NOTE:  Engines should not be trimmed when weather conditions require the nacelle anti-ice system to be on. The trim tables are based on a no airbleed condition. If the engines must be trimmed when icy conditions exist, the nacelle anti-ice system must be kept on during all engine operation except for the last 30 seconds of each trim period.
F.  A check sheet should be prepared to record engine operation data during the trim run. See Fig. 202 for sample check sheet layout. Ambient temperature and true barometric pressure as well as targets for idle rpm, trim Pt7 and takeoff EPR should be recorded before commencing the engine trim run. The idle, trim and takeoff target values are determined from the trim tables. Refer to 71-09-210, Fig. 202, for the trim table locator tabulation. The EPR (Pt7/Pt2) reading which corresponds to the trim target Pt7 value should also be noted to provide a check between the control cabin EPR indicator and the engine Pt7 test indicator.
G.  Trimming the engine is accomplished by adjusting the IDLE and MIL (Maximum) trim screws, on the forward end of the fuel control, with the part power trim stop in the activated position to limit throttle cross-shaft angle (Fig. 203). The engine thrust level is slightly below MAX CRUISE rating when the MIL trim screw is properly adjusted.
H.  After a satisfactory trim run has been accomplished, it is necessary to run the engine at takeoff power to ensure that the TAKEOFF rating and throttle "cushion" are obtainable. It is also necessary to check the reverse thrust detent, and to perform an engine acceleration/deceleration check to demonstrate satisfactory dynamic response.
500 
71-09-200 Page 202  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 01/00 

G42868
500  Wind Direction and Velocity Limits 
Feb 15/69  Figure 201  71-09-200 
Page 203 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

I.  Control cabin engine instruments may be used to trim an engine when trim equipment is not available and the control cabin instruments are known to be accurate. However, a complete trim run must be accomplished as soon as the calibrated trim instrumentation becomes available. Refer to trim table sections for part power trim target EPR for existing ambient temperature and true local barometric pressure. Trim sequence outlined should be used omitting reference to trim equipment and adjusting MIL trim screw to EPR target rather than Pt7 target.
J.  For engine deterioration ground check procedures previously mentioned in this section refer to P&WA JT8D Maintenance Manual Section 72-00.
2.  Equipment and Materials
A.  
Pt7 Pressure Engine Trim Gage - F72973-10, 0 to 70 in. Hg. Absolute 士 0.1 in. Hg readability,士 0.1 Hg accuracy.

B.  
Remote Tachometer - F70303, calibrated in percentage (with current calibration chart) and adapter harness with three position selector switch to enable test tachometer indicator and control cabin indicator to be used simultaneously.

NOTE:  The adapter harness plug must mate with the Amphenol test receptacle located on the right sidewall forward of panel P6 behind the first officer's seat. The tachometer indicator and selector switch are best mounted in a suitable shock resistant box which may be manufactured locally. If a direct reading test tachometer indicator is used, the actual rpm reading should be converted to percent rpm. The JT8D engine N2 tachometer gear ratio is 0.343:1.
C.  Thermometer for reading ambient air temperature at the airplane (-40 to + 1200F)
D.  Ground Low Pressure Air Source - Boeing Model 502. (Not required if airplane auxiliary power unit is used.)
E.  Ground Service Electrical Power Cart -90 KVA output required. (Not required if airplane auxiliary power unit is used.)
F.  Interphone Service Equipment
G.  Portable Trim Kit - Comp Air Inc., Burlingame, California
71-09-200 Feb 20/88 Page 204
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

A38242
500  Engine Trim Check Sheet 
Jan 20/83  Figure 202  71-09-200 
Page 205 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

3.  Prepare to Trim Engine
A.  Remove engine cowl panels.
B.  Check and clean up area, engine, and engine mounted accessories.
C.  Check that engine start and thrust control systems are rigged as described in Chapter 76, Engine Controls.
D.  If portable trim equipment is used, disassemble trimhead by loosening trimhead thumb screw before installation on fuel control unit.
NOTE:  To facilitate trim head installation on fuel control unit, removal of the tubing clamps holding the nose cowl anti-ice supply line and the vortex dissipater duct assembly may be required.
　
中國航空網(wǎng) www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：737 AMM 飛機維護手冊 動力裝置 POWER PLANT(39)