TRIPPED/COLLARED CBs IN FLIGHT DECK.
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TRIPPED/COLLARED CBs IN FLIGHT DECK.
Can anyone please inform me of the MM requirements for flight deck CB collaring?
Is it acceptable/desirable/legal/good sense to use BLACK nylon tie-wraps for this purpose?
Bearing in mind as Commander it is incumbent on me to know what's been disabled IAW MM and also what may have tripped due to malfunction, and the scan of the CBs panels is difficult enough at night in ambient manufacturers lighting without ADD tripping/collaring being difficult to observe with black rather than white or colour conspicuous tie-wraps being used.
I ask because I have got some odd looks and inadequate replies from line maintenance staff when I have queried such a practice.
Chapter and verse from any MM, especially Boeing would be appreciated!
Is it acceptable/desirable/legal/good sense to use BLACK nylon tie-wraps for this purpose?
Bearing in mind as Commander it is incumbent on me to know what's been disabled IAW MM and also what may have tripped due to malfunction, and the scan of the CBs panels is difficult enough at night in ambient manufacturers lighting without ADD tripping/collaring being difficult to observe with black rather than white or colour conspicuous tie-wraps being used.
I ask because I have got some odd looks and inadequate replies from line maintenance staff when I have queried such a practice.
Chapter and verse from any MM, especially Boeing would be appreciated!
Never seen or used tie wraps of any colour myself.
Seems bad practice to me.
Each airline does have different policies however. I don't think you will find it in the AMM. MEL or DDG maybe.
Seems bad practice to me.
Each airline does have different policies however. I don't think you will find it in the AMM. MEL or DDG maybe.
Circuit Breaker Lockout Collars
Depends what it says in the Minimum Equipment List (& Procedures) / Dispatch Deviation (Procedures) Guide (or whatever name your organisation uses for the same effect).
Any permissible defect will be listed in the (customised) MEL / DD(P)G, etc. which is based on the Master MEL (find them here: Flight Standards Information System (FSIMS)). If it's not listed in the Remarks and Exceptions column - or the Maintenance Procedure field - then it shouldn't be pulled / collared.
An exception would be when there are system modifications / deactivations that necessitate such action, but then you would hope that the operator would have a method of letting you know if that was the case......
Any permissible defect will be listed in the (customised) MEL / DD(P)G, etc. which is based on the Master MEL (find them here: Flight Standards Information System (FSIMS)). If it's not listed in the Remarks and Exceptions column - or the Maintenance Procedure field - then it shouldn't be pulled / collared.
An exception would be when there are system modifications / deactivations that necessitate such action, but then you would hope that the operator would have a method of letting you know if that was the case......
I think the point is about 'how' its collared, not 'if'.
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I'm not aware of any MM requirements to use official collars. But through experience I've found that when trying to cut off tie wraps with snips it's quite easy to damage the CB itself. I think it's preferable for the crew to be able to quickly identify inop systems, hence the collars are red. Try asking your respective airline to clarify their policy?
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I've seen black/white tywraps used on CB's. This has been done on systems that are being deactivated and/or removed from an aircraft. So if you were part way thru a modification/deactivation procedure, then you might be instructed to do this.
Now the instructions might come from an "in-house" EO,EA,Mod, etc. Then at a later date the rest of the procedure would be carried out. Usually the Tywrap would be black as to not appear "popped-out" on your scan.
As a pilots perspective, you might not see this in your logbook, because the task was part of an existing check/shop visit. So you would have to view that particular maintenance visit check paperwork, to view what was carried out on an task card. thus you do not see that entry in the logbook. So it does not mean that the CB was collared outside of AMM practices. But it is most likely that you would also see a sticker over the CB ident to say "deactivated" or "INOP". Also if used, notice to crew, as to advise you that a aircraft system is being removed/deactivated/not required and is part way thru the maintenance instruction.
On the other hand, I have also seen CB's locked out with tywraps due to that maintenance station not having correct CB collars available. Now thats when the company has run out of those items, does not stock those items, or its an culture with-in that organisation that does not/has not used correct CB collars at all.
So if you have asked maintenance about a tywrap on a CB, and you have been given weird looks, then its possible that its a culture issue.
Now the instructions might come from an "in-house" EO,EA,Mod, etc. Then at a later date the rest of the procedure would be carried out. Usually the Tywrap would be black as to not appear "popped-out" on your scan.
As a pilots perspective, you might not see this in your logbook, because the task was part of an existing check/shop visit. So you would have to view that particular maintenance visit check paperwork, to view what was carried out on an task card. thus you do not see that entry in the logbook. So it does not mean that the CB was collared outside of AMM practices. But it is most likely that you would also see a sticker over the CB ident to say "deactivated" or "INOP". Also if used, notice to crew, as to advise you that a aircraft system is being removed/deactivated/not required and is part way thru the maintenance instruction.
On the other hand, I have also seen CB's locked out with tywraps due to that maintenance station not having correct CB collars available. Now thats when the company has run out of those items, does not stock those items, or its an culture with-in that organisation that does not/has not used correct CB collars at all.
