Narrative:

After takeoff; climbing through approximately 7000 ft received EICAS smoke forward lower crew rest accompanied by very acrid odor throughout aircraft. Smoke alarms were going off in cabin. Cockpit crew donned oxygen masks and leveled aircraft at 10000 ft. While sorting through the caution; the EICAS message went away. Odor started to dissipate. Communication established with dispatch and maintenance via satphone/ACARS; after a bit of conversation; odor dissipated. Flight attendants reported they were ok. First officer went back through the cabin to the flight attendant crew bunk and reported all was normal. Decision was made to continue to ZZZ. After receiving clearance to climb and adding climb power; odor returned very strong. Leveled at 14000 ft. Flight attendants reported nausea; headaches and dizziness. Decision was made to divert back to ZZZ. Vectors received from ZZZ departure and approach to hold and dump fuel at 14000 ft. Dump took approximately 35 mins. Dump to maximum landing weight done due to xwinds at ZZZ and windshear advisories and reports on the field. Emergency was declared. Cabin advisory for the flight attendants. Uneventful landing. Odor was very acrid; but not easily recognizable. Mechanics back at ZZZ described it as an oil smell probably in the packs. Supplemental information from acn 766869: there was a noticeable mechanical odor in the cabin when we boarded the aircraft at the gate. Some comparison was made to equine excrement (I'm not being sarcastic; it really did have the odor of horse feces). The smell could also be described as slightly mechanical and oily; similar to hydraulic fluid but not precisely the same. All crew members I saw commented on the smell and purser asked captain if he would come back and investigate. He did but it wasn't apparent where smell originated; there was some discrepancy whether the smell was coming from aircraft or jetway. It is not at all unusual to have a strange smell on an airplane. This smell was stronger than some but not strong enough to cause any undue concern on my part. Within a min or so after takeoff I noticed a significant increase in the strength of the smell and several mins after takeoff we received an EICAS regarding smoke in the lower crew rest. We all donned oxygen and established communications. Cabin interphone began ringing with flight attendant alerting us to a smoke warning they received on their cabin service panels. Captain and flying first officer ran a smoke; fumes; odor checklist. We leveled at 10000 ft and got vectors from departure so we could investigate the problem without getting too far from an airfield. I was coordinating with flight attendants and had door 3R flight attendant investigate the lower crew rest bunk room. Flight attendant reported back that there was no evidence of any smoke or fire. Captain then requested that I exit cockpit and investigate the lower crew rest myself. I took the smoke hood and got a fire extinguisher from door 3. My investigation revealed nothing out of the ordinary. In the meantime the strength of the smell had noticeably diminished. After I returned to the cockpit a short discussion ensued and we determined that it was safe to continue. We received a climb clearance and as we began to climb the strength of the smell returned to that of after takeoff. The purser called and said passenger and flight attendants were getting nauseated by the smell. We all agreed that the time had come to solve this problem on the ground. We declared an emergency and received vectors from center for a safe spot to dump fuel. Ensuing fuel dump and return to airport was uneventful. My only concern in reviewing the event is the difficulty in handling cockpit security in this event. I made a judgement call to quickly exit the cockpit without a cart in place. I did this knowing the forward lavatory was empty and having surveyed the hall through the peephole in the cockpit door. Time was of the essence and the possibility of this being an engineered scenario to breach the cockpit seemed so remote as to be implausible. Perhaps I should have taken the time to have the flight attendant pull a cart and follow SOP security for the cockpit. That is easy to say knowing the event turned out satisfactorily; but the judgement call to leave the cockpit without following SOP security was made only knowing that we had a potential fire on the airplane. Callback conversation with reporter revealed the following information: the reporter stated that a cause of this smell was never determined. It was thought that an engine oil seal was defective. The engine was changed as well the APU. This event has occurred on this aircraft three additional times that this reporter knows of; each occurrence leading to an in-flight turn back.

