FAA Aircraft Dispatcher (ADX)Regulations (Part 121)Hard
A dispatcher is determining the maximum permissible cabin ozone concentration for a Part 121 turbine-powered airplane cruising at FL350. Under 14 CFR 121.578, what is the maximum ozone concentration allowed?
- A0.10 parts per million (ppm) by volume, average over any 3-hour period.
- B0.25 parts per million (ppm) by volume, average over any 3-hour period.
- C0.15 parts per million (ppm) by volume, average over any 3-hour period.
- D0.20 parts per million (ppm) by volume, average over any 3-hour period.
Show answer & explanationAnswer & explanation
Correct answer: A. 0.10 parts per million (ppm) by volume, average over any 3-hour period.
14 CFR 121.578(b) specifies that the ozone concentration in the cabin of a Part 121 airplane must not exceed 0.10 parts per million (ppm) by volume, average over any 3-hour period. It also has a short-term limit of 0.25 ppm.
Why the other options are wrong
- B. 0.25 ppm is the maximum short-term limit, not the 3-hour average limit.
- C. 0.15 ppm is not the correct average limit.
- D. 0.20 ppm is not the correct average limit.
Cabin Ozone Concentration (121.578)
Sets limits on the maximum permissible ozone concentration within the cabins of Part 121 aircraft to protect passenger and crew health, especially at high altitudes.
- Ozone levels increase with altitude.
- Average limit over 3 hours is 0.10 ppm.
- Short-term limit is 0.25 ppm.
Memory trick: Ozone: 'O' for Ozone, 'Z' for Zero point, 'O' for One zero. '3' hours, '0.10' ppm is the 'average' rule.