AMC 27.1593 Exposure to volcanic cloud hazards

ED Decision 2016/024/R

The aim of CS 27.1593 is to support commercial and non-commercial operators operating complex motor-powered rotorcraft 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 rotorcraft 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 itself, other elements of the volcanic cloud may also be undesirable to operate through, thus their effect on airworthiness should be assessed.

In determining the susceptibility of rotorcraft features to the effects of volcanic clouds as well as the necessary information to be provided to operators, the following points should be considered:

(a)     Identify the features of the rotorcraft that are susceptible to airworthiness effects of volcanic clouds. These may include but are not limited to the following:

(1)     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;

(2)     blockage of pitot and static sensors, resulting in unreliable airspeed indications and erroneous warnings;

(3)     windscreen abrasion, resulting in windscreens rendered partially or completely opaque;

(4)     fuel contamination;

(5)     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;

(6)     erosion, blockage or malfunction of external and internal rotorcraft components;

(7)     volcanic-cloud static discharge, leading to prolonged loss of communications; and

(8)     reduced cooling efficiency of electronic components, leading to a wide range of rotorcraft system failures.

(b)     The nature and severity of effects.

(c)      Details of any device or system installed on the rotorcraft that can detect the presence of volcanic cloud hazards (e.g. volcanic ash (particulate) sensors or volcanic gas sensors).

(d)     The effect of volcanic ash on operations arriving to or departing from contaminated aerodromes.

(e)     The related pre-flight, in-flight and post-flight precautions to be taken 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 detected on parked rotorcraft.

(f)      The recommended continuing-airworthiness inspections associated with operations in airspace contaminated by (a) volcanic cloud(s) and arriving to or departing from aerodromes contaminated by volcanic ash; this may take the form of Instructions for Continued Airworthiness (ICA) or other advice.

[Amdt 27/4]