TM 55-2840-254-23
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1-107 TEST ENGINE (AVIM) (Continued)
e. Snap N1 master hydronic control to flight idle and open customer air-bleed port. Time for decelera-
tion shall not exceed 6 seconds. Record time,
f. Retard N1 master hydronic control to ground idle (10 to 15 degrees) and close customer air-bleed
port. Run engine at ground idle for 2-1/2 minutes; then record a full reading.
g. Check accelerations to maximum power as specified in preceding step a., using criteria specified in
NOTE preceding step a.
h. Repeat steps f. and g. Record snap deceleration time from maximum power to ground idle; time shall
not exceed 8 seconds.
i. Advance N1 master hydronic control to fIight idle and open customer air-bleed port,
j. Advance N1 master hydronic control to PTIT obtained during preceding maximum power check
(step d.).
NOTE
Bleed band must remain closed during one minute operation at this
setting.
k. Retard N1 master hydronic control to flight idle and close customer air-bleed port.
14. WAVEOFF CHECK
a. Run engine at maximum trim throttle position for 2 minutes.
b. Perform a series of waveoffs in rapid succession from 90, 85, 80, 75, and 70 percent N1 speeds.
NOTE
To perform waveoffs, snap N1 master hdronic control lever from
maximum trim power position to allow N1speed to decelerate;
then return hydronic control lever to maximum trim power posi-
tion for each of the speeds specified above.
Waveoffs shall be surge free.
(1) N1 master hydronic control lever movement in either direction shall be accomplished in not more
than 0.5 second.
(2) Bleed band should open on snap deceleration and on jam to maximum trim power.
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