Aircraft Electrical Tapes

Several, depending on the type and application. MIL-I-19166C (with QPL-19166) is the primary US military specification for glass cloth electrical insulation tape — it defines the grades, classes, and minimum physical and electrical properties. The AS23053 series (formerly MIL-I-23053) covers heat-shrinkable insulation sleeving rather than tape directly, but you will encounter it in harness specifications alongside tape references. For polyimide film tape, the relevant OEM specifications and process specs vary by platform. When the approved maintenance documentation calls out a specific specification, that is the governing reference — not the tape manufacturer’s generic datasheet.

The classification refers to the maximum continuous operating temperature the insulation material is rated for, following the IEC 60085 thermal classification system. Class F is rated to 155 °C. Class H is rated to 180 °C. In aircraft harness applications, the insulation tape class must be compatible with or exceed the thermal class of the wire insulation it is applied to. Using a Class F tape on a harness routed through a Class H zone is a selection error. Verify the thermal class requirement against the harness specification and the zone classification before specifying or ordering.

The corrosion factor test puts copper strips in contact with the tape under heat and humidity, then measures the change in electrical resistance of the copper. A corrosion factor of 1.0 means the resistance of the copper after exposure is unchanged — the adhesive and backing chemistry have not attacked the conductor. It is not the same as a galvanic corrosion assessment between dissimilar metals. It specifically tells you the tape won’t chemically degrade the wire it is wrapped around over time. In a harness environment where the tape sits against copper conductors for years in humid conditions, a non-corrosive result is the minimum standard — anything above 1.0 should prompt you to check the adhesive chemistry before specifying.

Pressure-sensitive adhesive bonds under hand pressure at room temperature — no heat, no solvent, no curing step required. Most aircraft electrical tapes use PSA for this reason. The “thermosetting” part describes what happens after the tape is applied: the adhesive cross-links further when exposed to elevated operating temperatures, so performance improves with heat rather than degrading. This matters in a harness application where the tape will see repeated thermal cycling. A standard PSA softens and loses bond strength at temperature. A thermosetting PSA stiffens and stabilises. The distinction is relevant when selecting for high-temperature zones — confirm the adhesive type on the datasheet, not just the backing and temperature rating.

Glass cloth silicone above 180 °C, polyimide below it — but temperature isn’t the only factor.
Glass cloth is tougher. Better abrasion resistance, better in high-vibration zones, better where the bundle routes near structure. Thermosetting silicone constructions can reach 260 °C continuous — well above the PSA class ceiling.
Polyimide is thinner and more conformable. Better for tight geometries and small-diameter wire. Standard PSA ceiling is around 180 °C.
Either way, the AMM or OEM process spec takes precedence. This logic only applies where the approved data leaves you discretion.