Valve cap missing

[Dream Land]

Looked around for information on this subject but no luck, is a valve stem cap required to be installed prior to flight, I made our reluctant engineers produce one prior to our flight today. A321 MLG.

The sign off "none in stock, ADD raised".

[Golden Rivet]

The valve cap is the primary seal.

The is nothing in the MEL/DDG to allow you to defer .

[spannersatcx]

no it's the secondary seal, there's many things not in the MEL but you can still go!

[grounded27]

Clearly not a safety of flight issue, probably should have went on record in your NEF program "may be what an ADD is". He did his job correctly, sounds like you are being a pick and have intent to burn the guy.

[Dream Land]

Well I'm not really looking for someone to take my side, I am simply the last line in the Safety chain and want to ask the experts about the subject, and as Golden Rivet points out, it is not listed in the MEL.

Grounded27, it sounds like you have some major issues with flight crews, whatever your problem is, from your point of view, if the engineer followed proper procedure, how would I possibly burn him by delaying the flight until they find a valve cap, I would be the one having tea and biscuits with the CP?

Cheers, D.L.

[Krystal n chips]

spanners,

Erm, if it's not the primary seal, what is it's purpose and how come I was taught this many years ago and indeed, it is still taught today ?...we could get into the realm of semantics here of course,...dust cover vs primary seal..and then there's the cover for acc.charging points of course...

dream land....to be honest, you seem to have turned a non event into an event. A missing primary seal is hardly a stopper now is it?....and your comment about " I made " the engineers etc, etc, suggests you have taken the "I am the captain, do as I say " line....rather than, er, talk with the engineers and come to an agreement. Nobody is going to jeopardise an aircraft now are they...?

Why didn't they just take one off another wheel assy, ... and even if it was a line station, they would have a couple of spares...and then order a new one...simple solution really.

[Wirelock]

the cap i think you are referring to is for the charging valve of the mlg?
having a lot of experience working on landing gear i would have considered this as a cover to prevent dirt entering in the valve. the charging valve itself has a special operation. it needs to be loosened twice before you can service the gear.
regarding dispatch for sure you can fly without this cap so raising a HIL was the right thing to do.
you can also see them on brake bleeding ports, door accumulators as well as the resevoir charging port. there are a lot more.
hope this helps

[grease7]

Golden Rivet points out, it is not listed in the MEL.

If you want to have everything listed in the MEL, there wouldn't be an aircraft flying anymore. The MEL would also get really big

[Golden Rivet]

The wings aren't in the MEL, but you'll be needing them for an on time departure. Granted, the MEL preamble provides you with a statement along the lines of 'non-airworthiness items are not included'. But as far as know, the only person that can make this determination is the manufacturer.

[Wirelock]

many things attached to the wings are in the MEL so not a valid argument

[grease7]

But as far as know, the only person that can make this determination is the manufacturer.

So if that's your opinion you would ground an aircraft because of a piece of missing carpet (not in the MEL) while waiting for permission of the manufacturer

[cod liver oil]

Given the number of tire changes that are carried out on the ramp by line mtce personnel, I'd venture to say that a majority of engineers have spare caps either on hand or close by.

I'm surprised that the LAME in Dream Land's situation couldn't produce one.

K 'n c, the valve core is the primary seal. Is the cap considered a secondary seal or simply a dust cover? Let the thread continue

rgds

cod

[spannersatcx]

We once had a 3rd party customer 747 arrive with about 4 of the 18 caps remaining, suffice to say we didn't have enough for the rest of the wheels so DD'd them. I seem to remember there was something in the classic MM about the caps being a secondary seal so was quite happy to DD them. Unfortunately don't have those manuals anymore so can't look.

Anyway I could of course be wrong, it has been known , perhaps I have learnt something new again today.

[spannerhead]

http://www.airmichelin.com/uploadedF...ice_manual.pdf
This pdf from a manufacturer implies (p49 I think) that the cap is solely to keep dirt out. Surprised the hell out of me because I have always believed that the cap was the primary seal.

[Alber Ratman]

So there is no need for a core then..
A Valve cap is exactly .. a cap to protect the valve!

[Wirelock]

well before the thread is led astray. I just want to specify that i am talking about the A320 gear.from your comments it seems it is possible on other aircraft types that the cap has another function

[Tranwell]

The cap is a secondary seal. The primary seal is part of the valve core. The cap's functions are:

1: Prevent debris from entring the valve stem and depressing the core
2: To act as a secondary pressure seal in the case of core failure.

On an A320, a single tyre, let down under reletively controled conditions (core failure, so no explosive decompression), would not cause the aircraft to be uncontrolable on the ground. So worst case scenario is that you have one flat tyre. Its not in the MEL, so engineers must use COMMON SENSE / ENGINEERING KNOWLEDGE to dictate whether the aircraft should fly or not. Thats why you get paid big bucks!

[Alber Ratman]

ASFKAP... You mean there is a danger of brakes being fodded??

[TURIN]

I was taught many years ago that the cap is the primary seal. The valve is there as a convenient device to allow one to inflate the tyre and act as a secondary seal.

Was I led up the garden path all those years ago? Possibly, I'll have to dig out my copy of CAIPS, maybe it's in there.

It used to be a CAA oral question, How can you tell if the cap is servicable?

Answers on a post card........

[grounded27]

Quote:
But as far as know, the only person that can make this determination is the manufacturer.
So if that's your opinion you would ground an aircraft because of a piece of missing carpet (not in the MEL) while waiting for permission of the manufacturer

I brought up an acronym before NEF, it is used widely under FAA governance and would surprise me that every other CAA does not have guidelines for aircraft operaters to create a seperate lits of Non Essential for Flight items to be repaired or replaced usually before the next c check. NEF items are often AMM items. When not covered by the AMM or MEL a NEF item is generally approved for a non mel deferral by the operators maintenance controller. Are there not programs like this in the EU?

Education on this matter may help the OP from asking questions like this in the future.