(« CS-23 »)
(« FAR-23 »)
on certification specifications , including airworthiness
codes and acceptable means of compliance for normal
, utility , aerobatic and commuter category aeroplanes
.
This Part prescribes airworthiness standards for the issue
of type certificates, and changes to those certificates , for
airplanes in the normal , utility , acrobatic and commuter
categories.
CS 23.1435 Hydraulic systems
FAR 23.1435 Hydraulic systems
(« CS-25 »)
(« FAR-25 »)
on certification specifications , including This part prescribes airworthiness standards for the issue
airworthiness codes and acceptable means of of type certificates, and changes to those certificates, for
transport category airplanes.
compliance for Large Aeroplanes .
CS 25.1435 Hydraulic systems
FAR 25.1435 Hydraulic systems
CS 23.1435 Hydraulic systems
FAR 23.1435 Hydraulic systems
(a) Design.
(a) Design.
Each hydraulic system must be designed
as follows:
(1) Each hydraulic system and its
elements must withstand , without
yielding , the structural loads expected in
addition to hydraulic loads .
(2) A means to indicate the pressure in
each hydraulic system which supplies
two or more primary functions must be
provided to the flight crew.
Each hydraulic system must be designed
as follows :
(1) Each hydraulic system and its
elements must withstand, without
yielding, the structural loads expected in
addition to hydraulic loads.
(2) A means to indicate the pressure in
each hydraulic system which supplies
two or more primary functions must be
provided to the flight crew.
FAR 23.1435 Hydraulic systems.
CS 23.1435 Hydraulic systems
(3) There must be means to ensure that the (3) There must be means to ensure that the
pressure, including transient (surge) pressure, in pressure, including transient (surge) pressure, in
any part of the system will not exceed the safe any part of the system will not exceed the safe
limit above design operating pressure and to limit above design operating pressure and to
prevent excessive pressure resulting from fluid prevent excessive pressure resulting from fluid
volumetric changes in all lines which are likely volumetric changes in all lines which are likely
to remain closed long enough for such changes to remain closed long enough for such changes
to occur.
to occur.
(4) The minimum design burst pressure must (4) The minimum design burst pressure must be
be 2·5 times the operating pressure.
2.5 times the operating pressure.
CS 25.1435 Hydraulic Systems
FAR 25.1435 : Hydraulic systems.
(a) Element design .
Each element of the hydraulic system must be
designed to:
(1) Withstand the proof pressure without
permanent deformation that would prevent it
from performing its intended function , and the
ultimate pressure without rupture. The proof
and ultimate pressures are defined in terms of
the Design Operating Pressure (DOP) as follows:
(a) Element design .
Each element of the hydraulic system must
be designed to :
(1) Withstand the proof pressure without
permanent deformation that would prevent
it from performing its intended functions ,
and the ultimate pressure without rupture.
The proof and ultimate pressures are
defined in terms of the Design Operating
Pressure (DOP) as follows :
FAR 25.1435 : Hydraulic systems.
CS 25.1435 Hydraulic Systems
(2) Withstand, without deformation that
would prevent it from performing its
(2) Withstand , without deformation that would intended function, the design operating
prevent it from performing its intended function, pressure in combination with limit structural
the design operating pressure in combination loads that may be imposed;
with limit structural loads that may be imposed ;
(3) Withstand, without rupture, the design
(3) Withstand , without rupture , the design operating pressure multiplied by a factor of
operating pressure multiplied by a factor of 1.5 in 1.5 in combination with ultimate structural
load
that
can
reasonably
occur
combination with ultimate structural loads that simultaneously;
can reasonably occur simultaneously;
(4) Withstand the fatigue effects of all cyclic
pressures , including transients , and associated
externally induced loads , taking into account the
consequences of element failure; and
(4) Withstand the fatigue effects of all cyclic
pressures, including transients, and
associated externally induced loads, taking
into account the consequences of element
failure; and
(5) Perform as intended under all
(5) Perform as intended under all environmental environmental conditions for which the
conditions for which the airplane is certificated. airplane is certificated.
CS 23.1435 Hydraulic Systems
(b) System design
****
FAR 23.1435 : Hydraulic systems
(b) System design
****
CS 25.1435 Hydraulic Systems
FAR 25.1435 : Hydraulic systems
(b) System design
(b) System design
Each hydraulic system must:
(1) Have means located at a flight crew
member station to indicate appropriate
system parameters, if
(i) It performs a function necessary for
continued safe flight and landing; or
(ii) In the event of hydraulic system
malfunction, corrective action by the crew to
ensure continued safe flight and landing is
necessary;
Each hydraulic system must :
(1) Have means located at a flight crew station
to indicate appropriate system parameters, if
(i) It performs a function necessary for
continued safe flight and landing; or (ii) In the
event of hydraulic system malfunction,
corrective action by the crew to ensure
continued safe flight and landing is necessary;
(2) Have means to ensure that system
pressures, including transient pressures and
pressures from fluid volumetric changes in
elements that are likely to remain closed long
enough for such changes to occur, are within
the design capabilities of each element, such
that they meet the requirements defined in CS
25.1435(a)(1) through CS 25.1435(a)(5)
inclusive;
(2) Have means to ensure that system
pressures, including transient pressures and
pressures from fluid volumetric changes in
elements that are likely to remain closed long
enough for such changes to occur, are within
the design
capabilities of each element, such that they
meet the requirements defined in Sec.
