LANDING GEAR STRUTS

WORN SPOT ON STRUT...
From: ejectr@javanet.com (Bob Runge)
Hi Jim:
I have a worn spot on my Adel right strut. Can these be re plated? Thought I read somewhere that they were too thin to grind. Best regards.......Bob Runge

Bob,
If its just a spot that gets rusty, I would sand it with fine paper, and keep it polished and lubricated. The Adels originally only had a flash coating of chrome. the ELIs have several thousandths of chrome. Recent mfg. replacement Adel strut tubes have more chrome than the originals. Yes, the wall thickness is only about .090 for the Adel strut tubes, too thin to allow grinding. If you have straight cylinders, they could be re-chromed, if proper procedures to eliminate hydrogen embrittlement are followed. If the chrome ends up adding a little to the OD of the strut, you get a side benefit, if there is wear in the brass bushings that the struts ride in, they will probably fit real nice after chroming. If they fit TOO tight, chuck the tubes in a lathe and polish - and polish - and polish.....with 320 wet or dry, until they fit just right.  --  Jim

ADEL STRUT QUESTION...
Subject: Re: Adel Struts
ejectr@javanet.com writes:
Hi Jim: With the struts properly filled, how many inches of strut tube should be exposed?
Thanks Jim. Best regards....... Bob Runge

Bob,
The Swift Operators handbook doesn't give a figure for the Adel gear. The Adel gear is dependent on the spring installed in it for strut extension. You can also install 1/8" air valves in the 1/8" pipe threaded holes in the strut meant for adding fluid to the Adel strut. A few years ago they had some "extra length" springs made up, which I installed, mistake! My struts are only up an inch or two now. (note the picture of the gear on my web site) I have the air valves installed too, but the Adel "O" rings don't do a perfect job of holding air pressure, my right one leaks the air out after just a few days. The good news is, this is not critical, the gear still absorbs shock as well as a perfect Adel gear. The Adel is rougher than a properly inflated ELI gear, for this reason I don't run high tire pressure, and don't like the 15:6:00x6 tires. BTW - the book gives a figure for the ELI gear - 3.75 inches of extension at GW. Oh, the struts are properly filled, when on jacks and fully extended, the oil level extends to the filler hole. The 1946 fluid was AC 3580 what we have now is Mil 5606.  --  Jim

STRUT EXTENSION...
From: Dennis Friedrich (dennisd@televar.com)
Subject: Gear
Jim,
I own 3773K and when I received it the gear scissors were extended almost all the way. Several have questioned the nearly full extension.....what is the correct scissor attitude and what is the method of correcting it? Thanks,  Dennis

Dennis,
I presume you must have the ELI landing gear. The book figure is 3.75" extension at GW of the airplane. If its fully extended, that won't hurt anything, but may ride a little hard and will make not-so-perfect landings seem like crashes! Deflating them a little is kind of tricky, since the air is on top of the fluid and if you simply try to bleed them off at the air valve you get a face full of 5606. The right way to do it is on jacks, with the gear "up". If you lose fluid, you have to estimate how much and replace that amount. I used to have a setup made out of a Swift brake reservoir so I could blow in fluid and air together. The right way to do it is to drain the cylinder, then with the strut flat, fill it completely with 5606, then air it to 3.75". I prefer nitrogen, but you can use a strut pump. An air compressor with say, 200 psi, won't cut it. You need 400 psi available, although I think 200-300 psi will service the strut properly. Maybe you should just leave them the way they are! -- Jim

ADEL STUT MAINTENANCE...
Bob Runge (ejectr@javanet.com) writes:
My Adel struts have air fittings on them. Do I fill them with oil then pump a specific amount of air into them or do I run just air in them? How much air in either case?

