(8)
This procedure gives instructions for these subtasks:
(a)
Listing of available fan and turbine plane counterweights.
(b)
Instructions for the installation of the counterweights.
(c)
Operation of the CDU to get the vibration data.
(d)
How to calculate the weight location.
(9)
Definitions:
(a)
Once Per Revolution N1 Speed Reference: Once every revolution a signal is received by the N1 speed transducer. The short tooth of the tachometer gear on the turbine shaft coupling makes the signal.
(b)
N1 Reference Mark: Ink mark on a fan blade or the hub which
identifies the short tooth location.
(c)
1EL: The vibration of the low pressure rotor.
(d)
Vibration Units: Vibration should be in mils (mm) and
vibration velocity in inches per second (mm per second).
1 mil = 0.001 inch (0.025 mm)
(e)
Phase Angle Lag: If the low pressure rotor is not balanced, the vibration analyzer will give its angular location. The phase angle lag is the angle between the actual location of the unbalance and the location the analyzer shows.
NOTE: This procedure uses phase measurement equipment that
____ measures from the N1 speed pulse to the vibration pulse (maximum). Measure positive angles, in this coordinate system, in the opposite direction from the direction in which the engine turns. Some phase measurement equipment, such as the MTI equipment, measure positive angles in the direction in which the engine turns (lead angle).
(f)
Phase Angle: The angle between the signal from the vibration transducer and the signal from the N1 speed reference. The speed reference is given once per revolution.
(g)
Sensitivity: The moment weight that causes 1.0 mil (0.025 mm) of vibration.
(h)
Once Per Revolution N1 Speed Reference: Once every revolution a signal is received by the N1 speed transducer. The short tooth of the tachometer gear on the turbine shaft coupling makes the signal. As an alternative procedure, use an optical tachometer for the once per revolution N1 speed reference.
(i)
N1 Reference Blade: Fan blade with an ink mark to identify the short tooth location.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
72-31-00
ALL ú ú N01 Page 515 ú Feb 15/99
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / PW4000 SERIES /747-400 / ENGINES/MAINTENANCE MANUAL ////////////////////////
(j)
Stable Vibration: A Stable Vibration is a vibration of which the vibration maximum does not change by more than one-fourth of the average vibration during 30 seconds of the engine operation.
(k)
Vibration Survey: To do a test and write the engine vibration data against the rotational speed during an engine acceleration or deceleration. This finds which engine speeds give the maximum vibration levels which are not permitted.
(l)
Trim Balance Survey: To do a test and write the vibration amplitude and phase angle data of the low rotor. The vibration amplitude is measured while the engine is stable at the peak vibration level. You can then calculate the correct weight.
B.
Equipment
(1)
PWA 85306 Puller - Pratt & Whitney
(2)
PWA 85307 Puller - Knocker, Pratt & Whitney
(3)
PWA 85306 Puller - Pratt & Whitney
(4)
ENGINES POST-PW-SB 72-385;
0.190-32 Jackscrews - 8 are necessary
(5)
ENGINES PRE-PW-SB 72-385;
PWA 83507 Puller - Pratt & Whitney
C.
Consumable Materials
(1)
G00846 Pencil - Silver
(2)
D00504 Petrolatum - White
(3)
D00390 Oil - Engine
(4)
G00949 Ink
D.
References
(1)
AMM 71-00-00/201, Power Plant
(2)
AMM 71-00-00/501, Power Plant
(3)
AMM 72-31-01/401, Inlet Cone
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：747-400 AMM 飞机维护手册 发动机 ENGINE 1(120)
