NEWS:
In
this issue, I’ve done something that I should have done a long time ago and
have included several letters from Varga owners. There have been lots of good
questions and comments and I hope that the comments and the answers were
helpful at the time and might be helpful to you now or in the future.
LETTERS
(and emails): (I have done some minor editing to correct typos and such)
Max,
I had a couple of additional questions for you:
1. Do you know what type of paint was used on the Vargas? Mine is SN
108.
2. When servicing the main gear, do you have any recommendations as to where
to support the wing when servicing the main gear?
Thanks again.
Bob Abend
Bob,
If you think your plane has the original paint, call Don Copeland at Arizona
Aeropainting (phone number is in your newsletter) and give him your
"N"
number.
For landing gear service, there is an illustration on page 2-13 and
instructions on pages 2-23 and 2-24 of the maintenance manual. I also
have
a photo album made up by Hart Jewell and Janis Wild that shows step by step
procedures. I will send copies of the maintenance manual pages and the photo
album if you like. Just let me know.
Max
Date: July 12, 1998
From: Robert Abend
Max,
I thought further about adjusting the main gear by inserting or removing
washer thickness from between the top and bottom halves of the scissors, and I
think there may be a couple of problems with using that approach.
I think that for the scissors to work without binding, the bolt at the mid
point and the two steel tubes at the top and bottom must all be
parallel. If I am correct, there is only one total washer thickness that
will achieve that geometry. Adding or removing washers could then cause
the scissors to bind. Another potential problem is that if one of the
two washers were removed to reduce thickness, there would be an aluminum to
steel bearing at the mid point where the bolt joins the two
halves. My experience has been that steel and aluminum tend to not work
well as a bearing. Again, if I am correct, at least two washers are
necessary to provide a steel to steel bearing at the mid point.
Let me know your thoughts on this and thanks for putting my comments inthe
last newsletter; you really provide a lot of very valuable info to Varga
owners.
Regards,
Bob Abend
Bob,
All of the parts in the torque link installation have a range of tolerances
and allow some movement out of parallel alignment. If you were to jack
the gear up, remove the nut from the 5/16" trailing edge attach bolt and
push and pull the wheel fore and aft around the vertical strut, the torque
links would separate a certain amount before the bolt bound up. I
haven't done this in quite awhile so I don't remember how much separation you
would see on a new airplane but I think it is more than you might
expect. Of course, with wear and tear, an older airplane would probably
allow even more of an unbound gap.
The washers used in the torque link come in 2 thicknesses, 1/32"
(AN960-5L) and 1/16" (AN960-5). This gives a range of adjustment from
1/32" (1 AN960-5L washer) to an installation of 1/8" (2 1/16"
AN960-5 washers). This 5/32" total seemed to provide an adequate
adjustment range on all new airplanes. I don't remember ever installing more
than 2 thick washers at that factory but I wouldn't be surprised if a worn
airplane could accommodate at least one more thick washer (3/16" total)
without a problem. If a plane needed any more than that and I would look for
bent parts somewhere between the tire and the wing.
From my experience, as long as there is grease, friction is minimal and
aluminum against steel wears just fine. The 2024-T4 aluminum alloy that the
scissors are made of is relatively hard as aluminums go and the parts have
been hard anodized to make the surface even harder. You may not have
noticed, but the end of the scissors attached to the gear has no washers and
the steel gear attachment boss rubs directly against the
scissors. Another place where aluminum rubs against steel OK is your
aileron and flap hinges (aluminum hinge/steel pin). Perhaps your gear
had a problem but I've not seen any excessive wear at the tail end on the
used, broken and damaged scissors that have been given to me. Of all the worn
gear parts that I have seen, the steel against steel link pins and bushings
suffer the greatest loads and seem to be the parts that get the most wear.
In one of the next newsletters, I'll bring up this subject and find out if the
owners will tell me I need to learn a thing or two…
Happy flying!
Max
Date: Tuesday,
November 03, 1998
From: Phil Margo
Dear Mr. Bishop
I continue to enjoy and appreciate the VG-21 Squadron Newsletter. My aircraft
just came out of an annual and is in tip top shape but I will soon have to
replace the seal on the right main strut (Figure and Index number 18 of parts
manual page 3-12-- SEAL, C.R. IND. 18591). Where would I get that part?
Thank you again.
