Main landing gear rigging/ main gear issue

[OwenHopgood]

I have been fighting an issue with a T337H model. When the gear goes down the RH main gear will get hung up and require multiple cycles to get it unstuck. We have overhauled the main gear actuators and main gear down lock actuators. The power pack was new a few years ago. We are at a loss as to what could be causing it. Only other thing we have noticed was when the gear goes to move into the down and locked position the down locks shoot out and the main gear has to push them out of the way. On other skymasters usually the over center pin moved the down locks into place.

Hoping someone has any tips or can point to any adjustments that can be made to help remedy this issue. Thanks in advance.

[Learjetter]

It’s possible the pump cavitation put air in the system and some is trapped in the gear actuator. Assuming no leaks anywhere and everything else working normally, read everything in the service manual about the gear system. After you’ve identified the locations of all the parts, and know the gear up/down process, consider talking this over with your A&P:

Remove clean and replace both solenoids in the power pack.

Remove floor coverings and pilot side floor plates & tunnel plates. Service the accumulator with 500psi nitrogen. Open the doors with hand pump, ensure reservoir is full, then jack the aircraft. Put the gear up and see how she does. If still unsatisfactory:

Controversial part #1: Crack open the gear actuator hyd hoses one at a time until fluid runs out while raising and lowering gear manually. Tighten hoses. The idea is to get any trapped air out of the system at the actuator.

Then manually move each gear leg and door up and down almost to the locks multiple times,and keep adding fluid to reservoir as needed. Slightly overfull reservoir is better than slightly low. Then run the gear system with the handpump.

Controversial part #2: It is possible to pump gear both down and up. Pull 30A HYD CB and put gear handle up with battery ON and use handpump to pump gear up and close doors. Put gear handle down and turn off battery and pump gear doors open and gear down.

After a couple of those, hook up external power and reset the CB and run the gear up/down with the power pack several times while keeping reservior full. To fully bleed the system just takes lots of cycles. Cycling the gear and doors manually and with the handpump varies the local pressures and speeds of hyd fluid and may shake loose stubborn bubbles. The air will leave the system via the hyd overflow by the nose gear.

[hharney]

Does the issue happen every time or intermittently?

Was the actuator rebuilt because of this current issue or could it be a cause of the issue?

Does the issue happen on jacks while cycling the gear or just in the air?

What makes the RH main finally extend?

[Skycommander77]

Did you get your landing gear problem resolved?
If not call me.

Chris Bell
Skymaster Mods and Parts LLC
615-828-4195