Lower Rear gear door not closing completely

[Learjetter]

It’s possible the pump cavitation put air in the system and some is trapped in the door 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 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 doors close. If still unsatisfactory:

Controversial part #1: Crack open the door actuator hyd hoses one at a time until fluid runs out while raising and lowering door. 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.

[ET57C]

Thanks for that detail. I will take your advise to my A&P. and will report back.

[ET57C]

Thank you guys for your response. With the interior out and up on the jacks first thing we did was to service the accumulator. Finding little or no pressure we added the 500# nitrogen charge. While we planned on the whole bleeding scenario proposed, my A&P wanted to cycle the gear, check timing and door closing before going any further. It went perfectly!! 12.4 seconds and all doors closed tight. Thanks again.

[Joes]

What models had the nitrogen accumulator on the gear system? Thanks, Joe

[Kim Geyer]

I you have the hydro electric power pack, it has an accumulator. If it has engine driven pumps it does not.

[Joes]

I've looked extensively through my manuals, and the best I can come up with is that p3370149 and on have an accumulator attached to the hydraulic power pack. Can't find one for the p3370067, which I own; this one is just for the records. Thanks

[hharney]

The main gear accumulator was not offered before P3370149, 0149 looks to be the first with the accumulator. This attachment is from the Parts Catalog, the Service Manual does address the accumulator but does not indicate specific aircraft