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Can turbulence cause damage to old Kapton insulated wire?

Posted: Sat Aug 14, 2021 2:33 am
by convair880mfan
There are a lot of threads and posts on Kapton wire insulation but I am wondering whether old Kapton insulated wire can be damaged due to turbulence? Would turbulence cause wire bundles to chafe against the things[?] that hold them in place? Thanks for any and all responses.

Also . . . what was used before Kapton wire insulation and was it superior although heavier? Not sure there are any civilian airliners still in first line passenger use that have this kind of wire insulation.

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Sat Aug 14, 2021 6:40 am
by fr8mech
Normal aircraft vibrations can cause damage to any wire. Wire will rub against other wires, clamps, lacing or structure.

Properly bundled, laced, routed and clamped wire harnesses will reduce this type of damage.

Turbulence while not uncommon, really wouldn't cause the damage we typically see on wires. The damage we see is usually caused by long-term abrasion or chaffing...and the occasional errant twist drill bit. It happens.

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Sat Aug 14, 2021 3:38 pm
by convair880mfan
Errant twist drill bit?

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Sat Aug 14, 2021 3:39 pm
by convair880mfan
Errant twist drill bit?

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Sat Aug 14, 2021 3:42 pm
by DL_Mech
convair880mfan wrote:
Errant twist drill bit?


People drilling out rivets without knowing what is behind said rivet.

Most older Boeings used a wire called Poly-X before Kapton. Tefzel is also a popular wire which has a ethylene-tetrafluoroehtylene (ETFE) insulation.

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Sat Aug 14, 2021 4:47 pm
by convair880mfan
Were the Poly-X and Tefzel better than the Kapton? What has replaced Kapton?

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Sun Aug 15, 2021 3:58 am
by DL_Mech
convair880mfan wrote:
Were the Poly-X and Tefzel better than the Kapton? What has replaced Kapton?


Each wire type has their own properties and uses. Poly-X is no longer manufactured. I do not know offhand what has replaced Kapton, but all modern planes have new types of lightweight wiring.

A lot of your questions will be answered here:

http://www.iasa.com.au/folders/Safety_Issues/Aircraft_Wire/index.htm

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Sun Aug 15, 2021 4:35 pm
by convair880mfan
Thanks so much for your response, DL_Mech and the great articles you cited. What a wealth of information.

I wonder if Kapton insulted wiring played any part in the loss of TWA Flight 800. Not sure what kind of wiring was used in the wing tanks of those older Boeing 747's. Not even absolutely certain what really caused the crash of TWA Flight 800.

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Sun Aug 15, 2021 7:23 pm
by fr8mech
convair880mfan wrote:

I wonder if Kapton insulted wiring played any part in the loss of TWA Flight 800. Not sure what kind of wiring was used in the wing tanks of those older Boeing 747's. Not even absolutely certain what really caused the crash of TWA Flight 800.


https://www.ntsb.gov/investigations/Acc ... AR0003.pdf

See pages 22-24 for some information.

From note 53, page 24 of the referenced document:

According to Boeing’s 747 specifications, PTFE (or Teflon) has been used for FQIS wiring in fuel tanks and between the CWT and gauges at the flight engineer station in the cockpit. For simplicity, in this report, the trade name Teflon will be used to indicate PTFE wiring, per MIL-W-16878.

Re: Can turbulence cause damage to old Kapton insulated wire?

Posted: Mon Aug 16, 2021 3:40 pm
by VC10DC10
convair880mfan wrote:
There are a lot of threads and posts on Kapton wire insulation


Bundles of them, I dare say :rotfl: