[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

Forums: 

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] [LNC2] Fast taxi testing - found the problem
Date: Tue, 06 May 2014 12:38:57 -0400
To: <lml [at] lancaironline.net>

This morning I checked the alignment of the MLG wheels and they
weren't off by too much: 0.2º toe-out on the right wheel and 0.6º
toe out on the left wheel. That's probably not enough to worry about
but I may try and correct it if I can find an easy way.



I did discover the real problem, though. When I put the plane up on
jacks and spun the wheels, the left main and nose both spun about
1-1/4 turns. The right main would hardly turn at all. The
axle nut on the right wheel was one flat too tight.
The wheel was dragging and my brand new tire had several flat spots
on it. When I loosened the axle nut, the wheel turned freely so it
wasn't the brakes per se. I DO need to inspect the brakes on that
side as well because things got pretty hot over there.



I'm just glad it's not the oleo strut!



Do we have an end-play specification for tightening the axle nuts?



Thanks for all the suggestions, everybody --

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: <Sky2high [at] aol.com>
Subject: Re: [LML] Re: [LNC2] Fast taxi testing - found the problem
Date: Tue, 6 May 2014 13:36:39 -0400 (EDT)
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

1.  There are tapered shims available - Ck the wheel/axle manufacturer
or someone like aircraft spruce.  Toe out is an unstable
condition.
 
2.  If these are the original Matco wheels, note that the pin bearing
races are aligned conically.  Thus, one needs to make sure the axle nut
(with washer on the inside shoulder and under the nut) is snugged tight enough
to keep the bearings properly supporting the wheel.  Loose wheels will
destroy the bearings (nose wheel included).  The usual rule is that they
are properly tight if the wheel will not make a complete revolution when
hand spun whilst on jacks.  Remember to make sure the bearings are packed
with appropriate grease.
 
3. The brake pad float bushings should allow the pad mounts to move freely
(SS not rusty steel) and properly positioned so that relaxing brake pedal
pressure causes no pressure on the pad to the rotor.
 
4. Remember that when steering - one toe presses (or just
taps) the inside-the-turn pedal whilst the other foot holds the rudder
pedal steady so that you are not slamming the rudder over.
 
Good Luck
 
Grayhawk 
 
In a message dated 5/6/2014 12:06:29 P.M. Central Daylight Time,
snopercod [at] comporium.net writes:

This
morning I checked the alignment of the MLG wheels and they weren't off by too
much: 0.2º toe-out on the right wheel and 0.6º toe out on the left wheel.
That's probably not enough to worry about but I may try and correct it if I
can find an easy way.

I did discover the real problem, though. When I
put the plane up on jacks and spun the wheels, the left main and nose both
spun about 1-1/4 turns. The right main would hardly turn at all. The
axle nut on the right wheel was one flat too tight. The wheel was
dragging and my brand new tire had several flat spots on it. When I loosened
the axle nut, the wheel turned freely so it wasn't the brakes per se. I DO
need to inspect the brakes on that side as well because things got pretty hot
over there.

I'm just glad it's not the oleo strut!

Do we have an
end-play specification for tightening the axle nuts?

Thanks for all the
suggestions, everybody --

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML][LNC2] Fast taxi testing - found the problem
Date: Fri, 09 May 2014 07:53:51 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message
In response to Greyhawk:


listdigest-6861962 [at] logan.com" rel="noopener" type="cite">

Toe out is an unstable condition.

The jury seems to still be out on that subject. I can find
experienced pilots who swear by either toe-in or toe-out. Since my
toe-out condition is only a fraction of a degree, I'm just going
to leave it alone for now. If it becomes a problem later on, I'll
fix the 0.6º tire with a shim at the base of the axle. The 0.2º
isn't worth messing with. I want to get this plane flying sometime
before I die (grin).

listdigest-6861962 [at] logan.com" rel="noopener" type="cite">

2.  If these are the original Matco wheels, note
that the pin bearing races are aligned conically.  Thus,
one needs to make sure the axle nut (with washer on the
inside shoulder and under the nut) is snugged tight enough
to keep the bearings properly supporting the wheel.  Loose
wheels will destroy the bearings (nose wheel included). 
The usual rule is that they are properly tight if the
wheel will not make a complete revolution when hand spun
whilst on jacks.  Remember to make sure the bearings are
packed with appropriate grease.

