727 

Federal Aviation Administration, DOT 

§ 33.83 

(2) Continuation of the rain ingestion 

during subsequent rapid deceleration 
to minimum idle, then 

(3) Continuation of the rain ingestion 

during three minutes at minimum idle 
power to be certified for flight oper-
ation, then 

(4) Continuation of the rain ingestion 

during subsequent rapid acceleration 
to takeoff power. 

(c) 

Engines for supersonic airplanes. In 

addition to complying with paragraphs 
(a)(1) and (a)(2) of this section, a sepa-
rate test for supersonic airplane en-
gines only, shall be conducted with 
three hailstones ingested at supersonic 
cruise velocity. These hailstones shall 
be aimed at the engine’s critical face 
area, and their ingestion must not 
cause unacceptable mechanical damage 
or unacceptable power or thrust loss 
after the ingestion or require the en-
gine to be shut down. The size of these 
hailstones shall be determined from 
the linear variation in diameter from 1- 
inch (25 millimeters) at 35,000 feet 
(10,500 meters) to 

1

⁄

4

-inch (6 millime-

ters) at 60,000 feet (18,000 meters) using 
the diameter corresponding to the low-
est expected supersonic cruise altitude. 
Alternatively, three larger hailstones 
may be ingested at subsonic velocities 
such that the kinetic energy of these 
larger hailstones is equivalent to the 
applicable supersonic ingestion condi-
tions. 

(d) For an engine that incorporates 

or requires the use of a protection de-
vice, demonstration of the rain and 
hail ingestion capabilities of the en-
gine, as required in paragraphs (a), (b), 
and (c) of this section, may be waived 
wholly or in part by the Administrator 
if the applicant shows that: 

(1) The subject rain and hail con-

stituents are of a size that will not 
pass through the protection device; 

(2) The protection device will with-

stand the impact of the subject rain 
and hail constituents; and 

(3) The subject of rain and hail con-

stituents, stopped by the protection de-
vice, will not obstruct the flow of in-
duction air into the engine, resulting 
in damage, power or thrust loss, or 
other adverse engine anomalies in ex-
cess of what would be accepted in para-
graphs (a), (b), and (c) of this section. 

[Doc. No. 28652, 63 FR 14799, Mar. 26, 1998] 

§ 33.79

Fuel burning thrust augmentor. 

Each fuel burning thrust augmentor, 

including the nozzle, must— 

(a) Provide cutoff of the fuel burning 

thrust augmentor; 

(b) Permit on-off cycling; 
(c) Be controllable within the in-

tended range of operation; 

(d) Upon a failure or malfunction of 

augmentor combustion, not cause the 
engine to lose thrust other than that 
provided by the augmentor; and 

(e) Have controls that function com-

patibly with the other engine controls 
and automatically shut off augmentor 
fuel flow if the engine rotor speed drops 
below the minimum rotational speed at 
which the augmentor is intended to 
function. 

[Amdt. 33–6, 39 FR 35468, Oct. 1, 1974] 

Subpart F—Block Tests; Turbine 

Aircraft Engines 

§ 33.81

Applicability. 

This subpart prescribes the block 

tests and inspections for turbine en-
gines. 

[Doc. No. 3025, 29 FR 7453, June 10, 1964, as 
amended by Amdt. 33–6, 39 FR 35468, Oct. 1, 
1974] 

§ 33.82

General. 

Before each endurance test required 

by this subpart, the adjustment setting 
and functioning characteristic of each 
component having an adjustment set-
ting and a functioning characteristic 
that can be established independent of 
installation on the engine must be es-
tablished and recorded. 

[Amdt. 36–6, 39 FR 35468, Oct. 1, 1974] 

§ 33.83

Vibration test. 

(a) Each engine must undergo vibra-

tion surveys to establish that the vi-
bration characteristics of those compo-
nents that may be subject to mechani-
cally or aerodynamically induced vi-
bratory excitations are acceptable 
throughout the declared flight enve-
lope. The engine surveys shall be based 
upon an appropriate combination of ex-
perience, analysis, and component test 
and shall address, as a minimum, 
blades, vanes, rotor discs, spacers, and 
rotor shafts. 

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