Nose gear structure and oil sump drain clearance after mount rebuild..

[jasongould]

Howdy,

Has anyone else run into an issue with tight clearance between the nose gear tubing and the oil sump drain after a motor mount rebuild? I just hung the engine after an engine IRAN teardown and extensive firewall forward refurb, and the refurb'd motor mount (done by AMI/AWI) has shifted the engine so that the raised section of the oil sump drain is very close to the nose gear tubing (about 1/16"). I've double checked the motor mount to engine bushings (at 1.840"), and my AI and I are brainstorming on some possible solutions.

I did not have the nose gear mount refurb'd by AMI/AWI because it looked OK, though I'm guessing it's likely tweaked a bit more than we realized.



I was just curious if anyone else has ran into a similar issue and what they had good success with repair wise.

(I should note it's a '55 pa-22-150)

Best,
Jason

 

[N2709P]

From personal experience with AWI, I would suggest that motor mount or nose gear mount be purchased new from Univair. Many times it is less expensive to purchase new and Univair’s jigs seem to be spot on where I am not sure that AWI even jigs their repairs. My totally rebuilt nose gear mount was so distorted that we had to machine the bearing races to get the bearings to fit. We had to adjust the overhauled engine mount to get the proper offsets for the thrust line. Dawley was great. AWI, not so much.
N2709P

 

[Chewy]

We had the same issue with slightly more room. Had to replace the quick drain valve with the original plug to provide enough clearance. Sure makes oil changes a mess.

 

[Steve Pierce]

Jason, I have a New Old Stock engine mount that has never been installed if you want to check alignment. I recently had a bad experience with AWI and do not intend to ever use them again.

 

[jasongould]

Thanks everyone for the feedback, though I hate to hear everyone had trouble with AWI.

I finally got back down to the hangar today and decided to level the a/c and check the engine thrustline. Leveled out using the seat rail dimple / plumb bob method, though had to find the service bulletin to remember where the upper hole is.. The thrustline is pretty close to 4 degrees down and 2 degrees right. My firewall is not really flat (at least not flat enough for an accurate measurement of the angle differences), so I'm making the assumption that I can measure the correct pitch axis when the aircraft is leveled this way. The firewall was at 90degrees in several places, and close in others.. :lol: Hope that wasn't a wrong assumption!

Right side: (co-pilot)






















Left Side:






















Prop flange:






















Lateral (Right) from above.. again the firewall isn't super flat so it's hard to judge how accurate I can really be with a framing square):


Which leads me to think that my nose gear MUST be wonky. The nose gear tubing section that is causing the interference seems a bit off, but it's hard to tell with the extra support patches that were made years ago.







































Didn't have time to take any more measurements today, but one thing I was realizing just now was that the thrustline could be correct, but the engine could still be sitting off center, causing the interference. Still trying to figure out if it's worth having the nose gear repaired, or just ponying up for the new Univair. I did also see that SAF-AIR has a low profile drain valve (F50), but I don't think I even have enough clearance to make that work. The one good thing out of all of this is that my clearances between the intake tubes and the AWI "repaired" motor mount are MUCH better than before.

 

[Steve Pierce]

Here is what we ran into on my wife's Tri-Pacer. https://www.shortwingpipers.org/forum/showthread.php?6978-Tripacer-Nose-Wheel-and-Motor-Mount

 

[jasongould]

Wow! That was pretty bent! Mine doesn't seem to have that obvious of a tweak to it, and all the reinforcement patches added to the tubing surface years ago make it difficult to tell for sure with the naked eye.

I was going to dig through the SWPC drawing files later to see if I could find an angle measurement for the main oleo tube when level. I was thinking that might give some indication.

 

[Troy Hamon]

I have had two tripacers. One I could fit a quick drain onto, the current one I cannot.

 

[walt.buskey]

On mine, after the engine was overhauled and both mounts inspected, cleaned (one small repair made).... there was no way I could get the quick-drain that was there back on, though I had a bit more clearance than Jason did, about 3/8". My A&P and I did not find anything that looked off about either the nose gear mount or the engine mount, though I suppose that doesn't mean something wasn't tweaked at some point.

I tried various ways to get that quick-drain back on, and ended up using a new one which had a much smaller diameter than the original one -- that seems to have worked -- but here was another PA-22 with the same issue.

I should also point out that the old quick-drain, one of those built like a fuel sump drain with the two brass arms protruding to grasp, push & turn with, had already been "modified" (bent/mangled) so it would fit -- so I'm betting this wasn't the first time that drain elicited some four-letter words....