Date: 201301
Location: ZZZZ.ARTCC, FO
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb; Cruise
Airspace: Class A ZZZZ
ATC / advisory: Center ZZZZ
Aircraft component: Exterior Pax/Crew Door
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Human factors: Troubleshooting; Time Pressure; Distraction; Situational Awareness; Physiological - Other
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Flight Attendant; Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed
Contributing factors: Aircraft; Human Factors
Primary problem: Ambiguous

Narrative: Approximately 45 minutes after take off; one of the flight attendants called and reported a 'hissing noise' coming from one of the AFT doors. We asked her to keep us posted and report if it gets any worse. Approximately 15 minutes later; we had another call from a Flight Attendant reporting 'excessive pressure leak sound' coming from both doors 1L and 1R! We checked the pressurization system and everything was operating normally. Contacted Maintenance Control and were told there is no history of that problem on this aircraft and suggested we put some wet towels around the door to see if that helps with the hissing sound. We then received numerous calls from the flight attendants complaining about 'dizziness and bad air quality.' At this time I decided to go back and have a look at the situation; since it seemed to be escalating. I found only door 1L making an extremely loud pressure leak noise. The rest of the doors were normal. Walking back to the cabin; I found one of the flight attendants using O2 and most of them were complaining about the air quality. Two of them were complaining about a popping sensation in their ears and dizziness. I tried to reassure them that after talking to Maintenance Control and inspecting the doors personally; other than the loud hissing noise coming from the door seal; there was no other safety concerns and all the aircraft systems were operating normally and that I; myself after having spent about ten minutes in the cabin; did not feel any abnormalities in the cabin air quality; and informed them that at this point our decision is to continue to destination. I returned to the cockpit. We tried to climb in an attempt to reduce door 1L's hissing sound and also turned the recirc fans off to improve the cabin air quality. we were about an hour 30 minutes into the flight when the Lead Flight Attendant; called the cockpit and said that among the few flight attendants still complaining of dizziness; one of them was also complaining about chest pain. I asked her to come to the cockpit and we called Dispatch. We explained our situation to them and asked for a phone patch to our contract medical service. I asked the Lead to describe the Flight Attendant's symptoms to the to the medical service personnel. At this point we were certain that continuing to our filed destination was not the best course of action and depending on how bad the Flight Attendant was feeling we either would have to land at the nearest suitable airport or return to the departure airport. I asked the Lead to go back and ask the Flight Attendant if he felt his situation required a [diver] landing; or he felt OK enough to return and the difference would be about an hour. The Lead Flight Attendant said that his condition was not bad enough to require an immediate landing; but that he could not continue all the way to the destination. So; after consulting with the medical personnel; we decided to return and requested paramedics and an in-flight supervisor to meet the flight. We contacted Maintenance Control again to see if we should land over weight or dump. We were advised to dump; so we dumped. Fuel at the start of dumping +/- 135;000 LBS; landed with 51;000 LBS dumped +/- 80;000 LBS I would also like to mention the following two points: 1) Once we were heading back; we advised the Lead Flight Attendant that paramedics will be meeting the Flight Attendant that was complaining of chest pain. To our surprise; her response was that he is feeling fine now and that won't be necessary! But we told her to instruct that Flight Attendant not to disembark without the OK of the paramedics. After arrival paramedics examined the Flight Attendant; gave him an all OK and asked him if he wanted an EKG. The Flight Attendant said he felt OK. He was reminded he had to make a decision on taking the EKG and if he did not feel that he needed it; he would have to sign a form for them. He decided to sign the form. This was all in presence of the In-flight Supervisor. 2) The next day; coming back to our base; the First Officer was sitting next to a passenger who happened to have been on our previous flight and was a medical doctor. The passenger indicated that since she had seen one of the Flight Attendants on O2; she had informed one of the Flight Attendants that she was a medical doctor and asked if she could be of any help. The response to her had been: 'no thank you!'


Second narrative: [Narrative 2 contained no additional information.]


Synopsis: A B777's L1 and R1 doors produced a loud hissing noise in flight while indicating normal pressurization. One Flight Attendant temporarily complained of chest pain but recovered after the flight returned to the departure station.