T
RAINING
M
ANUAL
–
L
ANCAIR
IV/IVP
Decompression of a small cabin volume pressurized aircraft is more critical than
a large one, given the same size hole or conditions, primarily because of the
difference in cabin volumes. Actual decompression times are difficult to calculate
due to many variables involved (e.g., the type of failure, differential pressure,
cabin volume, etc) However, it is more probable that the crew of the small
aircraft will have less time in which to take lifesaving actions. There have been
several pilot door window failures related to improper builder window
installations.
(1) An explosive decompression is a change in cabin pressure faster
than the lungs can decompress. Most authorities consider a
decompression that occurs in less than 0.5 seconds as explosive and
potentially dangerous. This type of decompression is more likely to
occur in small volume pressurized aircraft than in large pressurized
aircraft, and often results in lung damage. To avoid potentially
dangerous flying debris in the event of an explosive decompression,
all loose items such as baggage and oxygen cylinders should be
properly secured.
(2) A rapid change in cabin pressure is where the lungs can decompress
faster than the cabin. The risk of lung damage is significantly
reduced in this decompression as compared with an explosive
decompression.
(3) Gradual or slow decompression is dangerous because it may not be
detected. Automatic visual and aural warning systems generally
provide an indication of a slow decompression.
(4) Recovery from all types of decompression is similar. Oxygen masks
should be donned, and a rapid descent initiated as soon as possible
to avoid the onset of hypoxia. The time allowed to make a recovery to
a safe altitude before loss of useful consciousness is, of course,
much less with an explosive than with a gradual decompression.
LOSS OF CABIN PRESSURIZATION
If cabin pressure loss is gradual
, after checking the pressurization controls in
proper positions:
1. Don oxygen mask, check O2 flow (100%) inform passengers.
2. Inform ATC of the problem and request lower altitude.
3. Make normal descent, keeping turbots at maximum output, consistent with
descent rate and airspeed limitations.
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85
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2007
LOBO
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