wierd problem!

[Antoine]

since a few months, my DA40 is exhibiting a strange problem. it feels like rudder trim is living its own life. sometimes the plane is normal, ie needs right rudder during climb ans ball centered during cruise, and sometime it does not need any right rudder during climb but it needs alot of left rudder pedal during cruise. Costs afew knots too!

I wondered if my NLG was not aligned during flight...

Today, after experiencing the problem, I did low and slow passes and got confirmation from observers that the NLG was sitting about 20 degrees off axis.

My A&P says they have carefully torqued this to Diamond specs...

What do you think???

[Rich]

A known and chronic problem. Some have reported that "all you have to do is get the nosewheel torque correct". I have not found that to be the case. Mine acts one way one day, another the next. I'm thinking of changing the grease used on the nosewheel pivot.

[Paul]

Most likely the nose gear. The fix is that there is a spec for how much resistance there should be for the nose gear to swing. I forget but I think the high end of the range is either 12 or 14 pounds as measured by a fish scale. You need to be at the high end not the low end. Also, the bearing has to be greased as specified during an annual or 100 hour inspection. If these two things are done properly, and it's the nose gear causing this, the issue will be solved.

[Rick]

As Rich mentioned, this is a common DA40 problem. Both '40s I've flown exhibit this problem, although it comes and goes in both of them. Playing with the NLG tension had an impact on both planes - as in, I could make it worse or better by adjusting the tension, but I can't say for certain what the "right" tension should be. It seems to vary over time, and between aircraft. Maybe temperature-related, or something...

My recommendation would be to measure the current tension, then either tighten or loosen the nut to move the tension 3-4 ft-lbs. Try that - if it makes it worse, go the other way (duh!). Keep good notes, and see if you can settle in on the "right" tension for your '40. I have gone quite a few months at a time without any problem, but then it seems to come back after a while and needs readjusting.

It's a really annoying problem when the nose wheel is cocked like that - I don't understand why Diamond can't figure out the underlying cause and fix it. Most of the professional photos of DA40's I've seen in magazines and such over the past few years show misaligned nose wheels!

[Graham]

Had the same problem here. I noticed it when the auto pilot was on and the plane was being held in a slight bank and the ball out of alignment. Usually yawing the plane back and forth seemed to align the wheel since the bank would go away. After checking the tension on the nose wheel it was found to be about 4lbs and was adjusted back up to 11lbs. Seems good so far but something Diamond says they get a lot of complaints about.

[Jean]

Same for us, the ball was out to the right at cruise setting and the plane would turn left as soon as I would disengage A/P.
We had the NLG pivot tension checked on last annual and now it seems to be fixed, the ball is centered at cruise setting.

[Keith M]

I've also suffered from this problem and it was fixed by tightening the nose wheel fork pivot nut. The AMM has this to say about it:

The nose-wheel must just castor when you apply a force of 30-50 N (6.75 - 11.25 lb) acting in the direction of the nose wheel axle. If the cotter pin hole does not align, tighten the nut to the next slot.

The best results are obtained when it's tightened to the top of that range.

[carym]

A known and chronic problem. Some have reported that "all you have to do is get the nosewheel torque correct". I have not found that to be the case. Mine acts one way one day, another the next. I'm thinking of changing the grease used on the nosewheel pivot.

It's funny but I don't seem to have this NLG problem in the DA42

Cary

[neongoby]

Same thing for me too. I thought some one messed with my rudder trim tab!

Look at the video by Diamond for the DA40NG and you can see this 'feature!'

http://www.flitelevel.tv/episode/Diamond-DA40-NG-1

[Rick]

Interesting observation - every DA40 picture and video I have seen shows the back of the NLG cocked toward the co-pilot side. I have attached a picture of my old DA40 taken from another plane I was flying in formation with, clearly showing the nose wheel alignment problem. Why always to the right, I wonder? Could it possibly have something to do with the NLG being offset from the center of the plane, and/or the slipstream from the prop?