MONTY THE ANSWER MAN ARCHIVE
Swift Landing Gear Emergency Extension
EXTENSION CABLE SLIPS OFF PULLY...
Subject: Re: Emergency Gear extension
I wanted to go flying last weekend and during the preflight check I found
the right emergency gear down cable has jumped of the actuator-pulley
(the one where the gear is). Playing a little bit with it I found that
it could have come loose because of some friction (it needs grease) in
the routing (all the pulleys in between) when I was lowering the gear
the last time.
Do you know of similar experiences? Regards -- George
Yes, this is quite a common occurrence. There are several things that
can be done. First, make sure the system is lubricated and operates freely.
Univair used to sell a cable guard ref. SB #35, I don't know if Swift
Parts still has these or not, but it is a worthwhile thing to have. I
would say having the Service Bulletins is a MUST! A cheaper, and perhaps
more effective way to keep the cable on the pully is to drill the actuator
pulley and install some .032 safety wire. The details of this are in a
book published by the Swift Association many years ago. You should also
have this book. It is available from the Swift Association. -- Jim
LANDING GEAR EMERGENCY
From: Steve Roth (StevenRoth@aol.com)
Subject: Re: Cable Gear Extension
I don't know if it is possible in short words but how does the cable emergency
gear extension work? I see that when you turn the crank, it is turning
a large screw. The other thing I know is that a central pulley is used
to pull up the cable (in the middle of its entire length) to put pressure
on the two sides of the cables that go to the actuators (thru a series
of pulleys). What I don't understand is this: With the gear emergency
in the normal position, how does that central pulley ride up/down as the
gear is actuated hydraulically? Is that pulley attached to a ring which
rides up/down over the screw shaft assisted by a spring? So, when you
do crank the emergency gear crank, it screws up a sleeve which pushes
on the underside of the sliding ring and that pulls up the pulley?
Well, I don't know how good I can answer this from memory off the top
of my head but........There are 2 stationary pullys that change the direction
of the cable 90 degrees, and another pulley which "pulls up" on the screw
when the crank is turned, this in turn pulls the gear down thru a drum
on the gear actuator OK - see the spring on the pull down screw/shaft
assy? This allows the big pulley (sleeve assy) to ride up and down under
normal gear retraction/extension. The best thing to do would be to watch
it next time you have it on jacks and cycle the gear. -- Monty.
EMERGENCY GEAR CABLE...(6399)
From: Jerry Swartz <JSw7211963@aol.com>
Subject: Re: Gear Cable
Last preflight, found gear cable off of large actuator pulley. Moved cable
guard, reinstalled cable on pulley, and then moved cable guard back in
place. When this happens, should the airplane not be flown or is this
a somewhat common happening. The cable does have a kink or two in it.
I suggest you look the cable over closely, (remove the upholstery by the
gear crank) then add the .032 safety wire per the Commings Hydraulic Manual
and the "Maintenance and Operation Information for the Swift." If there
is doubt about the system, the airplane should be put on jacks and the
gear cycled, normal and emergency. The cable will not come off IF the
pull down jackscrew is properly lubricated and if the cable guards are
in place, which they obviously weren't in your case. Be happy. You found
the problem on the ground, where it really isn't a problem! -- Jim
EMERGENCY GEAR EXTENTION
vs HYDRUALIC FLUID... (7299)
Subject: Emergency Gear Extension / Reset / Retraction
Recently I had Duane Golding do a pre-buy inspection on a Swift for me.
I wanted to do the emergency extension for the experience, never having
done one. Followed the checklist, put the gear down with the emergency
crank and everything worked as it was supposed to. "Un-cranked" the emergency
gear system and replaced the safety pin. Then we cycled the gear a few
more times, for the IA that was present, and hydraulic fluid came out
the breather cap of the gear/flap reservoir and ran all down the firewall.
The reservoir was not over serviced. My question is why? Duane said every
one he has ever done, bleeds fluid out of the vent after an emergency
extension/ reset / and subsequent normal retraction. Would appreciate
your comments. Cheers....Ed Lloyd
After giving it some thought... First, don't worry about it. Just cover
the reservoir with a rag and let it try to keep the mess to a minimum.
To have a low fluid level in flight is BAD and to try to keep the fluid
level low enough to avoid overflow is not worth the effort and subsequent
risk of nonfunctioning gear. Incidentally, a too low fluid level will
prevent the gear from going up, but it will go down, and the flaps will
operate. What is happening is the volume of fluid coming back to the reservoir
from the actuators is greater than the reservoir capacity. Back when I
was an A&P school instructor I made a mockup with an F-84 hydraulic
system. If I had the time and inclination today I could do the same with
a Swift hydraulic system and figure out exactly why the excess fluid doesn't
go to the extend side of the actuator. But I am willing to accept how
it works and am not losing any sleep over it! -- Jim
PS: As I sent the previous
mail it occurred to me, with the hydraulic pump not operating and the
fluid being displaced from the actuator by the gear being pulled down
the reservoir is going to overfill. The fluid can't get to the "down"
side of the actuator.
