landing gear transition on takeoff

When you cycle the gear to the up or down position are you getting a gear light indication. If you are getting a light but your handle is not returning to neutral it is the switch on the power pack. If your not getting a gear light indication it's probably a gear switch. When I visually inspected the switch on my hydraulic power pack it looked fine but after I took it off it was clearly cracked. A temporary fix I used was to just spray it with contact cleaner. Gently tapping the power pack with the toe of my boot worked too.

[rmorris]

The gear up light does not show on until the handle returns to the neutral position. It does this when I manually move the handle back to neutral, since it does not kick down on it's own. Gear down light works fine when it locks down in place.

I will buy some electrical contact cleaner tomorrow at auto zone, along with compressed air, and try the clean and dry again and go fly it. Will post results.
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Zoloft Prilosec Nexium

[rmorris]

OK, went by autozone and bought electrical contact cleaner, then by CVS to get compressed air

Cleaned off all three door uplock switches (2 main, + nose). Nose one is kinda hard to find at first, located behind strut in the tunnel area. Cleaned off the microswitch on powerpack, plus any other electrical connections I could find under panel (hey, I was there anyway).

Flew the plane and the same issue. Then tried to see if the hand pump would close the doors in the air, and it does !

So, the symptoms appear to be this - gear down, no issues with gear coming down, locking place, and doors closing, get green light, all is good.
gear up, doors open, gear goes up and locks into place, doors close, up light comes on for a couple of seconds then extinguishes and handle does not kick back to neutral. You can manually move the handle back to neutral (and light comes on), and the gear doors open up slightly (kind of like in one of herb's videos). If you leave it in neutral but use hand pump you can feel it pump easy for a few strokes and then get stiff, a flyby confirms that the gear doors did go up and are staying in place.

I got back on ground after many cycles of replicating above, and cleaned again, then repeated above - everything consistent. At least I can now put up my gear and shut my doors (using hand pump) and fly to a better mechanic.

If anyone has thoughts, please feel free to share.

In any case, I will post again once I figure out resolution.
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[K337A]

You might check that the nose strut is properly serviced. Since the strut retracts forward the aero load on the strut will collapse the strut a small amount if not serviced properly and cause a problem with the uplock switch.

[Mayhemxpc]

Start thinking about the engine driven pump.

Had very similar problems. All symptoms same as yours. Only think different was that I am not so brave to keep bringing the gear up and down like that. Like you, we started with the actuators, which were leaking and in desperate need of rebuild. After spending lots of money on that, and everything testing fine with the hand pump, we still had the same problem in the air. With no other alternative, my mechanic took off the engine driven pump. It was scrap metal, amazing it worked at all. It built enough pressure to drop the gear, but not enough to reliably bring it back up and close the gear doors. Got a rebuilt, changed the screen (screen was clogged with molten bits of the pump) and now it is fine.

Of course, there is always more to the story than what I can post here. In fact, my problem featured prominently in Don Nieser's presentation about O-2 maintenance at Oshkosh this year.

[Rmp]

Hi all I would like to explain a problem and after sometime how I over come this
Problem.
My undercarriage would retract up light would come on for moment then off. Rear doors would be partially open.
Would check fluid level and might be bit low, top up and bleed system. All would be well for a while then same thing this went on and off for couple of years. But each time we jacked plane and tested all worked fine.
The problem turned out to be the left rear up switch not adjusted correctly but close enough that if you tested it it would mega as a closed switch.
Only in flight would the switch not close and only occasionally.
Hope this helps anyone with similar problem in the future.

[hharney]

Originally Posted by Rmp

Hi all I would like to explain a problem and after sometime how I over come this
Problem.
My undercarriage would retract up light would come on for moment then off. Rear doors would be partially open.
Would check fluid level and might be bit low, top up and bleed system. All would be well for a while then same thing this went on and off for couple of years. But each time we jacked plane and tested all worked fine.
The problem turned out to be the left rear up switch not adjusted correctly but close enough that if you tested it it would mega as a closed switch.
Only in flight would the switch not close and only occasionally.
Hope this helps anyone with similar problem in the future.

Need to know what model you are dealing with here please

[n86121]

It has been decades, but....

The doors will not close until all the uplock micro switches are all closed (wired in series),
which also turns the UPLOCK light ON.

This makes sure everything cycles in sequence correctly
and prevents doors from closing while gear still in transit (or not all the way up).

As I recall,
that uplock light circuit also allows the system to pressurize to 1200-1500 PSI.
When it hits that pressure limit it pops the gear handle down.
The handle goes down, the system at rest,
and all is well in the land....

In your case
the the gear comes up,
the uplocks close UNDER PRESSURE (but not solidly!!!),
the microswitches are closed (under UP CYCLE pressure)
the uplock light comes on (briefly),
your doors close,
then the light goes off
but the down handle never occurs.

I would bet a nice doughnut against a dollar your uplocks not solidly going 'CLICK'

So under UP-CYCLE pressure they the uplocks in position
CAN AND DO close the microswitches,
but wont keep the switches closed without the UP CYCLE pressure.

So the final pressurization needed to pop the handle never occurs.

-------

ANSWER #1: Check /squirt get to know your uplocks.

ANSWER #2: If the system cannot hit the 1200-1500 PSI to shut off,
it wont lock the system UP correctly.

Yes, a leak or air will do this.
ON THE GROUND, try cycling the gear DOWN CYCLE position.
If system can hold pressure it will pop the gear handle 'up'
from DOWN-CYCLE to the DOWN LOCKED position.
No leaks.

The system is 'self-burping' so a bunch of cycles will burp out the air.

I will accept any decent chocolate-covered doughnut as reward.

EXTRA CREDIT

I have replaced those little beasts with tiny screw in 24 volts LEDs
Nice, cool, will never burn out (again).

D

[patrolpilot]

So, having flown only the "G," what model did the gear handle stop reacting to system sequencing? The "G" is easy, up/down, nothing moving or in-between.