McDonnell Douglas Undifferentiated or Other Model
Flight Crew Commercial
Aircraft Equipment Problem Critical
Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Declared Emergency
Aircraft
We were transporting a patient from [one] hospital to [another] hospital. We were in cruise flight at 2;000 FT and 140 KIAS. The aircraft began to experience a one to one vertical vibration and I felt feedback in the cyclic. I was abeam [airport] so I called Tower; declared an emergency; and executed a roll-on landing to Runway 18 without incident.We contacted our communication center; informed them of the situation; and they dispatched a unit to pick-up the patient. Maintenance arrived and upon inspection it was discovered that the lower bearing on the black pitch change link failed and came unstaked from the rod end.
Pilot of a medical helicopter noted a vibration in the cyclic during cruise flight; diverted and performed a roll-on landing at an airport. Pitch change link had failed.