CS-E 650  Vibration Surveys

ED Decision 2015/009/R

(See AMC E 650)

(a)     It must be established by test or a combination of test and validated analysis that the vibration characteristics of all components that may be subject to mechanically or aerodynamically induced vibratory responses are acceptable throughout the declared flight envelope.

(b)     The vibration surveys must cover the ranges of power or thrust and rotational speed for each rotor module, corresponding to operations throughout the range of ambient conditions in the declared flight envelope, from the minimum rotational speed up to at least the maximum of:

(1)     103 % of the maximum rotational speed permitted for rating periods of two minutes or longer;

(2)     100 % of the maximum rotational speed permitted for rating periods of less than two minutes;

(3)     100 % of any Maximum Engine Over-speeds declared under CS E 830.

(c)      If there is any indication that a rising response amplitude may lead to peak vibratory stresses occurring at a speed above the maximum rotational speed established under CS-E 650(b), the surveys must be extended sufficiently to reveal the maximum amplitude, except that the extension need not cover more than a further 2 percentage points increase beyond this speed.

(d)     The surveys must also cover the aerodynamic and aeromechanical factors which might induce or influence flutter in those systems susceptible to that form of vibration.

(e)     Evaluations must be made of the effects on vibration characteristics of operating with scheduled changes (including allowance for tolerances) to variable vane angles, compressor bleeds, accessory loading, the most adverse inlet airflow distortion pattern declared by the applicant and the most adverse conditions in the exhaust duct(s).

(f)      Except as provided by CS-E 650(g), the vibratory stresses associated with the vibration characteristics determined under this CS-E 650, when combined with the appropriate steady stresses, must provide suitable margins to the endurance limit of each component, after making due allowances for operating conditions and for the permitted variations in properties of the associated materials. The suitability of these stress margins must be justified for each component. If it is determined that certain operating conditions, or ranges, need to be limited, operating and installation limitations must be established.

(g)     The effects on vibration characteristics of excitation forces caused by Fault conditions must be evaluated and shown not to result in a Hazardous Engine Effect.

(h)     Compliance with this CS-E 650 must be substantiated for each specific installation configuration that can affect the vibration characteristics of the Engine. If these vibration effects cannot be fully investigated during Engine certification, the methods by which they can be evaluated and compliance shown must be substantiated and defined in the Engine instructions for installation required under CS-E 20(d).

[Amdt. No.: E/1]

[Amdt. No. E/4]