§29.907 Engine vibration

(a) Each engi ne m ust be i nstalled to prevent the harmful vibration of any part of t he engine or rotorcraft. (b) The addition of the rotor and the rotor drive sy stem t o t he engi ne may not subject the principal rotating parts of t he engi ne t o excessi ve vibration st resses. Thi s m ust be shown by a vibration investigation.