MONTY THE ANSWER MAN ARCHIVE SWIFT
HYDRAULIC SYSTEM
THE RED STUFF...
My experience with other aircraft has demonstrated to me that periodic
replacement of the hydraulic fluid is probably best. It gets very ugly
looking after a few years. I can easily do on the brake system, but what
is the best way to do on the landing gear/flap system? Is there a point
to force fluid in which will force it through the system to be expelled
at another point (the reservoir)? Steve Roth (stevenroth@aol.com)
Steve,
The gear/flap system on the Swift is self-bleeding, with the pressure/return
lines reversing function upon retraction/extension. If water accumulates
in the hydraulic fluid, due to condensation or leaking into the bleed
hole in the reservoir, it will be necessary to crack a fitting on each
gear, and at the flap actuator and cycle the gear and flaps until the
water is purged. The brakes are a "dead end" system, and the brakes should
be bled periodically. Read Dick Collins report on this on the Swift Home
Page. -- Jim
FLAP ACTUATOR O-RING
REPLACEMENT CAN CURE HYDRAULIC BLEED DOWN... (800100)
From: Al Andersen <72032.237@compuserve.com>
Subject: July #6 GTS Internet Update
Hearing about the hydraulic bleed down problem reminded me of a similar
thing that happened in my Swift back 20 years ago or so. I was plagued
with the cycling hydraulic pump in flight until I took the flap actuator
out of the airplane and resealed it. It had O rings in it that looked
original, and acted like they were 30 yrs old then. The landing gear tends
to get resealed as leaks develop, as they are usually external. The flap
actuator usually leaks internally, and therefore seldom gets attention.
Once I got on my back,&
pulled the flap actuator out of the airplane, (it's not the easiest thing
to do, and kind of messy) and resealed it, the problem with the cycling
hydraulic pump went away, and the pressure stayed up remarkably well in
the system. This doesn't totally address the overcenter up linkage problem,
but will tighten up your hydraulic system so it won't be so noticeable.
AL
HARRY SAYS...(110300)
From: Harry Asbury <gypsyone@tds.net>
Subject: Just something I learned many years ago
Hi Denis,
I enjoyed the newsletter very much and was very curious about the comments
on wing tips. Do I detect a tendency to ground loop the Swift a lot with
the present generation? I don't know if many people are aware of this
but I will throw it in just for information. On any hydraulic system,
brakes, flaps, servos, utility systems, if you let them set for four months
or longer without activation, the condensation that is mixed in with the
hydraulic oil will turn to water and settle to the lowest point in the
system. The first warning you will have of this will be a leak around
the seals at the lowest point of the system. What you will find is corrosion
from the water on the aluminum castings has caused pits in the castings.
The only recourse is to replace the casting. This could be wheel brake
cylinders and etc. The best course of action when putting an aircraft,
and even your car with power steering, up for a long period of time, is
to drain the system completely, and reservicing the system before storage,
to remove the water that has formed from condensation in the system. Keep
this in mind when buying an aircraft that has been sitting in one spot
without running during this dead storage time. One other thing I noticed
now. The owners of the Swifts seem to love to polish the birds. Great,
but don't polish the chrome on the oleo landing gear struts. If you do
this, you will cause the landing gear struts to wear the seals out at
a very rapid rate and then have leaking landing gear. I learned this on
working with the Marines on the Presidential Helicopters. They polish
everything and we had a very high rate of leakage of the oleo struts on
the VH3D helicopters. I got curious and watched them polish them one day
and figured out the problem right away. I very light coat of hydraulic
oil will prevent this. Yes I know it accumulates a lot of dust, but to
wipe the struts with an oily rag is a lot easier than replacing seals.
I hope this piece of information will help someone with their Swift if
they haven't already experienced this kind of problem. -- Harry Asbury
LANDING GEAR PROBLEMS?
BLEED THE AIR OUT..(120300)
From: Harry Asbury <gypsyone@tds.net>
Subject: Re: December #2 GTS Internet Update
Dear Jim, I'm not up to date on the Swift's hydraulic system, but I've
had a lot of experience on other hydraulic systems and one that has happened
to me quite often was to have some part of the system not to work under
load, such as the gear retracting in the air, but works fine on the ground.
I have found in most cases when I can't find anything else wrong with
the system, that there is a little air in the system and it will compress
enough to stop the actuator from performing to it's maximum limits under
load. The solution was always to bleed the system simply by jacking the
aircraft and actuating the gear at least twenty times. The way the actuator
is mounted in the aircraft sometimes lead it to trap air and it's awful
hard to get it out. Just a thought on the gear retracting problem. --
Harry
Harry,
Good point. If I were working on Steve's aircraft I would have cycled
the gear numerous times on jacks. I assume Steve and Ray also did this.