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Original NASA ASRS Text

Title: A B777 DEVELOPED AN ACRID SMELL AFTER TKOF. THE CREW INVESTIGATED BUT THE SMELL DISSIPATED. AS THE FLT CONTINUED CLB; SMELL RETURNED. AN EMER WAS DECLARED WITH A RTN TO LNDG.

Narrative: AFTER TKOF; CLBING THROUGH APPROX 7000 FT RECEIVED EICAS SMOKE FORWARD LOWER CREW REST ACCOMPANIED BY VERY ACRID ODOR THROUGHOUT ACFT. SMOKE ALARMS WERE GOING OFF IN CABIN. COCKPIT CREW DONNED OXYGEN MASKS AND LEVELED ACFT AT 10000 FT. WHILE SORTING THROUGH THE CAUTION; THE EICAS MESSAGE WENT AWAY. ODOR STARTED TO DISSIPATE. COM ESTABLISHED WITH DISPATCH AND MAINT VIA SATPHONE/ACARS; AFTER A BIT OF CONVERSATION; ODOR DISSIPATED. FLT ATTENDANTS RPTED THEY WERE OK. FO WENT BACK THROUGH THE CABIN TO THE FLT ATTENDANT CREW BUNK AND RPTED ALL WAS NORMAL. DECISION WAS MADE TO CONTINUE TO ZZZ. AFTER RECEIVING CLRNC TO CLB AND ADDING CLB PWR; ODOR RETURNED VERY STRONG. LEVELED AT 14000 FT. FLT ATTENDANTS RPTED NAUSEA; HEADACHES AND DIZZINESS. DECISION WAS MADE TO DIVERT BACK TO ZZZ. VECTORS RECEIVED FROM ZZZ DEP AND APCH TO HOLD AND DUMP FUEL AT 14000 FT. DUMP TOOK APPROX 35 MINS. DUMP TO MAX LNDG WT DONE DUE TO XWINDS AT ZZZ AND WINDSHEAR ADVISORIES AND RPTS ON THE FIELD. EMER WAS DECLARED. CABIN ADVISORY FOR THE FLT ATTENDANTS. UNEVENTFUL LNDG. ODOR WAS VERY ACRID; BUT NOT EASILY RECOGNIZABLE. MECHS BACK AT ZZZ DESCRIBED IT AS AN OIL SMELL PROBABLY IN THE PACKS. SUPPLEMENTAL INFO FROM ACN 766869: THERE WAS A NOTICEABLE MECHANICAL ODOR IN THE CABIN WHEN WE BOARDED THE ACFT AT THE GATE. SOME COMPARISON WAS MADE TO EQUINE EXCREMENT (I'M NOT BEING SARCASTIC; IT REALLY DID HAVE THE ODOR OF HORSE FECES). THE SMELL COULD ALSO BE DESCRIBED AS SLIGHTLY MECHANICAL AND OILY; SIMILAR TO HYD FLUID BUT NOT PRECISELY THE SAME. ALL CREW MEMBERS I SAW COMMENTED ON THE SMELL AND PURSER ASKED CAPT IF HE WOULD COME BACK AND INVESTIGATE. HE DID BUT IT WASN'T APPARENT WHERE SMELL ORIGINATED; THERE WAS SOME DISCREPANCY WHETHER THE SMELL WAS COMING FROM ACFT OR JETWAY. IT IS NOT AT ALL UNUSUAL TO HAVE A STRANGE SMELL ON AN AIRPLANE. THIS SMELL WAS STRONGER THAN SOME BUT NOT STRONG ENOUGH TO CAUSE ANY UNDUE CONCERN ON MY PART. WITHIN A MIN OR SO AFTER TKOF I NOTICED A SIGNIFICANT INCREASE IN THE STRENGTH OF THE SMELL AND SEVERAL MINS AFTER TKOF WE RECEIVED AN EICAS REGARDING SMOKE IN THE LOWER CREW REST. WE ALL DONNED OXYGEN AND ESTABLISHED