Gear issue

cjordan · #1 04-06-21, 10:08 PM

337G

Has anyone had issue when putting gear down the pump keeps running with no green light? Did usual cycle and pump by hand and still same issue. Landed and visually confirmed gear was locked, but doors were still open.
Had intermittent issue over past 2 mo when turned on master, gear horn was going off. No green. Popped breaker and cycled handle. Pushed in breaker, fixed with multiple cycles in air work and landing after. Ideas or experiences appreciated.

Rick Erwin · #2 04-07-21, 01:33 AM

Yes, on my plane, it was during retraction and the right main gear uplock switch was out of adjustment so the system did not know all the landing gears had retracted, so the doors would not close.

In your case, I would think it would be one of the gear downlock switches.

The power circuit for the gear down green light flows from:

Nose-Right Main-Left Main-Green Light.

Check for power at each downlock switch till you find the one that’s not letting power get past it. That switch might be the source of your problem. Report back if you can ...

Rick

cessnadriver · #3 04-07-21, 10:35 AM

CJORDAN.
Yes the up locks are in series so if one of the switches don't close the "cycle" is not completed and you'll not get the green light and or doors closed. I assume you have electric/hydraulic pump so the pump will continue due to the incomplete gear cycle. My 65 C337 has a mechanical pump and the only way you know the system is STILL pressurize is the handle does not return to neutral and if allowed to continue you'll smell over heated hydraulic fluid. As an A&P mechanic I installed extra wires (parallel) to each of the up lock switches ran those wires to three small switches that I can plug in from the cockpit and check each up lock switch individually, by isolating it (close). Works GREAT and no need to worry about doing a FAA Form 337 since it's only used as a testing device. I did log the wire modification in maintenance log book, as a owner produced part if asked by FAA, which will have to be remover prior to sell my airplane.
Hope this helps.
Regards, BILLS.
C337 owner, pilot, A&P mechanic.

mshac · #4 04-07-21, 11:05 AM

Hope the OP gets his problem sorted straight away.

I have a gear-related question - what causes the gear doors (rear in my case) to slowly droop open if the plane has been sitting for awhile? By slowly, I mean they may be an inch from fully closed after sitting three weeks.

I assume there is a leaky actuator or check valve causing this minor issue.

Upon powering the master, the electric pump kicks in and immediately shuts the doors. Would not want to be working in there when someone switched on the master without pulling the gear motor breaker!

Would one of our Skymaster Gearheads please point me in right direction to fix this?

Rick Erwin · #5 04-07-21, 11:25 AM

Mark, you might check the pressure in the accumulator located under the floor beneath the Captain’s chair.

Rick

mshac · #6 04-07-21, 01:40 PM

Quote:

Originally Posted by Rick Erwin

Mark, you might check the pressure in the accumulator located under the floor beneath the Captain’s chair.

Rick

Rick, I read the service manual. My understanding is that to service the accumulator, you first pump the gear doors open with the hand pump, which brings hydraulic pressure to zero inside the accumulator. Then you service the valve on the accumulator with nitrogen to 500psi +/- 50 psi. Is this the correct procedure?

The manual says the valve is not supposed to have a core in it? I'm confused how it is serviced without a core??? Says something about loosening a nut? I'm sure its obvious once you've done it.

I didn't know this accumulator existed, thanks for the education!

Rick Erwin · #7 04-07-21, 07:49 PM

Mark, the accumulator has a “nut” that contains the Schrader valve. I didn’t have to bleed down the accumulator as mine had lost its nitrogen precharge into the system hydraulic fluid turning it pink.

Rick Cox, of Cox Airparts, told me to check the pressure in the accumulator at the Schrader valve. If there was none, to back out the nut that contains the Schrader valve and check for hydraulic fluid in the accumulator. If it was wet to replace the O-rings and recharge. He was a wealth of information, if you hit a snag, give him a call.

cjordan · #8 04-14-21, 07:01 PM

Thanks to all for the input. Turned out to be a broken wire at the left gear downlock micro switch. New switch and wires fixed the issue.

Mshac, glad to have company on your issue. After sitting for a a week or so I have heard the same clunk when flipping on the master. I’m not sure they even sag 1/4”. Very slight and not every time.

Rick Erwin · #9 04-14-21, 10:41 PM

Thank you for the report back, I'm glad you got the problem solved.

Rick

cjordan · #10 06-14-21, 04:50 PM

Anyone had their gear horn go off when retracting the gear and the gear not move at all? Cycled gear handle 3 times and same result.. as soon as up, pump ran, horn and no movement. waited a few minutes then tried it again.. retracted normal. When I came into land I was ready to have to pump, etc… Non event, totally operated as normal.

Ideas?? G model

Rick Erwin · #11 06-14-21, 09:27 PM

Quote:

Originally Posted by cjordan

Anyone had their gear horn go off when retracting the gear and the gear not move at all? Cycled gear handle 3 times and same result.. as soon as up, pump ran, horn and no movement. waited a few minutes then tried it again.. retracted normal. When I came into land I was ready to have to pump, etc… Non event, totally operated as normal.

Ideas?? G model

It sounds like the landing gear safety switch on the nose gear is out of adjustment, or is broken, because the horn sounds when the gear switch is placed in the retract position. The switch must be thinking the airplane is still on the ground.

Rick