CS 25.1351 General

ED Decision 2016/010/R

(See AMC 25.1351)

(a) Electrical system capacity. The required generating capacity, and number and kinds of power sources must –

(1) Be determined by an electrical load analysis; and

(2) Meet the requirements of CS 25.1309.

(b) Generating system. The generating system includes electrical power sources, main power busses, transmission cables, and associated control, regulation, and protective devices. It must be designed so that –

(1) Power sources function properly when independent and when connected in combination;

(2) No failure or malfunction of any power source can create a hazard or impair the ability of remaining sources to supply essential loads;

(3) The system voltage and frequency (as applicable) at the terminals of all essential load equipment can be maintained within the limits for which the equipment is designed, during any probable operating condition;

(4) System transients due to switching, fault clearing, or other causes do not make essential loads inoperative, and do not cause a smoke or fire hazard;

(5) There are means accessible where necessary, in flight, to appropriate crew members for the individual and rapid disconnection of each electrical power source (see AMC 25.1351(b)(5)); and

(6) There are means to indicate to appropriate crew members the generating system quantities essential for the safe operation of the system, such as the voltage and current supplied by each generator (see AMC 25.1351(b)(6)).

(c) External power. If provisions are made for connecting external power to the aeroplane, and that external power can be electrically connected to equipment other than that used for engine starting, means must be provided to ensure that no external power supply having a reverse polarity, a reverse phase sequence (including crossed phase and neutral), open circuit line, incorrect frequency or voltage, can supply power to the aeroplane’s electrical system.

(d) Operation without normal electrical power. (See AMC 25.1351(d).) The following apply:

(1) Unless it can be shown that the loss of the normal electrical power generating system(s) is Extremely Improbable, alternate high integrity electrical power system(s), independent of the normal electrical power generating system(s), must be provided to power those services necessary to complete a flight and make a safe landing.

(2) The services to be powered must include –

(i) Those required for immediate safety and which must continue to operate following the loss of the normal electrical power generating system(s), without the need for flight crew action;

(ii) Those required for continued controlled flight; and

(iii) Those required for descent, approach and landing.

(3) Failures, including junction box, control panel or wire bundle fires, which would result in the loss of the normal and alternate systems must be shown to be Extremely Improbable.

[Amdt 25/18]

AMC 25.1351(b)(5) Generating System

ED Decision 2003/2/RM

1 The disconnect means required by CS 25.1351(b)(5) should be accessible to the appropriate flight-crew members in their normal seated positions.

2 The power source controls should be considered as cockpit controls and therefore also comply with CS 25.777.

3 It may not be necessary to provide disconnection controls for all power sources, for example RAT generators or engine control dedicated generators. Where it is necessary to isolate the alternate power source when normal generator power is restored, such isolation should be possible.

AMC 25.1351(b)(6) Generating System

ED Decision 2003/2/RM

Each source of electrical supply (e.g. generators and batteries) should be provided with means to give the flight crew immediate warning of the failure of its output. These warning means are additional to the system indication requirements of CS 25.1351(b)(6). For multiphase systems the warning should also indicate the loss of any phase.

AMC 25.1351(d) Operation without Normal Electrical Power

ED Decision 2020/024/R

1 Provision should be made to ensure adequate electrical supplies to those services, which are necessary to complete the flight and make a safe landing in the event of a failure of all normal generated electrical power. All components and wiring of the alternate supplies should be physically and electrically segregated from the normal system and be such that no single failure, including the effects of fire, the cutting of a cable bundle, the loss of a junction box or control panel, will affect both normal and alternate supplies.

2 When ensuring the adequacy of electrical supplies relative to alternate power source duration and integrity, special consideration should be given to aeroplanes such as those with fly-by-wire, for which the total loss of electrical supplies could result in an immediate loss of control.

3 In considering the services which should remain available following the loss of the normal generated electrical power systems, consideration should be given to the role and flight conditions of the aeroplane and the possible duration of flight time to reach an airfield and make a safe landing.

4 The services required by CS 25.1351(d)(1) may differ between aeroplane types and roles and should be agreed with the Agency. These should normally include –

a. Attitude information;

b. Radio communication and intercommunication;

c. Navigation;

d. Cockpit and instrument lighting;

e. Heading, airspeed and altitude, including appropriate pitot head heating;

f. Adequate flight controls;

g. Adequate engine control; and

Restart capability with critical type fuel (from the standpoint of flame-out and restart capability) and with the aeroplane initially at the maximum certificated altitude;

h. Adequate engine instrumentation;

i. Such warning, cautions and indications as are required for continued safe flight and landing;

j. Any other services required for continued safe flight and landing.

