Saratoga Gear Retract Problem

During day one of my 2000 Saratoga's annual today my mechanic and I observed
the following problem. If anyone has some experience with this or they have
a mechanic that has experience with this I would love to hear about it:

Here is a description of what we are observing:

1) Gear retraction is initiated with handle being placed into the gear
up position

2) Nose gear and main gear unlock and start retraction

3) Gear Unsafe light illuminates simultaneously with gear unlocks

4) In about 1-2 seconds, nose gear completes retraction first (this is
normal as far as what I have observed in the past both on my plane on jacks
and on observing others from the ground departing from airports)

5) Main gear comes up part way but hesitates until nose gear completes
retraction - again I believe this is normal

6) Main gear almost completes retraction in about 2 seconds after nose
gear - a few inches from being completely retracted - this is where
something has changed.

7) Pump Motor shuts off for approximately ¼ second

8) Pump Motor starts again for approximately ¼ second and gear moves
up a little more (maybe ½ inch to 1 inch)

9) Pump Motor shuts off again and restarts again 3-5 times in the same
pattern of quick off and ons before gear is completely retracted and pump
motor remains off

10) Gear warning light extinguishes about the time or slightly before the
pump motor shuts off for the last time


This process is very repeatable. Only the number of quick off-on cycles of
the pump varies slightly. The pump almost always remains off for many
minutes once the gear is completely retracted. The gear was left in the up
position for at least 5+ minutes at one point and we did not observe any
restart of the pump. We did observe a quick on-off cycle of the pump
perhaps 5 seconds after retraction during just one of 15-20 retraction tests
performed, but again, normally the pump would shut off after the last cycle
and remain off for many minutes during our testing.


Everything seems normal compared to what I have observed when we did the
annuals before except for the pump cycling off and on near the end of the
main gear retraction cycle. We have studied the hydraulic and electrical
schematics for the system and looks like there is a pressure limit switch
that is responsible for stopping the pump motor when the pressure reaches
approximately 1800 psi. This should occur after all the gear is retracted
and against the physical stops. We are theorizing that this switch or the
contactor that it operates could be faulty and prematurely stopping the pump
prior to the gear being completely retracted. If the switch opened at a
lower pressure for instance or cycled between opened and closed in a lower
pressure range then it was supposed to we are thinking that the symptoms we
are seeing would result. According to the maintenance manual the switch is
supposed to close at 200 to 400 psi and open at 1800 +/- 100 psi. We have
looked all over for anything impeding the main gear retraction and were not
able to identify any hang-ups there. We have also verified that adequate
5606 is available in the reservoir of the pump.


Again if anyone has some insights on my gear retract symptoms I would sure
like to hear about it. If you believe our theory about the pressure limit
switch being bad is unlikely and that it would be wiser to go down another
path I would also like to hear about that too. My mechanic and I will be
all over this tomorrow so if you know anything about this post what you
know.

- George

Well George, I don't know the first thing about your plane, but it seems a
straightforward way of troubleshooting the symptoms would be to place a
manually operated switch in the circuit in place of the hydraulic pressure
switch.
Another way to rule it in/out would be to put a test light on the load side
of the switch, see if it goes on/off when the pump does. Also, do you have a
way to monitor the hydraulic pressure while this is taking place? Perhaps
there is a partial blockage or other problem in the lines or in the
hydraulic actuators, causing the pressure to shoot up.

--
Hello, my name is Mike, and I am an airplane addict...

"Yahoo! News" wrote in message
t...
During day one of my 2000 Saratoga's annual today my mechanic and I
observed
the following problem. If anyone has some experience with this or they
have
a mechanic that has experience with this I would love to hear about it:

snip

Again if anyone has some insights on my gear retract symptoms I would sure
like to hear about it. If you believe our theory about the pressure limit
switch being bad is unlikely and that it would be wiser to go down another
path I would also like to hear about that too. My mechanic and I will be
all over this tomorrow so if you know anything about this post what you
know.

