Coupled approaches, a few questions
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Coupled approaches, a few questions
I have never used or had an AP and have a few questions about their use:
1, is there any required tolerance or recurring certification for an AP unit similar to the TXP, pitot static, VOR 30 day check, when used for IFR enroute or approach flying, or is there any special tests mandated during the annual to verify the AP is operating properly
2, Are all AP,s that are installed in certificated aircraft approved for use for coupled approaches I.e does the AP manual list the TYPE of approaches the Unit is approved for if any?
3 If the AP is a single axis is it easier to shoot approaches using the AP for roll and hand flying the descent or if the unit can not do both lateral and vertical control is it easier to just hand fly the whole thing.
4 How does the AP do a coordinated turn , is the rudder coordinated alongside aileron deflection initiated by the AP
I am thinking about generic legacy units with 1970,80's vintage installed in piper/cessna spam cans
1, is there any required tolerance or recurring certification for an AP unit similar to the TXP, pitot static, VOR 30 day check, when used for IFR enroute or approach flying, or is there any special tests mandated during the annual to verify the AP is operating properly
2, Are all AP,s that are installed in certificated aircraft approved for use for coupled approaches I.e does the AP manual list the TYPE of approaches the Unit is approved for if any?
3 If the AP is a single axis is it easier to shoot approaches using the AP for roll and hand flying the descent or if the unit can not do both lateral and vertical control is it easier to just hand fly the whole thing.
4 How does the AP do a coordinated turn , is the rudder coordinated alongside aileron deflection initiated by the AP
I am thinking about generic legacy units with 1970,80's vintage installed in piper/cessna spam cans
Maintenance requirements are specified in the manufacturer's Instruction for Continued Airworthiness. The POH/Flight manual will have a supplement that gives limitations & procedures for use. There is nearly always some form of pre-takeoff check that the AP is functioning correctly.
The POH supplement will specify what approaches the autopilot is approved to do.
Common GA autopilots (ignoring wing levellers) are 2 axis (roll & pitch) + heading hold. Those types don't coordinate turns. Others are 3 axis, sometimes via a yaw damper, and can be able to keep the turn balanced, or near nearly balanced.
The POH supplement will specify what approaches the autopilot is approved to do.
Common GA autopilots (ignoring wing levellers) are 2 axis (roll & pitch) + heading hold. Those types don't coordinate turns. Others are 3 axis, sometimes via a yaw damper, and can be able to keep the turn balanced, or near nearly balanced.
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Jock
I agree, sitting behind the thing wondering what it is going to do next is far more stressful than flying the ILS manually.
I did some years back read an accident report from the USA about an under confident pilot who relied heavily on the automatics, unfortunately the automatics let him down with a fatal result.
In my opinion you need more skill to identify and correct an autopilot malfunction during an approach than to fly the approach manualy, the conclusion being that old and unreliable autopilots are a hinderance rather than a help for those pilots new to instrument flying.
I did some years back read an accident report from the USA about an under confident pilot who relied heavily on the automatics, unfortunately the automatics let him down with a fatal result.
In my opinion you need more skill to identify and correct an autopilot malfunction during an approach than to fly the approach manualy, the conclusion being that old and unreliable autopilots are a hinderance rather than a help for those pilots new to instrument flying.
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Agree with above. Most light aircraft autopilots I prefer to leave alone especially for the approach. I really don't like the idea of the AP managing the roll and the pitch being manual for an approach. I have not come across this before but in my head I can see someone death gripping the controls and the autopilot not being able to control, and when it disconnects (or doesn't from my experience) the person is in such tunnel vision they don't notice things going wrong.
2 axis (roll + pitch) autopilots aren't going to coordinate turns for you, with the exception maybe being in aircraft that have the ailerons and rudder linked where you can get away without using rudder anyway.
2 axis (roll + pitch) autopilots aren't going to coordinate turns for you, with the exception maybe being in aircraft that have the ailerons and rudder linked where you can get away without using rudder anyway.
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I had an Archer 2 with a wing leveller which would follow a heading bug and it was great for reducing the workload en route, but naff all use on the latter phases of an approach, as others have said.
I now fly a Trinidad with a full 3 axis job coupled to a GTN 650 and only fly approaches manually for practice these days. The autopilot does a better job of flying the approach to minima than I do.
I now fly a Trinidad with a full 3 axis job coupled to a GTN 650 and only fly approaches manually for practice these days. The autopilot does a better job of flying the approach to minima than I do.
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The unit is a piper auto control IIIB made by Century if you zoom right in on the pics in the ad you can see 2 control panels one square the other circular it says it's been completely rebuilt but it looks like it is original equipment so would be 1979 on the Dakota
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I'm with the othe MJ on this one. Those old Cessna and Piper Century autopilots were just about acceptable in their day, but I wouldn't generally use them for anything but normal flight at a safe altitude these days.
I would have to see any individual light aircraft system, regardless of it's age, fly a number of coupled approaches to it's minima in VMC before I would cosider trusting it.
MJ
I would have to see any individual light aircraft system, regardless of it's age, fly a number of coupled approaches to it's minima in VMC before I would cosider trusting it.
MJ
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you actually have two parts to the AP.
The first part is the AP which you can control in pitch and roll Ie set the pitch and it will hold it and then the roll the same.
The bit that actually drives the fancy features is the flight director bit. And its actually the flight director which decides what the inputs should be to the AP.
Personally I would use it in the enroute phase but would take it out before intercept.
I have just had to many of those older types bugger off in the wrong direction or do something stupid and I really can't be bothered dealing with it just as we are intercepting. The other thing is you are invariably way out of trim when you release it when it throws a wobbly so it gives the whole airframe a huge judder as you take it out and get it back into trim.
Did 2 approaches today in 550m RVR and VV001 with an AP available but unused from 8 miles out before intercept. Part from anything else it gets your hands and feet moving in some resemblance of being coordinated.
The first part is the AP which you can control in pitch and roll Ie set the pitch and it will hold it and then the roll the same.
The bit that actually drives the fancy features is the flight director bit. And its actually the flight director which decides what the inputs should be to the AP.
Personally I would use it in the enroute phase but would take it out before intercept.
I have just had to many of those older types bugger off in the wrong direction or do something stupid and I really can't be bothered dealing with it just as we are intercepting. The other thing is you are invariably way out of trim when you release it when it throws a wobbly so it gives the whole airframe a huge judder as you take it out and get it back into trim.
Did 2 approaches today in 550m RVR and VV001 with an AP available but unused from 8 miles out before intercept. Part from anything else it gets your hands and feet moving in some resemblance of being coordinated.
