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  #1  
Unread 02-27-22, 09:33 PM
OhioSkymaster OhioSkymaster is offline
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Landing Gear Issue, 1967 T337B

When I placed the gear handle in the Retract position the gear retracted as far as I could see, but the amber "gear up" light did not illuminate and the gear handle stayed in the up position. When I manually moved the gear handle to the neutral position the amber light came on. When I extended the gear, the gear handle worked as it should and went back to neutral, and the green "gear down" light illuminated. I tried retracting the gear again and this time the amber light and gear handle worked as it should. Has anyone else experienced this? Thoughts?
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Unread 02-27-22, 11:11 PM
cessnadriver cessnadriver is offline
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Landing Gear Issue, 1967 T337B

Ohio skymaster.
You might check the micro switches. There is one at the bottom of the hydraulic power pack, and the three gear uplock switches. If any are not making good contact this will cause an intermittent lights.
Hope this helps.
Regards, BILLS
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Unread 02-28-22, 01:39 AM
wslade2 wslade2 is offline
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Granted, poorly operating micro switches can cause indicator light issues. You are a B model with engine driven hydraulic pump. you mentioned the gear handle not returning to the neutral position on its own and you manually moved it to center. Worrisome for a low pressure situation. The causes are numerous. So many times , stung by the basics. Check your fluid level first.
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Unread 02-28-22, 12:31 PM
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hharney hharney is offline
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All good comments and warranted likely causes. But don't get hung up on the obvious, it can be a microswitch but it can also just be a bad connection to the microswitch. This system is a daisy chain around the airplane that connects from point to point so it could be any connection along that chain. It is sometimes hard to tell if the connector or connection is bad so take some time and trouble shoot each point. It should be on jacks to do this as you will want to swing the gear to detect the fault. Remember a lot of issues only happen in the air because of vortexes from flying so they may not be duplicated on the jacks.
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  #5  
Unread 02-28-22, 04:24 PM
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Jhogan0101 Jhogan0101 is offline
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I have a 337B. During runup i always push the gear handle DOWN. It will usually pop back up to neutral in cold weather about 7 secs, 4-5 secs during warmer weather.
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Last edited by Jhogan0101 : 02-28-22 at 09:18 PM.
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Unread 02-28-22, 08:56 PM
GAdams GAdams is offline
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To state the obvious even more. Check hydraulic fluid level and be sure the system is adequately purged of air. I was surprised how many cycles we had to do on the jacks to get the air out of the system. And how much more fluid it took after each purging attempt.
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  #7  
Unread 02-28-22, 09:17 PM
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Jhogan0101 Jhogan0101 is offline
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Attached is another way from service manual to purge air from system without placing on jacks.

5-128. BLEEDING TIME-DELAY VALVE.
The
Time-delay valve in the Power Pack may be purged of
air by operating the engine-driven pump, or the
Hydro Test may be used.
2.
Make sure reservoir is full.
b
Start engine and let run at 1000 rpm, or connegt
Hydro Test in accordance with paragraph 5-125
Place landing gear handle in the down position
and hold for approximately one minute, while turning
the master switch OFF
until doors open,
then ON un-
til doors close.
d.
Repeat step "c" four times, waiting one minute
between steps.
e.
Check that time-delay operates properly by mov-
ing gear handle sharply to the down position and re-
cording time as handle returns to neutral.
NOTE
The time delay between closing of the landing
gear doors and releasing the landing gear
handle to neutral should be between 3 and 9
seconds at room temperature. Colder temper-
atures will cause a longer delay.
i.
Shut down engine, or disconnect Hydro Test in
accordance with paragraph 5-126.

https://ibb.co/P9P0bQ9
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Unread 03-01-22, 03:30 PM
OhioSkymaster OhioSkymaster is offline
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Thanks for the suggestions. My main concern is the gear handle issue. If I understand correctly the switches only control operation of the indicator lights and not the handle, so the indicators may actually be correctly showing that the gear is not fully stowed. We did a number of gear swings at annual time just last month and had no problems. We used a homebuilt "mule" built from a pump removed from a 337 and driven by an electric motor. I'm wondering if the pump may be suspect. We did check the fluid but will re-check and check for air. Had the same problem just before annual, so it wasn't introduced by connecting the mule.
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  #9  
Unread 03-01-22, 03:35 PM
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Jhogan0101 Jhogan0101 is offline
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I recently had a problem with air being introduced into the system, fluid was foaming out of the front hydraulic vent. The lock nut on the return side of the pump was loose and sucking air in like a venturi. I doubt this is what youre experiencing but who knows.
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Unread 03-01-22, 07:22 PM
GAdams GAdams is offline
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I had some loose nuts in the system and yes it does induce air. The handle is all about pressure. Put a wrench on every nut you can find. Top off frequently. Bleed the system again and again. Put the plane on the ramp and run the front engine. Put the handle down. Wait for it to retract. If it doesn't purge then fill, purge again. Repeat. Once you get the handle to return from the down position. Go fly it. Land. Do it again. Repeat as necessary. Many Many Many times.
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Unread 03-02-22, 12:48 AM
wslade2 wslade2 is offline
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Check the hydraulic screen and relief ball valve for clogging.

If youíre sucking air, it can make the fluid foam. Foamed up fluid is more compressible and wonít actuate the system firmly. ie-may not get firm up operation leading to unexpected lamp indication. Foamy fluid can come out the vent. Look for hydraulic fluid on the ground under the vent or streaking under belly of plane.

I capped off my pump and hooked a hand operated vacuum pump from auto part store to the other port to check for air leak at pump. If it doesnít hold vacuum, youíre sucking air at a worn pump shaft and bad internal seals.

If youíre on jacks, you can operate your on plane pump with splined socket from harbor freight hooked to a 1/2 inch drive drill and observe for issues.

If you unhook the lines from your pump, you can fill the intake side with hydraulic fluid (I use a hand pump oil can from tool store), then turn the prop by hand. A good functioning pump will move fluid to the output side efficiently and directly. You will see smart fluid movement without a lot of prop movement once primed. Observe for sluggish or no flow.

Look for hydraulic leak anywhere and everywhere. What wasnít leaking before can be leaking now. I did high speed taxi this weekend to check some brake work and darn if it didnít make a door actuator start leaking that wasnít before.

Last edited by wslade2 : 03-02-22 at 01:33 AM.
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