EMB-505 / Phenom 300 flight crew reported vibration and noise after takeoff. The flight crew performed an in flight shut down of the left engine and executed a return to the departure airport. It was discovered that the lavatory service cap had been left unsecured and was banging against the fuselage during flight.
Synopsis
EMB-505 / Phenom 300 flight crew reported vibration and noise after takeoff. The flight crew performed an in flight shut down of the left engine and executed a return to the departure airport. It was discovered that the lavatory service cap had been left unsecured and was banging against the fuselage during flight.
Narrative
During the climbout of ZZZ; we experienced a sudden loud vibration as we climbed above 13;000 feet. We leveled off and asked to return to ZZZ. We were given vectors back to ZZZ for the visual to XXR. My First Officer and I both felt the sound and vibration originated from the aft left of the aircraft. When I looked back at our passengers; the person nodded and pointed at the back left of the airplane. Once we were set up for the approach my First Officer suggested we look for an engine vibration checklist; which I did locate in the QRH. We ran a checklist. The checklist had us reduce power to see if the sound and vibration decreased; which they did although we could still hear and feel it; but more faintly. The checklist states; if the affected engine abnormal vibration persists; accomplish the engine shutdown procedure. At this point we transferred controls so that I was the pilot flying (PF). We followed our QRC for in flight engine shut down and shut down the left engine. We continued for the visual approach and landed on XXR without incident. Upon post flight inspection I discovered that the lavatory servicing cap was disconnected. I checked it before flight as I have been told that it creates pressurization bumps if it is not installed properly; and since this was our first flight in this airplane this morning I wasn't sure if the lav had been serviced. I never would have suspected that this loud of a sound and strong vibration could come from a disconnected lavatory servicing cap. I don't know if it was the source of the vibration or if the vibration caused it to come loose. I'm still awaiting a conclusion from Maintenance to find out what the source of the sound and vibration were; but in the future I will be doubly sure that the lavatory cap is secure before flight.
Second reporter narrative
We departed Runway YYL at ZZZ on the ZZZZZ departure with a climb via clearance and I was the Pilot Flying (PF). We leveled off at 13000 ft. per the SID requirements. Departure Control then gave us an instruction to climb to FL190 and we began so with the autopilot on. Soon after beginning the climb; we heard and felt a sudden and elevated vibration and both agreed that there was an issue. We began by scanning instruments and looking at different instrumentation pages on the Multi-function Flight Display (MFD). My initial reaction based on the sound and vibration was that there was an issue with our left engine as it was a mechanical loud humming sound. This was based upon only hearing the noise from the left side of the aircraft which my Captain agreed to as well. We then got in contact with ATC and said we would need to level off and return to ZZZ. They then gave us an altitude and vectors back to the airport. When leveling off and reducing throttle; I noticed that the noise changed in frequency which further led me to believe it was an engine issue. While being vectored; my Captain briefly turned around and spoke to the passengers to tell them that we had an issue and that we were returning out of abundance of caution.At the time; the passengers also recognized the noise. We then troubleshot some more and both agreed that this sound was coming from the left side of the aircraft. We both looked outside to see if there was any visible issue with any of the flight controls or the wing itself and we saw nothing. We briefed the approach and additional considerations of any and all possibilities that we could think of given the information that was at hand. I then asked if we could look to the QRH to see if we can get any more information from there. We utilized the 'Engine Abnormal Vibration' page and ran through the checklist. Upon completion of the troubleshooting portion of the checklist that the engine vibration persisted; we proceeded with the engine shutdown part of the checklist. I believe around this time; we transferred controls as well and continued with the rest of the checklists. Upon completion of those; we were being vectored on to the approach and made an approach and landing to Runway XXR at ZZZ and taxied the aircraft back to the FBO.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.