ASN Wikibase Occurrence # 200119
This record has been locked for editing.
Narrative:The crew assumed control of the Embraer 190 commercial aircraft, registration HB-JVN, on the morning of 12 January 2017 in Vienna, Austria for the scheduled flight LX1585 to Zurich, Switzerland. After starting the right-hand engine, the BLEED 2 FAIL message was displayed on the flight deck. This meant that there was no bleed air from the right-hand engine available for the cabin air conditioning and pressurization system and the wing anti-ice system.
|Date:||Thursday 12 January 2017|
Embraer ERJ-190LR (ERJ-190-100 LR)
|Owner/operator:||Helvetic Airways, opf Swiss|
|Fatalities:||Fatalities: 0 / Occupants: 50|
|Aircraft damage:|| None|
|Location:||10 km west of Kempten -
|Phase:|| En route|
|Nature:||Passenger - Scheduled|
|Departure airport:||Wien-Schwechat Airport (VIE/LOWW)|
|Destination airport:||Zürich-Kloten Airport (ZRH/LSZH) |
|Investigating agency: ||STSB|
|Confidence Rating:|| Accident investigation report completed and information captured|
The crew processed the steps specified in the relevant emergency and abnormal procedures checklist. As they were unable to resolve the failure, they shut down the engine. After consulting the MEL and contacting the aviation operator’s maintenance company, the crew decided to conduct the flight to Zurich despite the failure.
Cruising took place at flight level (FL) 300 and was uneventful. During the descent into Zurich, the aircraft was flying in icing conditions. At 07:30 UTC, the aircraft ice detectors indicated ice formation and the anti-ice system was switched back on. The difference between the required and available bleed air became so great that the air management system (AMS) automatically shut off PACK 2, which surprised the flight crew. At 07:31 UTC the ice detectors ceased indicating ice formation.
At 07:33 UTC, the BLEED 1 LEAK message was displayed on the flight deck and the engine bleed air from the left engine was automatically switched off. As a result, the cabin air conditioning and pressurization system and the wing anti-ice system failed. The aircraft was at FL 200. The commander decided to descend faster. To this effect, he transmitted the urgency message "Pan Pan" and requested clearance to descend. At the same time, the ice detectors indicated renewed ice formation. Air traffic control immediately issued clearance to descend to FL 130.
At 07:33 UTC, the commander started the APU. Seconds later, the A-I WING FAIL message was displayed on the flight deck, which made it clear to the flight crew that the anti-ice system was no longer available. At 07:34 UTC the APU FAIL message was also displayed, because the APU had not started. The commander requested immediate clearance to descend below FL 100 and immediately received clearance for FL 90. Between 07:34 UTC and landing, the ice detectors did not identify any further ice formation.
The commander then decided to declare an emergency. At 07:34 UTC, he transmitted the emergency message "Mayday" and informed air traffic control of his situation. Air traffic control issued clearance to descend to FL 60. At 07:35 UTC, the commander read a cabin pressure altitude of 4800 ft at an altitude of around 10 000 ft AMSL. At 07:36 UTC, he informed the cabin crew and told them to expect a normal landing in 20 minutes.
At 07:41 UTC, the commander began to process the BLEED 1 LEAK checklist. The flight crew rejected air traffic control's offer of the shortest possible approach on runway 28 at Zurich, because they no longer expected icing conditions. At 07:44 UTC, the commander began to process the A-I WING FAIL checklist. A second attempt to start the APU was then successful.
Air traffic control guided the aircraft onto the instrument landing system (ILS) for runway 14 using radar vectoring. The approach was uneventful. The flight crew adopted a higher approach speed than normal in order to deal with any residual ice on the wings. At 07:57 UTC, the aircraft touched down on runway 14 and taxied to the allocated stand. The passengers and flight crew disembarked the aircraft normally.
The Swiss Transportation Safety Investigation Board commented that by consulting the MEL and contacting the maintenance company, the flight crew reacted in a manner appropriate to the situation and in the spirit of the aviation operator. However, if a flight is conducted in accordance with the MEL, it is important to be aware of the fact that the lack of redundancy means a single failure can lead to complete failure of key systems (the cabin air conditioning and pressurization system and wing anti-ice system in the present case). The following information in the MEL: "The first dispatch condition on MEL has no icing condition restrictions, since the Cross Bleed Valve operates normally", may have contributed to the fact that the crew was not sufficiently aware of this.
The fundamental nature of the MEL is that it only mentions the conditions that must be fulfilled in order for a flight to be conducted despite component failures. The decision to conduct a flight in accordance with the MEL, however, is dependent upon other factors, e.g. the weather and other possible technical failures. These can have serious consequences on a flight conducted according to the MEL where the redundancy is already reduced.
| || |
|Investigating agency: ||STSB |
|Report number: || |
|Status: ||Investigation completed|
|Download report: || Final report|
||Updated [Source, Narrative]|
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