Adel,
You can leave the standby firewall powered on and run 'clusterXL_admin down' this will force the standby member to be 'down' when running a cphaprob stat. You can do your maintenance on the switch. When you are done with switch2, run 'clusterXL_admin up' on FW2, wait for them to be Active/Standby. Then, fail traffic over to FW02 when ready so you can do maintenance on SW1 but issuing the same 'clusterXL_admin down' command on FW1, forcing the failover to FW2.
Steps:
1.) Issue clusterXL_admin down on FW2
2.) Replace SW2 & being back online
3.) Issue clusterXL_admin up on FW2
4.) Verify cluster is back to Active (FW1)/Standby(FW2)
5.) If you want verify state table with fw tab -t connections -s on FW1/FW2 before moving on to next step
6.) Issue clusterXL_admin down on FW1
7.) Verify FW2 is active and passing traffic
8.) Replace SW1 & being back online
9.) Issue clusterXL_admin up on FW1
10.) Verify cluster is back to Active(FW2)/Standby(FW1)
11.) Fail back to FW1 to verify new switch config and successful traffic on new switch
a.) To fail back to FW1, go back through commands 1 & 3 to force the failover to FW1 and then bring FW2 back in as standby.