Thanks everyone for your comments. Tall Paul:
On this factory drawing of the T-28, the FRL goes thru the motor, parallel to the horizontal.
The only thing I could see that was parallel to the FRL on the T-28 was the border on the drawing, so I wasn't sure where to start. Based on Mike James' suggestion that the designer may have intended the FRL to be 90 degrees to the formers, it looks like on the T-28 drawing that the FRL is perpendicular to section lines B-B and D-D. Maybe the formers are parallel to those section lines. So once the FRL is drawn perpendicular to the formers, then in the drawing, the whole plane is oriented so the FRL is parallel to the drawing border- "the horizontal".
Thanks for your responses.
Marl