CS 25.905 Propellers — CS-25

IRImplementing rule

CS 25.905Propellers

(See AMC 25.905)

(a)reserved

(b)Engine power and propeller shaft rotational speed may not exceed the limits for which the propeller is certificated. (See CS-P 50.)

(c)Each component of the propeller blade pitch control system must meet the requirements of CS-P 420.

(d)Design precautions must be taken to minimise the hazards to the aeroplane in the event a propeller blade fails or is released by a hub failure. The hazards which must be considered include damage to structure and critical systems due to impact of a failed or released blade and the unbalance created by such failure or release. (See AMC 25.905(d).)

[Amdt 25/3]

[Amdt 25/18]

IR · CS 25.905 — CS-25 · ED Decision 2016/010/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

AMCAcceptable means of compliance

AMC 25.905(d)Release of Propeller Debris

Show the text

1 Propeller Installation. Design features of the propeller installation, including its control system, which are considered to influence the occurrence of propeller debris release and/or mode of such a failure should be taken into account when assessing the aeroplane against CS 25.905(d). 2 Aeroplane Design Conditions

2.1 Impact Damage Zone. All practical precautions should be taken in the aeroplane design to minimise, on the basis of good engineering judgement, the risk of Catastrophic Effects due to the release of part of, or a complete propeller blade. These precautions should be taken within an impact zone defined by the region between the surfaces generated by lines passing through the centre of the propeller hub making angles of at least five degrees forward and aft of the plane of rotation of each propeller. Within this zone at least the following should be considered. a. The vulnerability of critical components and systems (e.g. location, duplication, separation, protection); and b. The fire risk in the event of flammable fluid release in association with potential ignition sources (e.g. location, protection, shut-off means).

2.2 Other Considerations. Consideration should be given to the effects on the aeroplane resulting from – a. The likely out of balance forces due to the release of part of, or a complete propeller blade; and b. Loss of a complete propeller.

AMC · AMC 25.905(d) — CS-25 · ED Decision 2003/2/RM · CS-25 Easy Access Rules · EAR revision 26 Jan 2023