When I am trying to help via email I don't know if they for a fact did
that. Air in the system will indeed cause symptoms like what they are
experiencing. The Swift system will usually bleed itself out after a few
cycles. -- Jim
MORE FROM HARRY ON THE
IMPORTANCE OF BLEEDING THE HYDRAULIC SYSTEMS...(120300)
From: Harry Asbury <gypsyone@tds.net>
Many a time I would ask the military did they bleed the system and all
ways they would say yes! I have found that they would give it a half hearty
try and in some cases on the larger hydraulic systems they would never
get all of the air out. I know on the SH3s and HH53s this was a problem
with the landing gear. I've even seen it in the rescue hoist systems.
In that case it would cause a chattering on the up cycle with a weight
on the hook. The big internal winch system wouldn't even pull the cable
in if there was the slightest air in the system. I've even investigated
fatal crashes where the control system wasn't bleed properly and this
caused the pilot to get out of sync with the cyclic stick to the response
of the aircraft to the controls. It got so bad as that he was 180 out
with the response and crashed into the sea. I didn't figure that one out
until four years later when the same thing happened to another of the
same type aircraft and believe it or not, the co-pilot on the fatal crash
was the command pilot on the one we got back. Once on the ground, I tried
the controls in a low hover and right away I could feel the spongy respond
and knew it was air, due to a auxiliary servo change in the aircraft the
day before. They had failed to bleed the complete system. This gave me
the answer to the fatal crash. The same type of maintenance had been performed
on the fatal crashed aircraft. I guess if you stay in this business, you
will eventual see the same thing occur again down the line. Pardon my
long winded message, but I have always loved working and solving the little
mysteries of maintenance. -- Harry
YUCKY YELLOW... (040101)
From: Al Andersen <72032.237@compuserve.com>
Just a little insight into the strut oil on the ELI Gear being a different
color (yellowish). 5606, along with automotive brake fluid is hygroscopic,
which is a fancy word to say that it absorbs water over time. It is very
common in airplanes, (which seldom have the hydraulic fluid changed) to
see the 5606 hydraulic fluid turn a yucky yellowish color when it becomes
saturated with water. This is bad for the system because water creates
corosion in the calipers of the brakes, and in the interior areas of the
strut. The first time I saw this yellow fluid I thought that there must
bea different type of oil used in the older airplanes. Probably not. It
is more likely just old 5606 saturated with water. There is something
to be said for changing the brake and strut 5606 aboutevery 5-7 years
or so to prevent internal corrosion problems from happening to your airplane
as the fluid eventually saturates with water. AL
SOME ADVICE FROM MONTY... (050101)
Checking hydraulic quantity is a preflight item. I usually check before
every flight. If you have flown 30 some hours and not checked the hydraulic
fluid I can almost guarantee it is low. A full hydraulic reservoir is
probably the quickest, cheapest fix for slow gear retraction.
The early Swifts had a filler hole in the top of the reservoir with a
dipstick to check quantity. Later airplanes had a pipe elbow in the front
of the reservoir and you just filled it to that level. The early setup
was almost always overfilled and any spillage from filling ended up with
hydraulic fluid leaking thru openings in the firewall and running down
the gear and flap selector rods. Overfilling doesn't really hurt anything,
but when cranking the gear down on jacks, an overfilled system will blow
fluid thru the vent and all over the pilot's windshield.
LEAKING HYDRAULIC FLUID RESERVOIR...(030102)
Subj: Emergency Pulldown
From: Brian Silcox (briansilcox@harbornet.com)
Hi Monty,
I am doing my annual on N46GS, had a strange thing happen when I pulled
the gear down with the cable this time. I have been doing this each year
since I got the plane ten years ago, and never had this: As the second
(left) gear is reaching the stop limit, the reservoir over fills and squirts
several ounces of hydraulic fluid out the cap vent. Thinking it was a
transient anomaly, I reset the cable, refilled the reservoir and recycled
the gear up and down.... no problems. fluid level remained at the proper
level. I once again pulled the gear down manually (cap off, cowl open)
and watched the gusher a second time. I repeated the above one more time
to ensure I wasn't seeing things, and once again same! It works fine in
both the normal, hydraulic powered cycle, and extends fine manually. I
am suspecting a port problem in the powerpack... return fluid is moving
back to the reservoir, but not vice versa through the down lines during
the pulldown. When the overflow occurs, the reservoir is absolutely full,
and stays that way till you activate the system hydraulically, and then
it indicates the fluid loss on the stick. Ever seen this one? Thanks,
Brian Silcox
Brian
Unusual? No, that is a very USUAL happening. This is the first time in
10 years that that happened? You must run very low levels of hydraulic
oil in your reservoir. Ordinarily, when the gear is cranked down it is
quite common to have hydraulic oil spray out the vent and over the windshield.
Rather than repeat myself, go to the "Monty the Answer Man"
archive and read about "Landing Gear - Emergency Extension".
