Gear problem

[Hank]

On my 1965 Skymaster raising the gear, normally the gear up light comes on, then the gear doors close, then the gear handle goes back to neutral. Lately however the gear up light comes on briefly then goes out and the doors stay open. Bringing the gear down and up again cures the problem, though sometimes it takes 3 tries. The doors close normally every time on the gear down cycle. Any leads I can give my A&P would be appreciated.

[skymstr02]

Sounds like you have an up lock switch that is losing its contact when the gear settles into the up locks, or a wire going to the switch is deteriorated.

[Hank]

Thanks. I have visually checked the main gear uplocks and all appears fine, the nose gear uplock is under an inspection panel that only be opened when the plane is on jacks. Can the switches be tested when the plane is on the ground or does the plane need to be on jacks? And to add to the confusion sometimes the gear works normally on the first try.

[skymstr02]

The panel on the belly behind the nose gear can be opened without the plane on jacks. Take the two tie rods from the aft door to the NLG loose, and swing the door towards the gear. This will expose the row of screws on the leading edge of the panel.

[WebMaster]

Would anyone be willing to take some pictures of the various limit switches, up locks, and adjustment points??
Since the landing gear is always an issue, I would gladly make up a web page for gear issues.

[Skymaster337B]

Switches are the usual suspects. However, I always start with the basics. Is the hydraulic fluid full? Since the gear seems to work after trying it 2 or 3 times it might be low of fluid...because the pressure has to be build-up to complete the uplock sequence even after the limit switches have made contact. The other possibility is air in the system too, and since it is a "self bleeding" system after 2 or 3 cycles any air will "bled" out thus allowing pressure to build up on the 2nd or 3rd try.