Jonathan Dietch <<nmerider>>
writes:

A few days ago, the VG on my T2C 144 started going all clunky
after about the 10th pull on the rope. It got progressively worse with each
iteration but only when I'd pull on tension and not when I'd back off. I had no
clue what was causing this and after I landed I assumed it was the cover bag
tied in front of the X-bar joint impinging on the floating VG pulley. However,
this seemed less than believable since I have done hundreds of such flights with
no incidents. My T2C airframe was built in 2009, and I am well into the 380-hour
range of the second after retiring the first sail with 500 hours on it.

I decided it was time to replace the rear VG rope and inspect the right-hand
control bar leg for possible snags or twists. When I removed the stainless
bushing from the corner bracket I got a surprise. The little ball bearing had
all of the balls on one side of the race which explained the eccentric action
when I'd pull tension. It then fell apart and I took the photo with my cell
phone. I replaced the bearing with a spare that had 200 hours on it from another
glider and the next flight yielded lower VG friction than at any time in the
past 400 hours.

I ran into Steve Pearson at Andy Jackson and mentioned all of this. He told me
something to the effect that he replaces his every few hundred hours and that
these are stock bearings that can be purchased in small quantities as low as $2
per bearing. Longer lasting ceramic versions can be picked up for a lot more
money. After some researching it appears the standard designation is something
like R1810ZZ which produces the same size bearing that Wills Wing lists as
20P-1270 in its price list. I bought four on FleaBay for $6.56 ppd. These are
also commonly used in R/C helicopters and may be found at some hobby retailers.

Meanwhile, an inspection of all the Delrin ball bearing pulleys revealed that
most of these had around 4X the amount of play as a new pulley. I will be
replacing 7 more pulleys shortly. My T2C 144 airframe has roughly 890 hours and
most of the VG pulleys are the originals. It works great with the newer corner
bracket pulley but the last thing I want is another jam in flight.

No way I'm spending $50 on boutique pulley when I can buy steel versions for
$1.75 each then just swap 'em every few hundred hours. I need to get off my ass
and do more frequent and thorough periodic maintenance anyway. Pearson's running
joke with me is that I'm about the only Wills Wing customer who replaces
equipment before it goes obsolete because I wear it out first.

I have scary stories about pilots who didn't inspect and replace critical parts
and knew better. I don't want to have any stories like these to tell. I prefer a
boring life however I have had more potentially great X/C flights blown because
of some teeny tiny maintenance failure on my part. I had good flights but lost
great flights at least two dozen times due to this typical slacking.

I just found a good deal on ceramic hybrid bearings for the corner bracket:

http://www.bocabearings.com/bearing-inventory/Radial-Bearings/6771/0-3125x0-5000x0-1562-YCWK18102YSNB2

These are fully sealed for dirty environments and so I bought a set of 4 for
$17.89 including postage.

And they make a low-friction version for the more finicky pilot:
http://www.bocabearings.com/bearing-inventory/Radial-Bearings/15667/xx-SW1810COS7AF2

The latter kit includes two grease-filled and two oil-filled bearings. I feel
safer with grease even though the quantity of oil is probably miniscule, I just
don't want oil near my glider or harness.

The grease needs to be broken in but that's for R/C race cars and I doubt the
drag from the grease will even be noticed by a pilot whether it's been broken in
or not. After I test my new Boca ceramic hybrid bearing I will report back.

Meanwhile I have all new pulley to install for the rest of the VG system. It
will be fun to see if I even notice any difference or not. My friend left his
Lightspeed with Kraig Coomber for a VG system pulley overhaul and I am anxious
to hear how he likes the result of that transformation.