Aircraft Oxygen Bottles

[av8erab]

If an aircraft oxygen bottle leaks to zero, what must be done? Just refill it or is there more?

 

[Coool Hand Luke]

First, how do you know it's your O2 bottle leaking and not one of your O2 masks? What's the leak rate per day?

 

[avbug]

If your oxygen system isn't holding oxygen, then obviously it needs to be fixed. Perhaps I missed something, but I think you just asked if when a system is found to be malfunctioning, should you ignore it, or fix it. Is this so? Of course you fix it.

If the system is bleeding down, the source of the leak must be located and the problem solved, period. A bottle should never leak. If the bottle is leaking, you have a major problem and definitely should not fill the system or put it under pressure. Leaks occur at joints and fittings, and at the mask.

Gas pressure lines leak the gas under pressure around threaded fittings, cracks in lines, at the mask. If a soap solution is sprayed onto each potential leak site, bubbles will form where the gas leaks. What type of soloution depends on the gas. In this case, oxygen. You can't use any soloution with a petroleum base, because it reacts with with the oxygen. While some mechanics will use a dishsoap solution, a special solution is sold just for use with oxygen systems which doesn't leave a deposit, doesn't attract dirt or contaminants, and doesn't react with oxygen.

Finding and fixing the leak isn't preventative mx, especially with an oxygen system. Simple mistakes like improper use of sealant tapes or compounds can cause big problems in the oxygen system, to say nothing of improper torque on fittings, line flarings, etc.

Fix it.

 

[wrightflyer]

Depends on the operation but at the airlines the whole bottle must be replaced you cant just re-fill it, but of course you want to find the leak so it wont happen again.

 

[Mr Wu]

I think you're asking if there is any special inspection on the bottle itself because the pressure dropped to zero, like in scuba tanks?

I'm not quite sure but you should probably send it to overhaul to make sure that no crap or water got in there. Cheap insurance for when you need it.

 

[erj-145mech]

Check your type/model/series maintenance manual for specifics, but generally after a leak is located and repaired, the system must be purged before the airplane is released for service.

Also refer to your component maintenance manual, but your bottle may required a special internal inspection before servicing if the pressure was allowed to be reduced to less than 50 psi.

 

[av8erab]

That was it, is there any special procedure since it went really low? Obviously it needs to be fixed but is there more?

 

[avbug]

Depends on the bottle and system. Generally if the pressure drops and the bottle is within it's life limits, hydrostatic tests, and pressurization cycles (if applicable), then you'll do nothing more than purge the system and refill once the leak has been located and fixed.

In many cases, once the leak has been located and handled, the bottle will simply be refilled.

Different requirements apply to composite, aluminum, or steel bottles or tanks.

 

[A-Track]

If the pressures went below a certain level (I forget what it is off the top pf my head) then the bottle must be sent to a shop to be serviced and have a new / overhauled certification issued, once it's empty or below that level you can't just fill it up at the local FBO.

 

[avbug]

That is not correct as a general rule. Certain systems may have this as a requirement, but this is not a standard practice with all oxygen systems.

 

[Gatorman]

If a soap solution is sprayed onto each potential leak site, bubbles will form where the gas leaks. What type of soloution depends on the gas. In this case, oxygen. You can't use any soloution with a petroleum base, because it reacts with with the oxygen. While some mechanics will use a dishsoap solution, a special solution is sold just for use with oxygen systems which doesn't leave a deposit, doesn't attract dirt or contaminants, and doesn't react with oxygen.

Wow, I sould start visiting the site again more often.

It appears that his question is what to do with the bottle if it is found to have no pressure in it. Of course he will locate and repair the leak. BTW it is not recommended to use 'dish soap', the product used for detecting oxygen leaks is call SHERLOCK ( http://wintonproducts.com/id21.htm )
Anyway, back to the subject matter - I have always taken the safety route, so when it doubt sent it out and have it inspected. I was going to just leave it at that, but I knew that if I did some one would bust me on it.
So, here is what Uncle Fed sez :

Do not attempt to charge oxygen cylinders if any of the following
discrepancies exist:
1. Contaminated fittings on the manifold, cylinder, or outside filler valve.
If in doubt, wipe with stabilized trichloroethylene; however, do not permit
solvent to enter any internal parts. Let air dry.
2. Cylinder out of hydrostatic test date. DOT regulations require ICC or
DOT 3AA designation cylinders to be hydrostatic tested to 5/3 their
working pressure, every 5 years. Cylinders bearing designation ICC or
DOT 3HT must be hydrostatic tested to 5/3 their working pressure every 3
years, and retired from service 15 years or 4,380 filling cycles after date of
manufacture, whichever occurs first.
3. Cylinder is completely empty. Do not charge, as the cylinder must be​

removed, inspected, and cleaned

Here is the link where I found it:
http://www.tc.faa.gov/logistics/grants/pdf/1997/97-g-005.pdf

 

[avbug]

A random text by the technical center is not regulatory, so no, "Uncle Fed" doesn't dictate that a bottle be removed for testing if depleted.

