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Strut servicing


fryguyokc
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We've deflated the struts completely. We have an individual that suggests banging on the struts with a soft mallett to get any remaining air out of them before we top them off with fluid. He has a ton of experence with many other aircraft and claims he has done that for years. There isn't anything in the books saying to do it but was wondering if there are people out there doing it or if there are any reasons why it shouldn't be done. Thanks!

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After your through hittem' with a mallet try kicking the tire to check the tire press and then raise the crew door waist high and shake it side to side. Just a few other usless tricks some people do to a 130. HA Ha. Larry is correct, use the T.O. to service the strut properly. Just remember press vs. x measurement. Bill

Edited by Spectre623
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It works. For those that say don't obviously have zero experience in servicing struts. Fill the strut to the top of with fluid. It's not full. Because if you walk away and come back an hours later the fluild ISN"T topped off anymore. So you have to put more in. Hitting the strut with a mallet just speeds up the time you have to wait for the fluid to settle.

The Navy manual states

"Deflate Nitrogen & Remove servicing valve."

"WAIT 1/2 HOUR then fill with hydraulic fluid to top of service port"

"WAIT 1/2 HOUR, check hydraulic fluid level, repeat until full."

Hitting the strut with mallet bypasses the "WAIT 1/2 HOUR" over and over evolution. < You can hit the strut till its topped off, then wait the 1/2 hour and it will be still topped off, because you "Knocked" out all the air bubbles the fill, wait 1/2 hour, fill, wait 1/2, fill, wait 1/2 hour would accomplish.

Though haven't done in years. And it seems the Navy has some cool technology the Air Farce doesn't for once. last 8 years or so I was in the navy, we had a "Strut Servicing Machine" Hook up all three struts(P-3) and flush the gear all at once then serviced them to the correct fluid level and air pressure.

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I you try to service the struts according to the technical order, you are going to improperly service your struts - even when on jacks. The writers failed to take into account the trapped air or nitrogen in the struts, but you will be confident that you did it correctly.

Back when we had SOAP sample kits, we taught the new guys to slowly turn that curved tube while running it up and own inside the strut through the filler port. We also told them to get ready to duck - when they hit an air pocket, it was going to come up the filler port quickly and usually got someone wet with fluid. After doing that, we could usually add at least a half quart more fluid.

I found a method that seems to work well - if you are on jacks. I'd lower the strut about six inches and pour in another quart of fluid. Using a disassembled shrader valve with a clear hose attached, screw the valve into the strut and drop the other end into a bucket, I'd slowly raise the strut again until the fluid comes out. I can get much more even servicing of the stuts doing it that way.

The next technique that works better is to use a "Y" house with one gauge to service the nitrogen. That eliminates gauge error from causing uneven struts.

I'll try the soft-faced mallet next time.

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We've deflated the struts completely. We have an individual that suggests banging on the struts with a soft mallett to get any remaining air out of them before we top them off with fluid. He has a ton of experence with many other aircraft and claims he has done that for years. There isn't anything in the books saying to do it but was wondering if there are people out there doing it or if there are any reasons why it shouldn't be done. Thanks!

Yes, light tapplng on the strut will dislodge air bubbles that cling to the inside walls of the strut. Useing a single gauge and a "Y" hose when serviceing nitrogen is a good practice. Exercizeing the strut with the schrader valve open is also recommended. I never used the tube with the "U" bend but if I was still in the bussines I'd give it a try.

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Lots of very experienced current and past maintainers advocating subject procedure, citing different methods. However, in all the posts did not see a single TO, page and paragraph detailing hammering a deflated strut to ensure removal of air/nitrogen. Seems to me if this was, in fact, a valid procedure, it would be in the TO. As a flight line troop most of my career starting as a third wiper and concluding as sqd. superintendent including a tour as QA super. was adament about following tech data. In those instances where tech data was deficient or just plane dumb - and there were many - we made every effort to change it. If an AFTO 22 failed we made it a PMR/MMR adjenda item. The point am trying to make is if the procedure is valid it needs to be in the tech data!

