(e)  
Remove the bolts and move apart the forward and aft cages of the safety screen.

 CAUTION:_______REMOVE THE SAFETY SCREEN FORWARD CAGE CAREFULLY. IF THE CAGE TOUCHES THE TURBINE BLADES IT CAN CAUSE DAMAGE TO THE BLADES OR THE GOVERNER MECHANISM.

 (f)  
Move the forward cage away from the RAT with the lifting fixture.

 (g)  
Apply a strip of tape that is 1/2 by 2 inches, at one of these locations: 1) On the RAT turbine hub, from the center to the edge

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 29-21-00
 ALL  ú ú 09 Page 517 ú May 28/99
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL

 2) On the end of one RAT turbine blade.
 CAUTION:_______ SET THE SAFETY SCREEN FORWARD CAGE TO THE CORRECT HEIGHT
 BEFORE YOU MOVE IT INTO POSITION.  IF THE CAGE TOUCHES THE
 TURBINE BLADES, IT CAN CAUSE DAMAGE TO THE BLADES OR THE

 GOVERNER MECHANISM.
 (h)  
Raise the forward cage to the correct height with the lifting fixture.

 (i)  
Carefully move the forward cage into position around the RAT so that the cage does not hit the turbine blades.

 (j)  
Install the bolts to connect the forward and aft cages of the safety screen.

 (k)  
Lower the lifting fixture and move the fixture away from the safety screen.

 (l)  
Pressurize the center hydraulic system with a hydraulic service cart (Ref 29-11-00).

 (m)  
Move the control handle on the RAT checkout module, in the right wheel well, to the back-drive position.

 (n)  
Set the stroboscope to less than 1500 rpm.

 (o)  
Monitor the speed of the RAT turbine blades while you increase the adjustment of the stroboscope from 1500 rpm to 9440 rpm.

 (p)  
Make a record of the highest speed at which the strip of tape shows as one stable mark in the light of the stroboscope.

 (q)  
Make sure this speed is between 3980 and 4720 rpm.

 NOTE: If the governor in the RAT hub does not control the
____ speed correctly, a speed in the range of 1500 to 7500 rpm can occur.
 S 865-102
 (18)
 Quickly release the control handle from the back-drive position. Make sure the RAT green pressure light on the engine start/RAT control panel comes on.

 S 865-146

 (19)
 Make sure the RAT blades and hub stop.

 NOTE: It is possible that the RAT blades and hub will continue to
____ turn slowly after you release the control handle. The cause of this condition is a check valve, in the RAT strut, which did not open while the speed of the RAT blades decreased. The check valve will open when you remove the hydraulic pressure. When you supply hydraulic pressure again, the RAT blades will not move. It is not necessary to reject parts because of this condition.
 S 215-103
 (20) If the RAT blades and hub continue to slowly turn when the handle is not in the back-drive position, do these steps:
 (a)  Remove the center hydraulic system pressure (AMM 29-11-00/201).
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 29-21-00
 ALL  ú ú 08 Page 518 ú May 28/99
　
中國航空網(wǎng) m.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：757 AMM 飛機維護手冊 液壓 CHAPTER 29 - HYDRAULIC POWER 2(60)