FAA Aviation Mechanic Airframe (AMA)Airframe StructuresMedium
A composite structures technician is selecting core material for a sandwich panel repair that will be exposed to a moist environment and must resist moisture absorption better than standard aluminum honeycomb. Which core material is best suited for this application?
- AFoam core with open cells
- BAluminum honeycomb core
- CNomex (aramid fiber) honeycomb core
- DBalsa wood core
Show answer & explanationAnswer & explanation
Correct answer: C. Nomex (aramid fiber) honeycomb core
Nomex honeycomb core is made from aramid fiber paper coated in phenolic resin, which makes it highly resistant to moisture absorption and corrosion, unlike aluminum honeycomb, which can corrode when moisture is trapped inside the cells.
Why the other options are wrong
- A. Open-cell foam readily absorbs and traps moisture, making it a poor choice here.
- B. Aluminum honeycomb is prone to corrosion when moisture becomes trapped in the cells.
- D. Balsa wood absorbs moisture readily and is not ideal for a moist environment.
Nomex Honeycomb Core
A lightweight sandwich panel core material made of aramid fiber paper dipped in phenolic resin, valued for corrosion resistance, moisture resistance, and good strength-to-weight ratio compared to aluminum honeycomb.
- Does not corrode like aluminum honeycomb when exposed to moisture.
- Lighter than aluminum honeycomb of similar strength.
- Common in aircraft interior panels, fairings, and control surfaces.
Memory trick: Nomex = 'No More' corrosion in moist conditions