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The amount of air that may be loosened by this mallet method is not worth the possibility of someone using something other than a dead blow mallet and is just is not worth the aggravation. (worked few other airframes and never heard the strut banging thing) The Hydro Mite is the strut servicing cart the Navy has been using forever and is currently used at USAF C-130 ISO's and is the ALTERNATE PREFERRED method for servicing all strut without even jacking the aircraft. Hopefully we will have one here at Kadena soon (working on that).

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Just because the TO doesn't say to do it doesn't mean its a tech data violation to do it. I haven't seen any warnings, cautions, or notes in the TO saying you can't do this.

Rest assured you would be hard pressed to defend this position if in front of an accident investigation board. Suggest some research is in order to ascertain just exactly what a tech order is and is not.

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Just because the T.O. doesn't say not beat on the LOX bottle with a hammer doesn't make it the RIGHT way to do it!!

It's not a hammer, it's a mallet. And besides, if anyone can come up with a logical reason why hitting a strut (which is capable of supporting 100k + lbs) with a rubber mallet in ANY way is harmful, I'm all ears.

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Lots of very experienced current and past maintainers advocating subject procedure, citing different methods. However, in all the posts did not see a single TO, page and paragraph detailing hammering a deflated strut to ensure removal of air/nitrogen. Seems to me if this was, in fact, a valid procedure, it would be in the TO. As a flight line troop most of my career starting as a third wiper and concluding as sqd. superintendent including a tour as QA super. was adament about following tech data. In those instances where tech data was deficient or just plane dumb - and there were many - we made every effort to change it. If an AFTO 22 failed we made it a PMR/MMR adjenda item. The point am trying to make is if the procedure is valid it needs to be in the tech data!

You do have the perfect QA inspector position on the procedure - and sometimes we must send the QA guy on an errand so we can get the job done.

As for Tech Data, after several years at WR-ALC, I've seen how some T.O. changes take place. I can assure you that our technical orders are not corrected by experts and the suggestions that make it into tech data and those refused are sometimes done in error. There is such a thing as general practice that have proved themselves over time, and those techniques don't get included into tech data because they are not suggested or they are evaluated by the guy on the floor that is asked for his opinion - who might not use it himself - so it is then declared "dumb."

I've submitted AFTO 22's when I was AD that were turned down but then showed up in Tech Data several years later - only because of which guy on the floor the people from the T.O. office took the suggestion to.

Not all ideas that are not in the T.O. are dumb - they are just not in the T.O. If we want to see if a job violate the Technical Data, then we need to actually check for violations - not just "helpful procedures that are not there." Common sense is not illegal.

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I probably shouldnt say anything. But of course I've already started. Every once in awhile the fire warning control system would stop flashing the T handle in the cockpit. Behind each engine positioned in the wing was a fire warning control box. This little black box had a relay inside that would sometimes stick. A little tap on the box with a wrench would fix the problem more often than not.

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This has been a hot topic of discussion for a long time. The J publications only states: "A more accurate fluid level indication can be obtained by allowing SUFFICIENT TIME for as much entrapped air as possible to escape prior to checking fluid level" which is very open to interpretation. I have heard accounts that when an aircraft required both struts serviced on one side, the servicing was performed by a fairly inexperienced crew and as they did not leave enough time for all the air bubbles to escape, when they charged the strut and dropped it off jacks it seemed fine however possibly due to a dry, sticking strut (didn't lubricate chrome part of strut during servicing,) on landing, both struts bottomed out due to excess of gas in the strut and damn near tipped a wing. This probably could have been avoided had the crew tapped the strut with a mallet after servicing.

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This has been a hot topic of discussion for a long time. The J publications only states: "A more accurate fluid level indication can be obtained by allowing SUFFICIENT TIME for as much entrapped air as possible to escape prior to checking fluid level" which is very open to interpretation. I have heard accounts that when an aircraft required both struts serviced on one side, the servicing was performed by a fairly inexperienced crew and as they did not leave enough time for all the air bubbles to escape, when they charged the strut and dropped it off jacks it seemed fine however possibly due to a dry, sticking strut (didn't lubricate chrome part of strut during servicing,) on landing, both struts bottomed out due to excess of gas in the strut and damn near tipped a wing. This probably could have been avoided had the crew tapped the strut with a mallet after servicing.

Agreed, The answer to our younger troops should ALWAYS be follow what the tech order says period, not some old or new ways we found to do things unless it's in the book!!!

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