66 C337 #0199 Nose gear actuator
 

Said AC, nose gear doors would open during flight, pull the lever up and they would immediately close then re-open a short time later(2 mins?). As I understand there are two different actuators under the front engine, one, right inside the gear doors and another larger actuator that moves the nose gear itself.
My question is replacing the "o" rings in either actuator. What would be the hours involved with each? Second question, would replacing the nose gear actuator o rings solve the gear doors drooping during flight?
Fire away.
Thank you!
Keith 817-991-4318

Keith, there's a nitrogen-filled accumulator located under the pilot's seat that maintains hydraulic pressure on the gear doors so they don't droop. On my plane, the main gear doors would droop first. Same as you, if you switched on the master, they would close tight, but after a week or so, they would be drooping maybe 1/2-3/4". I do have the electric hydraulic pump.

So this was a slow droop, nothing like what you're seeing, but I would look at the accumulator for sure. IIRC, it takes 500PSI (+/- 50PSI) nitrogen when servicing. Its fairly easy to rebuild if its leaking, o-ring kits are available.

Did you ever get this problem fixed before? It appears to have been going on for a couple of years now: http://www.337skymaster.com/messages...ead.php?t=4577

S/N 0199 did not have the accumulator. I think the nose gear door actuator is leaking internally but really any of the 4 gear door actuators leaking internally could cause this. That is the cheapest thing to check. Next would be the door valve which is part of the power pack. Of course check your fluid level. Low fluid will make one do stupid stuff

Pilot's complain about the empty weight always creeping up on subsequent aircraft models. I guess its the addition of little things like the gear door accumulator that eventually add up in the newer models.

There is a thread on FB about a 337 that had its nose gear doors modified to operate mechanically from the nose gear. I guess at some point, the previous owner's last nerve was stepped on, and he ripped out the hydraulics! The new owner reinstalled the hydraulics.

Kim is correct, check valves and "hats" in the actuator cylinder, no nitrogen tank on this serial number. More importantly, would the nose gear actuator having a leak of some sort cause the same effect with the nose doors popping open in flight? On a side note, flight done, everything off you could pry the doors apart with one fingernail, correct procedure to close them, leaving the master switch ON.......no can do. Turn the master off, a faint click.......loose again. Fluid level up to par.
I am willing to fly the AC to whomever can check this out and adjust the REAR doors micro switch at my left knee. AC has gear door delete kit too btw.
Thank you for reading this.
Keith

Nose Gear
 

Keith,

From the symptoms you are providing, it sounds like the most probable cause is the nose gear door actuator. You should not be able to open with your fingernail, and if over time it drops, this means your actuator is not internally locking (the 6 little balls on the piston). Either it is worn out, balls are missing, or it is not rigged properly so that the actuator strokes all the way to engage the balls. Your S/N does not have check valves for the doors - just the internal actuator locks. Not likely your door vent valve in the power pack - that is for thermal expansion in the line.

I would say send that actuator to Cox for a proper rebuild, and have a trusted mechanic rig and install it.

As far as how long does it to just remove those actuators to replace the seals inside of them. Nose Gear Door actuator: Remove and install-1 hr, disassemble, reseal and reassemble-3hours, rig and do gear swings-3hrs. Total time-7hrs (this is a very generous estimate that I would give a customer, however would bill actual...likely around 5 hrs). BTW - I do not do work for people, I am just reaching back into my past on how I would have done it if I was still running a 145 repair shop.

Jeff

Jeff