Yes, I have the original
Matco wheels and the original Rosenhan brakes. I've adjusted
the axle nuts so the tire will spin 1-1/4 turns by hand. The
bearings are snug that way, yet it leaves a little room for
thermal expansion. We saw what happened when I turned the
axle nut one flat beyond that point and it wasn't pretty.
Yes, the bearings are well packed with high-temperature
grease. I checked that a few hours
ago.


listdigest-6861962 [at] logan.com" rel="noopener" type="cite">

3. The brake pad float bushings should allow the pad
mounts to move freely (SS not rusty steel) and properly
positioned so that relaxing brake pedal pressure causes no
pressure on the pad to the rotor.

Check.

listdigest-6861962 [at] logan.com" rel="noopener" type="cite">

4. Remember that when steering - one toe presses (or
just taps) the inside-the-turn pedal whilst the other foot
holds the rudder pedal steady so that you are not slamming
the rudder over.

That's the way I do it, but after all these years of using only
brakes to steer the plane, I find I have to retrain my mind to stay
off the brakes at over 30 KTs and let the rudder do the steering.



Thanks for the sage comments.

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: Chris Zavatson <chris_zavatson [at] yahoo.com>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] [LNC2] Fast taxi testing - found the problem
Date: Fri, 09 May 2014 07:59:43 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

John,
A little pre-load is actually beneficial in roller bearings.  You apparently had a too much on one wheel.
I re-grease my bearings every year and during installation tighten the nut until I get just under one revolution of spin.  It is a good idea to re-check this after a few hours of use.

Chris Zavatson
N91CZ
360std






I did discover the real problem, though. When I put the plane up on jacks and spun the wheels, the left main and nose
both spun about 1-1/4 turns. The right main would hardly turn at all. The axle nut on the right wheel was one flat too tight. The wheel was dragging and my brand new tire had several flat spots on it. When I loosened the axle nut, the wheel turned freely so it wasn't the brakes per se. I DO need to inspect the brakes on that side as well because things got pretty hot over there.

I'm just glad it's not the oleo strut!

Do we have an end-play specification for tightening the axle nuts?

Thanks for all the suggestions, everybody --

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: <Sky2high [at] aol.com>
Subject: Re: [LML] Re: [LML][LNC2] Fast taxi testing - found the problem
Date: Fri, 9 May 2014 08:43:15 -0400 (EDT)
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

OK then -
 
A Lancair 320 with the 70" Hartzell prop has strong left turning tendencies
- P-factor, torque, etc.  The small vertical stab and rudder do not take
control until some speed is achieved - on mine is was at about 40 KIAS and,
as you noted, you see some control at about 30.  The moving plane
wants to weather vane in crosswinds, especially those from the left. On the
ground quartering head winds have an effect on the upwind down flap whilst
the lee flap is partially blocked by the fuselage - more left turning if the
wind is from the left. 
 
If power is applied rapidly at the start of a takeoff run or fast taxi, the
left turning tendency is very strong.  It is best to apply power slowly
until rudder control is there. 
 
If all the left forcing factors are present, their effect is
additive.  Right brake tapping is useful. 
 
Grayhawk
 
PS If you are on the left side of a crowned taxiway or runway - well,
there's another factor.
 
PPS I loved right crosswinds for takeoffs and landings.
 
PPPS - If one main gear leg is vertical and the other is not, there is an
effect.
 
In a message dated 5/9/2014 7:05:47 A.M. Central Daylight Time,
snopercod [at] comporium.net writes:

In response to Greyhawk:

listdigest-6861962 [at] logan.com" rel="noopener" type="cite">

Toe out is an unstable
condition.

The jury seems to still
be out on that subject. I can find experienced pilots who swear by either
toe-in or toe-out. Since my toe-out condition is only a fraction of a degree,
I'm just going to leave it alone for now. If it becomes a problem later on,
I'll fix the 0.6º tire with a shim at the base of the axle. The 0.2º isn't
worth messing with. I want to get this plane flying sometime before I die
(grin).

listdigest-6861962 [at] logan.com" rel="noopener" type="cite">

2.  If these are the original Matco wheels, note that the pin
bearing races are aligned conically.  Thus, one needs to make sure the
axle nut (with washer on the inside shoulder and under the nut) is snugged
tight enough to keep the bearings properly supporting the wheel.  Loose
wheels will destroy the bearings (nose wheel included).  The usual rule
is that they are properly tight if the wheel will not make a complete
revolution when hand spun whilst on jacks.  Remember to make sure the
bearings are packed with appropriate
grease.