Many mx manuals specify purging if the bottle drops below a certain pressure or is depleted, primarily because with no positive pressure in the system, an unsealed system can admit atmospheric pressure, and therefore moisture.

Sending the bottle out for testing when depleted is not necessary unless specifically called for. Neither is hydrostatic testing or other inspection proceses, unless specifically called out.

You'll note that with regard to dish soap, I specifically stated that while many mechanics do use it, it's not acceptable...work on your reading comprehension.

Liquid leak detection will assist in locating gross leaks, but not all leaks. Many leaks do not even produce a bubble. Additional methods are available to locate system leakage, ranging from flourescent to ultrasonic to pressure systems using helium, to electronic detectors and gas analyzers. However, the most common method today is still visual detection using a liquid spray and bubble method.

 

[Gatorman]

Well, since you do not know from what manufacture this oxygen bottle comes from and you do not have a copy of their maintenance data.... you go ahead and just fill that puppy up!

I would rather go the safe route, maybe spend a few bucks more than to have an incident from being right all the time. Seems that an "I told you so" would not quite fair too well if this oxyen bottle got a little chip of corrosion (saying that is is a steel bottle) and it cloggs the regulator during a flight at altitude.

 

[avbug]

How about he just follows the mx data that he's required by law to follow, instead of blindly wasting time and money in the first place?

Nothing to do with knowing it all. The counsel that the bottle must be or even should be sent out for an inspection is ridiculous. "Uncle Fed" doesn't require it, we don't have enough information to go on with the original poster, nor do we know if the original poster is a mechanic.

Sending the bottle to "overhaul" is a bit over the top, simply because the system pressure bled down.

 

[STAL6]

The maintenance manual of the aircraft I'm currently working on says if the oxygen cylinder pressure drops below 50psi the cylinder must be replaced. It does not say what to do with it, so I would contact the manufacturer. I found that in ch. 12 servicing.

 

[Gatorman]

Ok Avbug, I know you know the answer to this one...

Given the information above, what are you going to do with STAL6's oxygen bottle?


Do you go with what the maintenance manual says?
- or -
Do you go with what the bottle manufacturer says?

Do you replace the bottle like the aircraft manufacturer states to do in their maintenance manual and buy another bottle?

 

[STAL6]

Gatorman, I would have to replace the bottle, no doubt, but I would call the manufacture to see what can be done with the bottle after I've changed it out.

Stal6

 

[avbug]

Do you go with what the maintenance manual says?
- or -
Do you go with what the bottle manufacturer says?

Do you replace the bottle like the aircraft manufacturer states to do in their maintenance manual and buy another bottle?

Seems like you've added a lot of choices in there that weren't in STAL6's post. He didn't stipulate anything about what the bottle manufacturer stated, and you've given the same choice twice: compliance with the maintenance manual...but provided it as an "or" selection to appear as three choices.

We haven't even been provided with details as to which maintenance manual is in question, know nothing about additional STC's or AD's on the matter, or any other pertinent information. What would I do? I'd get more information, because whereas you've expanded on a question that didn't have information to begin with and introduced things that weren't there...we don't even know if STAL6's use of "maintenance manual" refers to the bottle manufacturer, aircraft manufacturer, or other data.

When I see maintenance manuals for aircraft on which I work, I see the airframe maintenance manuals, I see individual manuals for brakes by the brake manufacturer, and yes, even maintenance pubs for the oxygen system. Further, I may see manuals which need to be addressed separate from the airframe manufacturer because of optional or STC'd equipment...so rather than make a reply to your question which introduced material not even in the posters statement, how about we seek a little clarity?

The maintenance manual of the aircraft I'm currently working on says if the oxygen cylinder pressure drops below 50psi the cylinder must be replaced. It does not say what to do with it, so I would contact the manufacturer. I found that in ch. 12 servicing.

I know a lot of folks who use old O2 tanks for service bottles or shop air at reduced pressures. I've worked in several shops where WWII bottles wee still in use as portables for minor service work on the line. Personally I take compressed gasses and their handling and servicing quite seriously. A ruptured tank can do more than ruin your whole day.

This, of course, doesn't address the original posters comments or the discussion that thence ensued.

 

[Gatorman]

Gawd... with all that hot air, you should be a balloon mechanic.

