Oil in Belly - Page 2

GAdams · #16 03-12-20, 09:37 PM

It is not sticky but is a heavier weight feel to it than the oil I use in the engine. But I do recall seeing the same fluid running from the right side of the front engine several months ago. I'll check the fluid color in the breaks as well.

wslade2 · #17 03-15-20, 05:46 PM

just as an experiment, I took some brand new red 5606 hydraulic fluid and put it on a dirty old paint can lid. Next morning it wasn't red. (I don't know why: because it spread out, dye evaporates, fluid evaporates or what.) Looked a lot like your picture.

Drying hydraulic fluid evaporates and thickens. More copious old hydraulic fluid very thick approaching gummy.

Your picture also looks a lot like what it looked like around my leaking emergency hand pump. I looked for a hydraulic leak and not an oil leak because that was what was most likely for the circumstances. I found a hydraulic leak and it stopped the problem.

5606 Hydraulic fluid is in the brakes as well as landing gear system.

GAdams · #18 07-14-20, 08:58 PM

I'm still trouble shooting the oil in the belly. We have discovered it is coming from the transmission that houses the worm gear which actually cranks the wheels up and down. Does anyone have a better name for this device? The hydraulic engine pump drives the worm gear based upon gear handle selection. When I select up it leaks when I select down it doesn't. I was trouble shooting why all the gear doors would not stay closed with the gear up. It turns out they will when the aircraft is on jacks and operated by a hydraulic mule. But when the engine pump is put on line and the fluid gets low in the reservoir the gear doors will not stay up. I'm talking a half pint low and bubbles are in the system. It seems when the seals leak on the transmission it draws in air when it is not under hydraulic pressure. Air being sucked into the transmission creates the bubbles and while it looks like you have sufficient fluid on the site glass it did not. Bubbles are bad for the system to work properly. The yellow fluid I was reporting is in fact older hydraulic and maybe it turns yellow because of the cavitation the system is experiencing. To get that transmission out is 2 days of work. The local mechanic won't open it up to replace the seals and wipes so off to the overhaul guy. $1700. Plus days and days of labor troubleshooting and R&R. Hopefully the gear doors will stay closed. Don't know.

JAG · #19 07-15-20, 09:57 AM

Thanks for the follow-up on this issue - sure is nice to have some closure when people discover something like this. That main gear actuator (aka transmission) is a bugger to get out - but looks like you have solved the issue. Thanks again for sharing.
Jeff

GAdams · #20 08-21-20, 12:06 PM

I finally got the old girl out of the shop. Doors close normally and stay closed. So Far...But not after some real gut wrenching trouble shooting. It took more than twenty gear cycles on jacks before the nose gear door would stay closed and some additional rigging of the nose gear door up actuator.

rrolland · #21 08-21-20, 08:51 PM

Glad you are making progress with that issue Gary.

OhioSkymaster · #22 03-17-21, 12:14 PM

So, did servicing the gear actuator/transmission seals fix the leak? I'm having the same issue of hydraulic fluid leaking from the belly. It's red, so no question of fluid type. After the last flight it leaked a puddle of fluid about 5 inches in diameter in just a few minutes after parking and shutting down, but after removing the interior and deck plates could not find any source of the leak. We're thinking of running the front engine and placing the gear lever in the Down position to pressurize the system and watch for leaks, before jacking and running the system with a mule.

wslade2 · #23 03-17-21, 12:52 PM

I had puddle this weekend on asphalt. Opened gear doors and more dripped out. Worried it was the worst. Checked hydraulic tank and no drop in fluid. took up floor panels, hydraulic fluid everywhere. felt brake line and right where the flexible line joins the swivel on the gear it was wet. But that drip had worked it's way into the belly around main landing gear drive and everything seemed wet with fluid. That fluid has a way of crawling through seams and around everywhere. Confirmation came with checking brake fluid reservoir and finding it was empty. Be careful to identify your source so you don't do something excessive.

But, on next annual I plan on overhauling main gear drive just like I did nose gear actuator this year to be on the safe side. It's been untouched for 50 years....long enough.

GAdams · #24 03-17-21, 02:46 PM

Servicing the actuator did work. You are on the right track by running the engine and putting the gear handle down and time the gear handle return to the normal position. Use the service manual for that procedure. If something is about to fail it will fail big time after 4-5 cycles. Getting that actuator in and out will be a lot of labor and getting the system primed will take way longer than it should. Also all the other seals in other actuators in the system that has not been touched will now start to seep because of the added pressure. Order some extra seals and be ready to chase door actuators and things like that. Word of caution. Jack the aircraft to remove the actuator. It must be off the gear or the gear will fold. My project took ten weeks from start to finish. But the gear works great now.

JAG · #25 03-17-21, 03:11 PM

Gents,
Had a similar event with oil on the floor, last month. It had been a few days after flying, there was a small puddle (2" diameter) on my hangar floor. (NOTE: I have resealed all my actuators, hand pump and replaced all flexible hydraulic hoses last year.)Oil had come out of drain holes in front of, and aft of, the handpump. I pulled up center floor board to note that the whole area was wet, and could not quite trace it to anything. started going upstream, and noticed it may be coming from pilot side forward. Looking at brakes, brake lines, etc, and did not see anything. Looked at power pack and did not notice anything major, but one line and a little fluid on it (not good). Looked in little drip tray under power pack, and there was a bit of fluid. Ran some mineral spirits down that tray drain tube, and voila - that confirmed the source. That drain tube does not drain overboard, but rather into your belly underneath the pilot's rudder pedals.
I ended up removing and overhauling my power pack - there was a hairline crack on the manifold at the "gear down" fitting.
Jeff

OhioSkymaster · #26 03-18-21, 12:44 AM

Thanks for the advice and suggestions! We will investigate further and I’ll report back to the group.

OhioSkymaster · #27 03-20-21, 03:07 PM

Well, it’s the main gear actuator. Any suggestions on sources for overhaul or replacement?

wslade2 · #28 03-20-21, 05:50 PM

Cox Airparts.