5 Consideration should also be given to the equipment and the duration of services required to make a controlled descent and forced landing in the event of failure and inability to restart all engines.

6 Alternate Power Source Duration and Integrity

6.1 Time Limited. Where an alternate power source provided to comply with CS 25.1351(d) is time limited (e.g. battery), the required duration will depend on the type and role of the aeroplane. Unless it can be shown that a lesser time is adequate, such a power source should have an endurance of at least 60 minutes, at least 30 minutes of which is available under IMC. An endurance of less than 30 minutes under IMC would not normally be acceptable. The endurances, with any associated procedures, should be specified in the Flight Manual. The endurance time should be determined by calculation or test, due to allowance being made for –

a. Delays in flight crew recognition of failures and completion of the appropriate drill where flight crew action is necessary. This should be assumed to be 5 minutes provided that the failure warning system has clear and unambiguous attention-getting characteristics and where such a delay is acceptable and compatible with the crew’s primary attention being given to other vital actions.

b. The minimum voltage acceptable for the required loads, the battery state of charge, the minimum capacity permitted during service life and the battery efficiency at the discharge rates and temperatures likely to be experienced. Unless otherwise agreed, for the purpose of this calculation, a battery capacity at normal ambient conditions of 80% of the nameplate rated capacity, at the one-hour rate, and a 90% state of charge, may be assumed (i.e. 72% of nominal demonstrated rated capacity at +20°C). The allowance for battery endurance presumes that adequate requirements for periodic battery maintenance have been agreed.

c. For those aeroplanes where the battery is also used for engine or APU starting on the ground, it should be shown that following engine starts, the charge rate of the battery is such that the battery is maintained in a state of charge that will ensure adequate alternate power source duration should a failure of generated power occur shortly after take-off.

NOTE: This may normally be achieved by ensuring that, following battery-powered starting, the battery charge current has fallen to a declared level prior to take-off.

d. For those aeroplanes where the battery is used for in-flight starting of the engines or APU, it may be necessary to include limitations on the number of attempted starts, or to provide a separate dedicated battery for such purposes.

6.2 Non-Time Limited. Where an alternate electrical supply is provided by a non time limited source, e.g. APU, ram air turbine, pneumatic or hydraulic motor, due account should be taken of any limitation imposed by aeroplane speed, attitude, altitude etc., which may affect the capabilities of that power source. In considering the power source, account should be taken of the following:

a. Auxiliary Power Unit (APU). An APU capable of continuous operation throughout an adequate flight envelope may be considered an acceptable means of supplying electrical power to the required services provided that its air start capability is adequate and may be guaranteed. Where, however the APU is dependent for its starting current on a battery source, which is supplying critical loads, such starting loads may prejudice the time duration of the flight if APU start is not achieved.

It may be necessary therefore to include limitations on the number of attempted starts or to provide a separate battery for APU starting, if this method of supplying electrical power is adopted. Consideration should also be given to the equipment, services and duration required prior to the APU generator coming online. Common failures, which could affect the operation of all engines and the APU, should be taken into consideration, e.g. fuel supply.

b. Ram Air Turbine (RAT). A ram air turbine may be utilised to provide an alternate electrical power source, but due consideration must be given to ensuring that the means of bringing the unit into use are not dependent on a source which may have been lost as a result of the original failure. This will normally necessitate independent, duplicate means of deployment. Particular attention should be given to ensuring that the RAT and its means of deployment satisfy the overall reliability requirements.

The continuity of electrical power to those services which must remain operative without crew action prior to the RAT being brought into operation, may necessitate the use of a battery, unless the operation of the emergency power source is automatic and is supplying power within a timespan so as not to jeopardise the continued safety of the aeroplane in the event of failure of normal generated electrical power.

c. Pneumatic or Hydraulic Motor Drive Power Source. A pneumatic or hydraulic motor driven electrical power source may be utilised subject to the same constraints on activation as the ram air turbine (see 6.2(b)). Care should be taken in ensuring that the operation of the pneumatic or hydraulic system is not prejudiced by faults leading to, or resulting from, the original failure, including the loss of, or inability to restart all engines.

