Gear down - doors stay open, pump running

[Learjetter]

Thanks Randy!

I’ll do both solenoids first, as logbooks have no record of the solenoids, or the power pack, or the actuating cylinders ever being done. It’s possible the aircraft has vintage 1977 hydraulic fluid in the lines!

Update: removed, clean and replaced packing (MS28775-014) on both solenoids. Jacked aircraft and ran gear 5 times in a row with no issues.
Instructions attached.

[Joes]

Any part numbers for the packing and the instructions would be nice.
Thanks, Joe

[RandyArizona]

337 parts manual, figure 125, item 11:

MS28775-014

One on each solenoid is required.

[Joes]

Randy, thanks you do a good job with the details. Your a lot alike some of the older guys on this site that have now passed. Very detail oriented, keep up the good work with all the others we currently have.
Joe

[RandyArizona]

Thank you sir,
I believe details and facts matter, much more than "my opinion".
Oddly enough, I have been told, that I am rather.. "Rude"? No, "spicy" was the term.
When dealing with aircraft that HAVE to be correct, facts matter.
Have a good day.

[Learjetter]

Welp, after cleaning solenoids and running the gear several times no problem…there is a problem.

No obvious hydraulic leaks. Adequate hydraulic fluid level in reservior. Using additional 24v ground power, not just ships battery.

Gear retraction is normal.

Gear extension is normal, but doesn’t “complete” in the prescribed time of 13-16 seconds. What we’re seeing is normal extension, followed by no green light until after about 20-30 seconds total pump run time. In flight or on jacks, same results.

I’ve read the service manual and examined the wiring diagrams. I’m thinking it could possibly be one of the power pack pressure switches?

[RandyArizona]

If the gear "falls" uneven, it is air in the system which is difficult to get out.
(Just a pain to do., not hard)
How much extra 24 volt ext power?
The gear motor is a heavy draw, so turn off any and all electrics, not attached to the gear.
If the motor is old.. (which is probably, yeah.), the motor may be tired, and need a rebuild.
Do all of the locks "click" closed, and then the pump runs for another 20 seconds??
This system is troublefree- until it isn't.
Good luck.

>>>>>EDIT: I just read that the doors have been deleted from this aircraft.. I've never done one with the deletion mod. Take what I posted above with a grain of salt.<<<<<<<