EMERGENCY EXTENSION CABLE SLIPS OFF PULLY...
From: gi@lucent.de
Subject: Re: Emergency Gear extension
Hi Monty,
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
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 EXTENSION... (3699)
From: Steve Roth (StevenRoth@aol.com)
Subject: Re: Cable Gear Extension
Monty:
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?
Steve,
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
Jim:
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. Jerry S.
Jerry:
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)
From: edlloydaustin@juno.com
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
Ed:
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... (11199)
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 the problem.
(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 Swift Club:
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
<cece@concentric.net> N2328B
Rich:
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
Rich...
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>
Rich,
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
<edlloydaustin@juno.com>
Rich,
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 <stevenroth@aol.com>
EMERGENCY GEAR CABLE TENSION... (040500)
To: Dennis Mee <jmmee@nh.ultranet.com>
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
Dennis,
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