Yours in Vargaland
Phil Margo
Phil,
You should be able to call around locally to some industrial place like King
Bearing that sells bearings, gears, belts, and seals and find one (CR stands
for Chicago Rawhide). I haven't had to buy one in years but recently
other Varga owners have been able to get them at or near where they
live. If the store can't find that part number they will be able to
cross reference it to an equivalent part of another brand that will work as
well or better.
Happy flying,
Max
Date: Saturday, November 07, 1998
From: Bill Weaver
Dear Max:
From time to time we hear of high oil temperature problems with the Shinn or
Varga. When I restored the Shinn N5122V in 1976 I installed a 160 hp 0-320. We
were required to put the aircraft in experimental category until we had flown
off our required hours and then the FAA performed flight tests to check out
the engine and overall handling characteristics of the airplane. The test went
well and we came out of experimental category. Everything was normal except
for oil temperature whereby the oil temperature reached 1o F below the allowed
maximum oil temperature. Over the years I have tried all kinds of things to
get the oil temperature to run cooler especially on hot Texas summer days of
100°F+. I would wash out the oil cooler with acetone at each oil change in
case there might be varnish build up, this made no difference - but I felt
better that I had the best possible heat exchanger properties in the cooler.
I sealed the engine baffles with copious quantities of high temp RTV so
there was no air leakage; this helped drop the oil temperature a little bit. I
installed a 3" air hose to the oil cooler in place of the 2" hose.
This helped a little bit. But on hot days during climb out I would have keep a
close eye on the oil temperature. On some occasions I would have to level out
until the oil temperature lowered, so step climb would be common place. Then
came the cure for high oil temperature. I was in Oshkosh admiring a
beautifully built one-of-a kind composite airplane a Cosy look- alike,
designed and built by an aeronautical engineer. When looking under the cowl I
noticed that the cabin heat was the output side of the oil cooler. I asked the
designer do you get enough heat out of the oil cooler? He said well, in the
winter it is a little bit marginal - so I increase the oil pressure to get
more heat. THE LIGHT CAME ON IN MY HEAD. My oil pressure had always been at
the maximum sometimes a little higher on cold days and I had always thought a
lot is better – not true. When I got back to Dallas I replaced the spring in
the oil pressure relief valve to lower the oil pressure (there were no washers
to remove) and behold lower oil temperature.
Lycoming springs used to regulate oil pressure
Lycoming P/N Color Code LBS
LW 11713 White
10.79 to 11.92
Most commonly used
77467
Yellow
6.2 to 7.1
68668
Purple 6.9 to 7.8
61084
no color
8.3 to 9.5
65703
no color 1 7.8
to 19.4 Possibly
not used in 320/360 engines
The source of the spring information came from the February addition of Light
Plane Maintenance. My thanks to LPM for the useful information.
Now if the oil temperature is too low you can have a problem with acid build
up in the oil. In an article written by Shell Oil Company they say that the
indicated oil temperature must be at least 180 degrees Fahrenheit this means
that the oil in the engine is reaching more than 212 degrees enough to boil
off the water which carries the acid. If not, excessive corrosion will occur
in the engine. I purchased a candy thermometer, which goes to 380degrees
Fahrenheit. Put the oil temp probe in a one-quart can full of oil. With a
propane torch I raised the oil temperature to 180 degrees and marked where the
180 point was on my oil temp gauge. In the wintertime I have to partially
restrict the airflow to the oil cooler to stop ensure a high enough oil
temperature….
Bill Weaver
Bill,
I never had this problem on my airplane but was concerned that I would when I
converted to 160hp so I precluded it by moving the oil cooler to the left air
inlet. Your solution is much cheaper and easier. If it's OK I'd like to
reprint it in one of the next newsletters.
Thank you and Happy flying.
Max
Date: Thursday,
January 14, 1999 6:08 PM
From: Dr. Robert E. Bailey
Subject: Shimmy
Dampener
Max
Sorry for the delayed response-my damper lost its O-rings and I replaced them
but the shaft itself is pitted which means the new O-rings will not be
functional very long. I really need a new shaft/piston to put in my
housing. Suggestions????? I could braze the shaft and lathe it back
standard but I'm not sure this is legal.
