Swiss A319 near Stockholm on Dec 11th 2012, several electrical malfunctions

Last Update: April 21, 2015 / 20:16:14 GMT/Zulu time

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Incident Facts

Date of incident
Dec 11, 2012

Classification
Incident

Airline
Swiss International Airlines

Flight number
LX-1250

Departure
Zurich, Switzerland

Destination
Stockholm, Sweden

Aircraft Registration
HB-IPX

Aircraft Type
Airbus A319

ICAO Type Designator
A319

A Swiss International Airlines Airbus A319-100, registration HB-IPX performing flight LX-1250 from Zurich (Switzerland) to Stockholm (Sweden) with 104 passengers and 5 crew, was enroute at FL390 about 240nm south of Stockholm when the crew encountered various electrical malfunctions. The flight continued to Stockholm for a safe landing on runway 01L about 45 minutes later. There were no injuries, the aircraft sustained no damage.

The Swiss Büro für Flugunfalluntersuchungen (BFU) reported they are investigating the serious incident.

The incident aircraft positioned to Zurich the following day leaving Stockholm about 20 hours after landing and resumed service about 26 hours after landing in Stockholm (about 4 hours after landing in Zurich).

On Apr 21st 2015 the Swiss SUST released their final report concluding:

The serious incident is attributable to repeated voltage lowering events and faults in the power supply to various busses.

The exact cause could not be determined.

The SUST reported that during the climb out of Zurich, at about FL200, DC Bus 1 suffered a brief voltage reduction which prompted the automatic system to rearrange the electrical supply, so that the essential bus no longer was supplied by transformer rectifier TR1 but the ESS TR (essential transformer rectifier). About one hour into the flight, at FL390 near Hamburg, the flight crew received indication "DC BUS 1 FAULT" followed by intermittent indications "BLOWER FAULT", "BRAKE SYST 1 FAULT" and "EXTRACT FAN FAULT". The electrical sytem reconfigured several times between TR1 and TR2 until TR1 was automatically shut down and DC BUS1 and BAT BUS were supplied via TR2 for the remainder of the flight.

The flight crew discussed the situation with the lead flight attendant just in case smoke would occur and preparted for a possible emergency descent. The crew assessed possible diversions to Copenhagen and other options along the route. The captain consulted with dispatch and maintenance in Zurich and carried out the recommendation received from Zurich to trigger circuit breaker AB10 to disable the power supply to TR1. In the minutes following the DC BUS 1 and DC BAT BUS experienced several brief voltage reductions although being supplied by TR2, and the indications "APU FIRE DET FAULT", "APU FIRE LOOP A FAULT" and "CARGO DISCH" appeared. The side stick solenoid of the first officer audibly activated several times even though the side stick remained inactive.

The voltage subsequently stabilized and remained stable for the remainder of the flight. The crew decided to continue the flight to Stockholm.

While on descent through FL350 towards Stockholm circuit breaker AB11 tripped automatically without any associated warning causing the loss of a number of systems including cockpit temperature control, the temperature in the cockpit fell below freezing. The lighting of several control panels failed. When the crew activated the engine anti-ice systems the control light for the right hand engine only illuminated.

Further into the descent the DS ESS Bus suffered a number of brief voltage reductions resulting in the loss of the captain's primary flight display, navigation display and upper ECAM display. The crew declared PAN and requested an immediate straight in ILS approach to runway 01L. The aircraft touched down on runway 01L, the crew engaged thrust reversers but only the right hand thrust reverser deployed while the left hand reverser remained stowed (without prior failure indication).

Following landing TR1 was examined with no anomaly found, TR1 worked flawlessly. Several contactors were tested with no anomaly.

Circuit Breaker 3XN1 was visually checked without any discolouration or other indications of overheating, it was noted that the release button was pushed in. The release button was pulled out, the fuses had continuity although they should have disconnecte. The release button was pushed in again, the contacts opened and the circuit breaker appeared normal. The circuit breaker was closed, power applied and the circuit breaker tripped properly disconnecting the load. Another cycle was initiated, this time the circuit breaker made unusual noises instead of disconnecting the load and smoke appeared. Power was turned off, the circuit breaker now showed substantial damage and the test was aborted.

SUST wrote: "The CB was then dismantled. The image obtained from the x-rays was confirmed. Based on the level of destruction it is assumed that a short-circuit had occurred between phases B and C. However, it must be stated that the considerable extent of destruction occurred on the occasion of the tests at Airbus on 25 June 2013 and not during the serious incident. It can also be assumed that it is highly probable that electrical arcing had already occurred between two phases during flight LX 1250, but with much less impact."
Aircraft Registration Data
Registration mark
HB-IPX
Country of Registration
Switzerland
Date of Registration
MiedjAjcmcpmAjg Subscribe to unlock
Certification Basis
Qlegqd Subscribe to unlock
Airworthyness Category
KfkjcAAA jApfdnn Subscribe to unlock
Legal Basis
Gbf Subscribe to unlock
TCDS Ident. No.
JnlbngmeAl Subscribe to unlock
Manufacturer
AIRBUS INDUSTRIE
Aircraft Model / Type
A319-112
ICAO Aircraft Type
A319
Year of Manufacture
Cqne Subscribe to unlock
Serial Number
Nhn Subscribe to unlock
Aircraft Address / Mode S Code (HEX)
A igkq Subscribe to unlock
Max. Operational Passenger Seating Capacity (MOPSC), indicative
Nkn Subscribe to unlock
Minimum Crew
B Subscribe to unlock
Maximum Take off Mass (MTOM) [kg]
Qgmch Subscribe to unlock
Engine Count
E Subscribe to unlock
Engine
Jkbcggddblc cpqpqn Subscribe to unlock
Incident Facts

Date of incident
Dec 11, 2012

Classification
Incident

Airline
Swiss International Airlines

Flight number
LX-1250

Departure
Zurich, Switzerland

Destination
Stockholm, Sweden

Aircraft Registration
HB-IPX

Aircraft Type
Airbus A319

ICAO Type Designator
A319

This article is published under license from Avherald.com. © of text by Avherald.com.
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