Date: 201202
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
Light: Daylight
Aircraft: B717 (Formerly MD-95)
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Interphone System
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface; Troubleshooting
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; General Maintenance Action; General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: In cruise flight the Flight Attendant call chime sounded; but no one was on the interphone. Call light could not be extinguished. Some minutes later; Lead Flight Attendant called (chime reoccurred); stating that aft flight attendant handset cord was hot-to-touch and was smoking slightly. There was no panic or major concern from flight attendants at this time. I gave aircraft control to First Officer and contacted Maintenance on company radio. At that time; I was most concerned about maintenance impact and whether they desired for the aircraft to continue or divert. I discussed options with Lead Flight Attendant; Dispatcher; and Maintenance Control. On my own initiative; I also pulled the CABIN INTERPHONE circuit breaker to isolate the circuit (see below). Since minor smoke had subsided; all parties agreed to continue to destination (about 120 miles away). I resumed control of the aircraft. During descent; about 60 miles from destination; Lead Flight Attendant advised that aft handset itself was now hot; melting; and smoking. At this point; we declared an emergency with center and were cleared direct. Emergency handling and communications with ATC were standard and professional; and we landed within about 12 minutes of declaration; and were in the gate with door open about four minutes later. Emergency equipment followed us to the gate; and on-call maintenance and firemen came aboard immediately upon arrival at the gate. Maintenance removed the melted handset; which we later returned to Maintenance. I maintained 300 KIAS below 10;000 FT for a period to expedite our arrival. The Lead Flight Attendant and I chose not to use handset communications after I had isolated the interphone; and instead would use a knock and crack-open the cockpit door to speak directly. After conditions deteriorated and we declared an emergency; we realized that the interphone system was not isolated; so I did use the interphone and PA to advise the flight attendants and passengers before landing. I did not have time to communicate further with the company until we were on the ground. Smoke was never profuse; but fumes became very noticeable in the aft cabin. Fumes were barely detectable in the cockpit. We were ready to don masks if conditions deteriorated; but it was never necessary. Passengers seemed calm and appreciative of the cabin crew's handling of the situation. My entire crew performed exceptionally. We did not land at the nearest suitable airport when we first learned of the problem because it appeared that the problem was localized; isolated; and controlled. I was considering input from the flight attendants who seemed very comfortable with our plan. But the problem did get worse later. While our outcome was good; I can't say we made the best choice. There is a QRH procedure for Electrical Smoke/Fumes of Unknown Origin; but no real procedure for an electrical problem of known origin. Further; the QRH procedure would leave the Emergency buses powered; which apparently would continue to power the interphone handsets. There is no way to unplug the handset; since the connector is behind a panel. The CABIN INTERPHONE circuit breaker does not power or disable the Cabin Interphone...instead it appears that the DCAS SERV/MAINT INTERPHONE is the correct breaker; but I simply couldn't find it in time (I looked through the alphabetical list under Cabin; Pilot; Interphone; etc.; but it's under DCAS). The aft flight attendant ultimately placed the hot handset on the floor of the lavatory and closed the door to contain the fumes. It was a good idea and worked well; but might ultimately have set-off the lavatory smoke detector; complicating the incident further. He would've had no good way to tell us to ignore that alarm. Develop procedures to isolate and handle potential electrical incidents where the source is known. - Expand the AOM alphabetical circuit breaker list to include variations of circuit breaker name (e.g.; add INTERPHONE; DCAS SERV/MAINT;PITOT HEATER; CAPTAIN'S; LOGO LTS; LEFT; etc.). - Add the alphabetical circuit breaker list to the cockpit laminated pages.




Synopsis: B717 Captain is informed that a handset cord is hot to the touch and smoking. The cabin interphone circuit breaker is pulled and the flight continues. Nearing top of descent it is reported that the handset itself is smoking. An emergency is declared with a landing at destination twelve minutes later.