Some additional thoughts
on this subject from Don Bartholomew...
The situation you have described
has happened to me many times. First, the fluid generally squirts out
when the gear is being cranked down. You may not notice it until a short
time later (eg another cycle or two). This is because an excess amount
of fluid goes back to the reservoir due to none being pumped into the
downs side of the cylinders.
There are a couple of things
that cause this. First is over full on the fluid level. Some of the original
pumps had a dipstick on the aft side of the reservoir, some did not. If
fluid is added to the elbow on the front of the reservoir, even though
the elbow is at the same level of the "full" mark of the dipstick, you
are overfilling the unit. This is because in the three point attitude,
the elbow is higher than dipstick giving an inaccurate indication. Typically
I have found that if the power pack has a dipstick and the fluid level
is between the indicator holes or marks, the spraying during emergency
crank down does not happen. Another thing that can cause the problem is
originally there was a flat, tin splash plate in the pump that deflected
the return stream of fluid from spraying onto the top of the pump (right
where the breather hole is). Sometimes I have found that when the power
pack was resealed, the plate left out.
A suggestion for filling
the power pack. If there is an elbow on the front of the unit, lift the
tail to the level flight position and then add fluid until the level is
at the BOTTOM of the elbow. If the elbow is a little loose, fill the reservoir
and unscrew the elbow half a turn so the excess fluid runs out. Happy
5606 cleaning! -- Don and Helo
EMERGENCY GEAR EXTENSION...
From: Steve Roth <StevenRoth@aol.com>
At annual in August I inspected, cleaned and lubed the emergency gear
extension system. I used light grease on the shaft and extension crank
screw. Shortly after that I talked to Joe who said not to use grease on
the mechanism since during cold weather the grease could stiffen and prevent
the mechanism from working. That made a lot of sense so I degreased the
mechanism with solvent. Then I relubed it with spray lube (WD-40).
In late October I was doing
the preflight check of pulling on the emergency gear extension cables
in the wheel wells. I could pull the cable out but they would not spring
back. So, I took the cover off the mechanism in the cockpit and could
find no mechanical reason the cable would not wind back. So, I again degreased/cleaned
the mechanism thoroughly (using a half can of spray brake cleaner in the
process) then lightly lubed it with a few drops of high quality gun oil.
That fixed it.
The next day I did the preflight
check again and the right emergency control cable was frozen (would not
pull out). I took the cover off the mechanism and found the right cable
had become stuck under the aluminum brace which it usually rides on. Each
side has these aluminum braces and they have fiber "plates" riveted to
them on the front as rub plates for the cable. Somehow the cable had gotten
stuck underneath this brace, probably from allowing too much slack to
form in the cable. Investigating this condition, I found out the importance
of having the safety wire "clamp" modification to the crank/pulley on
the gear actuator in the wheel well (the large one where the end of the
cable is anchored). This modification is mentioned on page 9 of the Blue
book - "Pull Down Cable Fix" (Maintenance and Operation Information for
the Swift). That safety wire "clamp" prevented the cable from coming out
of the groove and off the actuator pulley. With slack in the cable when
the gear is extended, the cable would definitely have come off the pulley.
Thus, if that cable came off the pulley when the gear was retracted, the
cable would have gotten tightly snarled somewhere outside the groove in
that pulley, either jamming it or eventually breaking it. What did I learn:
(1) Keep the gear emergency
system clean and degreased. Lube the mechanism lightly with thin oil products,
not susceptible to thickening in cold. Follow the procedures in the Blue
Book. I intend to do this several times between annuals.
(2) Perform the cable check
in the wheel wells at every preflight.
(3) When performing the
wheel well check, pull out the cable and let it slowly retract under spring
pressure. Don't pull the cable out and let it spring back -- it may get
jammed under the brace, as happened to me. If it binds in any way, investigate
(4) If not already done,
install the modification to the extension pulley that uses safety wire
to hold the cable in place (per page 9 of the Blue Book).
I pay particular attention
to the gear extension system since on my solo flight after Swift check
out the gear motor failed and I had to crank down the landing gear. Just
reinforced that after this episode, extra care is necessary. Thanks, Steve
Roth & N2397B
SWIFT EXPERTS RESPOND
TO A CABLE... (030600)
From the Yahoo! Globe Temco
The emergency gear extension cable came off of the large pully at the
upper part of the strut. Though I put it back on, it remains somewhat
lose. Could I tighten it by cranking the emergency handle counter clockwise?
or Clockwise? while the plane remains on the ground. Thanks for your help.