Yes, I have the original Matco wheels and the original Rosenhan
brakes. I've adjusted the axle nuts so the tire will spin 1-1/4 turns by hand.
The bearings are snug that way, yet it leaves a little room for thermal
expansion. We saw what happened when I turned the axle nut one flat beyond
that point and it wasn't pretty. Yes, the bearings are well packed with
high-temperature grease. I checked that a few hours
ago.

listdigest-6861962 [at] logan.com" rel="noopener" type="cite">

3. The brake pad float bushings should allow the pad mounts to
move freely (SS not rusty steel) and properly positioned so that
relaxing brake pedal pressure causes no pressure on the pad to the
rotor.

Check.

listdigest-6861962 [at] logan.com" rel="noopener" type="cite">

4. Remember that when steering - one toe presses (or just
taps) the inside-the-turn pedal whilst the other foot holds the rudder
pedal steady so that you are not slamming the rudder
over.

That's the way I do it, but after
all these years of using only brakes to steer the plane, I find I have to
retrain my mind to stay off the brakes at over 30 KTs and let the rudder do
the steering.

Thanks for the sage
comments.

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: <marv [at] lancair.net>
Subject: Re: [LML] [LNC2] Fast taxi testing - found the problem
Date: Fri, 09 May 2014 15:26:31 -0400
To: <lml>
Message Header


Undecoded Message
Posted for John Cooper <snopercod [at] comporium.net>:

>
I
was browsing through the long list of Lancair Service Difficulty Reports
>today and found this one from 1994:
>
>
*"Brake
locking/dragging problem with MATCO MC-1 and 3 shipped prior to
>1994"* Source: LNN p97 and 98
>
> Since I bought my kit in
1987,
I almost certainly have the MC-1 model
>installed. I'll be replacing those with the MC-4 (I think) with the external

>reservoir.
>

> Anybody know what happened to the Lancair Network News and are back issues
>available? I used to subscribe but don't know what I
did
with all my issues.
>
> Thanks to all who have helped me on this problem. --John

[I
probably
still have leftover hard copies of certain issues that I could dig up, as well as CDROMs with PDF versions of all issues ever published.  The
CDROMs are $39 including postage and I could probably work something out regarding individual issue hard copies, just drop me a private email at
marv [at] lancair.net if you'd like either one.  <Marv>   ]

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] [LNC2] Fast taxi testing - found the problem
Date: Mon, 12 May 2014 07:39:18 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Thanks for the link to the Timpken Engineering Manual. It was very
informative. All these years I had thought that bearings should have
a tiny bit of end-play to allow for thermal expansion, but Timken
says that's not true. On Pg. 82 they state:

"Generally, the ideal operating bearing setting is near
zero to

maximize bearing life (fig. 83). Most bearings are set with
endplay

at assembly to reach the desired near-zero setting at operating

temperature.



There is an ideal bearing setting value for every application. To

achieve this condition, the bearing setting must take into account

deflection under load (radial + axial) as well as thermal
expansions

and material used.

Figure 83 indicates that bearings have a longer life with a small
pre-load. Live and learn. I guess the only way to set the end play
accurately would be with a dial indicator so I just ordered one from
Amazon for $25. One would have to test the end play cold and then
hot.



So maybe my problem all along was the right brake locking up and not
the tightness of the bearings (or both)????




John,
A little pre-load is actually beneficial in roller bearings. 
You apparently had a too much on one wheel.
I re-grease my bearings every year and during installation
tighten the nut until I get just under one revolution of spin. 
It is a good idea to re-check this after a few hours of use.

Chris Zavatson
N91CZ
360std

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML][LNC2] Fast taxi testing - found the problem
Date: Mon, 12 May 2014 07:55:05 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Since I'll be replacing all the brake components
on my L-235, I figure I might as well replace the 27 y.o. nylon
tubing as well. So now the question becomes: should I use the
"standard" (.030) wall thickness Nylaflow tubing rated at 1,000 PSI
burst pressure, or the "high-burst" (.040) wall thickness Nylaflow,
rated at 2,500 PSI burst pressure. Lancair still sells the
"standard", but Aircraft Spruce sells both varieties. I ordered two
18" Russell SS/Teflon motorcycle brake hoses to connect to the brake
pucks, but plan to use the Nylaflow tubing the rest of the way
forward to the master cylinders. Will I get enough flow through the
thicker-wall tubing? Anybody have any thoughts?Thanks in advance...