Thanks--Bob Bailey-Shinn 5149V
Bob,
It probably wouldn't hurt to do what you suggest but your best bet is probably
to make a new shaft. You can make a new one while your plane is still flying
and, unless you're having shimmy problems, replace it at your next
maintenance interval. The original shaft was made from 3/8" x .095 wall
4130 steel tube, condition N, MIL-T-6736 (standard aircraft chrome moly
tubing). It was centerless ground to .3745/.3750 outside diameter,
drilled and tapped on one end with 1/4"-28 thread .75 deep and hard
chrome plated per QQ-A-320, type II, class 2 to a .0002/.0004 thickness.
Most people I've talked to with this problem have chosen to remake the shaft
from an equivalent strength stainless steel solid round bar or tube to avoid
the plating operation. I expect that this has worked just fine.
Unless the piston is badly damaged in some way, it is probably OK and
shouldn't need to be replaced. It doesn't even touch the cylinder walls
and should not wear out. Besides, you'll have to take an end cap off to
get the piston out. The end cap is pressed in and it's removal will
probably score the cylinder wall badly enough that the cap won't stay in when
you reassemble it. If you think you absolutely do need to replace the
piston, it was made from 1" diameter 2024-T3 Aluminum round bar, cut to
.500 thick with a .985/.988 outside diameter, with a .375 diameter hole
drilled in the center and with a 10-32 hole tapped through on the centerline
of one side. The piston was also alodined per MIL-A-8625 to protect it from
corrosion.
I hope this helps.
Good luck and Happy Flying
Max
Date: Sunday, February
14, 1999 8:03 AM
From: Thomas Herr
Max,
Thanks for the quick reply. I do have a question about the elevator
throw. Let me know if the following assumption is correct.
The neutral position of the elevator is when it is
parallel to the centerline of the horizontal stabilizer. When the
stabilizer is shimmed the elevator pushrod needs to be shortened so that the
"new" neutral position is parallel to the "new" centerline
of the stab and then the up and down stops need to be readjusted. When
the elevator is neutral the control sticks should be vertical.
Tom
Tom,
Except for the stick position, your assumption is correct. The neutral stick
position is whatever it turns out to be after you've adjusted the stops
(and/or the elevator push rod).
Stick (position) is mostly limited by the travel available to the rear stick.
There is a little tolerance but, generally speaking, if the stick travel is
too far forward the stick hits the front seat and if it's too far
back it hits the back seat. The way the elevator is adjusted ends up
being a compromise between rear stick travel and elevator position. I put a
curved stick in the rear seat of my plane which helps some but not much (if
he's like me, you still may have a problem with the passenger's belly). As
long as the elevator has 16 degrees up and 18 degrees down from the neutral
position [the elevator is faired with the stabilizer] as you have stated it,
and the rear stick doesn't hit anything when it moves from stop to stop (both
for and aft AND left to right), then everything should be OK.
Let me know if I've not been clear enough.
Happy flying!
Max
From: Harry Mertz
To: 'vg-21@vg-21.org'
Date: Wednesday, March 17, 1999 3:02 PM
Subject: VG-21 Fuel Pressure
Do other VG-21 owners
find your fuel pressure reading dropping to close to zero on hot days? I
get the nominal 3 PSI reading as long as the OAT is less than 70.
However, as the OAT rises above 75, fuel pressure on the gauge drops to close
to zero. It has been doing this for 12 years. Over the years I
replaced the pressure gauge and electric pump and put fire sleeve on the
supply lines, all with no effect.
Is this just a quirk of my Morrisey? Any opinions appreciated.
[Harry]
Harry,
Fuel pressure on new airplanes (Vargas at least) was always in the green (and
had to be for FAA certification) and flight tests were almost always conducted
in more than 70 degree air here in Phoenix. Sometimes it was at the low
end of the green (3 PSI) with only the mechanical pump on but always went to
the high end (6 PSI) when the electric pump was turned on.
I had a similar problem with the mechanical fuel pump on my airplane (an
experimental with an engine from a Grumman Cheetah and found that the second
diaphragm that separates crankcase oil from the fuel diaphragm was leaking and
hot engine oil was contacting the fuel diaphragm. The evidence for this was a
few drops of oil coming from the fuel pump vent and dripping on the ground
after each flight. The problem went away when I replaced the mechanical pump.
