Q: Can the ENM Quartz hourmeters be preset? Are the FAA PMA approved? Or Experimental only?
These cannot be preset, there is the option that you connect to a battery and allow the time to run the hourmeter. Or write a logbook entry with the time on the original. These are commonly used in experimental applications. Please refer to part # 15000 for the hourmeter used on most production aircraft.
Q: Will the T41 fit in same hole as the T56?
Yes, these two items have the same mounting dimensions as T56, so it will work in the same cutout.
Q: What is the size and spacing of the mounting holes?
The mounting holes are at 1.75 inches apart and are .150 inches in diameter.