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: Robert R Pastusek <rpastusek [at] htii.com>
Subject: RE: [LML] Re: [LML][LNC2] Fast taxi testing - found the problem
Date: Mon, 12 May 2014 12:30:48 +0000
To: Lancair Mailing List <lml [at] lancaironline.net>
Message Header


Undecoded Message

John,



You’ll not have any problem with flow rate using tubing down to about 1/16” ID--well less than you are considering. The actual fluid flow at brake application is almost nil. You can actually calculate it by measuring the change in volume of the brake actuator
(My estimate: about 2 square inches of surface, moving less than 1/16” during brake application) over the brake application time--hopefully not less than 1 second?
 Bottom line, it’s a very small amount of fluid being shuttled back and forth.

 

On my IV-P, I replaced the
nylaflow lines in the gear legs with 3/16” Teflon w/stainless braided cover, and left the
Nylaflow in the cockpit area. At 1200 hours TT, I’ve not had any problems at all with the braking system.

 

In addition to rupturing under high heat,
Nylaflow is prone to “kinking” damage. I helped an IV-P owner that had kinked his brake lines during construction and thought they were OK once he straightened them out again…although you could see the deformation and discoloration
(the tubing changes from translucent to white where kinked). If you ever kink/bend any of this tubing too much, it’s time to put it immediately in the scrap pile.

 

Bob

 

From:
Lancair Mailing List [lml [at] lancaironline.net]">mailto:lml [at] lancaironline.net] On Behalf Of John Cooper

Sent: Monday, May 12, 2014 7:55 AM

To: Lancair Mailing List

Subject: [LML] Re: [LML][LNC2] Fast taxi testing - found the problem

 

Since I'll be replacing
all
the brake components on my L-235, I figure I might as well replace the 27 y.o. nylon tubing as well. So now the question becomes: should I use the "standard" (.030) wall thickness Nylaflow tubing
rated at 1,000 PSI burst pressure, or the "high-burst" (.040) wall thickness Nylaflow, rated at 2,500 PSI burst pressure. Lancair still sells the "standard", but Aircraft Spruce sells both varieties. I ordered two 18" Russell SS/Teflon motorcycle brake hoses
to connect to the brake pucks, but plan to use the Nylaflow tubing the rest of the way forward to the master cylinders. Will I get enough flow through the thicker-wall tubing? Anybody have any thoughts?Thanks in advance...

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: Paul Miller <pjdmiller [at] gmail.com>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] Re: [LNC2] Fast taxi testing - found the problem
Date: Mon, 12 May 2014 09:50:48 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Aircraft wheel bearings settings are not the same as continuous load applications like machinery and automotive.  Cleveland, EAA, Grove all have manuals on inspecting and installing aircraft wheel bearings.   Parker/Cleveland state (and I use this method):



(g) Torque axle nut using value specified in aircraft manual or the following:

1 Rotate the wheel/tire while tightening axle nut to 150 to 200 inch-pounds (16.9 to

22.6 N•m) to seat the bearing.

2 Back off axle nut to zero torque.

3 Tighten axle nut to 30-40 inch-pounds (3.4 to 4.5 N•m) while rotating wheel/tire.

4 Rotate axle nut (clockwise or counterclockwise) to nearest slot and cotter pin hole,

and insert cotter pin. Bend ends of cotter pin around axle nut. Note: Wheel must

rotate freely without perceptible play.



The Parker manual is online with a Google search.  I think that Timken manual is not addressing aircraft bearings which have a preload requirement.  Forget the dial indicator.



Paul

Legacy

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] [LNC2] Fast taxi testing - found the problem
Date: Wed, 28 May 2014 14:15:43 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

While replacing the entire brake system on my L-235, I've had
occasion to speak with "Andy" at Matco a couple of times; He's
extremely knowledgeable. Today I called him because the pads in new
B5-4 brake assemblies didn't line up properly with the old disc.
Andy directed me to the Technical
Manual for 5 Inch Centrifugally Cast Internal Caliper Wheels
which provided instructions on how to shim the axle for proper disc
alignment with the pads. The manual also turned out to be a gold
mine of information for all things regarding the Matco wheels and
brakes. It contains instructions on how to determine when the pads
need replacing (the new pads have wear indicator marks), how to set
the geometry of the brake pedals vs. master cylinders, how to
properly bleed the brakes, how to torque the axle nuts for proper
bearing pre-load, how to mount the tire and tube, and much more.
Earlier there was a discussion on how to properly torque the axle
nut so, from the above manual, here is what Matco advises:



Your MATCO Mfg. wheel is equipped with Timken style tapered

roller bearings with integral grease seals on the bearing cone to

ensure the longest possible life. Torque procedures for bearings

with this type of seal are different than for bearings without them.

