Section 33.69

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

TABLE 1 - CONDITIONS THAT MUST BE DEMONSTRATED BY AN ENGINE TEST - Continued
Condition

Total air temperature

3. Glaze ice holding
conditions.
(Turbojet, turbofan,
and turboprop only).

Turbojet and Turbofan, only: 10 to
18 SectionF (Section12 to Section8
SectionC).
Turboprop, only: 2 to
10 SectionF (Section17 to Section12
SectionC).
Turbojet and Turbofan, only: Section10 to
0 SectionF (Section23 to Section18
SectionC).
Turboprop, only: 2 to
10 SectionF (Section17 to Section12
SectionC).

4. Rime ice holding
conditions.
(Turbojet, turbofan,
and turboprop only).

Supercooled water
concentrations
(minimum)

Median volume drop diameter

Duration

Alternating cycle: First
1.7 g/m3 (1 minute),
Then 0.3 g/m3 (6
minute).
.

20 to 30 microns ...................

Must show repetitive,
stabilized operation
(or 45 minutes
max).

0.25 g/m3 ...................

20 to 30 microns ...................

Must show repetitive,
stabilized operation
(or 45 minutes
max).

....................................

................................................

(d) Operate at ground idle speed for a
minimum of 30 minutes at each of the
following icing conditions shown in
Table 2 of this section with the available air bleed for icing protection at its
critical condition, without adverse effect, followed by acceleration to takeoff power or thrust. During the idle operation, the engine may be run up periodically to a moderate power or thrust
setting in a manner acceptable to the

Administrator. Analysis may be used
to show ambient temperatures below
the tested temperature are less critical. The applicant must document any
demonstrated run ups and minimum
ambient temperature capability in the
engine operating manual as mandatory
in icing conditions. The applicant must
demonstrate, with consideration of expected airport elevations, the following:

TABLE 2 - DEMONSTRATION METHODS FOR SPECIFIC ICING CONDITIONS
Condition
1. Rime ice condition
2. Glaze ice condition
3. Snow ice condition

4. Large drop glaze
ice condition (Turbojet, turbofan, and
turboprop only).

Supercooled water
concentrations
(minimum)

Mean effective particle diameter

Liquid - 0.3 g/m3 ........

15-25 microns .......................

By engine test.

Liquid - 0.3 g/m3 ........

15-25 microns .......................

By engine test.

Ice - 0.9 g/m3 ............

100 microns ...........................
(minimum) ..............................

Liquid - 0.3 g/m3 ........

100 microns (minimum) .........

By test, analysis or
combination of the
two.
By test, analysis or
combination of the
two.

Total air temperature
0 to 15 SectionF (Section18 to
Section9 SectionC).
20 to 30 SectionF (Section7 to
Section1 SectionC).
26 to 32 SectionF (Section3 to 0
SectionC).
15 to 30 SectionF (-9 to -1
SectionC).

spaschal on DSK3GDR082PROD with CFR

(e) Demonstrate by test, analysis, or
combination of the two, acceptable operation for turbojet, turbofan, and turboprop engines in mixed phase and ice
crystal icing conditions throughout
Appendix D of this part, icing envelope
throughout its flight power range, including
minimum
descent
idling
speeds.
[Amdt. 33-34, 79 FR 66536, Nov. 4, 2014]

Section 33.69

Demonstration

Ignitions system.

Each engine must be equipped with
an ignition system for starting the engine on the ground and in flight. An
electric ignition system must have at
least two igniters and two separate secondary electric circuits, except that
only one igniter is required for fuel
burning augmentation systems.
[Amdt. 33-6, 39 FR 35466, Oct. 1, 1974]

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