Another Varga owner who had a similar sounding problem found that the check
valve on his electric fuel pump stopped working and had to replace the
electric fuel pump. He also talked about reconnecting his fuel pumps in series
instead of parallel in order to preclude the problem in the future. I don't
know if he did that.
The bottom line is that your fuel pressure should always be in the green. I
hope this and/or advice from others helps you to fix the problem real soon.
Happy Flying,
Max
Date: Wednesday, March
17, 1999
From: Thomas Herr
Max,
I have been trying to eliminate the fuel siphoning on my Shinn and have been
doing some tests. As it turns out I have learned two things that I
thought I would tell you about and see if I could get your opinion.
Uneven fuel flow:
If the Shinn/Varga does not draw fuel equally from both tanks it is because
you are not flying wings level. The engine is effectively drawing fuel
from a common manifold. This setup also allows the fuel to transfer from
side to side and it will do this faster than the engine will draw the
fuel. Therefore fuel flow to the engine and a balanced/unbalanced fuel
load are not related. Even if you create an unbalanced fuel load by
maneuvering or unequal filling, the quantity in each will equalize quickly in
straight and level flight if the wings are level.
Siphoning from the vent:
When I purchased my new Shinn the fuel would not syphon from the vent no
matter what I tried. Since I knew this was a trait of the aircraft I
thought that it was a problem with the vent system. I completely
disassembled the vent system and found no obstructions or problems but when
everything was put back together I could only get a couple of drops of fuel
from the vent. Everything else worked fine and the aircraft flew great
so I did not think much of it.
Later while doing some maintenance I decided to
repaint the fuel caps. The rubber gaskets were very deteriorated and I
decided to replace them. With the new gaskets making a good seal my
aircraft now would syphon a lot fuel from the vent like my first Shinn
did. I remembered that the way I would stop the siphoning on my first
Shinn was to loosen the fuel caps to break the vacuum. Now that things
were working like they should I continued to fly the aircraft as I did my
first one.
We subscribe to a rather expensive service where we get AD notes on CD-ROM
every two weeks because I work on a number of aircraft. In my spare time
I like to read through them just to see what is going on with other
aircraft. In looking at them I came across a fuel vent problem on
another aircraft that was somewhat similar to what happens on the Shinn/ Varga.
The corrective action on this AD was to drill two small vent holes in the
locking flange portion of the fuel cap to break the vacuum. I drilled
the 1/32" holes in each of my fuel caps as shown on the drawing and found
that it eliminated large quantities of fuel from siphoning from the vent (just
as my bad gaskets had done). At most I now drain about a cup of fuel
when the tanks are filled to the top of the filler necks and then it stops
(the Varga should be less as their filler necks are shorter). Because no
vacuum is created the venting stops when the level in the tanks reaches the
vent location in the tank. If you park on a slope you will vent more
fuel than on a level surface but not the gallons as before. When parking
on a slope it is still important to shut off one of the fuel valves in the
cockpit to prevent cross feed. No fuel is pulled through the vent holes
in the cap
during flight.
This solution works very well but I wanted to get your opinion. Let me
know what you think.
Tom
Tom,
I think your observations about uneven fuel flow are probably correct.
In addition, the fuel lines from each tank have different routings and
fittings and probably provide different fuel flows.
As far as fuel siphoning is concerned, you have essentially created a vented
fuel cap. Personally, I think it's probably the best and cheapest solution to
a very nagging problem. The only drawback is that in an uncoordinated banked
turn fuel will fall out of the fuel cap and spray out over the wing
(coordinated turns, of course, are no problem because G forces hold the fuel
in the bottom of the tank). If I remember correctly from past conversations
with FAA flight test engineers and pilots, the reason for the elaborate
venting system was just that. Lots of student pilots might make lots of
uncoordinated turns. The problem with the current vent would also have been
less significant if the fuel vent outlet had been welded (or otherwise
installed) at a higher point in the tank but changing this now is too
difficult and expensive for most owners.
I obviously regret not being able to do something about it while I was
building Vargas. I don't feel too bad now because, at the time, as you may
learn with your new amphibian venture, there were a lot more problems than
there were hours in a day and I could only do so much with what I had.
I hope your solution continues to work well.
Happy Flyin'
Max
FLYING THE WEB:
EVENTS:
Just
as a reminder from last time. Dr. Jack Shuler says he is willing to plan and
shepherd a 'caravan' type Varga fly-in to Oshkosh in 2002.