d. Regaining of Main Generators. In the event of a major loss of electrical power, provision may be made for regaining the output of one or more generators using separate control and switching arrangements on the generator side of the normal generator line contactor. Such a system would not normally be acceptable on aeroplanes with less than three engine-driven generators, as the probability of the loss of all engine-driven generators is unlikely to meet the requirements of CS 25.1351(d). To comply with CS 25.1351(d)(2) the system should be designed such that the loss of both the main and alternate means of control and distribution is Extremely Improbable. Consideration should be given to the services and duration required prior to the activation of the system and to enable a descent and forced landing to be made, in the event of the inability to restart all engines.

e. Usage of a battery system to ensure continuity of electrical power. This subparagraph applies if a battery system is used to ensure the continuity of electrical power when the non-time-limited alternate electrical power source(s) is(are) not providing electrical power. When establishing the minimum battery endurance requirements, the following conditions should be considered:

             It should be shown that following the loss of normal electrical power, and during the time periods when the non-time limited alternate electrical power source(s) does(do) not provide electrical power (per design), the battery system provides an adequate electrical power supply to those services which are necessary to make a controlled descent and landing, stop and complete a safe evacuation of the aeroplane (CS 25.1351(d) and 25.1362).

             The applicant should take into account the transient time period between the loss of normal electrical power and the non-time limited alternate electrical power source being operational, as well as other time period(s) when the non-time limited alternate electrical power source is not available. For example, the time period between when the RAT electrical generator goes off-line and when the aeroplane is stopped on ground and a safe evacuation of the aeroplane is performed.

             The most critical configuration, from a battery system point of view, should be considered. The loss of normal electrical power is usually associated with one of the following conditions: either the all-engine out case or the loss of power coming from the primary power centre. In the second case, the proximity of a battery to the power centre should be taken into account. Any battery located near this power centre should be considered as part of the normal electrical power generating system (ref. CS 25.1351(d)(1).

             The time periods corresponding to the intended usage of the battery system in the emergency scenario will need to be substantiated, with a due margin taken for any uncertainty. Any permanent load on the battery system (i.e. a hot bus) will also have to be accounted for.

             For determining the capacity of the battery system, Section 6.1(b) of this AMC, on time-limited power sources, applies.

             The capability of the backup battery system to provide adequate power for the required minimum duration should be demonstrated by actual testing or demonstrated equivalent means.

             Instructions for Continued Airworthiness for the battery system should be provided. These instructions should ensure that adequate battery power is available between maintenance cycles. There should be a means for the flight crew or maintenance personnel to determine the actual battery system charge state prior to take-off.

[Amdt 25/26]

CS 25.1353 Electrical equipment and installations

ED Decision 2016/010/R

(See AMC 25.1353)

(a) Electrical equipment and controls, must be installed so that operation of any one unit or system of units will not adversely affect the simultaneous operation of any other electrical unit or system essential to the safe operation. Any electrical interference likely to be present in the aeroplane must not result in hazardous effects upon the aeroplane or its systems except under extremely remote conditions. (See AMC 25.1353(a).)

(b) Electrical Wiring Interconnection System components must meet the requirements of 25.1703, 25.1707, 25.1711 and 25.1717.

(c) Storage batteries must be designed and installed as follows:

(1) Safe cell temperatures and pressures must be maintained during any probable charging or discharging condition. No uncontrolled increase in cell temperature may result when the battery is recharged (after previous complete discharge) –

(i) At maximum regulated voltage or power;

(ii) During a flight of maximum duration; and

(iii) Under the most adverse cooling condition likely to occur in service.

(2) Compliance with sub-paragraph (1) of this paragraph must be shown by test unless experience with similar batteries and installations has shown that maintaining safe cell temperatures and pressures presents no problem.

(3) No explosive or toxic gases emitted by any battery in normal operation, or as the result of any probable malfunction in the charging system or battery installation, may accumulate in hazardous quantities within the aeroplane.

(4) No corrosive fluids or gases that may escape from the battery may damage surrounding aeroplane structures or adjacent essential equipment.

(5) Each nickel cadmium battery installation must have provisions to prevent any hazardous effect on structure or essential systems that may be caused by the maximum amount of heat the battery can generate during a short circuit of the battery or of individual cells.

