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735 

Federal Aviation Administration, DOT 

§ 33.91 

starts may be made at any time, in-
cluding the period of endurance test-
ing. 

[Doc. No. 3025, 29 FR 7453, June 10, 1964, as 
amended by Amdt. 33–3, 32 FR 3737, Mar. 4, 
1967; Amdt. 33–6, 39 FR 35468, Oct. 1, 1974; 
Amdt. 33–10, 49 FR 6853, Feb. 23, 1984; Amdt. 
33–12, 53 FR 34220, Sept. 2, 1988; Amdt. 33–18, 
61 FR 31328, June 19, 1996; Amdt. 33–25, 73 FR 
48123, Aug. 18, 2008; Amdt. 33–30, 74 FR 45311, 
Sept. 2, 2009; Amdt. 33–32, 77 FR 22187, Apr. 
13, 2012] 

§ 33.88

Engine overtemperature test. 

(a) Each engine must run for 5 min-

utes at maximum permissible rpm with 
the gas temperature at least 75 

°

F (42 

°

C) higher than the maximum rating’s 

steady-state operating limit, excluding 
maximum values of rpm and gas tem-
perature associated with the 30-second 
OEI and 2-minute OEI ratings. Fol-
lowing this run, the turbine assembly 
must be within serviceable limits. 

(b) In addition to the test require-

ments in paragraph (a) of this section, 
each engine for which 30-second OEI 
and 2-minute OEI ratings are desired, 
that incorporates a means for auto-
matic temperature control within its 
operating limitations in accordance 
with § 33.28(k), must run for a period of 
4 minutes at the maximum power-on 
rpm with the gas temperature at least 
35 

°

F (19 

°

C) higher than the maximum 

operating limit at 30-second OEI rat-
ing. Following this run, the turbine as-
sembly may exhibit distress beyond the 
limits for an overtemperature condi-
tion provided the engine is shown by 
analysis or test, as found necessary by 
the FAA, to maintain the integrity of 
the turbine assembly. 

(c) A separate test vehicle may be 

used for each test condition. 

[Doc. No. 26019, 61 FR 31329, June 19, 1996, as 
amended by Amdt. 33–25, 73 FR 48124, Aug. 18, 
2008; Amdt. 33–26, 73 FR 48285, Aug. 19, 2008] 

§ 33.89

Operation test. 

(a) The operation test must include 

testing found necessary by the Admin-
istrator to demonstrate— 

(1) Starting, idling, acceleration, 

overspeeding, ignition, functioning of 
the propeller (if the engine is des-
ignated to operate with a propeller); 

(2) Compliance with the engine re-

sponse requirements of § 33.73; and 

(3) The minimum power or thrust re-

sponse time to 95 percent rated takeoff 
power or thrust, from power lever posi-
tions representative of minimum idle 
and of minimum flight idle, starting 
from stabilized idle operation, under 
the following engine load conditions: 

(i) No bleed air and power extraction 

for aircraft use. 

(ii) Maximum allowable bleed air and 

power extraction for aircraft use. 

(iii) An intermediate value for bleed 

air and power extraction representa-
tive of that which might be used as a 
maximum for aircraft during approach 
to a landing. 

(4) If testing facilities are not avail-

able, the determination of power ex-
traction required in paragraph (a)(3)(ii) 
and (iii) of this section may be accom-
plished through appropriate analytical 
means. 

(b) The operation test must include 

all testing found necessary by the Ad-
ministrator to demonstrate that the 
engine has safe operating characteris-
tics throughout its specified operating 
envelope. 

[Amdt. 33–4, 36 FR 5493, Mar. 24, 1971, as 
amended by Amdt. 33–6, 39 FR 35469, Oct. 1, 
1974; Amdt. 33–10, 49 FR 6853, Feb. 23, 1984] 

§ 33.90

Initial maintenance inspection 

test. 

Each applicant, except an applicant 

for an engine being type certificated 
through amendment of an existing type 
certificate or through supplemental 
type certification procedures, must 
complete one of the following tests on 
an engine that substantially conforms 
to the type design to establish when 
the initial maintenance inspection is 
required: 

(a) An approved engine test that sim-

ulates the conditions in which the en-
gine is expected to operate in service, 
including typical start-stop cycles. 

(b) An approved engine test con-

ducted in accordance with § 33.201 (c) 
through (f). 

[Doc. No. FAA–2002–6717, 72 FR 1877, Jan. 16, 
2007] 

§ 33.91

Engine system and component 

tests. 

(a) For those systems or components 

that cannot be adequately substan-
tiated in accordance with endurance 

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