Bearing Replacement

Just a reminder of sorts to myself so maybe I don't have to learn the whole process everytime I change bearings.  I changed main bearings (front and rear) on my OS 120 Surpass III the last two days.  Not a whole lot of fun, but very satisfying once all done!  Here are some notes to self:

1.  Bought these bearings for just over $10 for the pair from McGuire Bearing Co at 2125 N Commercial St, NE.  They are both shielded on both sides, but I still don't fully understand shielded vs sealed vs not.  Main thing is Bax at OS Engine Support on RCU says it's ok to go unsealed or sealed.  Got the dimensions (IDxODxWidth) from places selling the bearings for certain engines, such as Boca Bearings. 

2.  When dismantling the engine, remember stuff like where the little dot on the cam was at TDC.  For the 120 Surpass, the dot is at the bottom of the cam directly in line with the pushrods.

3.  To remove the piston requires (on the OS 120) sliding out the cylinder sleeve first, by pushing from the bottom.  Then I have to hold my tongue just right to slide the stirrup under the piston off the cam shaft.  Putting it back on is even harder.

4.  Once left with just the crankcase, the crankshaft, and the PITA bearings, it's time to heat the mess up in the oven.  Guys recommended 275F for 20 minutes and 400F for 10 minutes.  These removals never work easily like everyone seems to say they do. I heated the case up 400F for about 15 minutes. When I rapped the engine on the rear, the rear bearing inner race and ball bearings fell out. The outer race stayed in the engine. I did more heating, and the front bearing came out in one piece with a little help from a screwdriver and dowel.  I gave up last night with the outer race stuck in the engine.  This morning I tried heating the engine at 400F for 10 minutes in the oven...NADA. Went to 450F for another 10 minutes...with my needle nose pliers, I think I saw the outer ring of the rear bearing rotate a smidge. Went to 500F and it rotated more and I got it pulled out half way. Went to 530F and after 5 minutes more, a gave the engine a tap on the wood block, and the outer ring of the bearing FINALLY FELL OUT!

Here is a quote from Bax for future reference:  "You can use a regular kitchen oven to heat the case, but make sure you've completely degdreased/de-oiled the case and bearings. You don't want any petroleum smoke inside a food overn. You can also use a heat gun, such as used for shrinking film covering. A butane torch will also do the job. j With both the heat gun and butane torch you have to keep them moving around the case to make sure it gets evenly heated. The heat won't affect the bearings. The aluminum case will expand more than the steel bearing races and will allow them to come out. If the bearings are especially stubborn, we've added more heat. As long as the case is heated evenly, we've not had problems."  Some guys are concerned that 500F can damage the engine, but we'll see when I try to start and fly this engine!


5.  The sad thing is that the new bearings would not simply drop in place.  I had to heat the engine up again to 500F to get them back in, and I also froze the new bearings for half an hour.  Had to tap on the crankshaft to get the rear bearing seated, and then had to slip the front bearing on over the prop shaft and that required some tapping with hammer and wood block to get it seated, but luckily the assembly went together with just one heating in the oven.  Only burned two fingers on my left hand when I missed the pot holder while grabbing the engine.

6.  Reassembly was not bad, the only hard part being getting that piston stirrup back on the camshaft.  Took many tries and a little tapping.  Seems it fell apart but would not just fall back together.

7.  Gaps seemed fine, so I did not readjust.  Not a hard thing to do with this engine since the head is exposed on the Yak-54 cowl.  Also the plug looks ok, and it is easy enough to change if need be later.

Anxious to try her at the field...it won't sound like a farm tractor anymore!

Wing Bags!

Made my own wing bags for the AW Ultimate today.  Cost was about $27 using bubble insulation from Home Depot(24"x25' roll) and a roll of Chrome colored Duck brand duct tape.  Ran out of the chrome at the end so I used yellow for the handles and strap hold downs.  The bag is basically about 72" long by 20" wide to fit the wings that are 68" long.  Will need to put 4 long pillow cases over each wing half to prevent stratching of the covering by the insulation.  Yes, smooth as it looks, the insulation etches the wing covering with every movement.  Here are some pics of the construction:

Intentional grain selection for bag to fold properly.

FINAL PRODUCT!