So if you have asked maintenance about a tywrap on a CB, and you have been given weird looks, then its possible that its a culture issue.
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We have 2 basic types of collars, one is relatively easy to clip on or pull off usually used during maintenance or deferral. Basic practice is not to push in a popped breaker unless you can identify and isolate the reason the breaker is popping. Also not to collar a popped breaker until the root cause is identified or isolated, I also feel I should have a supporting E.A. etc when doing so.
The 2nd type usually need to be pried off and they are usually used on deactivated systems.
Bottom line to the O/P is that there is nothing wrong with using a tye wrap, so long as the breaker can not be pushed back in. Not ideal, I don't really care if the C/B is damaged upon removal so long as it is operational or is replaced afterward.
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The 2nd type usually need to be pried off and they are usually used on deactivated systems.
Bottom line to the O/P is that there is nothing wrong with using a tye wrap, so long as the breaker can not be pushed back in. Not ideal, I don't really care if the C/B is damaged upon removal so long as it is operational or is replaced afterward.
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In my experience tie-wrapped cb's are normally for circuits that have been permanently deactivated,capped cb's are for temporarily deactivated systems - MEL items for example.Saying that, I cannot recall ever seeing any specific info regarding capping of cb's.
Whilst I appreciate A red CB collar is the preferred method are you telling me you will ground a machine because you do not have any rather than disable the CB with a Tie wrap?
As for damaging cbs when you cut them off you obviously do not know how to cut a tie wrap.....
As for damaging cbs when you cut them off you obviously do not know how to cut a tie wrap.....
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You might prefer the ones made out of angled aluminum attached to a terry clip - when in place on the overhead panel if you haven't noticed it as you try to get in the seat it cuts your head open - fortunately being red the blood don't show and the airline saves a few pennies so thats OK!
Last edited by time-ex; 14th Jul 2013 at 22:26.
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Color IS mandatory, and coded... red, yellow... description comes in standard practices. ESPM for Airbus and SWPM for Boeing. Other manufacturers also have, it is mandatory to, in order to have a TC.
A line Eng would always have some in the toolbox. Unless you're a "pen" Eng.
A line Eng would always have some in the toolbox. Unless you're a "pen" Eng.
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On the occasion when I did not have a red cb collar to hand (we keep them with the spare bulbs on the a/c) I did not use a ty-wrap, but wrapped a bright orange ADD sticker around the pulled CB, and subsequently stated this in the write up.
I would not use ty-wrap (not even sure we are allowed to!) just seems bad practice to me, but what do I know.
Airbus says:
Circuit Breaker Safety Practices and Clips:
A. General
(Ref. Fig. 029)
(1) It is necessary to safety an open circuit breaker with safety clips when:
- there is work on an electrically controlled or supplied system during maintenance.
- such a system is deactivated and not serviceable. In this case, it is necessary, for safety reasons, to identify them differently from temporarily clipped circuit breakers.
The manufacturer recommends safety clips P/N ABS0772 but the operator can use equivalents that obey the requirements that follow:
(2) It is important to use safety clips that:
- are easy to install and remove
- do not cause damage to the circuit breaker or circuit breaker panel.
It is always better to use plastic safety clips because they prevent the risk of accidental short circuits (if they fall in an electrical panel, for example).
(3) Use:
- a white safety clip if full provision in the flight operations.
- a red safety clip for a flight operation in MMEL conditions or for ground operations.
NOTE: Some circuit breakers (A320 family only) have a red threaded bush (P/N A92529086000). This bush prevents a reset of the circuit breaker in flight (the crew cannot pull it).
If, for maintenance safety reasons, it is necessary to open such a circuit breaker, you can remove the red threaded bush with a standard wrench.
I would not use ty-wrap (not even sure we are allowed to!) just seems bad practice to me, but what do I know.
Airbus says:
Circuit Breaker Safety Practices and Clips:
A. General
(Ref. Fig. 029)
(1) It is necessary to safety an open circuit breaker with safety clips when:
- there is work on an electrically controlled or supplied system during maintenance.
- such a system is deactivated and not serviceable. In this case, it is necessary, for safety reasons, to identify them differently from temporarily clipped circuit breakers.
The manufacturer recommends safety clips P/N ABS0772 but the operator can use equivalents that obey the requirements that follow:
(2) It is important to use safety clips that:
- are easy to install and remove
- do not cause damage to the circuit breaker or circuit breaker panel.
It is always better to use plastic safety clips because they prevent the risk of accidental short circuits (if they fall in an electrical panel, for example).
(3) Use:
- a white safety clip if full provision in the flight operations.
- a red safety clip for a flight operation in MMEL conditions or for ground operations.
NOTE: Some circuit breakers (A320 family only) have a red threaded bush (P/N A92529086000). This bush prevents a reset of the circuit breaker in flight (the crew cannot pull it).
If, for maintenance safety reasons, it is necessary to open such a circuit breaker, you can remove the red threaded bush with a standard wrench.
Last edited by spannersatcx; 18th Jul 2013 at 19:32.
