landing gear transition on takeoff

[Roger]

As I mentioned before, just go buy some electric cleaner and spray the switches yourself. Blow them off with air.

I don't know this for a fact but I have always felt that the reason the doors might close on jacks vs in the air, is because in flight when the doors are open they probably create a bit of a vacuum in the area of the gear bays.

This negative pressure could be drawing the gear back out/down and away from the locks util the doors are closed. Of course if the gear doesn't seat well enough to activate the switches, the doors will never close, therein aggravating the problem.

Just a thought on why it may only happen in the air.

[rmorris]

Originally Posted by Roger

As I mentioned before, just go buy some electric cleaner and spray the switches yourself. Blow them off with air.

I don't know this for a fact but I have always felt that the reason the doors might close on jacks vs in the air, is because in flight when the doors are open they probably create a bit of a vacuum in the area of the gear bays.

This negative pressure could be drawing the gear back out/down and away from the locks util the doors are closed. Of course if the gear doesn't seat well enough to activate the switches, the doors will never close, therein aggravating the problem.

Just a thought on why it may only happen in the air.

I had him clean the switches today, don't think he used electrical cleaner but some sort of solvent, then saw him blow them off and check with an ohmeter. said the switches were fine, but I went back and test flew - same symptom.

So, not sure it's not the switches, but don't think so on the door switches (mains and nose). He visually examind the microswitch on the powerpack last week, but not sure he did much else on that one - my money is there, since it seems to match previous posts as a culprit, and one of the few things not touched yet.
________
Medical marijuana patients

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.
________
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.
________
003

[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.