Ya give the man a simple question and you provide the answer and he STILL doesn't answer it.

Years ago when I first came across this site, I had a lot of respect for you....


The answer is, you go with what the aircraft manufacturer's maintenance manual says. If it is not aircraft manual, you then go to the next level - who installed it.
Who ever installed it in the aircraft has to have gone by the bottle manufacturer's specifications.

Example:
If the bottle manufacturer tells you to replace it with a new one every 12 years and the aircraft manufacturer tells you to replace it every 10 years - you replace it every 10 years.

 

[avbug]

You failed to give a simple question. And you expected an answer to a items you made up and introduced. Are you not able to stick to the facts?

Fact: STAL6 didn't state which manual he used (aircraft manual could refer to any number of the).

Fact: STAL6 didn't state what other documents might be applicable.

Fact: STAL6 didn't state if he meant the airframe manufacturer or the bottle manufacturer.

Fact: We don't even know if the bottle that's in the aircraft is original equipment, or if additional documentation might apply.

The answer is, you go with what the aircraft manufacturer's maintenance manual says.

No. You go with the what the component manufacturer's approved publications and data have to say on the subject. The airframe manufacturer may or may not have anything to say about a bottle manufactured by someone else. Where a conflict exists on life limits, yes, the most conservative provision applies. However, simply because an item or appliance is installed in a particular airframe does not mean that the documentation or instruction ends with the airframe manufacturers data. It doesn't.

A common example is a powerplant, in which the airframe serves as the customer to the powerplant. Want engine data? Go to the engine manufacturer.

Want to know what to do with Cleveland wheels or BF Goodrich brakes? Go to their publications. Want to know about an airborne pump? You can't just look to the airframe manufacturer; yo go to the appliance or component manufacturers data, too. Which is precisely why I said we needed more information to answer a question which lacked any semblance of information in the first place.

If it is not aircraft manual, you then go to the next level - who installed it.

Absolutely NOT. The installer doesn't set the parameters for the product that's been installed. I can't install an item, for example, and then establish the airworthiness limitations and components life limits merely because I installed it.

If an item has been installed by a supplemental type certificate, then the STC should spell out either the limitations themselves, or point to the approved data where that information will be located. In many cases, STC's ammend what's published in the airframe manufacturer's data, requiring additional mx manuals, additional publications, and additional data.

I didn't complicate anything; the issue is more complex than a vague reference to a "maintenance manual" with the hope of gleaning somethin definitive from that reference alone. You know this. Or you should.

Who ever installed it in the aircraft has to have gone by the bottle manufacturer's specifications.

That really has no bearing on the life limits or other constraints which might be imposed by AD, STC, bottle or airframe official publications and data. That the installer may or may not have adhered to the bottle manufacturer's requirements is subject to what you see when you inspect the system, and whether the installer did it correctly or not, you're responsible for all previous work when you return that component to service. If you accept what's been done before and don't re-do it yourself, then you're now responsible for what others have done...regardless of whether they complied with any specific requirements or not.

Moreover, I've seen plenty of work done by mechanics and installers in the past which was incorect. Sometimes grossly so. As assumption that anybody properly complied in the past is a very dangerous one to make indeed. Especially when your fingerprints are now on the work, too. You know better than to assume.

What others did to comply in the past is also really quite irrelevant, so long as you're working on the product, because your job is to ensure that it's compliant now, and that when it leaves your hands, with your signature intact, it's 100% compliant with ALL relevant data. Not merely the airframe manufacturers, and not merely the bottle manufacturers. You may have additional relevant data with which to comply which doesn't apply to either one, such as the manufacturer of the regulator which is attached to the bottle etc.

Data is often applicable by effectivity only, segregated by serial number or part number. It may be applicable to one bottle, or one bottle type and not the next, and this information may be found in only one of the several sources discussed above. It's just not as simple as going to chapter 12 and being done with the matter...and it's CERTAINLY not as simple as referencing the installer of the equipment.

Years ago when I first came across this site, I had a lot of respect for you....

I suppose that's very sweet, but I really don't care.

Ya give the man a simple question and you provide the answer and he STILL doesn't answer it.

You didn't do that, of course. You provided a question regarding STAL6's post, then proceded to introduce things that weren't in his post in a nonsensical manner which served only to muddy what should have been a rhetorical question in the first place. It was neither a simple nor a correct question, and deserved only the reply it received.

You've argued throughout the thread falsehoods and assertions which are incorrect. You showed us references to "Uncle Fed" which weren't really accurate, difinitive, nor regulatory, and suggested throwing out the baby with the bathwater just to be on the safe side.

If you want to get specific, then let's do so. But use real data, and all the data, and quit making things up. You'll fare much better.