Bob,
Remove the fittings, fill the struts with 6506 with them extended, reinstall the fittings, air, some guys get by with 20 psi. There is no specific amount of air. Originally, the amount of air in the strut was what was trapped above the fluid level. (not much) Mine leak, so I air to about 100 psi, and the left one holds pressure for a while, but the right is almost flat in a couple days. The air valves are "unofficial", so you are on your own.  --  Jim

HOW TO MAKE AN ADEL GEAR FORK FIT AN ELI...
Jim Montague (monty747@aol.com) writes:
I have taken Adel forks, welded up the keeper bolt hole, (3/8”, I think) and had my machine shop owner friend bore them out for the ELI strut dia. (-.001-.002) The air valve can be located as original with more machining, or re-located near the top of the strut, (like it should have been in the first place) I don’t have any ELI parts, or know of any, but I have some Adel forks.

WE GONNA PUMP YOU UP...  (050399)
Keith Bracht <kab_bjb@skat.net> wrote on the Yahoo! Globe Temco Swift Club...
After some touch and goes yesterday I noticed the right strut had about 2" of chrome showing and the left was still at 3.75". Do I need to service the low strut? In the Answer Man archives Jim mentioned a strut pump. Is this something I should get? Who sells them and how much does one cost? Thanks.

Keith:
Most FBO's have either a strut pump or a high pressure nitrogen bottle for airing struts.  I would hope you won't need either often enough to need to buy them. A strut pump will need to be capable of 400 psi at low volume. Sometimes you can find these at FBO auctions at very low prices. New? Probably more than you want to spend! Your airline probably uses high pressure nitrogen. Can you taxi in to one of their gates and get a "squirt"? -- Jim

BUT WAIT!!! THERE'S MORE ELI LANDING GEAR... (8199)
From: "George N2451B" <gi@globe-swift.net>
Subject: RE: ELI gear
Hi Monty,
Now here is the next problem: While we pushed the Swift back into her hangar the gear (strut) came up a lot. Now I feared that it might come out completely so I let out all nitrogen. Unfortunately we still cannot push the strut back in (we have not tried very hard though in order not to damage anything...) Could it be that it is already sitting on the gaskets? Is there a trick to get it back in? Since my Adel on N2451B already sits low I was thinking of getting new springs for it (or sending it to the states to get it rebuild). Does it make more sense to install an ELI instead if one can still get one? Thanks for your help! Regards, George

George,
Just remove the remnants (if any!) of the scissors (what is the common name for the torque link) and the brake. Then pull the strut out of the upper cylinder. When you get the strut cylinder/fork/axle assy. out inspect the "O" ring inside the outer cylinder. It may be twisted or just dry. Inspect all the parts. If the "O" ring is worn or cut replace it. If it is deformed, it may come back in shape if you soak it in 5606 for a day or two. With a serviceable "O" ring in place, lubricate it with a copious amount of Vaseline (petroleum jelly) and reinstall the strut. The only thing that keeps it from blowing out is the scissors - thus the requirement for a STEEL part. Fill the cylinder with MIL5606 with the strut flat. There is an allen head pipe plug at the top of the outer cylinder which holds the metering tube and also provides a place to put in the oil. You obviously will need a new scissors, contact Joe, sorry I can't tell you where there are any ELI scissors' - if the other side is aluminum, you need two. Don't air the strut until the scissors is installed! With everything in place, air to 3.75" strut extension. You will need a strut pump or a nitrogen bottle with approximately 500 psi available. (the strut will take 300-400 psi) I also suggest a bolt and bushing kit if there is excess wear. See previous letters on this!

I like the ELI better. It's much easier to replace the seal etc. It's also harder to service afterward. The big advantage to the ELI is, when properly serviced, it rides like Cadillac vs. a Model "T" Ford. It also is a little lighter than the Adel gear. (If you folks in Europe are not familiar with the Model "T" - believe me, the ride is ROUGH, kind of like a Swift with Adel gear ;-)

...and BTW, if you are going to groundloop a Swift, do it with the Adel gear! The forging blank for the fork is the same, but the ELI has a larger dia. strut cylinder, thus the wall after machining is thinner. Plus, they made a hole there for the air valve, not a good move. I broke one once! (details on request) The forks can be interchanged. (kind of) To use ELI on an Adel, a bushing must be made up with the Adel strut ID and the ELI fork OD (.001" tight on each) The 3/8" keeper bolt holes need to be welded up and the fork machined smooth. To use an Adel on an ELI, the fork must be machined to the correct dia. to accept the ELI strut. Don Bartholomew expressed concern about the heat treatment of the welded parts, my guy claims he can take care of that. Another thing - the chrome is much better on the ELI struts.

