Date: 201504
Local time of day: 1201-1800
Location: ZZZZ.ARTCC, FO
Flight conditions: VMC
Light: Daylight
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Aircraft component: Cooling Fan; any cooling fan
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Distraction; Physiological - Other; Troubleshooting; Workload
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Landed As Precaution; Flight Crew Took Evasive Action; General Maintenance Action
Contributing factors: Manuals; Aircraft; Procedure
Primary problem: Aircraft

Narrative: After departing and climbing through approximately FL240 the pilot flying and I noted an unusual vibration that lasted about 10 seconds. We both commented but the vibration ended quickly.  About an hour later at FL340 we both noted a steady and unusual humming sound very slowly getting louder. We thought it was located forward of the flight deck. As we discussed it (vent blower fault; nose gear door open; PACK failure etc...) and checked systems it grew into a slight vibration. We sent a message describing the unusual loud hum and slight vibration to Maintenance Control via ACARS. Shortly thereafter it grew to an intensity that the lead Flight Attendant (FA) called to report an unusual hum and vibration by the flight deck door. I told him we are aware of the situation; all systems are indicating normally; let us know if the noise changes; and check with the aft crew for any unusual noises or vibration. In retrospect; having had a Mom that was a public school music teacher for 40 years; I believe the loud hum was pretty darn close to a low E Major chord on a 1965 Wurlitzer organ. I kept that information to myself. We detected a distinct smell of burning oil from the air outlets which quickly became light fumes. The First Officer (FO) as PF executed an emergency descent as we began an immediate diversion to a nearby airport. As this began the lead FA reported the smell of burning fumes in the cabin and I quickly told him yes we are diverting now and I'll call him back with his TEST information as soon as I can but start preparing. We suspected a PACK fault from prior experience and as we descended through about 13;000 FT I grabbed the COM and as I selected PACK 1 off it was immediately followed by a VENT BLOWER OVRD command. That took all of three seconds and the loud humming immediately stopped and the fumes dissipated as well.I gave the lead FA the TEST information; made an announcement that of course we had an abnormal condition but we believe we had isolated the problem and we'd be making a precautionary landing. Landed without incident; stopped on the high speed taxiway; and gave the remain seated command. ARFF noted no smoke or visible heat signatures. As the loud humming and fumes had immediately stopped with ECAM actions we taxied to the gate. Turns out it wasn't PACK 1 although when I talked to Maintenance Control he said he was getting 'all kinds of weird information on PACK 1 on his side.' It was the Blower Fan that gradually came apart.  I guess it took the strain of turning off one pack to finally and immediately throw the ECAM message and Fault light. It would have been easier to use the QRH COM procedure if 'air conditioning smoke suspected' was a separate procedure with its own tab.




Synopsis: Early in the flight a hum and vibration were detected; which the A320 crew suspected to be a pack malfunction. Later when fumes developed the crew began to divert to a suitable airport. Once the COM QRH procedure was commenced; a VENT BLOWER OVRD ECAM confirmed a VENT Fan failure.