FAA Aviation Mechanic Airframe (AMA)Fuel, Cabin and Ice Control SystemsHard
A technician inspects pneumatic deicer boots on an aircraft that has been stored outdoors for an extended period and finds fine surface cracking (crazing) unrelated to normal flexing damage. What is the most likely cause of this condition?
- AExcessive cycling of the pneumatic distributor valve
- BOver-inflation of the boots during ground testing
- CContamination with hydraulic fluid during servicing
- DOzone and ultraviolet exposure deteriorating the rubber compound
Show answer & explanationAnswer & explanation
Correct answer: D. Ozone and ultraviolet exposure deteriorating the rubber compound
Prolonged exposure to ozone and ultraviolet radiation causes oxidation and breakdown of the rubber compound in deicer boots, producing fine surface crazing distinct from mechanical fatigue cracking caused by repeated flexing.
Why the other options are wrong
- A. Distributor valve cycling relates to inflation timing, not material degradation of the boot surface.
- B. Over-inflation typically causes ballooning or bursting, not fine surface crazing.
- C. Hydraulic fluid contamination causes swelling and softening, not crazing.
Deicer Boot Ozone/UV Deterioration
Environmental degradation of pneumatic deicer boot rubber caused by prolonged exposure to ozone and ultraviolet light, resulting in fine surface crazing.
- Distinct from mechanical flex-fatigue cracking
- Accelerated by outdoor storage and sun exposure
- Requires boot replacement if cracking is significant
Memory trick: Sun and smog age rubber like sunburned skin, cracking the surface.