Widebody Transport
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 150; Flight Crew Total 24000; Flight Crew Type 6000
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Other / Unknown
Flight Crew Diverted; Flight Crew Landed As Precaution
Aircraft
We departed Europe. During an intermediate level off at FL240 when we felt a loud muffled bang in the floor of the cockpit. All aircraft system indications showed normal. I checked with the Lead to make sure the cabin was secure. All was normal except for the thud. About [eight minutes later] and at FL340 came a second mysterious thud. I contacted Dispatch and [Maintenance] via HF. Our [relief] crew reported the sound seemed to come from the floor of First Class. A third bang was felt [later]. We were about twenty minutes out of [a suitable diversion airport] and I decided to land there. We followed the divert checklist and had [Maintenance] put in the write up for the thuds and the overweight landing. At [the diversion airport] we found the two forward cargo containers contained pharmaceutical products. On top of these boxes were large heavy plastic paper covered inflatable airbags to prevent the movement of boxes within the containers. In one container we found two burst bags and one inflated bag. In the second tin we found one burst and three inflated airbags. A total of seven airbags; three had burst and four were still intact. No damage to the aircraft.
I left cockpit to go on first break and heard a loud muffled bang while sitting in seat 2A which seemed to come from forward cargo pit or E&E compartment. Approximately eight minutes later another similar bang happened and I discussed with cockpit what I heard. After another five minutes there was another bang and I was recalled to cockpit for the divert.
A widebody international aircraft Captain and relief First Officer reported strange noises from lower deck while still over Europe. They diverted and found that some packing material had ruptured causing the noise.