(6) Nickel cadmium battery installations must have –

(i) A system to control the charging rate of the battery automatically so as to prevent battery overheating or;

(ii) A battery temperature sensing and over-temperature warning system with a means for disconnecting the battery from its charging source in the event of an overtemperature condition; or

(iii) A battery failure sensing and warning system with a means for disconnecting the battery from its charging source in the event of battery failure. (See AMC 25.1353(c)(6)(ii) and (iii).)

 (d) Reserved

 (e) Electrical bonding must provide an adequate electrical return path under both normal and fault conditions, on aeroplanes having earthed electrical systems (see CS 25.899).

[Amdt 25/5]

[Amdt 25/18]

AMC 25.1353(a) Electrical equipment and installations

ED Decision 2003/2/RM

The possible sources of interference to be considered should include –

a. Conducted and radiated interference caused by electrical noise generation from apparatus connected to the busbars,

b. Coupling between electrical cables or between cables and aerial feeders,

c. Malfunctioning of electrically-powered apparatus,

d. Parasitic currents and voltages in the electrical distribution and earth systems, including the effects of lightning currents or static discharge,

e. Difference frequencies between generating or other systems, and

f. The requirements of CS 25.1309 should also be satisfied.

AMC 25.1353(c)(6)(ii) and (iii) Electrical equipment and installations

ED Decision 2003/2/RM

Where temperature sensing and over-temperature warning devices are installed to comply with CS 25.1353(c)(6)(ii) or (iii), their correct operations should be verified at agreed maintenance intervals in addition to compliance with CS 25.1309(a) and (b).

CS 25.1355 Distribution system

ED Decision 2016/010/R

(See AMC 25.1355)

(a) The distribution system includes the distribution busses, their associated feeders, and each control protective device.

(b) Reserved.

(c) If two independent sources of electrical power for particular equipment or systems are required for certification, or by operating rules, in the event of the failure of one power source for such equipment or system, another power source (including its separate feeder) must be automatically provided or be manually selectable to maintain equipment or system operation. (See AMC 25.1355(c) and AMC 25.1310(a).)

[Amdt 25/18]

AMC 25.1355(c) Distribution system

ED Decision 2003/2/RM

The arrangement, protection and control of the feeders from the busbars to the distribution points, and the divisions of loads among the feeders, should be such that no single fault occurring in any feeder or associated control circuit will hazard the aeroplane.

CS 25.1357 Circuit protective devices

ED Decision 2016/010/R

(See AMC 25.1357)

(a) Automatic protective devices must be used to minimise distress to the electrical system and hazard to the aeroplane in the event of wiring faults or serious malfunction of the system or connected equipment. (See AMC 25.1357(a).)

(b) The protective and control devices in the generating system must be designed to de-energise and disconnect faulty power sources and power transmission equipment from their associated busses with sufficient rapidity to provide protection from hazardous over-voltage and other malfunctioning.

(c) Each re-settable circuit protective device must be designed so that, when an overload or circuit fault exists, it will open the circuit irrespective of the position of the operating control.

(d) If the ability to reset a circuit breaker or replace a fuse is essential to safety in flight, that circuit breaker or fuse must be located and identified so that it can be readily reset or replaced in flight. Where fuses are used, there must be spare fuses for use in-flight equal to at least 50% of the number of fuses of each rating required for complete circuit protection.

(e) Each circuit for essential loads must have individual circuit protection. However, individual protection for each circuit in an essential load system (such as each position light circuit in a system) is not required.

(f) For aeroplane systems for which the ability to remove or reset power during normal operations is necessary, the system must be designed so that circuit breakers are not the primary means to remove or reset system power, unless specifically designed for use as a switch. (see AMC 25.1357(f)).

(g) Automatic reset circuit breakers may be used as integral protectors for electrical equipment (such as thermal cutouts) if there is circuit protection to protect the cable to the equipment.

[Amdt 25/5]

[Amdt 25/18]

AMC 25.1357(a) Circuit protective devices

ED Decision 2003/2/RM

No hazard should result from the effects of variations in ambient temperatures on either the protective device or the equipment it protects. See also CS 25.1309.

AMC 25.1357(f) System Power Removal

ED Decision 2008/006/R

1 Subparagraph 25.1357(f) requires that circuit breakers are not used as the primary means to remove or reset system power for those aeroplane systems for which the ability to remove or reset power during normal operation is necessary.

