Section 33.37

14 CFR Ch. I (1-1-19 Edition)

permit the use of a means for ice prevention.
(c) The type and degree of fuel filtering necessary for protection of the
engine fuel system against foreign particles in the fuel must be specified. The
applicant must show that foreign particles passing through the prescribed
filtering means will not critically impair engine fuel system functioning.
(d) Each passage in the induction system that conducts a mixture of fuel
and air must be self-draining, to prevent a liquid lock in the cylinders, in
all attitudes that the applicant establishes as those the engine can have
when the aircraft in which it is installed is in the static ground attitude.
(e) If provided as part of the engine,
the applicant must show for each fluid
injection (other than fuel) system and
its controls that the flow of the injected fluid is adequately controlled.
[Doc. No. 3025, 29 FR 7453, June 10, 1964, as
amended by Amdt. 33-10, 49 FR 6851, Feb. 23,
1984]

Section 33.37

Ignition system.

Each spark ignition engine must
have a dual ignition system with at
least two spark plugs for each cylinder
and two separate electric circuits with
separate sources of electrical energy,
or have an ignition system of equivalent in-flight reliability.

spaschal on DSK3GDR082PROD with CFR

Section 33.39

Lubrication system.

(a) The lubrication system of the engine must be designed and constructed
so that it will function properly in all
flight attitudes and atmospheric conditions in which the airplane is expected
to operate. In wet sump engines, this
requirement must be met when only
one-half of the maximum lubricant
supply is in the engine.
(b) The lubrication system of the engine must be designed and constructed
to allow installing a means of cooling
the lubricant.
(c) The crankcase must be vented to
the atmosphere to preclude leakage of
oil from excessive pressure in the
crankcase.

Subpart D - Block Tests;
Reciprocating Aircraft Engines
Section 33.41 Applicability.
This subpart prescribes the block
tests and inspections for reciprocating
aircraft engines.
Section 33.42 General.
Before each endurance test required
by this subpart, the adjustment setting
and functioning characteristic of each
component having an adjustment setting and a functioning characteristic
that can be established independent of
installation on the engine must be established and recorded.
[Amdt. 33-6, 39 FR 35465, Oct. 1, 1974]

Section 33.43 Vibration test.
(a) Each engine must undergo a vibration survey to establish the torsional and bending vibration characteristics of the crankshaft and the propeller shaft or other output shaft, over
the range of crankshaft speed and engine power, under steady state and
transient conditions, from idling speed
to either 110 percent of the desired
maximum continuous speed rating or
103 percent of the maximum desired
takeoff speed rating, whichever is higher. The survey must be conducted
using, for airplane engines, the same
configuration of the propeller type
which is used for the endurance test,
and using, for other engines, the same
configuration of the loading device
type which is used for the endurance
test.
(b) The torsional and bending vibration stresses of the crankshaft and the
propeller shaft or other output shaft
may not exceed the endurance limit
stress of the material from which the
shaft is made. If the maximum stress
in the shaft cannot be shown to be
below the endurance limit by measurement, the vibration frequency and amplitude must be measured. The peak
amplitude must be shown to produce a
stress below the endurance limit; if
not, the engine must be run at the condition producing the peak amplitude
until, for steel shafts, 10 million stress
reversals have been sustained without
fatigue failure and, for other shafts,
until it is shown that fatigue will not

708

VerDate Sep<11>2014

12:50 Apr 30, 2019

Jkt 247046

PO 00000

Frm 00718

Fmt 8010

Sfmt 8010

Y:\SGML\247046.XXX

247046