This was formerly located in section 424.66, and now located in 110.26 with all the clearance requirements. This section applies to VAV boxes, duct heaters, and other ventilation equipment installed above a drop ceiling. This area above the ceiling is usually limited and workers are standing on ladders while performing maintenance. It states in (d) that the cross members are allowed in this working space but you still have to maintain the working clearances for the safety of the workers.
Can’t see the whole picture just click on it.
Till next time be safe work safe.
Jake