KX155 Issue & Drift Left on Takeoff

[TheAv8r]

Hi all,

I'm a new owner of a 1965 M20E, I owned one in the past and it's always been my favourite of the Mooneys. With a new plane, as usual, comes new quirks! 2 I'm having a hard time figuring out... hoping I can rely on the knowledge here to help point me in the right direction .

1. On almost every takeoff, once the weight is leaving the wheels, right as she's starting to get airbourne and the plane is generating lift, the plane starts drifting left, hard. Yesterday I was departing on Runway 17 and the winds were 110 at 5, so a left crosswind, and she still drifted left, so I don't think it's lack of crosswind input. It doesn't happen on landing, and it's not darting anywhere so I doubt it's nosewheel slop. In cruise, she flies straight and level hands off so I doubt it's a rigging turning tendency issue. Only thing I can think of is I'm not keeping enough right rudder in, but I kind of doubt that personally. Any ideas?

2. The KX155 second Nav/COMM has COMM receiving issues. Sometimes it's not receiving at all, sometimes it receives crystal-clear but is broken. I took it out and cleaned all the contacts with contact cleaner, but that didn't seem to make a difference. During yesterday's flight, I was playing with the audio button, and noticed if I pushed up on the button and held it, suddenly it would start receiving. Moment I let go, it stopped. Did it again, same thing. So something with the button is up... any ideas? Is there something I can do to fix/troubleshoot without sending it off?

[ShuRugal]

>Only thing I can think of is I'm not keeping enough right rudder in, but I kind of doubt that personally. Any ideas?

What's the ball say? If the ball is centered, but you still drift, you aren't correcting for wind enough.

Straight and level hands off is a good start, what do you cruise speeds look like vs the book? Pick a density altitude that matches one of the tables in the book, set power and mixture per the table, and let the speed stabilize over ~10 minutes, then math it out.

If you're close to the book speed for your altitude and power, your rigging is correct.

Sent from my Pixel 3a using Tapatalk

[N201MKTurbo]

I think your rudder/nose wheel steering are not rigged correctly. It sounds like the peddle position needed to track straight down the runway is giving you a bunch of left rudder.

I would need to fly it to know for sure, or just re-rig it.

[N201MKTurbo]

It sounds like your volume pot is shot or its solder connections are fractured. Unless you are very handy with a soldering iron, you should send it off.

[TheAv8r]

5 hours ago, N201MKTurbo said:

I think your rudder/nose wheel steering are not rigged correctly. It sounds like the peddle position needed to track straight down the runway is giving you a bunch of left rudder.

I would need to fly it to know for sure, or just re-rig it.

Thanks Rich, this was my guess as well. Yesterday definitely showed it wasn't a wind thing when I had a left crosswind and was drifting left on rotation. It taxis fine and lands fine with normal rudder inputs, it's only on takeoff it does this. I may add to my list to fly it over to Don Maxwell and let him do his thing.

[Jim Peace]

On 10/21/2021 at 3:47 PM, jacenbourne said:

 drifting left on rotation. 

When you say rotation....do you mean when the mains are still on the ground and only the nose is in the air or just after rotation when all three are not on the ground?

my plane takes a good amount of rudder when just the nose leave the pavement....and I continue to push slowly as the mains lift and I track straight ahead....

[carusoam]

We can thank Dr. Coriolis for defining what happens as we rotate the nose upwards.

All that rotating mass up front (gyro)…. Combined with the small rotation of the rotating mass as we lift the nose up….

As we lift the nose… it wants to point left…

If we lowered the nose… it would want to be right back where it started….

 

Then we add all the rotational affects of air spiraling towards the tail….

 

Expect to be adding various amounts of right rudder to keep the nose pointing straight forwards… 

 

It is quite possible the pilot is sensing this phenomena for the first time with so many ponies up front… attached to so much weight…

By the time you have added extra cylinders and 310hp… rotating at 2700rpm… you start wondering if the tail is going to be large enough…  (it is!) 

For fun… you can read about Coriolis accelerations… and the right hand rule.

PP thoughts only, not a CFI… or  Dynamics guy….

Best regards,

-a-

[takair]

1.  Does it track straight on taxi?  Is the ball centered in cruise?  When checking people out in a Mooney, I often find myself asking for more right rudder on rotation and climb. There are times I even remind myself to put in more….rarely is it less…. Perhaps try more rudder before doing anything with rigging. I know you said you had previous time in Mooney, but our muscle memory gets altered with different airframes or lack of flying. 
 

Ref. 155, agree with others, may be the volume pot. But, make sure it is not the rack. Jiggle the radio vs the pot to see if it makes a difference. 

[Shiny moose]

9 minutes ago, takair said:

1.  Does it track straight on taxi?  Is the ball centered in cruise?  When checking people out in a Mooney, I often find myself asking for more right rudder on rotation and climb. There are times I even remind myself to put in more….rarely is it less…. Perhaps try more rudder before doing anything with rigging. I know you said you had previous time in Mooney, but our muscle memory gets altered with different airframes or lack of flying. 
 

Ref. 155, agree with others, may be the volume pot. But, make sure it is not the rack. Jiggle the radio vs the pot to see if it makes a difference. 

The First Ball centering check should be accomplished on the ground, level your plane witha level on the seat rails, check your ball for centered, adjust as needed. Then flight checks for proper rigging.  I might also suggest your not using enough rudder for take off and inital climb, you can try low AS high power climbs at altitude, wings level, hold a heading, that will give you a fair assesment of needed rudder pressure.

My .02 

 

[Schinderhannes]

On 10/21/2021 at 7:12 AM, jacenbourne said:

During yesterday's flight, I was playing with the audio button, and noticed if I pushed up on the button and held it, suddenly it would start receiving. Moment I let go, it stopped. Did it again, same thing. So something with the button is up... any ideas? Is there something I can do to fix/troubleshoot without sending it off?

The switches can go bad. You might want to spray the inside of the switch with contact cleaner, but I doubt it will do the trick. I saw recently a quote of $650 from Bevan for this repair. I have multiple switches if you feel comfortable tackling it yourself. You will need a soldering iron and a solder sucker. If soldering is not your game I might be able to help with the repair.   

[Ragsf15e]

On 10/21/2021 at 12:47 PM, jacenbourne said:

Thanks Rich, this was my guess as well. Yesterday definitely showed it wasn't a wind thing when I had a left crosswind and was drifting left on rotation. It taxis fine and lands fine with normal rudder inputs, it's only on takeoff it does this. I may add to my list to fly it over to Don Maxwell and let him do his thing.

Remember, a left crosswind can turn the nose left and thus drift you left before the mains are off due to weathervane.  I also think you need more right rudder (and left aileron into the x wind).

[Keith20EH]

The E also has a “short” rudder, at least compared to a MSE or long body.  Not sure about some of the other models. Depending on the x-wind or when lifting the nose off early on a soft field, it may take full rudder travel to keep it straight with full power.  Reduced travel the faster you go, so if you hit the stop and it’s still turning, lower the nose and gain some speed.