Are technical skills mandatory for a project manager?

theoretically NO, it is not mandatory.in reality a PM  with technical knowlegde could better handle the project .

An ideal Project Manager would be the one who himself has gone through all the technical levels for which he is going to take work from his staff. But it is not necessary that he should be as expert (or as quick in performing those duties) as the actual person who has to perform the specific job. It is very important that the Manager must be aware of the standard effeciency levels of the staff he needs not to be deceived by the shirking staff.

Technical Skills are not Mandatory.

But technical skills are just an added benefit for the Project Manager to better understand the scope of work by the team and to ensure that the team members do not take him for a ride.

Yes the technical skills are required for a project manager.
In case of IT project manger he will not have skills related to mechanical stuff but yes he may have the man management skill.
So in that case it will not work.
But suppose a project manager in steel industry is offered job on Oil rigs then it will work as he understand the basic concept of Mechanical engineering.

Yes mandatory in functional organization.
no need in projectized organization recommended in matrix organization.

as a project manager, you need to be able to perform project management tasks, which would not be that different in different industries, however, you need to have a team of experts to guide you in specific matters related to tasks, communication and stakeholders, in addition to risks.

As a project manager you would usually have a team that you would rely on to acheive project goals.
Most teams are technically capable of handle tech issues without the presence of a project manager.
But it is best to enhance knowledge and obtain a moderate comprehension of what project you are managing.
That gives you an extra edge when resolving issues and following up with team members.
It also enhances your overall image to your team members and customers as well.

Technical skills are not mandatory, but it is an added advantage if the PM has a certain level of technical skills in the area of the project being implemented. It will give him a better judgement sense while Planning contingency reserves for Project issues and risks..

We must differentiate between technical skills and managerial skills in another word PM must have the main managerial skills as organizing,planning, controlling,supporting and monitoring to facilitate the desicion making procedures but it is essential to know a round figures of technical issues to handle the technical solutions taken by the technical specialists this make the project managment environment more powerful but it is not essential at all for the project manager to be a technical specialist or know every technical details

Generally a project manager doest need product technical skills but it is always an Added Advantage...

Yes he should know what he is managing