I don't know if you can find any, (ELI gear), they are scarce as hens teeth as they say. The ELI also takes different gear doors BTW. (factory type) The so called P-51 gear doors should work on either. My Adel gear on N2431B sits low too - when I rebuilt them I used the "extra length" springs - which was a mistake. The springs are regular die springs available here in the states from any spring shop. I think I would like to. get a set heat treated to maintain their "set". I'm not sure I understand spring engineering, but I've been told a longer spring makes a softer ride. I guess I need to get a textbook and read up on that subject! I have overhauled a LOT of Adel landing gears and it's not too bad if you have Mr. Cummins book (hydraulic manual - available from Swift Association) and a press to compress the spring while you get the snap ring out. -- Jim

STRUT PROBLEM... (8199)
My left gear strut is fully extended and will not compress at all. Even with a bunch of air bled off it is still rigid. I know about the 3.75" extension but how many pounds of air should be in there? I've even greased the chrome but nothing seems to compress it, not even my landings! Thanks. Keith Bracht <kab_bjb@skat.net>

Keith: I suspect the "O" ring is dry inside the outer cylinder. Try putting Vaseline on the strut and jumping up and down (gently!)on the wing walk. You may have to release more air. -- Jim

STRUT YOUR STUFF..  (9499)
Subj: Adel Chrome Gear Strut
From: Bob Runge <ejectr@javanet.com>
Hi Jim:
How's it going? We survived Floyd with just a lot of rain (which we needed) and some minimal gusts. Not too bad. I read in the latest newsletter that the Adel chrome struts were going to be available through Swift parts. They are talking about just the chrome tube.......correct?

Bob,
Yes, that's just the chrome strut tube -- they were getting $400.00 for them - I don't know how much the new ones will be. To change them requires an experienced mechanic. The spring on the strut needs to be compressed to get a snap ring out, and heat needs to be applied to get the fork off. -- Jim

ELI LANDING GEAR...  (11299)
From: Pete King <peetking@earthlink.net>
CC: arbeau@napanet.net
Was there a pattern for the use of Eli gear? -- my 665 has them but they seem to be random in their use...

Pete,
The ELI gear was used on many of the Kilo series airplanes. On N80665 it must have been installed later. I had them on N2334B, but they were installed by me. The Buckaroos, which were made around 1950 also used the ELI gear. -- Jim

"AIR'IN UP" THE STRUTS... (060200)
Subject: Re: ELI gear
From: joenorton@webzone.net
Jim: Need some info on putting hydraulic fluid and nitrogen in my ELI struts. I know this is not the prescribed way to do so but please tell me if the way I'm doing it will be okay. I put the plane on jacks and let out any air pressure and hydraulic by removing the Schrader valve. I then hook a hose to the opened valve and place the other end in measuring cup with hydraulic fluid in it, lift up on the wheel let it come down which sucks up the hydraulic fluid. I do this until there is about 4oz of fluid in the strut. Close up the Schrader valve and then hook up the valve to a nitrogen bottle. Last time I did this Joe advise me to put in 180lbs in the strut. The result was a fully extended strut. Now I'm going to have to try and let out a little pressure but I don't think I can control the flow to get down to the 3.75". I guess my question to you though is this an okay way to get the job done. -- Joe Norton

Joe,
I would say that method should work ok. As you know, if a little air (nitrogen) is bled off, you will lose fluid since the air is on top of the fluid. I was always going to relocate the air valve near the top of the strut to avoid that, but never got around to it. Perhaps you could bleed out a little air with the gear retracted. I never tried that when I had an ELI gear, but was told it works. Usually, if the strut is fully extended, but not way overfilled with air, it will work ok. -- Jim

