428 

14 CFR Ch. I (1–1–19 Edition) 

Pt. 25, App. F 

(6) Leave the burner in position for 15 sec-

onds and then remove to a position at least 
2 inches (51 mm) above the specimen. 

(g) Report. (1) Identify and describe the 

test specimen. 

(2) Report any shrinkage or melting of the 

test specimen. 

(3) Report the flame propagation distance. 

If this distance is less than 2 inches, report 
this as a pass (no measurement required). 

(4) Report the after-flame time. 
(h) 

Requirements. 

(1) There must be no 

flame propagation beyond 2 inches (51 mm) 

to the left of the centerline of the pilot 
flame application. 

(2) The flame time after removal of the 

pilot burner may not exceed 3 seconds on any 
specimen. 

Part VII—Test Method To Determine the 

Burnthrough Resistance of Thermal/Acoustic 
Insulation Materials 

Use the following test method to evaluate 

the burnthrough resistance characteristics 
of aircraft thermal/acoustic insulation mate-
rials when exposed to a high intensity open 
flame. 

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