25.1435(a)(1) through (a)(5);
CS 25.1435 Hydraulic Systems
FAR 25.1435 : Hydraulic systems
(3) Have means to minimise the release of
harmful or hazardous concentrations of
hydraulic fluid or vapours into the crew
and passenger compartments during
flight;
(3) Have means to minimize the release
of harmful or hazardous concentrations
of hydraulic fluid or vapors into the crew
and passenger compartments during
flight;
(4) Meet the applicable requirements of
(4) Meet the applicable requirements of Secs. 25.863, 25.1183, 25.1185, and
CS 25.863, 25.1183, 25.1185 and 25.1189 if 25.1189 if a flammable hydraulic fluid is
a flammable hydraulic fluid is used; and
used; and
(5) Be designed to use any suitable
hydraulic fluid specified by the aeroplane
manufacturer, which must be identified by
appropriate markings as required by
CS 25.1541
(5) Be designed to use any suitable
hydraulic fluid specified by the airplane
manufacturer, which must be identified
by appropriate markings as required by
Sec. 25.1541.
CS 23.1435 Hydraulic systems
FAR 23.1435 Hydraulic systems
(b) Tests.
(b) Tests.
Each system must be substantiated by proof
pressure tests. When proof-tested, no part of
any system may fail, malfunction, or experience a
permanent set. The proof load of each system
must be at least 1·5 times the maximum
operating pressure of that system.
Each system must be substantiated by proof
pressure tests. When proof tested, no part of
any system may fail, malfunction, or experience
a permanent set. The proof load of each system
must be at least 1.5 times the maximum
operating pressure of that system.
(c) Accumulators.
(c) Accumulators.
A hydraulic accumulator or reservoirs may be A hydraulic accumulator or reservoir may be
installed on the engine side of any firewall, if–
installed on the engine side of any firewall if –
(1) It is an integral part of an engine or propeller (1) It is an integral part of an engine or
propeller system, or
system, or
(2) The reservoir is non pressurised and the (2) The reservoir is non pressurized and the
total capacity of all such non pressurised total capacity of all such non pressurized
reservoirs is one quart or less.] Amdt. 23-49, Eff.
reservoirs is one litre (one US-quart) or less.
03/11/96
CS 25.1435 Hydraulic Systems
(c) Tests.
Tests must be conducted on the hydraulic
system(s) , and/or subsystem(s) and element(s)
, except that analysis may be used in place of
or to supplement testing where the analysis is
shown to be reliable and appropriate. All
internal and external influences must be taken
into account to an extent necessary to evaluate
their effects, and to assure reliable system and
element functioning and integration. Failure or
unacceptable deficiency of an element or
system must be corrected and be sufficiently
retested, where necessary.
FAR 25.1435 : Hydraulic systems
(c) Tests.
Tests must be conducted on the hydraulic
system(s), and/ or subsystem(s) and elements,
except that analysis may be used in place of or
to supplement testing, where the analysis is
shown to be reliable and appropriate. All
internal and external influences must be taken
into account to an extent necessary to
evaluate their effects, and to assure reliable
system and element functioning and
integration. Failure or unacceptable deficiency
of an element or system must be corrected
and be sufficiently retested, where necessary.
(1) The system(s), subsystem(s), or element(s)
must be subjected to performance,
(1) The system(s), subsystem(s), or element(s)
fatigue,
and
endurance
tests
must be subjected to performance, fatigue,
representative of airplane ground and
and endurance tests representative of
flight operations.
aeroplane ground and flight operations.
CS 25.1435 Hydraulic Systems
FAR 25.1435 : Hydraulic systems
(2) The complete system must be tested to
determine proper functional performance and
relation to other systems, including simulation of
relevant failure conditions, and to support or
validate element design .
(2) proper functional performance and relation
to the other systems, including simulation of
relevant failure conditions, and to support or
validate element design .
(3) The complete hydraulic system(s) must be
functionally tested on the aeroplane in normal
operation over the range of motion of all
associated user systems. The test must be
conducted at the relief pressure or 1.25 times
the DOP if a system pressure relief device is not
part of the system design. Clearances between
hydraulic system elements and other systems or
structural elements must remain adequate and
there must be no detrimental effects.
[Amdt. No.:25/2]
(3) The complete hydraulic system(s) must be
functionally tested on the airplane in normal
operation over the range of motion of all
associated user systems. The test must be
conducted at the system relief pressure or 1.25
times the DOP if a system pressure relief device
is not part of the system design. Clearances
between hydraulic system elements and other
systems or structural elements must remain
adequate and there must be no detrimental
effects.
Amdt . 25-104, Eff. 6/15/2001