Narrative:

The flight was on a route (nat V) from boston to prestwick, scotland. The aircraft flown on this route was equipped with 3 INS sets, which were operating in triple mix. A previous write-up on engine #3 fire detector circuit B showing full scale deflection on the needle and a fault light had reappeared in the climb. After level-off at 33000' a loop on engine #3 showed a needle deflection of 2.0. This value slowly increased to a value of 7.9. Any value over 8.0 is a recommended shutdown of the engine (company procedure). Since we were over the atlantic, and out of range of gander oceanic on VHF frequencys, we were using HF radios. We established a HF radio phone patch (through rainbow radio-halifax) to minneapolis maintenance control. Msp maintenance control authority/authorized a return to either gander (shortest in time) or bos (nearest suitable). Fuel was not a problem for the upcoming 3 engine flight, so we opted for bos. I told the copilot to declare an emergency with gander oceanic on HF, and request a return course back to springdale (our exit point onto the north atlantic tracks). Position (N5/50.8 west 4622.8) and west/O a clearance, we left the nat structure using the approved exit procedure. This consists of a 90 degree turn off course to 30 NM abeam, and then a paralleling of the track back to the exit point. We received the clearance from gander oceanic for a return to springdale as requested (30 NM abeam and FL290). The only confusing and potential ATC problem occurred during the 5 mins between leaving track (captain's emergency authority) and receiving a formal clearance to do so. The copilot may not have used the words, 'declaring an emergency' with the request for a return clearance. Since we had to shut the engine down, we waited until we were 30 NM abeam before a descent was started and the engine shutdown. Returning to bos was uneventful, as was the landing. In the rush of all of the above events, a simple phrase was missed (maybe)--a phrase that allows a captain to use his emergency authority with some confidence.

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Original NASA ASRS Text

Title: NACELLE HEAT LOOP TEMPERATURE DICTATED SHUTDOWN OF ENGINE OVER THE ATLANTIC AND RETURN TO BOS. CAPT DEPARTED NAT ROUTE AND REVERSED COURSE, THINKING FO HAD DECLARED AN EMERGENCY WHEN HE HAD NOT.

Narrative: THE FLT WAS ON A ROUTE (NAT V) FROM BOSTON TO PRESTWICK, SCOTLAND. THE ACFT FLOWN ON THIS ROUTE WAS EQUIPPED WITH 3 INS SETS, WHICH WERE OPERATING IN TRIPLE MIX. A PREVIOUS WRITE-UP ON ENG #3 FIRE DETECTOR CIRCUIT B SHOWING FULL SCALE DEFLECTION ON THE NEEDLE AND A FAULT LIGHT HAD REAPPEARED IN THE CLB. AFTER LEVEL-OFF AT 33000' A LOOP ON ENG #3 SHOWED A NEEDLE DEFLECTION OF 2.0. THIS VALUE SLOWLY INCREASED TO A VALUE OF 7.9. ANY VALUE OVER 8.0 IS A RECOMMENDED SHUTDOWN OF THE ENG (COMPANY PROC). SINCE WE WERE OVER THE ATLANTIC, AND OUT OF RANGE OF GANDER OCEANIC ON VHF FREQS, WE WERE USING HF RADIOS. WE ESTABLISHED A HF RADIO PHONE PATCH (THROUGH RAINBOW RADIO-HALIFAX) TO MINNEAPOLIS MAINT CTL. MSP MAINT CTL AUTH A RETURN TO EITHER GANDER (SHORTEST IN TIME) OR BOS (NEAREST SUITABLE). FUEL WAS NOT A PROB FOR THE UPCOMING 3 ENG FLT, SO WE OPTED FOR BOS. I TOLD THE COPLT TO DECLARE AN EMER WITH GANDER OCEANIC ON HF, AND REQUEST A RETURN COURSE BACK TO SPRINGDALE (OUR EXIT POINT ONTO THE N ATLANTIC TRACKS). POS (N5/50.8 W 4622.8) AND W/O A CLRNC, WE LEFT THE NAT STRUCTURE USING THE APPROVED EXIT PROC. THIS CONSISTS OF A 90 DEG TURN OFF COURSE TO 30 NM ABEAM, AND THEN A PARALLELING OF THE TRACK BACK TO THE EXIT POINT. WE RECEIVED THE CLRNC FROM GANDER OCEANIC FOR A RETURN TO SPRINGDALE AS REQUESTED (30 NM ABEAM AND FL290). THE ONLY CONFUSING AND POTENTIAL ATC PROB OCCURRED DURING THE 5 MINS BTWN LEAVING TRACK (CAPT'S EMER AUTHORITY) AND RECEIVING A FORMAL CLRNC TO DO SO. THE COPLT MAY NOT HAVE USED THE WORDS, 'DECLARING AN EMER' WITH THE REQUEST FOR A RETURN CLRNC. SINCE WE HAD TO SHUT THE ENG DOWN, WE WAITED UNTIL WE WERE 30 NM ABEAM BEFORE A DSCNT WAS STARTED AND THE ENG SHUTDOWN. RETURNING TO BOS WAS UNEVENTFUL, AS WAS THE LNDG. IN THE RUSH OF ALL OF THE ABOVE EVENTS, A SIMPLE PHRASE WAS MISSED (MAYBE)--A PHRASE THAT ALLOWS A CAPT TO USE HIS EMER AUTHORITY WITH SOME CONFIDENCE.

Data retrieved from NASA's ASRS site as of August 2007 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.