- George

Michael Ware wrote:
Well George, I don't know the first thing about your plane, but it seems a
straightforward way of troubleshooting the symptoms would be to place a
manually operated switch in the circuit in place of the hydraulic pressure
switch.
Another way to rule it in/out would be to put a test light on the load side
of the switch, see if it goes on/off when the pump does. Also, do you have a
way to monitor the hydraulic pressure while this is taking place? Perhaps
there is a partial blockage or other problem in the lines or in the
hydraulic actuators, causing the pressure to shoot up.

Ditto for me:

Or the pump is overloading if it has an internal thermal reset that
tripping as it gets loaded up...

Thanks Mike,

We thought about replacing the switch with a manual switch to test with but
I did not want to stress the lines or acutators to 3000 psi where the
internal pump relief opens. The idea about placing a light across the
external pressure switch is a good one though. If the light comes on when
the gear stops going up for that 1/4 second we will then know it is due to
the pressure switch opening up and not some other electrical problem. I
guess if we determine the switch is opening up we will also have to try a
get a high pressure gauge and see if we can read it fast enough while the
cycling is going on to determine if the switch is opening up prematurly. I
received other documentation on the switch this morning that says that the
working range is only 200 - 400 psi (open at 1800 psi, close at 1400 -
1600 - much tighter than I thought the maintenance manual indicated closing
at 200 - 400 psi. This makes me even more learly of the switch.

- George
"Michael Ware" wrote in message
m...
Well George, I don't know the first thing about your plane, but it seems a
straightforward way of troubleshooting the symptoms would be to place a
manually operated switch in the circuit in place of the hydraulic pressure
switch.
Another way to rule it in/out would be to put a test light on the load
side
of the switch, see if it goes on/off when the pump does. Also, do you have
a
way to monitor the hydraulic pressure while this is taking place? Perhaps
there is a partial blockage or other problem in the lines or in the
hydraulic actuators, causing the pressure to shoot up.

--
Hello, my name is Mike, and I am an airplane addict...

"Yahoo! News" wrote in message
t...
During day one of my 2000 Saratoga's annual today my mechanic and I
observed
the following problem. If anyone has some experience with this or they
have
a mechanic that has experience with this I would love to hear about it:

snip

Again if anyone has some insights on my gear retract symptoms I would
sure
like to hear about it. If you believe our theory about the pressure
limit
switch being bad is unlikely and that it would be wiser to go down
another
path I would also like to hear about that too. My mechanic and I will be
all over this tomorrow so if you know anything about this post what you
know.

- George

I had a similar problem with my Arrow and the solution was to rebuild
the hydraulic pump - check the actual pressure being generated. THe
high pressure switch might also be defective.

I have a seneca 3. My problem started out like that, easy to sort of fly
with. Then it got worse. Sometimes wouldn't at all retract, or just
partially then pump would go off.

We, flushed out and changed fluid, swaped up and down relays(they are
the same), measured pump pressure, changed pump/motor, gear was in no
way binding. The last thing checked was an over pressure limit switch
that was going faulty and shutting the pump off.

2000 Saratoga? Mmmmm, nice.

Our gear is probably similar in design?? Good Luck.

John

Yahoo! News wrote:
During day one of my 2000 Saratoga's annual today my mechanic and I observed
the following problem. If anyone has some experience with this or they have
a mechanic that has experience with this I would love to hear about it:

Here is a description of what we are observing:

1) Gear retraction is initiated with handle being placed into the gear
up position

2) Nose gear and main gear unlock and start retraction

3) Gear Unsafe light illuminates simultaneously with gear unlocks

4) In about 1-2 seconds, nose gear completes retraction first (this is
normal as far as what I have observed in the past both on my plane on jacks
and on observing others from the ground departing from airports)

5) Main gear comes up part way but hesitates until nose gear completes
retraction - again I believe this is normal

6) Main gear almost completes retraction in about 2 seconds after nose
gear - a few inches from being completely retracted - this is where
something has changed.