LEAKING STRUT... (080600)
Subj: ELI Struts
From: jerrycobb@mindspring.com (JERRY COBB)
Jim,
As the designated caretaker of 3301K (#1294) since 1972, I am asking for ideas in regard to my leaking right ELI strut. Since the resurrection of "Old Hurricane" by Swift Works in 1997, I have been plagued with a strut leaking down over a period of 4-6 weeks. The other strut has never required air. You may recall that this is the Swift that was destroyed by Hurricane Andrew 8 years ago today in MIA and "resurrected" (Charlie's word). I have removed the plug at the top of the strut and serviced the strut with 1506 per the original Swift manual. When the air (nitrogen) charge continued to leak with no evidence of fluid at the Schrader valve, bottom plug, or on the barrel, I began to tighten the top plug a little more each time that I serviced the strut with nitrogen. I have applied liquid dish soap with a little water added around the top plug, but no bubbles are visible. As I stated, this is a very slow leak. During the a/c rebuild the struts were overhauled. It seems that a long time ago that I had a similar problem and it turned out to be a small leak around the top plug. Any ideas or suggestions would be welcomed. Would an air leak around the barrel seal leave a fluid residue? What is a good way to tighten the top plug?  Thank you for your time and effort in being the "Answer Man" and to Dennis for putting forth the "Electronic Effort". Best Regards, Jerry Cobb

Jerry,

Gee, have you "only" had N3301K since 1972? I well remember the picture of N3301K and the D'Arcy Swift inverted over Miami. It seems like you have had it forever! With air loss and no sign of fluid leakage it does indeed sound like the top plug is leaking. I guess I would start over and replace the "O" ring and service the fluid, then with the top plug removed, I would clean the threads on the plug by polishing on a rotary wire brush. Also clean the threads in the upper cylinder. Then I would apply some super sealant to both sides and reassemble. (Use something made by Locktite or 3M that will not be affected by hydraulic oil) While you have the chrome strut removed, polish it with 400 wet or dry sandpaper. Remember, when the gear is "up" during flight, a portion of the "O" ring will be at the high point of the gear air and fluid, so the small leak may occur at that time. Does the gear leak down if you don't fly the airplane? Also the Schrader valve may leak when it does not have the viscosity of the hydraulic fluid acting on it. -- Jim

SERVICING THE ADEL STRUT IS DIFFERENT THAN THE ELI...  (090100)
Subj: Landing gear fluid
From: marvin@accesstoledo.com (marvin-h)
Jim, I have done my homework but I would like to confirm this with you. About filling the Adel landing gear with hydraulic fluid. It says to fill the struts with 5606 while the plane is jacked up and the gear is fully extended. Fill with fluid to the top of the filler plug. Since this is exactly backward to what I am used to doing on another brand X airplane it seems strange to me. How about setting me straight. Marvin Homsley N80740

Marvin,
That is right. The only air that the Adel struts are designed to have in them is what is above the fluid level when filled to the level of the filler plug. Some guys discard the filler plug and install a 1/8 pipe air valve and air the strut to between 20 and 100 lbs. If the "O" ring seal is not perfect, the strut will leak down in a short period because there is not much volume. The way most air/oil struts are serviced is with the strut flat, fill with oil, then air to the desired extension. This is the way the ELI gear is serviced. -- Jim

WOBBLY GEAR FORK ON THE EARLY ADEL GEAR... (090300)
From: Roy Cook <RCook63133@aol.com>
Jim,  Hello again, hope you are well. I told you about changing the brakes on my GC-1A and I finally got around to it. In the process I found that the left gear needed to be rebotled and rebushed, that went OK, when I got done doing that I found that the gear fork had a lot of movement from side to side, I didn't measure the movement but I estimate it at about 1/16 to 1/8 of an inch. That seems like a lot of slop. Can you tell me what others have done for this problem. I have had others tell me that plating the strut end to build it up and then grinding it size, is this the way to repair this or is there a better way. Any help you can give me would welcomed. Thanks, Roy

