CS-E 840  Rotor Integrity

ED Decision 2007/015/R

(See AMC E 840)

(a)     For each fan, compressor, and turbine rotor, it must be established by test, analysis, or combination thereof, that a rotor which has the most adverse combination of material properties and dimensional tolerances allowed by its type design will not burst when it is operated in the Engine for five minutes at whichever of the conditions defined in CS-E 840(b) is the most critical with respect to the integrity of such a rotor.

However, where that required condition is determined by either CS-E 840(b)(3) or (b)(4), but the associated Failure condition is of a sudden transient nature, such as loss of load, and it precludes any further operation of the affected rotor, then the time period of that Failure condition is an acceptable duration for showing compliance by means of an Engine test provided the required test speeds are achieved. Test rotors which do not have the most adverse combination of material properties and dimensional tolerances must comply at appropriately adjusted test parameters, e.g. speed, temperature, loads.

(b)     When determining the operating conditions applicable to each rotor for compliance with CS-E 840(a) and (c), each of the following speeds must be evaluated in conjunction with their associated temperatures and temperature gradients, throughout the Engine's operating envelope:

(1)     120% of the maximum permissible rotor speeds associated with any of the ratings except OEI ratings of less than 2½-minutes.

(2)     115% of the maximum permissible rotor speeds associated with any OEI ratings of less than 2½-minutes.

(3)     105% of the highest rotor speed that would result from either -

(i)      The Failure of the component or system which, in a representative installation of the Engine, is the most critical with respect to over-speeding when operating at any rating condition except OEI ratings of less than 2½-minutes, or

(ii)     The Failure of any component or system in a representative installation of the Engine, in combination with any other Failure of a component or system that would not normally be detected during a routine pre-flight check or during normal flight operation that is the most critical with respect to over-speeding, except as provided by CS-E 840(c), when operating at any rating condition except OEI ratings of less than 2½-minutes.

(4)     100% of the highest rotor speed that would result from the Failure of the component or system which, in a representative installation of the Engine, is the most critical with respect to over-speeding when operating at any OEI ratings of less than 2½-minutes.

(c)      The highest over-speed which will result from a complete loss of load on a turbine rotor, unless it can be shown to be Extremely Remote under the provisions of CS-E 850, must be included in the over-speeds considered under each of CS-E 840(b)(3)(i), (ii) and (b)(4), irrespective of whether it is the result of a Failure within the Engine or external to the Engine.

Over-speeds resulting from any other single Failure must be considered. Over-speeds resulting from multiple Failures must also be considered unless they can be shown to be Extremely Remote.

(d)     In addition, for each fan, compressor, and turbine rotor, it must be established by test, analysis, or combination thereof, that a rotor which has the most adverse combination of material properties and dimensional tolerances allowed by its type design and which is operated in the Engine for five minutes at 100% of the most critical speed and temperature conditions resulting from any Failure or combination of Failures considered under CS-E 840(b)(3) and (b)(4), will meet the acceptance criteria prescribed below in CS-E 840(d)(1) and (d)(2).

However, where the Failure condition is of a sudden transient nature, such as loss of load, and it precludes any further operation of the affected rotor, the time period of that Failure condition is an acceptable duration for showing compliance by means of an Engine test.

Test rotors which do not have the most adverse combination of material properties and dimensional tolerances must comply at appropriately adjusted test parameters, e.g. speed, temperature, loads.

(1)     Growth of the rotor while it is operating at the applicable conditions must not cause the Engine to:

(i)      Catch fire,

(ii)     Release high energy debris through the Engine's casing or result in a hazardous Failure of the Engine's casing,

(iii)     Generate loads greater than those ultimate loads for which the Engine's mountings have been designed in compliance with CS-E 100(b), or

(iv)     Lose the capability of being shut down.

(2)     After the applicable period of operation, the rotor must not exhibit conditions such as cracking or distortion which preclude the safe operation of the Engine during any likely continued operation following such an over-speed event in service.

[Amdt No: E/1]