Low gearbox oil level

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baldesk
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Low gearbox oil level

Post by baldesk »

Hi Diamond friends. I have a DA42-VI with ~115 hours and have recently noticed the gearbox oil level on the right side engine has been creeping ever so slightly downward (so little I thought the plane may simply not be on a level surface) since around the annual back in September. The level feels too low for comfort now (about 1/8th of the inspection hole) so my mechanic is overnighting gearbox oil to me to replenish. According to the AFM I must also have them figure out why the level is low, which I will do. However I wanted to ping this audience to see if other people have experienced similar issues. Thanks!
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Re: Low gearbox oil level

Post by Colin »

At my last oil change I asked my mechanic if he *ever* saw a gearbox oil leak (I like to know how often things happen that I am trying to catch on a pre-flight inspection). He said that out of the dozens of DA42s and DA62s he had two and box were, essentially, large failure modes (all fluid lost in a single flight). So yours is the first I have heard of where there's a slow change.
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Re: Low gearbox oil level

Post by CFIDave »

I've never heard of an Austro gearbox oil leak that caused the level to decrease. But it's normal to see fluctuations in the level shown in the little round window, based on time-of-year temperatures, aircraft not being level, etc. Are you experiencing colder weather?

If you can still see SOME oil in the window -- I wouldn't do anything but keep an eye on it. You or your mechanic will need to add a slight amount of oil as part of each 100 hour service, i.e., draining the oil through the "coffee filter" provided as part of Diamond's 100-hour kit, and then pouring the used oil right back into the gearbox for re-use. I'm guessing that when your last service at 100 hours was performed, that only a very small amount of oil may have been added to bring the level back up.
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baldesk
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Re: Low gearbox oil level

Post by baldesk »

Thanks for the replies. Yes the temperatures have been falling in the Northeast however my left engine gearbox oil level has held steady at around 50% of the view window while the right engine is now about 10% hence my concern. I’ll be opening the cowling tomorrow to take a peek and add some oil. Fingers crossed there is no visible leaks.
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Re: Low gearbox oil level

Post by rdrobson »

After my 300 hour oil replacement, my DA62 right engine came out of the shop with me being able to see only the smallest amount of air at the top of the window. Over the next 50 hours it slowly crept down to where it was just a bit below the center dot. I had my mechanic check to make sure there were no leaks and he found none but added a bit of oil to brink it up the window again.

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Re: Low gearbox oil level

Post by chili4way »

I have a DA40NG, and I'm having some gearbox oil seepage that appears to be coming from the drain plug (see photo). I'm planning to have the mechanic who did my (first) 100-hour service repeat the key elements of the gearbox-related procedures and top off the oil level. This means having to purchase 4 of the hose clamps (the hose between the intercooler and the charged air distributor apparently needs to be removed to properly access/close/secure the gearbox fill port) and the washer/seal for the magnetic plug. Hopefully, once the drain plug has been installed with a new washer, the seepage will stop.

The specified gearbox oil, Shell SPIRAX GSX 75W-80, seems to be discontinued (at least it's not on the Shell product list). There appears to be a successor product, SPIRAX S6 GXME 75W-80, but I haven't found documentation that permits the substitution. I'd welcome any references to such documentation regarding the gearbox oil.

IMG_5724.jpeg
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chili4way
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Re: Low gearbox oil level

Post by chili4way »

SPIRAX S6 GXME 75W-80 is approved for the Austro gearbox. AustroEngine customer support provided a quick answer.

It's on page 3-10 of the Austro Operation Manual (E4.01.01).  It's also on page 2-9 of the DA40NG AFM.  This information has not been updated on the Austro Maintenance manual on page 85-18 (which is where I first looked).
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Re: Low gearbox oil level

Post by baldesk »

Well I had my mechanic overnight gearbox oil to me ahead of a trip from NJ to Fla. I’m happy to report that I only needed to add a small amount to fill up to the 3/4 point of the round window. While the cowling was off I confirmed no visual signs of leakage. My trip to Fla and back was smooth with no noticeable reduction in gearbox oil. I’ll be monitoring closely.
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Re: Low gearbox oil level

Post by Davestation »

The AE are somewhat prone to gearoil leakage from the rear shaft seal. Pretty hard to determine except for eventually seeing oil collecting on the lower hardware of the gearbox that seems to come from nowhere. It is not a big issue because these don't have clutches, but at your next 300hr TVD inspection the mechanic should check the seal out and replace as required - very easy fix.
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