...It would help me if you know a reference that I can use to prove my case...
Hopefully, the information and link below will be what you're looking for:
The requirement for the airplane manufacturer to conduct an evacuation demonstration for airplanes having a seating capacity of more than 44 passengers was established in Part 25 (25.803) by Amendment 25-15, effective October 24; 1967. The time limit for the manufacturer's demonstration was established at 90 seconds, and the Part 121 time limit was reduced to 90 seconds. It was considered that the manufacturer's demonstration would show the basic capability of the new airplane and, as before, the Part 121 demonstration was intended to account for crew training and adequate crew procedures. Therefore, the test conditions were somewhat different.
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A full-scale demonstration is conducted to assess the evacuation capability of the airplane and, when compliance with 5 25.803(c)(7)(i) is requested, to also demonstrate the effectiveness of crew training and emergency procedures. Section 25.803(c) specifies the conditions for conduct of the evacuation demonstration.
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To constitute a successful test, all passengers and crewmembers used in the demonstration must be evacuated to the ground or to an off-wing stand or ramp, if used, within 90 seconds. Use only the number of passengers for which approved seating is provided, not to exceed the limits of 5 25.807(c) or (d). No credit is given for the number of evacuees on the ground at 90 seconds if all persons have not been evacuated.
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Neither the crew nor passengers should hear or otherwise receive any. indication that the demonstration is about to begin. The first indication to persons on board the airplane should be the test start signal.
AC 25.803-1 Emergency Evaluation Demonstrations