TM 55-2840-254-23
1-107 TEST ENGINE (AVIM) (Continued)
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22. ENGINE RATING
Accepted engines shall be rated for N1 speed and PTIT by using data record on engine test log. The rating
states the speed and temperature which will be obtained at sea level, standard conditions with power lever
in maximum power position when fuel control is trimmed in accordance with adjust maximum trim (Ref.
Paragraph 9).
This trim setting is designed to produce required power on a 95 F (35 C) day, and will give 4200 SHP on a
sea level standard day instead of the rated maximum power of 3750 SHP.
a. Determine rated N1 speed as follows:
Locate N1 speed and ambient temperature readings recorded at maximum trim adjustment'
(1)
(Ref. Paragraph 9, step e).
NOTE
If cold weather stop was used in maximum trim adjustment (Ref.
Paragraph 9), use following step (2) instead of prior step (1 ). If not
disregard step (2).
Add N1 speed determined in maximum trim adjustment (Ref. Paragraph 9, step g. (4)) to N1
(2)
speed determined in maximum trim adjustment (Ref. Paragraph 9, step g. (6)).
Using following graph, determine correction factor for recorded Test ambient temperature.
(3)
Multiply N1 speed determined in preceding step by correction factor determined in preceding
(4)
step.
Result is corrected gas producer (N1) speed.
(5)
Record corrected N1 speed on engine log sheet and data plate.
(6)
Correction Factor for Determining Standard Day N1 Speed
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