Update task locked field value based project custom field on project server 2013

Hi,

We are created a custom project field with name Project Archived-flag field -default value isNo when new project creating.

we added Locked (Project Server System Field) Field on  task summeryview on Schedule page , which contains default value isNo.

But my requirement is when project manager changes the Project Archivedfield changed to Yes need to change on Locked field toYes on task summery view.

Let us knowout of b any idea to do this,using ox or customization

like workflows,server side event handlers and formulas to do this,

your help is really appreciated,

Thank you,

SENA

SENA