AMC
25.1593 Exposure to volcanic cloud hazards
ED Decision 2016/010/R
The aim of CS 25.1593 is to
support operators by identifying and assessing airworthiness hazards
associated with operations in contaminated airspace. Providing such data to
operators will enable those hazards to be properly managed as part of an
established management system.
Acceptable means of establishing the susceptibility of aeroplane
features to the effects of volcanic clouds should include a combination of
experience, studies, analysis, and/or testing of parts or sub-assemblies.
Information necessary for safe operation should be contained in the
unapproved part of the flight manual, or other appropriate manual, and should
be readily usable by operators in preparing a safety risk assessment as part
of their overall management system.
A volcanic cloud comprises volcanic ash together with gases and other
chemicals. Although the primary hazard is volcanic ash, other elements of the
volcanic cloud may also be undesirable to operate through, and their effect on
airworthiness should be assessed.
In determining the susceptibility of aeroplane features to the effects
of volcanic clouds and the necessary information to operators, the following
points should be considered:
(1) Identify
the features of the aeroplane that are susceptible to airworthiness effects
from volcanic clouds. These may include, but are not limited to, the
following:
a. The
malfunction or failure of one or more engines, leading not only to reduction
or complete loss of thrust but also to failures of electrical, pneumatic, and
hydraulic systems;
b. Blockage
of pitot and static sensors, resulting in unreliable airspeed indications and
erroneous warnings;
c. Windscreen
abrasion, resulting in windscreens being rendered partially or completely
opaque;
d. Fuel
contamination;
e. Volcanic
ash and/or toxic chemical contamination of cabin air-conditioning packs,
possibly leading to loss of cabin pressurisation or noxious fumes in the
cockpit and/or cabin;
f. Erosion,
blockage, or malfunction of external and internal aeroplane components;
g. Volcanic
cloud static discharge, leading to prolonged loss of communications; and
h. Reduced
cooling efficiency of electronic components, leading to a wide range of
aeroplane system failures.
(2) The
nature and severity of effects.
(3) Details
of any device or system installed on the aeroplane that can detect the
presence of volcanic cloud hazards (e.g. volcanic ash (particulate) sensors or
volcanic gas sensors).
(4) The
effect of volcanic ash on operations to/from contaminated aerodromes. In
particular, deposits of volcanic ash on a runway can lead to degraded braking
performance, most significantly if the ash is wet.
(5) The
related pre-flight, in-flight and post-flight precautions to be observed by
the operator including any necessary amendments to Aircraft Operating Manuals,
Aircraft Maintenance Manuals, Master Minimum Equipment List/Dispatch
Deviation, or equivalents required to support the operator. Pre-flight
precautions should include clearly defined procedures for the removal of any
volcanic ash found on parked aeroplanes.
(6) The
recommended continuing airworthiness inspections associated with operations in
volcanic cloud contaminated airspace and to/from volcanic ash-contaminated
aerodromes; this may take the form of Instructions for Continued Airworthiness
or other advice.
[Amdt 25/13]
[Amdt 25/18]