A common torque method for bearings without seals is to tighten

the axle nut until the wheel stops spinning freely then back off to

the nearest locking feature. THIS TECHNIQUE DOES NOT

WORK ON BEARINGS WITH AN INTEGRAL SEAL

.

The reason for using a different technique lies in the grease seal

which under normal circumstances, produces some drag and

makes the wheel feel somewhat stiff when rotated. Reducing the

axle nut torque until the wheel spins freely will allow the grease

seal and the bearing cone to rotate improperly with the wheel.

THE CONE MUST NOT ROTATE RELATIVE TO THE AXLE



1.The higher rolling drag is completely normal for this bearing and

allows for longer bearing life since the seal will keep most

contaminants out.Timken specifications state that the two 1.25 inch

tapered roller bearings used on the 5’’ wheel, produce 8-10 inch

pounds of torque (drag) when properly installed. A light coating

of grease on the seal will help reduce the drag on initial

installation. The drag will also reduce after the bearings have

been installed and the seal relaxes in the bore. It is important
that

the axle nut torque be sufficient to keep the seal from rotating

with the wheel. The following technique will ensure the longest

possible bearing life.



2 Tightened the axle nut until all play is out of the assembly.
Rotate

the wheel back and forth while tightening the nut to help seat the

bearings. When all play is out and the wheel rotates freely,

tighten to the next slot and insert cotter pin.



3. The rubber seal on the tapered roller bearing should remain

stationary while the wheel rotates around it. If the seal is
spinning

on the axle, tighten the nut further until the seal stops spinning

with the wheel. (See Note Above).



4. When using MATCO mfg flanged axles, they can be shimmed

for toe-in / toe-out conditions or spaced out from the wheel if

necessary for the brake disc attachment screws to clear the

landing gear leg.

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] [LNC2] Fast taxi testing - found the problem
Date: Fri, 30 May 2014 08:02:52 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Today I temporarily mounted my shiny new Matco B5-4 brake assembly
on the left wheel, and hooked up my shiny new Russell 18" motorcycle
brake hose and tied it in with my shiny new heavy-wall Nylaflow
tubing. When going from the original Rosenhan brakes to the new
Matcos, some shimming is required between the brake mounting plate
and the axle. The old Rosenhan die-cast mounting plate was .210
thick, and the new steel Matco plate is .125 thick. I'm still
working with Matco on the proper dimensions...The length of the axle
mounting bolts have to be adjusted accordingly.



/files/LML/70082-02-01-R/part1.06040600.08020803 [at] comporium.net" sandbox="" width="877" height="585">



Although I still need to shim things up for proper brake pad
centering, it looks like the new model should work. I had to saw
off  1/4" of the mounting bolt and use a reduced-dimension metal
locknut where it interfered with the middle gear door bracket.
S.O.P:



/files/LML/70082-02-01-R/part2.07090801.09070703 [at] comporium.net" sandbox="" width="585" height="877">



I plan to wrap the bottom 5" of the teflon/ss/vinyl brake hose with
Thermoflex
for added protection.



--John


Image


Transformed_Lancair left brake 001.JPG


Image


Transformed_Lancair left brake 008.JPG

[LNC2] Fast taxi testing - found the problem

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] [LNC2] Fast taxi testing - found the problem
Date: Mon, 02 Jun 2014 15:38:45 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Today I fabricated the shims to go between the brake mounting plates
and axles on my L-235. These were necessary to compensate for the
different thickness of the old Rosenhan brakes that came with the
kit, and the new Matco B5-4 replacements (see previous photo). These
are .090 thick, and I plan to use 2 or 3 of them on each axle,
depending upon how the brake pads fit. I used a 2-3/4" hole saw to
cut the shims out of a sheet, a 1-1/4" chassis punch for the center
hole, and a drill press for the rest. In my younger days I would
have Alodyned and Zinc-Chromated these shims, but in my old age, I
say "screw it!" (grin) I feel like I'll be ready to re-perform the
fast taxi testing in another week or so after I put the airplane
back together. Wish me luck.



/files/LML/70105-02-01-R/part1.04070104.09030804 [at] comporium.net" sandbox="" width="585" height="877">





Image


Transformed_Lancair axle washers 001.JPG