Bonding Strap Condition

A discrepancy report describing a frayed elevator bonding strap that is contacting and rubbing against elevator cable attachment hardware sits at the intersection of two very different maintenance categories: static bonding provisions and primary flight control rigging. Bonding straps (also called static jumpers or grounding straps) are electrically conductive links that equalize potential between moving control surfaces and the airframe, primarily to dissipate static charge and provide a lightning current path, and to a lesser degree to ensure continuity for anti-static/radio noise suppression. They are not structural, and by themselves a worn or frayed bonding strap is a minor discrepancy typically addressed under general condition and continued-airworthiness standards rather than a specific numeric wear limit in most piston single/twin maintenance manuals. That absence of an explicit manual callout is likely why the mechanic characterized it as a non-issue. However, the reported finding here is not simply "strap is frayed" — it is "frayed strap is contacting/rubbing elevator cable attachment hardware," which changes the analysis considerably.

Any chafing or interference between a bonding strap and a primary flight control cable, turnbuckle, or cable-to-horn attachment is a legitimate airworthiness concern independent of the strap's electrical function. Frayed strap wire strands can act like an abrasive file against cable strands, accelerating wire wear, notching, or broken strands at the attachment point, which is precisely the failure mode inspectors look for during cable condition checks per AC 43.13-1B guidance on cable wear, corrosion, and broken wire limits. Even if the strap itself is "airworthy" as a bonding device, its routing constitutes an interference condition that can degrade an airworthy cable into a non-airworthy one over time, and it may also cause intermittent binding, added friction, or unpredictable feedback in elevator movement — a flight control freedom-of-movement issue that absolutely falls under airworthiness. AC 43.13-1B and most airframe manufacturers' structural repair/maintenance manuals require control cables and pulleys to be free of interference from any object, and bonding straps are explicitly supposed to be routed and secured so they cannot contact moving control components. A mechanic signing this off as "good to go" without addressing the interference and re-routing or replacing the strap, and without inspecting the cable at the point of contact for wear, is treating the symptom description too narrowly.

For working pilots — flight instructors, charter pilots, and owners renting or operating from FBOs and flight schools — this kind of writeup is a good reminder that squawks describing "minor" hardware (bonding straps, static wicks, small brackets) can mask secondary damage to structurally or functionally critical systems. A pilot's job during preflight and postflight discrepancy reporting isn't to adjudicate airworthiness determinations, but it is entirely reasonable to ask maintenance for the specific inspection findings on the cable itself, not just the strap. If the mechanic's logbook entry only addresses the bonding strap and doesn't document a cable condition check at the contact point, that's a gap worth raising, especially in a training environment where aircraft see high cycle counts and rushed turnarounds between lessons. This is also a good case study for CFIs to use with students on how to read and question maintenance sign-offs rather than simply accepting a verbal "it's fine" from the shop.

More broadly, this fits a recurring theme in general aviation maintenance oversight: informal, verbal reassurances from maintenance personnel are not a substitute for a documented inspection and corrective action tied to the actual discrepancy as written. NTSB and FAA service difficulty reports contain numerous examples where secondary chafing damage from unrelated components (wiring bundles, straps, placards) against control cables went undetected until cable failure or near-failure was found on subsequent inspection. Operators — whether Part 91 flight schools, 135 charter outfits, or corporate flight departments — should treat any strap-to-control-cable contact as a "no, unless proven otherwise" item: replace or reroute the strap, inspect the cable per AC 43.13-1B wear criteria, and document both actions distinctly in the maintenance record. The underlying lesson for pilots operating any aircraft, from trainers to business jets, is that squawks involving contact or rubbing near primary flight controls deserve a documented answer that addresses both components involved, not just the one named first in the discrepancy.