7) Pump Motor shuts off for approximately ¼ second

8) Pump Motor starts again for approximately ¼ second and gear moves
up a little more (maybe ½ inch to 1 inch)

9) Pump Motor shuts off again and restarts again 3-5 times in the same
pattern of quick off and ons before gear is completely retracted and pump
motor remains off

10) Gear warning light extinguishes about the time or slightly before the
pump motor shuts off for the last time


This process is very repeatable. Only the number of quick off-on cycles of
the pump varies slightly. The pump almost always remains off for many
minutes once the gear is completely retracted. The gear was left in the up
position for at least 5+ minutes at one point and we did not observe any
restart of the pump. We did observe a quick on-off cycle of the pump
perhaps 5 seconds after retraction during just one of 15-20 retraction tests
performed, but again, normally the pump would shut off after the last cycle
and remain off for many minutes during our testing.


Everything seems normal compared to what I have observed when we did the
annuals before except for the pump cycling off and on near the end of the
main gear retraction cycle. We have studied the hydraulic and electrical
schematics for the system and looks like there is a pressure limit switch
that is responsible for stopping the pump motor when the pressure reaches
approximately 1800 psi. This should occur after all the gear is retracted
and against the physical stops. We are theorizing that this switch or the
contactor that it operates could be faulty and prematurely stopping the pump
prior to the gear being completely retracted. If the switch opened at a
lower pressure for instance or cycled between opened and closed in a lower
pressure range then it was supposed to we are thinking that the symptoms we
are seeing would result. According to the maintenance manual the switch is
supposed to close at 200 to 400 psi and open at 1800 +/- 100 psi. We have
looked all over for anything impeding the main gear retraction and were not
able to identify any hang-ups there. We have also verified that adequate
5606 is available in the reservoir of the pump.


Again if anyone has some insights on my gear retract symptoms I would sure
like to hear about it. If you believe our theory about the pressure limit
switch being bad is unlikely and that it would be wiser to go down another
path I would also like to hear about that too. My mechanic and I will be
all over this tomorrow so if you know anything about this post what you
know.

- George

Sure hope my problem is the same as yours. I just ordered the $672 switch
from Piper! Hopefully, my mechanic's discount he has setup with them will
bring the price down 30%. Do you remember what you payed for the pressure
limit switch (Piper part number 587-847)?

-George

"The Visitor" wrote in message
...
I have a seneca 3. My problem started out like that, easy to sort of fly
with. Then it got worse. Sometimes wouldn't at all retract, or just
partially then pump would go off.

We, flushed out and changed fluid, swaped up and down relays(they are the
same), measured pump pressure, changed pump/motor, gear was in no way
binding. The last thing checked was an over pressure limit switch that was
going faulty and shutting the pump off.

2000 Saratoga? Mmmmm, nice.

Our gear is probably similar in design?? Good Luck.

John

Yahoo! News wrote:
During day one of my 2000 Saratoga's annual today my mechanic and I
observed the following problem. If anyone has some experience with this
or they have a mechanic that has experience with this I would love to
hear about it:

Here is a description of what we are observing:

1) Gear retraction is initiated with handle being placed into the
gear up position

2) Nose gear and main gear unlock and start retraction

3) Gear Unsafe light illuminates simultaneously with gear unlocks

4) In about 1-2 seconds, nose gear completes retraction first (this
is normal as far as what I have observed in the past both on my plane on
jacks and on observing others from the ground departing from airports)

5) Main gear comes up part way but hesitates until nose gear
completes retraction - again I believe this is normal

6) Main gear almost completes retraction in about 2 seconds after
nose gear - a few inches from being completely retracted - this is where
something has changed.

