J41 Autopilot

[stretch1365 40]

Hi all,Has anybody had any problems with the Autopilot not seeming to work.I take off ok, set a heading and altitude, the Autopilot is on, but it doesn't seem to actually turn the aircraft or stop the climb or decent when the required altitude is reached. If i manually correct these the Autopilot disconnects, as i imagine it's supposed to. The heading and altitude lights are on,on the coaming panel too. Usually with this aircraft, which i think i great, it's me not doing something not the planes fault at all. This one has me stumped though.Thanks for any help.Dave Phillips

[Turbine777 13]

Hi Dave, I have no idea on the disconnects part, but I recently asked the same question in regards to the Alt. The AP does not work unless you are close to the Altitude, so it won't take you from say 500' to FL140. I'll look for the original post if I can. But sure someone else will post more exacts.

[ckyliu 1,749]

May I be so bold as to you run you through the relevant buttons on the glareshield briefly:* ALT - This is altitude hold mode, it will maintain your present altitude only. It will NOT climb or descend you.* ALT SEL - This is altitude capture mode. Its function is very simple; it engages ALT mode when you reached the preselected altitude visible on the EADI. It performs no other function, again it will NOT climb or descend the aircraft for you.* IAS - This is speed hold mode, it will hold the aircraft's present speed by adjusting pitch as necessary. If you are in level flight with this mode engaged and reduce power, the aircraft will nose down to maintain speed at target. Conversely, if you increase power, the nose will raise lower speed back to the target. Please note the target speed is NOT any of the bugs on the EADI, the target is your speed when the IAS button is engaged. The target can be adjusted by using the thumbwheel located on the pedestal.* VS - This is vertical speed hold mode, it holds the aircraft's present vertical speed. Again, the target value can be adjusted with the thumb wheel on the pedestal. Therefore, in order to climb or descend via autopilot you must use IAS or VS modes. In conjunction with those modes, if you would like the aircraft to level off at a predetermined altitude, use ALT SEL. To maintain level flight use ALT. Hope this helps,Chris.

[Great Ozzie 101]

The AP does not work unless you are close to the Altitude, so it won't take you from say 500' to FL140.

Hi Dan,It should do that np (barring the 500' AGL minimum engagement or other Limitation)...You can e.g. set Heading (& Set HDG - On) Altitude to desired (& Set ALTSEL - On) Set VS - On (and set rate for initial climb rate preference)... after takeoff "A/P Engage" and start your climb to the desired (pre-set) Altitude. Then you can say switch to "IAS" to set/adjust to a 170kt Climb. The Autopilot should level off at 14,000' (or whatever set) as long as like Chris posted, the ALTSEL is ON. Works well for me...

[stretch1365 40]

Thanks for the reply Chris.I think i see what i'm doing wrong, reading through your explanation, the autopilot isn't like on a Boeing. The ALT SEL won't make the aircraft climb or descend, you have to trim it manually to initiate the climb/descent, ALT SEL will level the aircraft out at the altitude, when you reach it. Then change to ALT to keep you at the required altitude.Thanks for the very useful explanations, actually better than the manual.Happy Simming Dave quote name='ckyliu' timestamp='1282260338' post='1813933']May I be so bold as to you run you through the relevant buttons on the glareshield briefly:* ALT - This is altitude hold mode, it will maintain your present altitude only. It will NOT climb or descend you.* ALT SEL - This is altitude capture mode. Its function is very simple; it engages ALT mode when you reached the preselected altitude visible on the EADI. It performs no other function, again it will NOT climb or descend the aircraft for you.* IAS - This is speed hold mode, it will hold the aircraft's present speed by adjusting pitch as necessary. If you are in level flight with this mode engaged and reduce power, the aircraft will nose down to maintain speed at target. Conversely, if you increase power, the nose will raise lower speed back to the target. Please note the target speed is NOT any of the bugs on the EADI, the target is your speed when the IAS button is engaged. The target can be adjusted by using the thumbwheel located on the pedestal.* VS - This is vertical speed hold mode, it holds the aircraft's present vertical speed. Again, the target value can be adjusted with the thumb wheel on the pedestal. Therefore, in order to climb or descend via autopilot you must use IAS or VS modes. In conjunction with those modes, if you would like the aircraft to level off at a predetermined altitude, use ALT SEL. To maintain level flight use ALT. Hope this helps,Chris.

[Turbine777 13]

Thanks for the clarification Rob & Chris. I've been kind of forcing myself to only fly the aircraft I have in my virtual airling for FSPassengers lately so put off my JS41 training. A couple million bucks to go before I can afford the JS41 but bookmarked this topic for when I finally get to fly it again. By the time I can use it to get up enough money to buy the MD-11 I should be pretty proficient at it I hope :(