CS 25J1103 Air intake system ducts

(a)Each air intake system duct must be:

(1)Drained to prevent accumulation of hazardous quantities of flammable fluid and moisture in the ground attitude. The drain(s) must not discharge in locations that might cause a fire hazard; and

(2)Constructed of materials that will not absorb or trap sufficient quantities of flammable fluids such as to create a fire hazard.

(b)Each duct must be:

(1)Designed to prevent air intake system failures resulting from reverse flow, APU surging, or inlet door closure; and

(2)Fireproof within the APU compartment and for a sufficient distance upstream of the APU compartment to prevent hot gases reverse flow from burning through the APU air intake system ducts and entering any other compartment or area of the aeroplane in which a hazard would be created resulting from the entry of hot gases. The materials used to form the remainder of the air intake system duct and plenum chamber of the APU must be capable of resisting the maximum heat conditions likely to occur.

(c)Each duct connected to components between which relative motion could exist must have means for flexibility.

[Amdt 25/1]