I think Charlie Nelson even talked about that same thing in this months
newsletter. Jim
HYDRAULIC SYSTEM QUESTION...(800402)
Subj: Hydaulic system
From: Pat Waters <GPWATERS@aol.com>
I have a question as to the hydraulic system. When I bought my Swift,
it had this elbow and glass fitting which vented and upon use of the flaps,
would project fluid out onto the cowl. I called the office in Athens for
help and was told that the system did not need a 'vent hole' as was in
the top of the elbow. I also have a bolt/plug in the after part of the
pump housing which is not real tight, but I do not see fluid emitting
from it. My question, is does this system need to have a vent as in the
elbow or is it a closed system. Athens said to just put a #10 plug in
where the elbow was and go flying. I have done this a little, but fear
I am building a pressure somehow on the system that may cause it to burst.
Please advise as I am grounding myself until I am sure. Also, if the elbowis
requires, my glass was broken when I dropped it. How or where do I find
a complete glass elbow? One more question, is the cylinder resovor next
to the pump/resivor for the breaks or a reserve for the pump? Thanking
you in advance, Pat Waters
Pat
I'm not sure I follow you entirely, but the hydraulic reservoir should
be vented. The vent is just a simple small hole (#50 or smaller) in the
dip stick on the top of the reservoir. The later reservoirs had an elbow
on the front of the reservoir with an 1/8 pipe plug which is removed for
filling with mil 5606. This is located to prevent overfilling. These later
reservoirs had a small vent hole just aft of the motor. If you have an
early style reservoir with the plug on top, just drill it. If you have
the later style with the filler at the front you should have the vent
hole on top. The problem that can arise is when the late reservoir is
used with the early top and a plain pipe plug is installed in the dip
stick hole that is not drilled. To solve that problem, just drill it.
You may be overfilling the reservoir. It is common to have fluid come
out the vent when cranking the gear down, but not when simply operating
the flaps. There is supposed to be a baffle in the reservoir to minimize
fluid loss thru the vent, maybe somone has removed it. The reservoir next
to the hydraulic package is the brake reservoir. Keep it near full and
also, it should be vented. -- Jim
HYDRAULIC FLUID ALL OVER
THE BELLY...(OCT 02)
Subj: Hydraulic leak
From: Marvin Homsely <marvin@accesstoledo.com>
Jim, more stuff that may be of interest to someone. I landed last weekend
and had hydraulic fluid all over the belly. It turned out that I had a
pin hole in a hydraulic line where it goes thru the bottom of the firewall.
On my plane there is a phenolic block there that all six hydraulic lines
go thru. After removing the block and inspecting the lines five of the
six had severe wear from that block. One line had no wear at all. I decided
to replace all of the lines. After further study it looked like it would
be very difficult if not impossible to pull the line out of the belly
of the plane. It is one piece and there is just not enough room to pull
it out with that 90 degree bend in it. It is just too close to the motor
mount. I ended up replacing just the damaged tubing. Just cut the tubing
several inches above the bottom of the firewall and again several inches
back inside the belly. Make a new piece with a simple 90 degree bend in
it and splice it in the line. I do not believe this new line will ever
need replaced but it would be an easy job if necessary. Bleed the lines
real good, cycle the gear and flaps several times and it is as good as
new, maybe better. Total cost was around fifty dollars. I wonder what
a shop would have charged for this. Marvin Homsley N80740 marvin@accesstoledo.com
Marvin
Yes, that is a common problem. On Mick Supina's Swift we installed AN833-4D
elbows in the firewall for those lines. That is not an original idea,
Temco did the same with the Buckaroo. -- Jim
WHAT BRAND OF FLUID? (APRIL 04)
Subj: Hydraulic Fluid and Filling Tips, Etc.
From: James Cummiskey <jccummis@yahoo.com>
Hello, Jim. Can you clarify what brand and type of hydraulic fluid I should
be using in my Swift? Also, I read in the archive that it is easy to overfill
the older style reservoir with the filler hole and dipstick on top. Do
you have a recommended procedure to avoid overfilling? Is Par-al-ketone
a good choice for lubricating the emergency gear cables? I had one of
my cables jump the pulley on me (I have the cable guards installed), and
I intend to drill the actuator pulley per the Swift Association "Maintenance
and Operation Information for the Swift." Finally, do you recommend
the GAMI injectors for the IO-360? Looks like I'll be flying N3800K with
her new paint job out to the Nationals in Athens. See everyone there!
Regards, Jim N3800K
Jim
The hydraulic oil is 5606, Mil-H-5606, made by just about every major
oil company. (Shell, Texaco etc.) The early reservoir should have a dip
stick and you should not fill above the top hole. If you don't have a
dipstick they might have one at Swift Parts or you could make one. Paralketone
is fine for any cable. Several of my friends have the GAMI injectors and
swear by them, although one of them has a fuel injection problem right
now, if it turns out to be the GAMI injectors I will let you know! --
Jim
|