Flight Log: 05/17/2011

Got distracted and forgot to post in my log the other day!  On Tues, I flew the Giles 202, and was the only one at the field while I was there.  On the first flight, the engine died suddenly in mid flight.  How come?  I landed in the field closeby without incident.  Came back and started the 160 right up, richened a bit, and took off again.  Had a full flight, but I noticed the engine note changed, and the idle was real high for landing.  Guessed that the muffler was loose.  Had to go around several times, each time trimming the idle lower.  Got down fine and inspected the plane.  Sure enough the muffler was dangling.   One bolt was missing, the other barely hanging on.

Came home.  I had been fooling with the loose muffler on the OS 120 in the Yak 54 the last few days, because it came loose on its last outing.  The bracket between the muffler and the engine mount had fatigued and broken in half, allowing the rest of the muffler to vibrate more and come even looser.  When looking for a replacement bracket in my stuff, I came across another bracket that comes with the muffler for the OS 160.  Might it work?  Nope, but how come I am not using it on the OS 160?  AHA!  That is why the muffler is coming loose on the 160 on both my Giles AND Jeremy's Extra.  DOH!  I installed it in the Giles, used red threadlock on the bolt for the bracket to the muffler and the bolts for the muffler to the engine...a good healthy dose on each bolt.  I think the muffler will stay put a long, long, long time!  At least I hope so.  :)   Mentioned it to Tad, and he found his unused bracket and gave it to Jeremy for his plane.  Problem solved...we hope.  The TIP is to use the darn brackets when provided by Slimline for a reason, haha.  They grab the muffler at far reach from the cylinder connection point to greatly stabilize the attachment and reduce vibration effects, i.e. loosening.

Hangar Hangers

Too many planes were on the garage floor, so I bought more shelving brackets and pipe insulation, and attached them to the wall per the pic.  The storage on the left side of the pic is the new stuff...it has 3 fuselages on it.  I still have the Yak 54 on the floor and the SNAFU on the workbench.  Additionally I have the 50cc planes to store somewhere...the Extra is on the floor next to the car, and the Ultimate is still in the bonus room!  SOMEDAY I have to part with some planes to get any new ones, but I love em all!

Hold that Tiger!

One good thing that came of yesterday's fiasco at the field is that my hold down for the plane worked real good.  I made a hold down using two rope loops that clip to a carabiner thingy from Lowes, which in turn is attached to a long spike.  The spike is nailed into solid dirt with a hammer, till almost flush with the ground.  Put one loop on each side of the stabilizer, and pull the plane forward to make the rope taut.  Once the plane is started and idled down, just pull the plane back and slide the loops off.  This is a good thing as it forces you to adjust idle so the plane doesn't roll forward while releasing the rope.  When done flying, just remove the spike with the claw hammer.  This was the first time I used it, and alone too, which is what it's for.  IT WORKED REALLY GREAT!

Insult to Injury!

CRAPS, I should have stayed home today.  When I started the truck to go flying, it was weak, but I figured it would start again.  Right there was my first mistake!  I should not have gone.  As soon as I got to the field, I tried to restart the engine.  I figured it surely would work after charging on the 15 minute drive.  NOPE, nada, zero, zilch.  What to do.  I decided to fly since I was stuck, and I figured someone would come to fly in perfect weather like today with calm air, sunshine (no clouds at all), 50F, wowsers!  10:30 when I arrived.

I had a good first flight with the 50cc Extra 330L.  Landed a little fast, but it stopped on the runway, so all was good.  The engine restarted well and up I went again.  I got the idle slowed a bit and was making a perfect landing.  I thought it was a done deal.  I must have been one inch too low because my LG got cleanly wiped off the bottom of the fuselage.   I couldn't believe my eyes as the Extra rolled over the LG and belly slid to a stop.  Broken prop, broken muffler pipe still dangling to the muffler can, typical hole in the bottom of the wing due to the sharp end (of course) of the wheel pants, ripped out some LG braces, and  tore 2' of chinakote off the very bottom of the fuselage.  A couple longerons were broken in spots.  I call it a major minor repair...not a major disaster, but lots of work still must be done.  Of course the wheel pants are cracked here and there, as well as the cowl.

Ok, so I hung around taking my time because I needed help to get the truck started...either a kick start or a jump start.  NOBODY came for an hour.   At 1PM I had to take matters into my own hands.  I tried to push the truck to the old house so that I could kick start it on the little hill.  Couldn't move it but 30' and then it was slightly uphill to the house and I could not get it there.  I then pushed it back, and even tried to kick start in reverse, but could not get enough speed.  So I put the fuselage in the shed and everything else in the cab, locked her up, and headed for help.  I went across the street, slightly north, and there were young hispanics at the repair shop outside, so I asked for use of a phone, or a jump start.  First one guy let me a cell, then another said they could jump start me, so he took me and his cables in his pickup to the field and we got the truck started immediately.  I gave the guy $10 which he gladly took, and drove off.  I got my fuselage out of the shed and headed home uneventfully but fully aware of heeding the need to not kill the engine at anytime!