Roy,
Um, rebotled? I'm not sure I understand where the wear is. Most of the landing gear wear limits are given in AD 47-06-01 and AD 51-11-04. Do you have the Adel gear? The early GC-1A's had a Globe gear that is similar, but different. The chrome strut rides in a brass bushing, which is usually where any wear will be evident. I think Swift Parts has that bushing for the Adel gear, if you have the Globe gear you will have to try and find a used one, I think it's different. Swift Parts might have a used one. I know Allan Erickson has a set of those early landing gears. <swiftalbon@earthlink.net> If the chrome looks good on your strut that is not where the problem is. That early gear was made by ELI and the chrome is much better than the Adel gear. The Adel gear just has a flash coat of chrome and the early and the late ELI gear have perhaps .010 of chrome. (BTW - the early gear can be identified by welded construction and a fluid reservoir at the top inboard of the trunion) Perhaps someone out there has a set of those early gears (if that's what you have) and will offer to part with them. -- Jim

WOBBLY GEAR FORKPART 2... (090300)
Subj: Re: GC-1A landing gear
From: Roy Cook <RCook63133@aol.com>
Jim,  I think the wear is in the connection of the fork and the strut lower end. Thanks, Roy

Roy,
If the strut is loose in the fork that is unusual nut not a difficult fix. The fork should be removed and a short piece of steel tubing obtained. You want the ID to match the strut, less about .001 or .002. Then the fork should be machined out to the OD of the tubing less .001 or .002. You want tubing with a wall thickness of .062 or less, a couple inches long. Reassemble using heat to obtain a tight fit. Having said that, I went over to Mark Holiday's hangar and we disassembled one of those early landing gears. They don't have the brass sleeve like the Adel. There is one brass sleeve about 3/4" high near the lower end of the upper cylinder and a similar "cap" at the upper end of the chrome part of the strut. To remove the lower end of that type of gear is very easy. Just remove the gear door clamps. At the lower end there are 4 ea. 3/16" AN426 rivets holding the "guts" in the gear, not shot, just in shear with the clamp holding them in. With the brake removed, pry out those 4 rivets with a dental pick and then the lower end slides out. (The scissors must be removed, and the airplane must be on jacks of course) From your previous description, I presumed the wear was between the lower sleeve and the side of the steel portion of the upper cylinder. Any wear at that point could be fixed by the installation of a little stainless shim stock. At the upper end, there is an "O" ring which should be replaced, it is an AN6227-32. That is the simple fix, if it is necessary to replace the "O" rings on the inside of the bushings, it will be necessary to compress the strut and remove the springs, which is a lot harder job. If replacement of the brass sleeve is necessary there aren't any parts available, but the lower one could be made from an Adel part by cutting it off the right length and otherwise copying the old part. If you cannot repair your gear using these instructions, I would suggest you hire a knowledgeable aircraft mechanic. -- Jim

JUST A DROP OR TWO... (090300)
Subj: ELI Gear
From: Phil Howell <POPPAPOU@aol.com>
Hi Monty:  I realize you have probably covered this else where, but I haven't been able to locate it. I have a slight oil leak at the bottom of my left ELI MLG strut. It appears to be coming from next to the outer edge of the cylinder. Just a drop or two in 1/2 hr. Need your advice of what to do. I really appreciate your help and advice, not only to me, but to the whole Swift gang. Thanks again, Phil N3313K

Phil,
I wonder if it's really leaking there, or if it's leaking at the "O" ring and showing up there? If it is, in fact, leaking at the bottom of the cylinder, it will be necessary to jack the airplane, deflate the strut, remove the brake and scissors, and remove the strut and fork assembly from the gear. Then using heat, remove the fork from the strut cylinder. Next, braze around the lower plug, reattaching it to the cylinder tubing. Use caution to avoid heat damage to the strut chrome. If you can't do this, or don't know anyone who can, you might try thoroughly degreasing the strut and applying a little Locktite No. 620 Green. It will fill spaces to 1.5 mills and is good to a temp. of 450 deg. I have never heard of an ELI leaking there, although one run of Adel struts unfortunately, did leak at that point commonly. If you do use the Locktite, be sure to follow their directions. A few hours at an elevated temperature may help set it up. Like in an oven. -- Jim

