AP "Hunts" Heading constantly

[OldFlyboy 30]

This is a very nice plane but the nose is constantly wandering left and right a couple of degrees. It is the only plane that does it in the sim and I have never seen it in a real plane. The manifold pressures are balanced and RPM synchronized.Is there some mod I can make in the aircraft.cfg to stop this?Happy flyingNeal H.

[felixthreeone 0]

I noticed the same problem, Neal. I only really noticed it recently; Flying the ILS to runway 10R @ KBOI, the plane was set up for approach, and while on approach the nose was hunting left and right and swinging back and forth....I would be curious as to if this an air file or cfg solution...

[Jacoba 55]

If its just a couple of degrees either side of desired heading, then this IS normal in a multi-engine plane especially one being flown on autopilot.One needs to remember this is a light plane, not a 737... it has no auto throttles nor engine sync abilities so wind and slightly out of sync engines will cause twins to fishtail ever so slightly.Now if its wide swings, of say more than 5 degrees either side of the desired heading then it's a problem. IIRC, per FAA maintenance requirements on installed autopilots a heading hold error of +/- 1.5 degrees is acceptable. But this does not take into account any deviation caused by wind. Its simply the acceptable level of mechanical error the FAA allows. In a real plane you would first look at the autopilot as the possible culprit.I've never flown a Cessna 340, but I have many hours in a Cessna 421 and they do exhibit the characteristics you are describing.

Edited January 14, 2012 by Jacoba

[felixthreeone 0]

Yes, Jacoba...I am describing swings in/around the vicinity of +/- 7-10 degrees. Quite strange....and not the kind of behavior I see with other twins in my hangar...

[Guest BeaverDriver]

Jacoba - that's really good info - thanks! Love the 421 - I wish Carenado would do one. I'm wondering if Matt needs to confirm his engines are as close to being in sync as possible (same RPM, same manifold pressures) on approach? I'm thinking that could do it, although you'd think it would stabilize itself after a time. Also, if there was a gusty crosswind, might that have that degree of an impact? In smooth weather it should track pretty straight, but with gusting crosswinds it can get pretty bouncy coming down the ILS. What do you think on that?

[OldFlyboy 30]

Thanks for the responses and FAA info. My C340's drift is within specs. but still a bit distracting. My actual flight time doesn't include any Cessna twins, only Pipers. Maybe the Comanche wandered as well but I just have forgotten.Still, the 340 is a nice machine especially with the engine upgrade.