So insult to injury is what I got!  Double whammy of dead battery and busted plane.  ALL IN ALL, A GREAT OUTING, HAHA.  I took it in stride...came home and ate then removed the dead battery for going to Walmart tomorrow, mowed the lawn, spread moss killer on the lawn, sprayed moss killer on the roof, and here I am contemplating what repair on my Extra to do first.  RAAAATTS!

Oh the tips:  follow your instincts...I had a feeling the battery was too far gone, and I should have stayed home!  What a lousy start to my Year of the Golden Rabbit!

Beefing Up

Just a pic of triangular stock installed to beef up the connection of the engine box to the fuselage firewall.  Another guy on RCU posted how he crashed his Ultimate doing a flat inverted spin, and that the engine box broke cleanly from the fuselage.  Upon reading that I checked my Ultimate and decided to add the triangular stock just to strengthen the joints there so they resist vibration fatigue better.  There is just a single layer of wimpy 1/8" lite ply that forms the top/bottom/sides of the engine box and that run continuously into the fuselage behind the firewall.  The triangular stock is 1/2" on the sides and 3/4" on the bottom of the engine box.  There is no space on the top of the engine box to add traingular stock there.  I used FG resin to glue the braces in and to coat them just like the rest of the engine box and firewall.  Final note: it's just weird that Aeroworks did not do this strengthening already since it is extremely common on most big planes!

Rejuvenation of Resin

I had a bottle of the resin half of the 2 part epoxy (30 minute) go bad once before.  It looked like honey crystalizing.  Tower gave me a new 2 part epoxy resin to replace it about 7 months ago.  Recently I noticed the same thing was happening to the resin half yet again.   It has not happened to my 6 minute epoxy nor the slow curing finishing resin.  WEIRD that it's happening again.  It made me second guess how I handle or store my epoxies but why would it happen to just the 30 minute but not the 6 minute or finishing epoxy resins?  I don't have the answer, but I remember seeing on RCU that guys have heated up the resin in the microwave to renew it.  With nothing to lose, I tried it myself.  IT WORKS!  Amazingly, just 10 seconds in the microwave turned the resin very thin, and in fact when I used it, it set up way faster than normal.  Hours later now, it is not overly thin anymore and it set up normally.  There are no crystals yet.  Looks like I won't have to complain to Tower about their epoxy again, lol.

FG repairs made easier!

Thanks to Joe, repair of my fiberglass wheelpants has been made much easier and neater!  Briefly, the steps below let you create fiberglass or nylon repair "tape" using 3M Super 77 multi-purpose spray adhesive, wax paper, and the fiberglass cloth or nylon tape of your choice.  After the FG or nylon is cured on the wax paper, you can cut swatches for your repairs of pants or cowls easily with just a scissors and not get those nasty loose fibers that keep unraveling at the edges.  When you remove the swatch from the wax paper, there is a slight tackiness that allows the swatch to be pressed onto the pants, fully conforming to the contours of the pants.  It's easy to just brush epoxy resin onto the swatch to complete the repair.  The method works so well that you can even use one piece to cover the outside of a crack, and the inside, by just bending the swatch around the edge of the pants...it sticks that good!  Here are the steps(stealing some of Joe's own words):

1.  Select and spray a piece of FG cloth with the spray adhesive.  The 3M Super 77 adhesive is real thin compared to most and it will dissolve in the resin that is applied later. It might not work with something thicker/stronger like some of the yellow ones or the “trim adhesive” styles that are a lot thicker and stronger.

2.  After the spray is tacky, lay and flatten wax paper to adhere to all of the sprayed cloth. 

3.  Then pull the cloth and paper up from the base while it’s still tacky or it might never come off or take part of the table with it.

4.  Smooth it out and flatten any ripples or bubbles.  Let dry.

5.  Cut a patch of the prepared tape when ready for repair.

6.  Remove wax paper backing.

7.  Stick the repair swatch to the part being repaired (after using CA and sanding if necessary).

8.  Spread resin or CA of choice on the swatch.  Joe uses alcohol to thin if needed.

9.  Done!

Here is a pic of the Super 77 and a couple pieces of repair tape ready to use (nylon on left, FG on right):