

3 minutes ago, Airways said:

Yes, seems like an interesting experiment. TGI(almost)F !

You're (almost) Flying??

[Sixstring2k]

19 hours ago, Ragsf15e said:

I’d hate to start a civil war on here, but after my annual at Top Gun several years ago they straightened all the rigging.  On the test flight it rolled pretty hard. Tom R. Used duckbill pliers to very slightly bend the aft edge of one aileron (unnoticeable).  She’s flown straight ever since.  I don’t think we’ll find that in the manual, but they had already rigged the airplane first.

Edit: it is in the manual!  Top Gun definitely knows Mooney!

for something like this I would go to either maxwell’s, topgun and one other place whose name escapes me. Maxwell has most likely dealt with this issue more than anyone still around and as mentioned topgun knows what they are doing. 

[Hank]

2 hours ago, Sixstring2k said:

for something like this I would go to either maxwell’s, topgun and one other place whose name escapes me. Maxwell has most likely dealt with this issue more than anyone still around and as mentioned topgun knows what they are doing. 

SWTA?

I would also trust other respected, experienced MSCs like Cole and AGL, Henry Weber, etc.

[carusoam]

12 hours ago, FlyingDude said:

Could you explain more? Thanks

Over the decades things get mounted in the Wings and removed from the wings or get abandoned in the wings...

Fuel systems are the least standardized system in all of the Mooneys...

M20Ks got the most unique designs over the years...

So... when you have a chance... with all of the inspection panels opened up... have a look over every inch to see what may be hiding in there...

 Best regards,

-a-

[FlyingDude]

1 hour ago, carusoam said:

what may be hiding in there

Skeletons Hopefully not loose items. Unexpected clinks and clanks can be very unsettling...

The other day my phone started ringing while in flight. It was unexpected, as my personal phone is always on silent. I turned the Ringer was on that morning because I was expecting contractors at home. Anyway, it sounded differently with David Clarks on and scared the hell out of me. Clinks coming from the wing would be much worse...