Saratoga Gear Retract Problem

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? :-))

"john smith" wrote
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? :-))

Don't feel bad, it's the left engine on our Aztec, no electric hyd pump.

Now... along those lines... what would cause a sudden "over flow puddle"
from our Aztec's hyd system? Plane's annual was this summer, hyd system
topped off with fluid, we've flown it about 40 hours since then. Saturday,
the engines were due for fresh oil and filters so I took her out for a short
joy ride to warm everything up. Changed the oil and filters but didn't have
a chance to pull it back out and do a run up to check for leaks. So last
night I go up to the hanger to do that and I notice a puddle of hyd fluid
directly below the overflow tube near the rear of the nose gear wheel well.

The drop hanging from the overflow tube confirmed where it was coming from,
nothing else wet or washed off, but why? why after 40 hours of flying and
probably a dozen gear/flap extensions and retractions would it decide to
overflow any excess fluid at this time??

I was able to add about 6-8 oz of fluid to the system to top it off. Ran
the flaps up and down, no leaks noticed anywhere, no additional overflow out
the overflow tube. System fill tube stayed full.

Any ideas??? TC what ya think??

Thanks
Jim

The problem was indeed the pressure sensor switch. Gear retract time is now
3-4 seconds total and smooth.

"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:

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