-- Rich Pizzi <firstname.lastname@example.org> N2328B
The first thing that should be done is to get the airplane up on jacks
and to make sure the system operates properly. There are several items
which will keep the cable in the groove, one is a cable guide, SB #35,
the other is a simple addition of a loop of .032 safety wire, see the
Commings Manual. If the cable is too tight in the "down" position, it
will be too tight and possibly break in the up position or pull the pully
brackets off the spar web. DO NOT CRANK THE SYSTEM PARTIALLY DOWN TO TIGHTEN
UP THE CABLE -- Jim
I know everyone talks about the "Maintenance and Operation Information
Manual" available from Swift Parts, but who reads it? Please!!!! Get a
copy... On page 10 it covers what is most likely your problem, i.e., "Emergency
Gear System Lubrication." Just in case you do not have a copy handy, in
part here is what it says... "The most common complaint is the cable was
off the pulley someplace. Lubrication of the worm gear assembly and regular
thorough check of the entire system usually eliminates most of the problems...
." Whatever you do, Rich, do NOT operate with the cable partially retracted!!!
Check the worm gear and spring. Make sure they are clean and well lubricated
with "light" lubricant (NOT grease). Make sure it is not in contact with
boot (upholstery) covering the front spar. Check it once in a while (at
least at each annual). May the force be with you... Steve Wilson <SteveWlson@aol.com>
I'm reading something in your message that the others have not mentioned.
Study the gear system and especially the emergency pulldown so you know
what's happening in your aircraft's system. Put the airplane on jacks
as Monty has suggested and pull the bottom panel under the spar area.
Secondly, pull the panel of the floor just in front of the seats. That
exposes the emergency pull down mechanism below the emergency crank down
handle. You get under the airplane and have someone (using checklist)
crank the gear down for you so you can see what the emergency pull down
system does for you. UNCRANK the system and cycle the gear using the normal
gear system. Then you get in the cockpit and do the emergency crank down
using the Emergency Pull Down Checklist yourself. Have someone watch from
outside to tell you when the gear downlocks are locked on BOTH gear. This
way you can see the emergency pull down do it's thing from the bottom
and the top as well as FEEL the pressures involved in cranking the gear
down. You will have an appreciation for what the simple system does for
you. If you ever have to crank the gear down you will understand what
is going on and be a better Swift pilot in the end. Also, follow the suggestion
to clean and lube the jack screw so the sleeve assembly (PN 2882) moves
freely during the cranking operation. Look in the Swift parts manual on
page 12&13 and you can see how the system is put together. Another
hint, when you preflight, pull smoothly down on the emergency pull down
cable a couple inches in each wheel well and release the cable slowly
back to it's proper location. This will give you an idea of how the cable
routing is working and may disclose whether the cable is off the pulleys
somewhere in the system. Hope this helps you understand your bird better.
Added note: Plan on coming to National this year and attend the maintenance
seminars. Wealth of information discussed there and IT'S FREE. Ed Lloyd
Hoping to not appear that I am piling on ----- I had similar problem with
slack gear cable. It began with the pulling on the emergency gear cable
in pre-flight. Cable would not go back smoothly so I examined the screw
mechanism. I had some grease on it and cold weather had made it thick.
The idler pully that rides up/down on that shaft would not move freely,
so the spring would not keep the cable tight easily. So, I completely
degreased the mechanism and used only light gun oil to lube it. That did
the trick. But, then, while doing all of that I managed to get the cable
beneath a stringer as it passes to the wings and it eventually got jammed,
got some slack in it and came off the large pully on the actuator. Fortunately,
I found that condition as I did my preflight by checking the gear cables.
What really saved the day was the modification of adding the safety wire
recommended in "the book" had been done. That prevented the cable from
really getting jammed.
I wrote this up and Denis
published my whole story in his electronic newsletter several months ago.
The bottom line for me was
(1) keep the mechanism cleaned (several times a year) and lubed with light
gun oil; (2) make sure the safety wire modification is installed; (3)
when checking during pre-flight if you pull cable out to check for free
movement let it go back slowly so as not to "jump" and get caught on anything.
Steve Roth <email@example.com>
EMERGENCY GEAR CABLE TENSION...
To: Dennis Mee <firstname.lastname@example.org>
Hi Jim, My question is how tight should the emg ext cable be when
the gear is retracted? I can pull the left gear down with the hyd system
depressurized, it takes a good pull but it will unlock. The emg ext cable
is pretty tight with the gear up so I intend to loosen it but don't know
how far to back it off, any suggestions? Thanks, Dennis Mee
The pull down cable gets pretty tight. If you can pull the gear out with
the selector "up" but with he system depressurized, it may not be going
over center enough. The cause is usually that the teeth on the rack are
mis-indexed on the gear in the actuator, (one tooth off) or the pull down
cable is too tight. Before you tear out the actuator back off the tension
on the pull down cable. Back it off enough that the gear won't crank down
and lock, then add just enough tension so it will. The right amount of
tension is the minimum amount that will get the job done. I presume you
know that it takes approximately 52 turns of the crank. Be sure the screw
does not unthread. Read the service bulletin on this. (the serial numbers
in the service bulletin may not be right) -- Jim
to: Swift Landing Gear Emergency Extension Page Two