7) Pump Motor shuts off for approximately ¼ second

8) Pump Motor starts again for approximately ¼ second and gear
moves up a little more (maybe ½ inch to 1 inch)

9) Pump Motor shuts off again and restarts again 3-5 times in the
same pattern of quick off and ons before gear is completely retracted and
pump motor remains off

10) Gear warning light extinguishes about the time or slightly before
the pump motor shuts off for the last time


This process is very repeatable. Only the number of quick off-on cycles
of the pump varies slightly. The pump almost always remains off for many
minutes once the gear is completely retracted. The gear was left in the
up position for at least 5+ minutes at one point and we did not observe
any restart of the pump. We did observe a quick on-off cycle of the pump
perhaps 5 seconds after retraction during just one of 15-20 retraction
tests performed, but again, normally the pump would shut off after the
last cycle and remain off for many minutes during our testing.


Everything seems normal compared to what I have observed when we did the
annuals before except for the pump cycling off and on near the end of the
main gear retraction cycle. We have studied the hydraulic and electrical
schematics for the system and looks like there is a pressure limit switch
that is responsible for stopping the pump motor when the pressure reaches
approximately 1800 psi. This should occur after all the gear is retracted
and against the physical stops. We are theorizing that this switch or
the contactor that it operates could be faulty and prematurely stopping
the pump prior to the gear being completely retracted. If the switch
opened at a lower pressure for instance or cycled between opened and
closed in a lower pressure range then it was supposed to we are thinking
that the symptoms we are seeing would result. According to the
maintenance manual the switch is supposed to close at 200 to 400 psi and
open at 1800 +/- 100 psi. We have looked all over for anything impeding
the main gear retraction and were not able to identify any hang-ups
there. We have also verified that adequate 5606 is available in the
reservoir of the pump.


Again if anyone has some insights on my gear retract symptoms I would
sure like to hear about it. If you believe our theory about the pressure
limit switch being bad is unlikely and that it would be wiser to go down
another path I would also like to hear about that too. My mechanic and I
will be all over this tomorrow so if you know anything about this post
what you know.

- George

I have a seneca 3. My problem started out like that, easy to sort of fly
with. Then it got worse. Sometimes wouldn't at all retract, or just
partially then pump would go off.
We, flushed out and changed fluid, swaped up and down relays(they are
the same), measured pump pressure, changed pump/motor, gear was in no
way binding. The last thing checked was an over pressure limit switch
that was going faulty and shutting the pump off.
2000 Saratoga? Mmmmm, nice.
Our gear is probably similar in design?? Good Luck.

John, which engine on the Seneca drives the hydraulic pump?

On Mon, 28 Nov 2005 22:19:54 GMT, john smith wrote:

I have a seneca 3. My problem started out like that, easy to sort of fly
with. Then it got worse. Sometimes wouldn't at all retract, or just
partially then pump would go off.
We, flushed out and changed fluid, swaped up and down relays(they are
the same), measured pump pressure, changed pump/motor, gear was in no
way binding. The last thing checked was an over pressure limit switch
that was going faulty and shutting the pump off.
2000 Saratoga? Mmmmm, nice.
Our gear is probably similar in design?? Good Luck.

John, which engine on the Seneca drives the hydraulic pump?

The electric one bolted to the top of the powerpack-think Meyer snow
plow.

TC

In article ,
wrote:

On Mon, 28 Nov 2005 22:19:54 GMT, john smith wrote:

I have a seneca 3. My problem started out like that, easy to sort of fly
with. Then it got worse. Sometimes wouldn't at all retract, or just
partially then pump would go off.
We, flushed out and changed fluid, swaped up and down relays(they are
the same), measured pump pressure, changed pump/motor, gear was in no
way binding. The last thing checked was an over pressure limit switch
that was going faulty and shutting the pump off.
2000 Saratoga? Mmmmm, nice.
Our gear is probably similar in design?? Good Luck.

John, which engine on the Seneca drives the hydraulic pump?

The electric one bolted to the top of the powerpack-think Meyer snow
plow.

(Sound of Homer Simpson "dope slap")
Can you tell I'm not a multi-pilot? :-))