Safeguarding the EWIS
Chafing, abrasion & short circuit arcing in the critical “Electrical Wiring Interconnect System” (EWIS) have always been a major concern. Chafing and abrasion can have a serious impact on the safe functioning of aircraft systems.
This problem was thought to be prevalent in older Part 25 aircraft with 20 years + time in service (TIS). However, documented mishaps show that even new or recently produced OEM aircraft are susceptible to wire chafing.
Reported EWIS Incidents
Aviation Week recently reported a story about recommendations made to the FAA and Brazil’s ANAC stemming from a November 2019 incident with a Republic Airways Embraer 175. Part of the problem was chafed flight control system wires.
The Atlanta to La Guardia flight experienced an excessive un-commanded pitch-up just 4 minutes into the flight. The flight crew solved the problem and landed safely but two switches did not work due to chafed wire insulation. The chafing was on the horizontal stabilizer actuator control electronics to the captain’s pitch-trim switch and the autopilot/trim disconnect button.
Subsequently, Republic found nine aircraft with chafed wiring. According to the NTSB other unidentified operators have found issues as well.
This “simple” problem caused potential life-threatening issues. With so much at stake, OEM/MRO/FBOs can no longer rely on the standard manufacturing approach to maintaining wire/cable integrity. This has become more critical as recognition has grown that wiring – the EWIS- is a critical system on all aircraft.
Solution to Chafing
Part of the solution is to apply best-in-class protection to prevent wiring chafe. Rather than glued-in nylon grommets, Spring-Fast protective Edge Grommets coupled with Protect-Fast wire wrap.
Spring-Fast grommets in particular provide best-in-class wire chafe protection at half the installed cost of the old slow and costly nylon glued-in grommets.
DTi products are ideally suited for installation on operational aircraft requiring a minimum of downtime and are installed without messy adhesives or Toxic VOCs. Find out more about Spring-Fast here
Source: Aviation Week