2 It is not the intent of the requirement that every electrically powered system in the aeroplane has a means to remove power other than a circuit breaker.  The phrase “normally requiring power removal” is used to distinguish between aeroplane systems normally turned on and off during normal operations, and those systems normally powered at all times, such as flight deck multi-function displays or the flight-management computer. But if, for example, the flight-management computer did require power cycling regularly, for whatever reason, this system would be required to have a means to do this other than using the circuit breakers.

3 Systems requiring power removal during normal operations should be designed so that power is removed from the system as closely as practical to the source of power instead of simply deactivating the outputs of the systems power supplies.

4 A separate, or integrated, power switch may be used to show compliance with CS 25.1357(f).  If an integrated switch is used (that is, a switch that controls power to multiple aeroplane systems), then it must be shown that removing or resetting power for those multiple systems will not adversely affect safe flight.

5 A switch-rated circuit breaker can be used if it is shown to be appropriately rated for the number of switch cycles expected to be executed during the service life of the system or of the circuit breaker.

[Amdt 25/5]

CS 25.1360 Precautions against injury

ED Decision 2016/010/R

(See AMC 25.1360)

(a) Shock. The electrical system must be designed so as to minimise the risk of electric shock to crew, passengers and servicing personnel and also to maintenance personnel using normal precautions. (See AMC 25.1360(a) and CS 25.899.)

(b) Burns. The temperature of any part, which has to be handled during normal operation by the flight crew, must not be such as to cause dangerous inadvertent movement, or injury to the crewmember. (See AMC 25.1360(b).)

[Amdt 25/18]

AMC 25.1360(a) Precaution against injury

ED Decision 2007/010/R

1 Where there may be a hazard during maintenance or servicing, aeroplane panels, etc., carrying voltages of above 50V RMS, should be marked with the voltage.

2 Where socket outlets are provided, these should be labelled as to use and with the output voltage or voltages. Where the output voltage exceeds 100 volts d.c. and/or 50 volts a.c. RMS either the output should be electrically isolated from the aeroplane structure, or means shall be provided to prevent inadvertent contact with live parts.

[Amdt 25/3]

AMC 25.1360(b) Precaution against injury

ED Decision 2007/010/R

1 For equipment which has to be handled during normal operation by the flight or cabin crew, a temperature rise of the order of 25°C, for metal parts, should not be exceeded. For other equipment, mounted in parts of the aeroplane normally accessible to passengers or crew, or which may come into contact with objects such as clothing or paper, the surface temperature should not exceed 100°C, in an ambient temperature of 20°C.

2 The heating surfaces of properly installed cooking apparatus are excluded from these requirements.

3 The provision of guards around hot surfaces is an acceptable method of complying with these requirements.

[Amdt 25/3]

CS 25.1362 Electrical supplies for emergency conditions

ED Decision 2003/2/RM

(See AMC 25.1362)

A suitable supply must be provided to those services, which are required, in order that emergency procedures may be carried out, after an emergency landing or ditching. The circuits for these services must be so designed, protected and installed such that the risk of their causing a fire, under these conditions, is minimised.

AMC 25.1362 Electrical supplies for emergency conditions

ED Decision 2003/2/RM

1 The emergency services which may require a supply include fuel shut-off valves, hydraulic shut-off valves and engine / APU fire extinguisher systems.

2 An appropriate design and/or unambiguous AFM procedures should be provided in order to prevent disconnection of the electrical supply to the required services before the emergency procedures are fully completed.

CS 25.1363 Electrical system tests

ED Decision 2003/2/RM

(See AMC 25.1363)

(a) Tests must be made to determine that the performance of the electrical supply systems meets the requirements of this CS-25 under all the appropriate normal and failure conditions. When laboratory tests of the electrical system are conducted –

(1) The tests must be performed on a mock-up using the same generating equipment used in the aeroplane;

(2) The equipment must simulate the electrical characteristics of the distribution wiring and connected loads to the extent necessary for valid test results; and

(3) Laboratory generator drives must simulate the actual prime movers on the aeroplane with respect to their reaction to generator loading, including loading due to faults.

(b) For each flight condition that cannot be simulated adequately in the laboratory or by ground tests on the aeroplane, flight tests must be made.

AMC 25.1363 Electrical systems tests

ED Decision 2003/2/RM

1 In carrying out the tests due account should be taken of load switching and flight crew operation of the system.

2 Laboratory or Ground Tests

2.1 All tests should be carried out with all equipment as representative as possible of the actual aeroplane. In particular, the simulation should include the correct representation of aeroplane cables in size, length and impedance, the correct ground (airframe) impedance and relative ground plane location and their location to other cables or systems that could influence performance. System loads and the generator drive system should also be correctly simulated.

