Baron issues

Well, in three days of flying a long cross country to West Texas from
Wisconsin, my autopilot went nuts in the roll axis- wouldn't capture flight
director or heading bug info, and just tried to do uncommanded turns.
Altitude and pitch worked fine.

Suspected a bad roll servo- could be driver transistors or even a motor. Was
told a new motor (if available) could be up to $3000. Had to hand fly back
from Texas in IMC- not much fun and pretty tiring.

Pulled the back cover off and yes, it sure looks like a servo- but no way to
tell if it works until it gets into the avionics shop.

Any help on testing the unit while still installed? There is resistance to
aileron input with the autopilot on, but the servo won't turn or capture
heading bug or FD input.

Then, in a routine post flight, I tried the strobes- no luck. The tail flash
tube looks a little blackened- does anyone know if the wing tip units will
continue to work if the tail tube is dead?

Or, does this sound like a power supply issue?

All of this is getting to sound expensive as well as being a pain- any
advice or commiseration would be appreciated. BTW the plane is a B-55 Baron.

TIA

Is this a Century? What model? I can probably
help U figure out what is wrong from symptoms.

Bill Hale


Viperdoc wrote:
Well, in three days of flying a long cross country to West Texas from
Wisconsin, my autopilot went nuts in the roll axis- wouldn't capture flight
director or heading bug info, and just tried to do uncommanded turns.
Altitude and pitch worked fine.

Suspected a bad roll servo- could be driver transistors or even a motor. Was
told a new motor (if available) could be up to $3000. Had to hand fly back
from Texas in IMC- not much fun and pretty tiring.

Pulled the back cover off and yes, it sure looks like a servo- but no way to
tell if it works until it gets into the avionics shop.

Any help on testing the unit while still installed? There is resistance to
aileron input with the autopilot on, but the servo won't turn or capture
heading bug or FD input.

Then, in a routine post flight, I tried the strobes- no luck. The tail flash
tube looks a little blackened- does anyone know if the wing tip units will
continue to work if the tail tube is dead?

Or, does this sound like a power supply issue?

All of this is getting to sound expensive as well as being a pain- any
advice or commiseration would be appreciated. BTW the plane is a B-55 Baron.

TIA

King KFC 200

Viperdoc wrote:

All of this is getting to sound expensive as well as being a pain- any
advice or commiseration would be appreciated.

Commiseration only: In the last two years my Bonanza needed a rebuilt
engine, a starter, two new alternators, an overhaul of the STEC HSI gyro, a
new attitude indicator, a repair of the Garmin GNS430 for a failed
glideslope receiver, a repair of the GNS430 for a failed localizer receiver
(both GNS430 repairs happened separately and beyond their six month
warranty period), two batteries, main gear brake lines, and, in what
appears to be a precursor to your problem, an AP that deviates 5 degrees
from either heading or GPS steer course once every six hours or so.

In looking for commiseration among aviation-interested friends locally, I
believe I accidentally scared two of them away for ever owning their own
aircraft.

--
Peter

In the kfc 200, there is very little circuitry downstream
of the attitude bars other than that in the servos. One
summing amplifier is about it.

So if the bars work correctly, but the controls don't move
absolutely one for one with the bars, it's likely
the servos.

If the controls move in one direction or other
when the bars are neutral-- likely is the servo.

Bill H.

Viperdoc wrote:
King KFC 200

One obviously has to have a prepurchase inspection done.

In a perfect world:

1)The inspection would be by a mechanic that is familiar with the aircraft type.
2)The inspection would be done by the mechanic that is going to maintain the plane on an ongoing basis.
3)The inspection is not done by the mechanic that was maintaining the plane.

If the plane in question is out of your area how do you do 1,2,3?

How is this problem solved?

If you have a remote mechanic do the prepurchase, how do you trust the
care and honesty of someone you will only do business with once and
is far far away?


Paul

I don't think things have gotten so bad that he is selling his Baron and
looking for another.

Jim Burns


wrote in message
...
One obviously has to have a prepurchase inspection done.

In a perfect world:

1)The inspection would be by a mechanic that is familiar with the aircraft
type.
2)The inspection would be done by the mechanic that is going to maintain
the plane on an ongoing basis.
3)The inspection is not done by the mechanic that was maintaining the
plane.

If the plane in question is out of your area how do you do 1,2,3?

How is this problem solved?

If you have a remote mechanic do the prepurchase, how do you trust the
care and honesty of someone you will only do business with once and
is far far away?


Paul

I'd call Autopilots Central. I've talked with Bob Ferguson a couple times
and he's always had good advice for our situations.
Jim

"Viperdoc" wrote in message
...
Well, in three days of flying a long cross country to West Texas from
Wisconsin, my autopilot went nuts in the roll axis- wouldn't capture
flight director or heading bug info, and just tried to do uncommanded
turns. Altitude and pitch worked fine.

Suspected a bad roll servo- could be driver transistors or even a motor.
Was told a new motor (if available) could be up to $3000. Had to hand fly
back from Texas in IMC- not much fun and pretty tiring.

Pulled the back cover off and yes, it sure looks like a servo- but no way
to tell if it works until it gets into the avionics shop.

Any help on testing the unit while still installed? There is resistance to
aileron input with the autopilot on, but the servo won't turn or capture
heading bug or FD input.

Then, in a routine post flight, I tried the strobes- no luck. The tail
flash tube looks a little blackened- does anyone know if the wing tip
units will continue to work if the tail tube is dead?

Or, does this sound like a power supply issue?

All of this is getting to sound expensive as well as being a pain- any
advice or commiseration would be appreciated. BTW the plane is a B-55
Baron.

TIA

I've had this plane for nearly five years, and am happy with its condition
and performance. It is not new to me, and I had an extensive pre-buy/annual
prior to the purchase.

Short of buying something that burns kerosene (which I can't afford) I'm
sticking with it for a while. I expect stuff to break or need replacement
periodically.

It looks like the roll servo is the culprit- it needs a new motor and drive
transistors, along with a new resistor.

The strobe problem is likely the power supply, which will also need
replacement. The whole thing is likely to be around $2500+.

I don't remember where I read it, but I recall an article that talked about
how the servo motors in our autopilots normally run for such short intervals
and at slow speed that they can "gum up" or the dust that the brushes create
can build up and or the commentator can varnish over. The article suggested
using the heading bug, trim, and or test modes to run the servos at high
speed first one direction and then the other occasionally, say once per
month, to "blow" things out and to scrub the brushes and armature.

YMMV, just something I remember reading.
Jim

"Viperdoc" wrote in message
...
I've had this plane for nearly five years, and am happy with its condition
and performance. It is not new to me, and I had an extensive
pre-buy/annual prior to the purchase.

Short of buying something that burns kerosene (which I can't afford) I'm
sticking with it for a while. I expect stuff to break or need replacement
periodically.

It looks like the roll servo is the culprit- it needs a new motor and
drive transistors, along with a new resistor.

The strobe problem is likely the power supply, which will also need
replacement. The whole thing is likely to be around $2500+.