title-14-part-33-sec33-29

706

14 CFR Ch. I (1–1–24 Edition)

§ 33.29

demonstrate by test or other accept-
able means that the overspeed function
remains available between inspection
and maintenance periods.

(g)

Software. The applicant must de-

sign, implement, and verify all associ-
ated software to minimize the exist-
ence of errors by using a method, ap-
proved by the FAA, consistent with the
criticality of the performed functions.

(h)

Aircraft-supplied data. Single fail-

ures leading to loss, interruption or
corruption of aircraft-supplied data
(other than thrust or power command
signals from the aircraft), or data
shared between engines must:

(1) Not result in a hazardous engine

effect for any engine; and

(2) Be detected and accommodated.

The accommodation strategy must not
result in an unacceptable change in
thrust or power or an unacceptable
change in engine operating and start-
ing characteristics. The applicant must
evaluate and document in the engine
installation instructions the effects of
these failures on engine power or
thrust, engine operability, and starting
characteristics throughout the flight
envelope.

(i)

Aircraft-supplied electrical power. (1)

The applicant must design the engine
control system so that the loss, mal-
function, or interruption of electrical
power supplied from the aircraft to the
engine control system will not result
in any of the following:

(i) A hazardous engine effect, or
(ii) The unacceptable transmission of

erroneous data.

(2) When an engine dedicated power

source is required for compliance with
paragraph (i)(1) of this section, its ca-
pacity should provide sufficient margin
to account for engine operation below
idle where the engine control system is
designed and expected to recover en-
gine operation automatically.

(3) The applicant must identify and

declare the need for, and the character-
istics of, any electrical power supplied
from the aircraft to the engine control
system for starting and operating the
engine, including transient and steady
state voltage limits, in the engine in-
structions for installation.

(4) Low voltage transients outside

the power supply voltage limitations
declared in paragraph (i)(3) of this sec-

tion must meet the requirements of
paragraph (i)(1) of this section. The en-
gine control system must be capable of
resuming normal operation when air-
craft-supplied power returns to within
the declared limits.

(j)

Air pressure signal. The applicant

must consider the effects of blockage
or leakage of the signal lines on the en-
gine control system as part of the Sys-
tem Safety Assessment of paragraph
(e) of this section and must adopt the
appropriate design precautions.

(k)

Automatic availability and control

of engine power for 30-second OEI rating.
Rotorcraft engines having a 30-second
OEI rating must incorporate a means,
or a provision for a means, for auto-
matic availability and automatic con-
trol of the 30-second OEI power within
its operating limitations.

(l)

Engine shut down means. Means

must be provided for shutting down the
engine rapidly.

(m)

Programmable logic devices. The

development of programmable logic de-
vices using digital logic or other com-
plex design technologies must provide
a level of assurance for the encoded
logic commensurate with the hazard
associated with the failure or malfunc-
tion of the systems in which the de-
vices are located. The applicant must
provide evidence that the development
of these devices has been done by using
a method, approved by the FAA, that is
consistent with the criticality of the
performed function.

[Amdt. 33–26, 73 FR 48284, Aug. 19, 2008]

§ 33.29

Instrument connection.

(a) Unless it is constructed to pre-

vent its connection to an incorrect in-
strument, each connection provided for
powerplant instruments required by
aircraft airworthiness regulations or
necessary to insure operation of the en-
gine in compliance with any engine
limitation must be marked to identify
it with its corresponding instrument.

(b) A connection must be provided on

each turbojet engine for an indicator
system to indicate rotor system unbal-
ance.

having a 30-second OEI rating and a 2-
minute OEI rating must have a means
or a provision for a means to:

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§ 33.35

(1) Alert the pilot when the engine is

at the 30-second OEI and the 2-minute
OEI power levels, when the event be-
gins, and when the time interval ex-
pires;

(2) Automatically record each usage

and duration of power at the 30-second
OEI and 2-minute OEI levels;

(3) Alert maintenance personnel in a

positive manner that the engine has
been operated at either or both of the
30-second and 2-minute OEI power lev-
els, and permit retrieval of the re-
corded data; and

(4) Enable routine verification of the

proper operation of the above means.

(d) The means, or the provision for a

means, of paragraphs (c)(2) and (c)(3) of
this section must not be capable of
being reset in flight.

(e) The applicant must make provi-

sion for the installation of instrumen-
tation necessary to ensure operation in
compliance with engine operating limi-
tations. Where, in presenting the safe-
ty analysis, or complying with any
other requirement, dependence is
placed on instrumentation that is not
otherwise mandatory in the assumed
aircraft installation, then the appli-
cant must specify this instrumentation
in the engine installation instructions
and declare it mandatory in the engine
approval documentation.

(f) As part of the System Safety As-

sessment of § 33.28(e), the applicant
must assess the possibility and subse-
quent effect of incorrect fit of instru-
ments, sensors, or connectors. Where
necessary, the applicant must take de-
sign precautions to prevent incorrect
configuration of the system.

(g) The sensors, together with associ-

ated wiring and signal conditioning,
must be segregated, electrically and
physically, to the extent necessary to
ensure that the probability of a fault
propagating from instrumentation and
monitoring functions to control func-
tions, or vice versa, is consistent with
the failure effect of the fault.

(h) The applicant must provide in-

strumentation enabling the flight crew
to monitor the functioning of the tur-
bine cooling system unless appropriate
inspections are published in the rel-
evant manuals and evidence shows
that:

(1) Other existing instrumentation

provides adequate warning of failure or
impending failure;

(2) Failure of the cooling system

would not lead to hazardous engine ef-
fects before detection; or

(3) The probability of failure of the

cooling system is extremely remote.

[Amdt. 33–5, 39 FR 1831, Jan. 15, 1974, as
amended by Amdt. 33–6, 39 FR 35465, Oct. 1,
1974; Amdt. 33–18, 61 FR 31328, June 19, 1996;
Amdt. 33–25, 73 FR 48123, Aug. 18, 2008; Amdt.
33–26, 73 FR 48285, Aug. 19, 2008]

Subpart C—Design and Construc-

tion; Reciprocating Aircraft
Engines

§ 33.31

Applicability.

This subpart prescribes additional de-

sign and construction requirements for
reciprocating aircraft engines.

§ 33.33

Vibration.

The engine must be designed and con-

structed to function throughout its
normal operating range of crankshaft
rotational speeds and engine powers
without inducing excessive stress in
any of the engine parts because of vi-
bration and without imparting exces-
sive vibration forces to the aircraft
structure.

§ 33.34

Turbocharger rotors.

Each turbocharger case must be de-

signed and constructed to be able to
contain fragments of a compressor or
turbine that fails at the highest speed
that is obtainable with normal speed
control devices inoperative.

[Amdt. 33–22, 72 FR 50860, Sept. 4, 2007]

§ 33.35

Fuel and induction system.

(a) The fuel system of the engine

must be designed and constructed to
supply an appropriate mixture of fuel
to the cylinders throughout the com-
plete operating range of the engine
under all flight and atmospheric condi-
tions.

(b) The intake passages of the engine

through which air or fuel in combina-
tion with air passes for combustion
purposes must be designed and con-
structed to minimize the danger of ice
accretion in those passages. The engine
must be designed and constructed to