Citation Excel (C560XL)
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Troubleshooting
Aircraft Equipment Problem Less Severe
General None Reported / Taken
Aircraft
Upon initiating the descent from FL390 to our destination in VMC and no turbulence at a KIAS of about 230-240; we started to hear a rumbling noise as a first indication. This was followed by vibrations that were felt through the floor boards; followed by both control yokes starting to visibly and tactilely to vibrate. The vibration stopped upon acceleration past about a KIAS of 250. At this point we referenced the QRH and were not able to find any checklist that would apply. We did review the total loss of primary flight controls checklist just to be on the safe side. We then slowed down again from about 300 KIAS to 230-240 KIAS and were able to duplicate the discrepancy. The vibration did not seem to reoccur below about FL250 at any speed. We did not declare an emergency; or request priority handling. We landed without further issues and submitted the required Maintenance discrepancy.
CE-560XLS pilot reported a vibration in floor boards and yokes during descent.