(j)  
Make sure that the ELEV (L, C and R) HYD PRESS messages are shown on the EICAS display.

 (k)  
Put the L, C, and R FLT CONTROL SHUTOFF valve switches on the P61 panel to the ON position.

 (l)  
Make sure that the ELEV (L, C, and R) HYD PRESS messages stay on the EICAS display.

 (m)  
Remove the power from the left, center, and right hydraulic systems (Ref 29-11-00/201).

 (n)  
Make sure that the ELEV (L, C, and R) HYD PRESS messages stay on the EICAS display.

 WARNING: KEEP PERSONS AND EQUIPMENT AWAY FROM ALL CONTROL SURFACES
_______ WHEN HYDRAULIC POWER IS SUPPLIED. AILERONS, ELEVATORS, RUDDER, FLAPS, SLATS, SPOILERS, AND STABILIZER ARE FULLY POWERED SURFACES. INJURY TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR WHEN HYDRAULIC POWER IS SUPPLIED.
 (o)  
Pressurize the left, center, and right hydraulic systems (Ref 29-11-00/201).

 (p)  
Do the EICAS status and maintenance message erase procedure (Ref 31-41-00/201)

 (q)  
Make sure that the ELEV (L, C, and R) HYD PRESS messages are not shown on the EICAS display.

 (r)  
Remove the power from the left, right, and center hydraulic systems (Ref 29-11-00/201).

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 ALL  ú ú 01 Page 410 ú Sep 20/91
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A

757 MAINTENANCE MANUAL
 G. Install the Bypass Valve (Fig. 401)
 S 424-023
 (1)  
Install the bolts and washers (3 locations) that attach the bypass valve to the support bracket.

 S 434-024

 (2)  
Remove the plugs from the hydraulic lines and the caps from the bypass valve ports (4 locations).

 S 434-032

 (3)  
Connect the hydraulic lines to the bypass valve.

 S 714-025

 (4)  
Do a test on the bypass valve installation with these steps:

 WARNING: KEEP PERSONS AND EQUIPMENT AWAY FROM ALL CONTROL SURFACES
_______ WHEN HYDRAULIC POWER IS SUPPLIED. AILERONS, ELEVATORS, RUDDER, FLAPS, SLATS, SPOILERS, AND STABILIZER ARE FULLY POWERED SURFACES. INJURY TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR WHEN HYDRAULIC POWER IS SUPPLIED.
 (a)  
Pressurize the left, right, and center hydraulic systems (Ref 29-11-00/201).

 (b)  
Move the horizontal stabilizer until Dimension B on the stabilizer ballscrew actuator is 15.89 | 0.01 inches

 (403.6 +/- 0.25 mm) (Fig. 402).
 (c)  
Move the captain's column forward and aft, then let it go to the neutral position.

 (d)  
Put a piece of tape on the side of the airplane adjacent to the left elevator trailing edge.

 (e)  
Make a mark at the neutral position of the left elevator on the tape.

 NOTE: Elevator travel, for this test, is the straight line
____ distance from the neutral position to the new inboard trailing edge position. You must make a mark and measure the elevator movement in the time specified in the steps.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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 ALL  ú ú 01 Page 411 ú Jan 28/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL

 (f)  
Use the tail flight control shutoff valves to remove the power from the left and right hydraulic systems.

 WARNING:  DO NOT EXTEND THE POGO MORE THAN 0.25 INCH (6.3 mm). MAKE SURE THAT THE TOOL IS CLEAR OF ALL OF THE LINKAGES, THE ELEVATOR AND THE HORIZONTAL STABILIZER. INJURY TO PERSONS CAN OCCUR.

 (g)  
Use pogo tools to extend the pogos at the left middle and left outboard PCAs by 0.20 to 0.25 inch (5.1-6.3 mm) (Fig. 403).

 NOTE: Do not move the control column again until the test
____
 on the byass valve is completed.

 (h)  
Use the tail flight control shutoff valve to supply power to the left hydraulic system.

 (i)  
After 28 to 32 seconds, make sure the left elevator moves down

 2.5 to 3.5 inches (64-88 mm).
 NOTE: If the bypass valve does not pass the test, do these
　
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