I have agreed to go. If
any of you are interested in such an adventure, please contact Jack at:
Dr.
Jack Shuler
30
Litchfield Road
Londonderry,
New Hampshire 03053
email:
doc@empire.net
Home
phone: (603) 434-6683
Work
phone: (603) 434-0044
PLANES & PARTS:
Tom
Stumpf replaced both flap springs on his Varga. In order to get two springs,
he had to
take a minimum order of 9 new springs. He bought the springs through the
Century Spring Co., Inc., Los Angeles, CA. P/N 128 for a 2150A Varga. He would
like to sell the other 7 springs at $3.50 per spring if anyone is interested.
You can reach Tom at (888) 452-4858.
VARGAS
FOR SALE
Bill
McIntyre (480) 962-1373
1979
Varga 2150A
1086
TTSN November 2000 annual
King
KX 170B VOR/LOC/GS
King
KR86 ADF
Audio
Panel
NDH
$39,900
MEMBERS
& OWNERS:
VG-21
Membership: A $20 annual donation will cover all the printing and mailing
costs for at least four issues a year and will help pay for return phone
calls, letters and postage when you have questions or comments that require a
quick or personal response. Beery VG-21 Newsletters: $10 covers most of the
printing and mailing costs for all issues. Old Bishop VG-21 Newsletters: $1.00
per issue (includes postage).
For those of you who don't know, I am the former
Varga Aircraft Corporation engineering manager (1975-1982) and may be able to
help you with a problem. I can be reached at:
Max Bishop
2062 West Gila
Chandler, Arizona 85224
(480) 786-3578 (evenings)
(480) 891-6152 (days)
email:
maxbishop@gowebway.com
or
raymond.m.bishop@boeing.com
I
may also be found at hanger A9 or hanger RR2 at Falcon Field in Mesa.
DESIGN:
Axiom:
Simplicity is not simple.
MAINTENANCE
& REPAIR:
Just
a reminder. For airplanes, as in all things, an ounce of prevention is worth a
pound of cure.
PERSONAL
NOTES: A personal history of
Varga Aircraft (post mortem).
As
I said in the last episode, Varga closed its’ doors in June of 1982.
In
September of that year, with the economy down and having no luck at job
hunting, Al Wilson and I asked, and Mr. Varga and Ken Giles (the holder of all
the Varga Aircraft assets) consented, to let us use VAC’s manufacturing
equipment and open up part of the factory as a sheet metal shop. We called the
business Tech-Fab. The assembly
area was fenced off from the machinery of the fabrication area so that the
assembly line could be left in place for a potential buyer to see.
Al and I then called up people that Varga had done work for before the
plant closure and we started to get jobs right away.
We
were only paying ourselves minimum wage until we got the business going and,
in February of ’83, I got a job offer from a friend to be a project and
process engineer at a local glass and mirror maker called Binswanger, so I
took it.
I
had set up Tech-Fab as a sole proprietor in my name so, while I worked at
Binswanger, aside from a few part time and temporary employees off and on, Al
was the one who ran the store and did most of the work. I did the payroll,
banking, taxes and invoicing and made parts now and then on nights and
weekends. Although I had to sell my Cessna Cardinal when Varga shut down, Al
was able to keep his Varga 2150A and we were able to continue to fly.
In
December of ’84, through one of Tech-Fab’s customers, I got an offer at
Hughes Helicopters and I changed jobs.
In
the fall of 1985, after about 2 years of Tech-Fab’s successful operation
(well, we at least broke even), Al Wilson’s wife, Sybil, who was a senior
lab technician at Motorola, was offered a job in Austin, Texas and she took
it. When Al left, we closed the doors to the sheet metal shop.
Fortunately,
Al left his airplane in Chandler for me to operate and I was able to set up a
flying club with three other guys from Hughes to help him cover operating
expenses.
The
factory sat idle until the summer of ’86 when all the remaining assets were
sold and moved to Montana. Just before the sale, I found out that Al Wilson’s
airplane was about to be purchased along with Varga’s assets so I got two of
my flying club partners to put up some money and we bought a ship set of Varga
parts before everything left.
Al’s
airplane left for Montana in the fall of ’86 and I started work on N2103Z in
my garage and back yard. Had my airplane been completed at the factory it
would have been serial number VAC 190, the 141st Varga.
(To
be continued)