2.2 The tests may be carried out on representative laboratory rigs or in an actual aeroplane, as appropriate.

2.3 Test procedures should be prepared to cover each test condition in the programme.

3 Aeroplane Flight Tests

3.1 If not adequately simulated by laboratory or ground testing, flight tests should be carried out as necessary.

3.2 Temperature tests should be carried out on equipment to establish the adequacy of the cooling media under all ground and flight conditions.

3.3 Measurements should be made to ensure that all equipment, particularly the aeroplane battery, is operating within its specified environmental conditions.

3.4 Test procedures should be prepared to cover the conditions of the tests.

CS 25.1365 Electrical appliances, motors and transformers

ED Decision 2017/015/R

(See AMC 25.1365)

(a) Domestic appliances must be so designed and installed that in the event of failures of the electrical supply or control system, the requirements of CS 25.1309(b) and (c) will be satisfied.

(b) The installation of galleys and cooking appliances must be such as to minimise the risk of overheat, fire, burns, or spilled liquids to the aeroplane, passengers, and crew (See AMC 25.1365(b)).

(c) Domestic appliances, particularly those in galley areas, must be so installed or protected as to prevent damage or contamination of other equipment or systems from fluids or vapours which may be present during normal operation or as a result of spillage, where such damage or contamination may hazard the aeroplane.

(d) Unless it can be shown that compliance with CS 25.1309(b) is provided by the circuit protective device required by CS 25.1357(a), electric motors and transformers etc. (including those installed in domestic systems, such as galleys and toilet flush systems) must be provided with a suitable thermal protection device if necessary to prevent them overheating such as to create a smoke or fire hazard under normal operation and failure conditions.

[Amdt 25/2]

[Amdt 25/19]

AMC 25.1365 Electrical appliances, motors and transformers

ED Decision 2003/2/RM

1. Heated Domestic Appliances (Galley Equipment)

In showing compliance with CS 25.1365(a), the following should be taken into consideration:

1.1 The design and installation of heated domestic appliances should be such that no single failure (e.g. welded thermostat or contactor, loss of water supply) can result in dangerous overheating and consequent risk of fire or smoke or injury to occupants.

An acceptable method of achieving this is by the provision of a means independent of the normal temperature control system, which will automatically interrupt the electrical power supply to the unit in the event of an overheat condition occurring. The means adopted should be such that it cannot be reset in flight.

1.2 The design and installation of microwave ovens should be such that no hazard could be caused to the occupants or the equipment of the aeroplane under either normal operation or single failure conditions.

1.3 Heated liquid containers, e.g. water boilers, coffee makers should, in addition to overheat protection, be provided with an effective means to relieve overpressure, either in the equipment itself or in its installations.

1.4 When considering failures of domestic appliances, the effect of the loss of the water supply to a water heater, with the electrical supply maintained, should be taken into account.

NOTES:

Due account should be taken of the possible effects of lime scale deposit both in the design and maintenance procedures of water heating equipment.

The design of galley and cooking appliance installations should be such as to facilitate cleaning to limit the accumulation of extraneous substances, which may constitute a fire risk.

2. Electric Overheat Protection Equipment

In showing compliance with CS 25.1365(d), the following should be taken into consideration:

a. Failures of any automatic control systems, e.g. automatic timer systems, which may cause the motor to run continuously;

b. Short circuit failures of motor windings or transformer windings to each other or to the motor or transformer frame;

c. Open circuit of one or more phases on multi-phase motors;

d. Motor seizures;

e. The proximity of flammable materials or fluids;

f. The proximity of other aeroplane installations;

g. Spillage of fluids, such as toilet waste;

h. Accumulation of combustible material; and

i. Cooling air discharge under normal operating or failure conditions.

3. Water Systems

3.1 Where water is provided in the aeroplane for consumption, or use by the occupant, the associated system should be designed so as to ensure that no hazard to the aeroplane could result from water coming into contact with electrical or other systems.

3.2 Service connections (filling points) should be of a different type from those used for other services, such that water could not inadvertently be introduced into the systems for other services.

