View Full Version : Bonding Straps

28th Jul 2007, 23:04
So, are they allowable under MEL or CDL etc if they are missing or broken?

I have only found one ref in an MMEL that refers to Surface Bonding Straps "All must be intact".

Is it particular to type or is there a general rule? Cos I can't find it! :confused::uhoh:

Cheers. :ok:

28th Jul 2007, 23:42
It's almost impossible to say what's required on other fleets.

I'd just go with what's required by your documentation.

If your book says all are required, well, there you have it.

Fly safe.

29th Jul 2007, 11:57
Are you enquiring to bonding straps or static dischargers?
I guess your talking about Static dischargers which trail from most commonly flight controls, fairings etc as oppose to bonding straps which earth components and structure.

Dischargers can be found in the CDL, as a rough guide:
747 69 fitted Min23
744 68 min 68
777 50 min 20
330 48 20% missing
340 46 20% missing

CDL further breaks down location (i.e. not allo n one wing) Generally the minium is only allowed if operations are not primary dependant on ADF, HF.

29th Jul 2007, 13:38

Are we talking about Bonding Straps or Static wicks as there are replies that show some confusion??

Bonding straps are betweem parts, and control surfaces, probably invisible to the average pilot given airplanes size etc.

Static wicks are on the extremities of the wings, tail and control surfaces. The MEL/CDL will give the number that must be present. An example may be that," three may be missing, but, all must be present on the ailerons."

As for bonding straps it is unlikely that the CDL/MEL will address them as they are normally hidden, and a maintenance inspection item. They would be checked after a lightening strike, for instance.

Whatever you think, your company manuals are the overriding factor. It is always possible to have a difference between the manufacturers information and your companys. It will usually be more conservative.

Speedbird 48.

30th Jul 2007, 06:39
Without a bonding strap in place, the electrical path between a flight surface and a control surface exists along the control hinges. That's a bad thing.

30th Jul 2007, 21:26
Gentlemen (and ladies to be fair as I have no idea of your gender no matter what you say on your profiles).
Where was I?
Oh yes,
Please don't misunderstand. I am talking about bonding straps. You know, the bits of flexible metal with an eye at each end that you bolt to a componant to ensure continuity.
Thankyou one and all.
I have looked through all the company documentation available. (MEL/CDL/AMM etc) and I still can not find the relevant section that describes how many if any straps are allowed to be missing/broken for flight dispatch.
As a clue Airbus would be the aircraft type of choice in the particular scenario I encountered recently. :ok:

31st Jul 2007, 00:56
If you cannot find any specific guidance then you must take the most conservative approach and infer that *all* bonding straps are required to be installed.

Good luck!

31st Jul 2007, 01:40
Kinda impossible to check that all bonding leads are intact unless the aircraft is in the hangar undergoing a heavy check. Lots of internal oofer-doofers are bonded and they can't be examined without removing lot's of whatchamacallits from the aircraft.

31st Jul 2007, 04:54
Can't say that I recall any documentation that says it is ok to go with them missing. Regularly change a few on 'A' checks. Only leads that can be seen are changed during a transit.

The only effect I can imagine happening (very remote chance) is some radio interference or degraded protection during a lightening strike. ie. might blow a hole in the fibreglass or metal structure (usually bits hanging of the the main fuselage, gear doors, wing to body fairings etc.).


kiwi chick
31st Jul 2007, 05:09
Ohhhhh... BONDING straps... I came into this forum misled.

Bye :E

31st Jul 2007, 11:46
Standard wiring practices manual 20-20-00 has a table which states the number of broken strands allowed in various bonding jumper types.

All jumpers must be installed, some are allowed up to 6 broken strands, others, for example within fuel tanks or insulated jumpers are not allowed any broken strands.

I assume Airbus have a similar document to the SWPM?

31st Jul 2007, 12:09
kiwi chick ...:

Uh, you're not the only one!

31st Jul 2007, 12:56
I fail to see the need to check bonding straps as this falls within the realms of a engineers/service remit.(most of them are hidden).
On a standard walkaround it would not involve one having to check the bonds.

31st Jul 2007, 14:34
Lets go back to basics.

If it isn't in the MEL/CDL you can't go without it!!

I know some clever clogs is going to say you may be able to on a Ferry Permit, but I am talking regular line operations.

Speedbird 48.

31st Jul 2007, 17:07

I am fully aware that the cabin furnishings don't come under the realm of the MEL/CDL, but I thought we were talking about the basic airplane. The thing doesn't have to have any interior in order to fly, such as on delivery flights and that is just a weight and balance issue.

As you so rightly say there are a multitude of bonding straps that a pilot cannot see on a walkround, although if he/she should find a broken one they would of course bring it to the attention of an engineer/mechanic. There are normally several between the various parts, dependant upon size of airplane, and they ensure a multi path route for electrical discharges without welding the hinges, and that is real bad!!

There is a spectacular series of shots of an All Nippon 747 climbing out of Osaka, and being hit by lightning on the internet at the moment. If I was bright I would know how to transfer it from my e-mail to this forum, but???

Speedbird 48.

kiwi chick
1st Aug 2007, 00:42

perhaps we need to start another thread for those who were misled :E

1st Aug 2007, 17:06
It depends on the Number present between the surfaces in the 1st place.There would a need for a certain number in place.

1st Aug 2007, 23:02
Keep in mind that the easiest way for the flightcrew to address the niceties for low importance items .. is to snag it and have the ginger beers sign it off as not requiring fixing at the time. Engineering will have access to more information than the flightcrew and the decision is moved to a more appropriate forum.

This doesn't suggest that the commander should not insist on widget X being fixed if he/she has a sensible reason for so insisting ..

2nd Aug 2007, 00:45
no pilot or eng. doing a P.D.I. would have a clue as to how many bonding straps were intact or broken . During C Check I can regularly find broken or frayed straps on on flight controls. which could have been in that condition for months. And thats the way they would stay until a job card calls for an inspection that would make an engineer aware of the defect. you can't reference an M.E.L. for things you don't know are broken.

2nd Aug 2007, 11:07
Personally, I would feel more comfortable explaining to my QA manager how and why I deferred the replacement of a broken bonding lead than explaining to my line manager how I managed to clock up a tech delay while I replaced a broken bonding lead.

Unfortunately my employer does not feel the same way. Logic does not come into it! :ugh:

As mentioned before, checking of bonding straps is more of a maintenance function than a crew walk round item, if you find one please bring it to my attention but don't get too upset if I simply defer it to be replaced at a more convenient time.

I would agree with that statement except that in the current climate every item that is deferred requires a reference, whether it be MEL/CDL/AMM/SRM/WDM etc. My question is; where is it stated how many missing/damaged can be deferred during a transit?
Terreplaneblues seems to have the answer but whether Airbus' are the same remains to be seen.

Thanks one and all for your input. :ok:

I'm off to Kiwichicks mysterious world of S&M as getting flogged on a regular basis is becoming an occupational hazard so I may as well learn to enjoy it. :ok::O