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CS 25J901 Installation

Large Aeroplanes (CS-25) · CS-25 · EAR revision 26 Jan 2023

IRImplementing rule

CS 25J901 Installation

(See AMC 25J901)

(a)For the purpose of this subpart, the APU installation includes:

(1)The APU;

(2)Each component that affects the control of the APU;

(3)Each component that affects the safety of the APU.

(b)For the purpose of this subpart,

(1)An essential APU is defined as an APU whose function is required for the dispatch of the aeroplane and/or continued safe flight.

(2)A non-essential APU is defined as an APU whose function is a matter of convenience, either on the ground or in flight, and may be shut down without jeopardising safe aeroplane operation.

(c)For each APU:

(1)The installation must comply with:

(i)The installation instructions provided under CS-APU, and

(ii)The applicable provisions of this subpart for non-essential APUs, or

(iii)The applicable provisions of this subpart for essential APUs.

(2)The components of the installation must be constructed, arranged, and installed so as to ensure their continued safe operation between normal inspections or overhauls. (See AMC 25J901(c)(2).)

(3)The installation must be accessible for necessary inspections and maintenance; and

(4)The major components of the installation must be electrically bonded to the other parts of the aeroplane. (See AMC 25J901(c)(4).)

(d)The APU installation must comply with CS 25.1309, except that the effects of the following need not comply with CS 25.1309(b) (see AMC 25.901(c)):

(1)APU case burn through or rupture; and

(2)Uncontained APU rotor failure.

[Amdt 25/1]

[Amdt 25/18]

IR — CS-25 · ED Decision 2016/010/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

All rules in SUBPART J – AUXILIARY POWER UNIT INSTALLATIONS

Consolidated from the EASA Easy Access Rules (revision 26 Jan 2023, extracted 17 Aug 2026) for convenience. Not the official publication — verify against the Official Journal of the European Union and the EASA publications before operational use.

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