When its necessary to equalize the fluid levels between the A and B hydraulic reservoirs , you can use the procedures below.
Make sure the total quantity displayed on the gauge is approx 2/3 between refill and FULL (classic) , or approx 92% on the DU (NG). This is to prevent overfilling and fumes in the airco system , see maintenance tip 737-MT-12-002.
Hydraulic fluid transfer:
A > B
1. A pump ON
2. Park brake ON
3. B pump ON
4. A pump OFF
5. Depress A sys (continiously moving the aileron wheel is a good option)
6. Park brake OFF
7. A pump ON
8. B pump OFF
9. Depress B sys
10. Repeat step 2 to 8 as required
(can be 10 to 15 times)
B > A
1. Alt flap switch ON
2. Reverse #1 DEPLOY
3. Alt flap switch OFF
4. A pump ON
5. Reverse #1 STOW
6. A pump OFF
7. Depress A syst.
8. Repeat step 1 to 7 as required (1 to 3 times)
Make sure the REV light on the P5 OVHD panel extinguishes after T/R stow, else reset.
Another easy method is almost similar, but transfers the fluid in small steps from B to A:
In both cases A pump must be ON.
From A > B: 1-apply brakes, 2-b pump on, 3-release brakes, 4-b pump off, repeat as required.
From B>A: 1-b pump on, 2-apply brakes, 3-b pump off, 4-release brakes, repeat as required. When switching b pump, wait a moment (approx 2 sec.) with the next step, so the system can switch from alt to norm or from norm to alt. This can be felt/heard as a click on the brake pedals. Thanks to Virgil.