Broken bonding wire grounds aircraft?

[waterguy]

how many bonding wires are on that flight control? one or two? Is this a question of safty or legality?

 

[DaveJ]

This model C172 just has one wire per elevator half. The question is not a safety of flight quesion, but is it legal to fly with a broken grounding wire if fixing it is deferred until the next 100 hour inspection.

 

[Avimec]

ding ding, you're right!!!

I've seen several A/C hit by lightning. Usually on a prop tip and usually exits off the rudder and or elevator. Seen static wick bases gone but control surfaces blown off or hanging by the bonding strap? Gimme a break!!!!

Where did i say........control surface??? I cant find it maybe you can help me. You are right in a prop plane usally that is what happens. good job! But it dosent have to happen like that, it can hit the top of wing and punch holes in the belly every 2 in. or blow of a winglet. But none of that was the point All i said was its only a bonding wire, yes get it fixed when you can, but its not flight critical!!!! All i'm sayin.

 

[skydivinguy]

Where did i say........control surface??? I cant find it maybe you can help me. You are right in a prop plane usally that is what happens. good job! But it dosent have to happen like that, it can hit the top of wing and punch holes in the belly every 2 in. or blow of a winglet. But none of that was the point All i said was its only a bonding wire, yes get it fixed when you can, but its not flight critical!!!! All i'm sayin.

You didn't say contol surface, you said parts were hanging on by the bonding strap. Not sure what you work on but only control surfaces have bonding wires where I am.

 

[AgDownUnder]

If there aren't any static wicks on the flight control, then the bonding wire serves absolutely no purpose what so ever.

Common sense must overcome stupid behavior.

Yes it does actually, whether or not you have static wicks. It is there to save the bearings from a current flow caused by a difference in electrical potential between the airframe structure and control surface. Granted, it is typically not much, but there is a static difference, and when this current runs thru the bearing, it can cause pitting and premature failure. As to the lightning strike issue someone else brought up, it won't make a difference since the potential charge is still equalized through the bearing.

 

[Avimec]

You didn't say contol surface, you said parts were hanging on by the bonding strap. Not sure what you work on but only control surfaces have bonding wires where I am.

Well have you worked on many airplanes? Control sufaces are not, by far the the only thing that has bonding wires. Most everything in airplanes are bonded somehow, even composite parts. Ex. Vertical stab tip Do328 blown off in lightning strike (bonded). Wing tip(s) Crj200 blown off about 6 in worth. Never even touched the static wick. Holes blown in fus. on jets What about the bonding wires then. Doors are bonding wired. some lights are bonding wired. most electronics, and yes bonding wires are mel'd alot. All im saying is its a bonding wire.

 

[MauleSkinner]

(2) The inoperative instruments and equipment are not--
(i) Part of the VFR-day type certification instruments and equipment prescribed in the applicable airworthiness regulations under which the aircraft was type certificated;

If the airplane is certificated under the current Part 23, you'd have

Electrical Bonding and Lighting Protection
§ 23.867 Electrical bonding and protection against lightning and static electricity.
(a) The airplane must be protected against catastrophic effects from lightning.
(b) For metallic components, compliance with paragraph (a) of this section may be shown by -
(1) Bonding the components properly to the airframe; or
(2) Designing the components so that a strike will not endanger the airplane.
(c) For nonmetallic components, compliance with paragraph (a) of this section may be shown by -
(1) Designing the components to minimize the effect of a strike; or
(2) Incorporating acceptable means of diverting the resulting electrical current so as not to endanger the airplane.

I couldn't find anything that says it only needs to be bonded for certain operations, so technically, it probably needs to be repaired (again, assuming certification under current Part 23).

Fly safe!

David

 

[cforst513]

Well have you worked on many airplanes? Control sufaces are not, by far the the only thing that has bonding wires. Most everything in airplanes are bonded somehow, even composite parts. Ex. Vertical stab tip Do328 blown off in lightning strike (bonded). Wing tip(s) Crj200 blown off about 6 in worth. Never even touched the static wick. Holes blown in fus. on jets What about the bonding wires then. Doors are bonding wired. some lights are bonding wired. most electronics, and yes bonding wires are mel'd alot. All im saying is its a bonding wire.

doesn't the engine have a big bonding wire too?

 

[DaveJ]

Yeah, but the one on the engine block is not for static electricity. You wouldn't be able to start the engine if that one was broken.

 

[RafaelThielmann]

What can i say after all what was said already?
If you aren't able to fly it according to the manual, DON'T DO IT!
I've seen some stupid accidents when the pilot thinks his experience will make him able to overcome any mechanichal problems...

 

[cforst513]

does it matter if the airplane will be flying in severe-clear weather?

 

[MauleSkinner]

does it matter if the airplane will be flying in severe-clear weather?

Not unless you can find something that says it's weather-dependent.

David

 

[DaveJ]

We're going to fix it

The question wasn't really whether or not to replace the broken bonding wire, we are going to replace it at the next 100 hour. The question is can the broken wire be defered and the plane flown legally until we get it fixed.

One of the pilots who is also an A&P says yes, another pilot says no. I'm just trying to get opinons on the question.

 

[RafaelThielmann]

Now you got me... but i'm sure that where you're going to perform the 100 hour they can tell you if that's a grounding item or not.

 

[MauleSkinner]

The question wasn't really whether or not to replace the broken bonding wire, we are going to replace it at the next 100 hour. The question is can the broken wire be defered and the plane flown legally until we get it fixed.

One of the pilots who is also an A&P says yes, another pilot says no. I'm just trying to get opinons on the question.

Remember...opinions don't count. "Just" go through 91.213(d) step by step, and you'll have your answer.

David