BAe 125 Series 800
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Human-Machine Interface; Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance
Flight Crew Diverted; General Maintenance Action; General Release Refused / Aircraft Not Accepted
Aircraft; Human Factors; Procedure
The subject aircraft was returned to service after a maintenance inspection was allegedly performed. When I performed my walk around inspection; the damaged stators were not recognizably damaged; but I did take some extra time looking. Shortly after departure the Captain noticed a vibration in the control wheel and asked me to confirm it. At that time I noticed a slower-than-normal airspeed indication. I accepted the controls and radios while he called the Chief Pilot. Collectively; we decided to divert to a nearby airport. Upon landing; the captain performed a full power run up for 15 seconds. The buzzing sound at full power and a vibration in the control wheel were still present and pronounced. After shutdown; I inspected the No. 1 engine with the captain and we discovered unquestionable damage and blood stains which are documented in the photos [provided to the company]. I then climbed up on the right wing for a close inspection and noticed that there was one stator that is questionable.Have maintenance personnel do a thorough inspection and fix any damaged items.
I then proceeded to inspect the No. 1 engine where I discovered unquestionable damage and blood stains which is documented in the photos. Simply stated; better maintenance inspections are required.
Despite the HS-125 having just successfully undergone a maintenance inspection for possible engine damage (for reasons not provided) and returned to service the next assigned flight crew experienced vibrations and buzzing sounds they deemed serious enough to divert for further maintenance.  More acute inspection after landing illuminated one stator potentially damaged on the right engine and unquestionable blood and damage to the left.