AMC 25.1365(b) Installation of Cooktops

ED Decision 2017/015/R

The following acceptable means of compliance are applicable to cooktops with electrically powered heating elements. Use of other types of heat sources, such as gas, is unlikely to be acceptable. If such a design is desired, EASA should be contacted for advice.

(1)  Suitable means, such as conspicuous element ‘on’ indicators, physical barriers, or handholds, should be installed to minimise the potential of inadvertent personnel contact with hot surfaces of both the cooktop and cookware. Conditions of turbulence should also be considered.

(2)  Sufficient design means should be provided to restrain cookware, including their contents, in place on the cooktop against flight loads and turbulence.

(a)  Restraints should be provided to preclude hazardous movement of cookware and contents thereof. These restraints should accommodate the cookware that is approved for use with the cooktop.

(b)  Restraints should be designed to be easily used and effective in service. The cookware restraint system should also be designed in a way that it may not be easily disabled, thus rendering it unusable.

(c)  Appropriate placarding should be installed prohibiting the use of cookware not approved for use with the cooktop.

(3)  Appropriate placarding should be installed prohibiting the use of cooktops (i.e. power on any heating surface) during taxiing, take-off, and landing.

(4)  Suitable means should be provided to address the possibility of a fire starting on the cooktop or in its immediate vicinity. The following two means are acceptable:

(a)  Appropriate placarding should be installed that prohibits any heating surface from being powered when the cooktop is unattended (Note: this would prohibit a single person from cooking on the cooktop and intermittently serving food to passengers while any surface is powered). A fire detector should be installed in the vicinity of the cooktop, which provides a warning audible throughout the passenger cabin; moreover, a fire extinguisher of appropriate size and extinguishing agent should be installed in the immediate vicinity of the cooktop. Access to the extinguisher should not be blocked by a possible fire on or around the cooktop. One of the fire extinguishers required by CS 25.851 may be used to satisfy this requirement if it is located in the vicinity of the cooktop and the total complement of extinguishers remains evenly distributed throughout the cabin. If this is not possible, then the extinguisher in the cooktop area should be additional to those required by CS 25.851; or

(b)  An automatic (e.g. thermally activated) system should be installed to extinguish a fire at the cooktop and immediately adjacent surfaces. The agent used in the system should be an approved flooding agent suitable for use in an occupied area. The fire suppression system should have an appropriately located manual activation control. Activation of the fire suppression system (automatic or manual) should also automatically shut off power to the cooktop.

(5)  The surfaces of the galley surrounding the cooktop, which would be exposed to a fire on the cooktop surface or in cookware on the cooktop, should be constructed of materials that comply with the flame penetration resistance requirements of Appendix F, Part III. During the selection of all galley materials in the vicinity of the cooktop, consideration should be given to ensure that the flammability resistance characteristics of the materials will not be adversely affected by the use of cleaning agents and utensils used to remove cooking stains.

(6)  The cooktop should be ventilated with a system independent of the aeroplane cabin and cargo ventilation system. Maintenance procedures and time intervalsshould be established for inspection and cleaning or replacement of ventilation system components to prevent the accumulation of flammable oils creating a fire hazard. These procedures and time intervals should be included in the instructions for continued airworthiness as required by CS 25.1529. The ventilation system ducting should be protected by a flame arrester (Note: the applicant may find additional useful information in Society of Automotive Engineers (SAE) Aerospace Recommended Practice (ARP) No 85, Revision E, ARP85E ‘Air Conditioning Systems for Subsonic Airplanes’ of 1 August 1991).

(7)  Means should be provided to contain spilled foods or fluids in a manner that will prevent the creation of a slipping hazard to occupants as well as the loss of structural strength due to aeroplane corrosion.

(8)  Cooktop installations should provide adequate space for the user to immediately escape a hazardous cooktop condition.

(9)  A means to shut off power to the cooktop should be provided at the galley containing the cooktop and in the cockpit. If one (or more) dedicated switch(es) is (are) provided in the cockpit, smoke or fire emergency procedures should be provided in the AFM to cover their use.

(10)  The cooktop should have either a lid that will completely enclose the cooking surface, or an appropriately located fire blanket of a size sufficient to completely cover the cooking surface should be provided. If a lid is installed, there should be a means to automatically shut off power to the cooktop when the lid is closed. The fire blanket material should be demonstrated to meet the European Standard (EN) 1869:1997, Fire blankets, or equivalent.

[Amdt 25/19]