Landing gear doors won't close

hharney · #1 09-01-17, 11:45 AM

It's really pretty simple but thought I would post an issue we resolved for fun and to keep us sharp with these aging birds.

I just finished flying 20 or so hours in Nova Scotia (should have been there with us, it was amazing flying adventure) and got home last Thursday. Plane sat in the hanger Friday and jumped in Saturday for the annual Newman's Breakfast Fly in (4N0) at Larry's airport. When I departed Riverview runway 14 (08C) I turned right toward Kzoo and reached to retract the landing gear. I noticed that the amber light was flashing and I could virtually feel the gear doors opening and closing at a fast rate. I pulled the gear handle manually to neutral to stop the hydraulic system operation. I looked out to the mirror on the wing and the doors were open. Uhmmmm. I extended the gear, that operation was normal and then retracted the gear up again. It went up normally. Ok, all good...................not!

FYI, "1968" "C" model, so the hydraulic pump is on the front engine. Later models, 1973 and on, had the electric pump unit.

kbecker · #2 09-01-17, 02:08 PM

Do tell! The doors were repeatedly opening and closing while the gear was retracted?

hharney · #3 09-01-17, 06:50 PM

Quote:

Originally Posted by kbecker

Do tell! The doors were repeatedly opening and closing while the gear was retracted?

Yes, very quickly and violently. Once I manually selected neutral on the gear handle (remember this is the older gear system with the engine driven pump) it stopped but the doors remained open.

JimC · #4 09-01-17, 09:37 PM

Was it a failure in the pump itself that caused it to oscillate between pressure & no pressure on each revolution?

hharney · #5 09-04-17, 10:55 AM

So off to the shop and up on jacks. After taking the time to raise the airframe I opened the doors and started a visual inspection of the up lock switches. I started with the right main as I exited the cabin from extending the doors only. As I looked at the micro switch it looked ok but I touched the wires to see how secure they were and one of the wires came right off in my hand. BINGO!!!!! Here's the problem, why did I take the time to put the plane on jacks? I could have identified that without jacking the plane. While Craig replaced the both connectors on the switch I prepared to lower the plane back to the floor. We removed the jacks and pulled the plane out so that I can be on my way back home and prepare for the trip to NYC the next day in the early AM. As I departed I selected the landing gear up and the gear doors still did not close. WHAT!!!!! You have got to be kidding me. I circled around and started the downwind to land while trying the gear retract several times. No good, back to the shop and it's already 6 PM. Now what?

With these symptoms it's got to be an up-lock switch. The system protects the door from colliding with the gear until the up-lock switch's are satisfied........

JAG · #6 09-05-17, 09:39 AM

Herb - in your first post, you indicate at the end of the post, after cycling the gear, it came up normally. Does that mean that the gear doors closed on that last cycle, or in ALL cases, the doors never closed? Just trying to understand if this was intermittent, or a hard failure. Do the doors close when the gear is down and locked?
Jeff