THE PRESSURE IS ON... (100400)
From: Steve Wilson <SteveWlson@aol.com>
Subject: Re: October #3 GTS Internet Update
In a message dated 10/9/00 21:43:49 Central Daylight Time, arbeau@napanet.net writes:
<< The reason that it seals better is the fact that it always has positive air pressure, and that is exactly what an O-right seal wants. Bob Williams from Lansing, MI, has replaced the filler plug on his Adel landing gear with a Schrader plug (i.e. 1/8" pipe fitting with a valve core) and puts about 25 psi in the strut. I examined his struts and they were the driest Adels I have ever seen. I believe he said they were on there for 2 1/2 years now with touching them! >>

Sorry it took folks so long to catch onto this. Since about 1969 I have been pressurizing the Adel struts. I found that with good struts (meaning no pits) somewhere around 50 psi did the trick (maybe lower would work, I dunno). I have run as high as 85 psi with no problems, but that was with "Quad-X" seals. The only problem is that with higher pressures touchdowns are kinda like landing on ball-bearings if you run more than 25 psi in the tires (remember recommended pressure is 20 psi). It probably depends on the weight of the airplane, but with an 1825 GWT on my stock airplane 25/60 works out OK. -- Steve Wilson

STRUT SEAL...  DON'T DO IT!!! (110500)
Subj: Hydraulic Resevoir
From: Bob Runge <ejectr@javanet.com>
Jim, Any harm in putting strut seal in the hydraulic reservoir? Someone suggested I do it. I said "I I I I I I I I I... don't think so! Thanks. Bob Runge

Bob, Don't do it! Strut seal swells the seals, the idea is to keep them from leaking. If you have some leaking seals in the hydraulic system, it may stop the leaks in the short term - but the seals won't last very long. Then you would be faced with replacing every seal in the actuators, downlocks and power pack. --- Jim

RON'S IDEA OF FUN...(010101)
Subj: ELI strut fun
From: Ron Williamson <rwwilliamson@earthlink.net>
Monty,
Keeping with this month's hydraulic scheme . . . what exactly is inside an ELI strut? I have a seal to replace and have never quite understood how the innards work. In my struts, the tapered top plug has an attached tube with a cone shaped end which only loosely fits inside the inside tube of the lower assembly. I'm guessing the large chrome bottom assembly is basically a tube within a tube and the cone thing acts as a crude metering device to reduce the bouncing on those less than perfect landings. I've followed the filling directions in the manual and it seems like very little fluid is pumped in before it runs out the top plug. Do you know of a cutaway drawing or any more details on what's inside?

25 years ago when I bought 40K, the hex drive taper plugs had been rounded out so badly that I had to braze a bolt into the plug to make it into an "outie". The head is short enough that it clears everything while giving me a good grab with a 6-point socket, but it still requires teflon tape, thread sealer and serious torque to keep from losing pressure. Is this normal? I've thought about machining out the pipe threads to straight, facing the top of the strut and using a straight thread plug with an o-ring. But, there's the issue of how that metering rod thing gets attached. Ideas?

Ron,
The plug at the top of top of the strut is regular pipe plug, a 3/8" I think, I never could eyeball pipe fittings and it's been a while! Attached to that plug is the metering valve, which "floats" on a rivet. The only part that usually needs replacing is the "O" ring. I would think if your pipe threads are damaged or corroded a pipe tap will clean them up. If the plug itself needs replacing you will have to look how the original is assembled and if you have the capability to duplicate the rivet. I can't give you great detail on this point because I haven't looked at one for years and I don't remember everything! As long as you have the metering rod plug removed just fill the strut up completely with 5606. (with it flat) Then later, when reinstalled on the airplane, fill it with nitrogen to the 3 3/4" figure. -- Jim

ON TO PAGE TWO OF LANDING GEAR STRUTS...