Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 18000
Aircraft Equipment Problem Less Severe
Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft
The aircraft was experiencing a vibration shortly after takeoff that neither the cockpit crew nor the cabin crew had experienced before. The vibration was not due to engine vibration and all systems indications were normal. No ECAM warnings or messages. We continued to climb on our route while the First Officer and I talked about possibilities and decide on a course of action. The vibration stopped around FL260. We continued to climb to FL360 and reduced speed to .73 Mach/280 knots. After contacting Dispatch and Maintenance; I made the decision not to continue to [destination] and coordinated with Dispatch to divert [to an alternate]. Approach and landing were uneventful.After arriving at gate; Maintenance believes the vibration was due to either:1. A faulty hydraulic service panel door that would not close flush with the fuselage and could possibly have departed the aircraft in flight; or2. A cracked sealant on a panel beneath the fuselage; or3. A seal on the right wing root.None of the possible causes would have been detected by crew walk around. The hydraulic service panel door had to be handled to ascertain that it would not close properly.
A320 Captain reported diverting to an alternate airport after experiencing inflight vibration that was possibly due to a service panel door or a wing root seal.