COMS. CABIN INTERPHONE BEGAN RINGING WITH FLT ATTENDANT ALERTING US TO A SMOKE WARNING THEY RECEIVED ON THEIR CABIN SVC PANELS. CAPT AND FLYING FO RAN A SMOKE; FUMES; ODOR CHKLIST. WE LEVELED AT 10000 FT AND GOT VECTORS FROM DEP SO WE COULD INVESTIGATE THE PROB WITHOUT GETTING TOO FAR FROM AN AIRFIELD. I WAS COORDINATING WITH FLT ATTENDANTS AND HAD DOOR 3R FLT ATTENDANT INVESTIGATE THE LOWER CREW REST BUNK ROOM. FLT ATTENDANT RPTED BACK THAT THERE WAS NO EVIDENCE OF ANY SMOKE OR FIRE. CAPT THEN REQUESTED THAT I EXIT COCKPIT AND INVESTIGATE THE LOWER CREW REST MYSELF. I TOOK THE SMOKE HOOD AND GOT A FIRE EXTINGUISHER FROM DOOR 3. MY INVESTIGATION REVEALED NOTHING OUT OF THE ORDINARY. IN THE MEANTIME THE STRENGTH OF THE SMELL HAD NOTICEABLY DIMINISHED. AFTER I RETURNED TO THE COCKPIT A SHORT DISCUSSION ENSUED AND WE DETERMINED THAT IT WAS SAFE TO CONTINUE. WE RECEIVED A CLB CLRNC AND AS WE BEGAN TO CLB THE STRENGTH OF THE SMELL RETURNED TO THAT OF AFTER TKOF. THE PURSER CALLED AND SAID PAX AND FLT ATTENDANTS WERE GETTING NAUSEATED BY THE SMELL. WE ALL AGREED THAT THE TIME HAD COME TO SOLVE THIS PROB ON THE GND. WE DECLARED AN EMER AND RECEIVED VECTORS FROM CTR FOR A SAFE SPOT TO DUMP FUEL. ENSUING FUEL DUMP AND RETURN TO ARPT WAS UNEVENTFUL. MY ONLY CONCERN IN REVIEWING THE EVENT IS THE DIFFICULTY IN HANDLING COCKPIT SECURITY IN THIS EVENT. I MADE A JUDGEMENT CALL TO QUICKLY EXIT THE COCKPIT WITHOUT A CART IN PLACE. I DID THIS KNOWING THE FORWARD LAVATORY WAS EMPTY AND HAVING SURVEYED THE HALL THROUGH THE PEEPHOLE IN THE COCKPIT DOOR. TIME WAS OF THE ESSENCE AND THE POSSIBILITY OF THIS BEING AN ENGINEERED SCENARIO TO BREACH THE COCKPIT SEEMED SO REMOTE AS TO BE IMPLAUSIBLE. PERHAPS I SHOULD HAVE TAKEN THE TIME TO HAVE THE FLT ATTENDANT PULL A CART AND FOLLOW SOP SECURITY FOR THE COCKPIT. THAT IS EASY TO SAY KNOWING THE EVENT TURNED OUT SATISFACTORILY; BUT THE JUDGEMENT CALL TO LEAVE THE COCKPIT WITHOUT FOLLOWING SOP SECURITY WAS MADE ONLY KNOWING THAT WE HAD A POTENTIAL FIRE ON THE AIRPLANE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER STATED THAT A CAUSE OF THIS SMELL WAS NEVER DETERMINED. IT WAS THOUGHT THAT AN ENG OIL SEAL WAS DEFECTIVE. THE ENG WAS CHANGED AS WELL THE APU. THIS EVENT HAS OCCURRED ON THIS ACFT THREE ADDITIONAL TIMES THAT THIS REPORTER KNOWS OF; EACH OCCURRENCE LEADING TO AN INFLT TURN BACK.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.