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ASN Wikibase Occurrence # 162583
Last updated: 16 December 2018
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Date:28-NOV-2013
Time:07:40
Type:Silhouette image of generic SB20 model; specific model in this crash may look slightly different
Saab 2000
Owner/operator:Darwin Airline
Registration: HB-IZW
C/n / msn: 39
Fatalities:Fatalities: 0 / Occupants: 28
Other fatalities:0
Aircraft damage: None
Category:Serious incident
Location:nr Lugano -   Switzerland
Phase: Initial climb
Nature:Domestic Scheduled Passenger
Departure airport:Lugano Airport (LUG/LSZA)
Destination airport:Zürich-Kloten Airport (ZRH/LSZH)
Investigating agency: STSB Switzerland
Narrative:
Flight LX2903 (SWR73KU), a Saab 2000, registration HB-IZW, took off from Lugano Airport, bound for Zurich, Switzerland.
It climbed in southerly direction to follow standard instrument departure route SID CANNE 1U towards Zurich. When the aircraft had reached approximately 2500 ft QNH, the captain, who was Pilot Flying instructed the copilot, who was Pilot Monitoring (PM) to retract the flaps. The PM then set the engines to climb power by pressing the CLB button on the power management unit (PMU). Shortly afterwards, the air traffic controller (ATCO) at Lugano instructed SWR73KU to contact the Milan Radar, which was done without delay. The Milan Radar ATCO issued a climb clearance to FL 180. HB-IZW accelerated as planned to approximately 170 knots. Then, at 06:37:21 UTC, the autopilot was engaged.
The planned left turn towards waypoint CANNE then followed. Shortly after the crew had switched the altimeters to standard pressure, the commander asked the copilot whether he too had noticed a brief "yawing". The latter said that he had not.
After passing FL 100, an aural indication was given to the cabin attendant, to inform her that she could now take care of the passengers.
Just as the copilot was busy reading off the take-off time from the flight management system, the crew noticed that HB-IZW distinctly yawed twice to the right and back. According to the observations of the crew, the amber master warning light illuminated together with an aural tone plus the indications R ENG FAULT and R GEN FAULT, which appeared on part of the central screens in the cockpit. Furthermore, at 06:39 UTC, the caution R PROP CTL FAULT was logged.
At this time HB-IZW was climbing at FL 110 over the municipality of Muzzano, east of Lugano. The commander asked the copilot to acknowledge the indication by pressing the warning light and to analyse the situation. It was determined that power from the left engine was normal, that the aircraft was still climbing and that the flaps and landing gear were retracted. The turbine rotation speed of the right engine was reducing and the rotation speed of the right propeller indicated approximately 1100 rpm instead of 950 rpm.
The copilot then announced a fault in the right engine to the commander and stated that the right propeller had not been brought automatically to the feathered position.
The commander instructed the copilot to start the checklist for an engine fault.
The list included various manipulations which were processed by memory after mutual confirmation. First, with the manual feather push-button depressed, the right power lever was moved to the idle position. Then the condition lever was moved from run to stop. After the propeller speed NP had reached a value of 100 rpm, the copilot released the manual feather button.
The commander disengaged the autopilot and flew the aircraft manually. The Saab 2000 was climbing at FL115 with an airspeed of approximately 160 to 170 KIAS. The overall situation was then analysed. The crew decided to discontinue the planned flight over the Alps and, after transmitting a distress call (PAN-PAN), requested to stop the climb at FL130 and to divert to Milan-Malpensa (LIMC). The Milan ATCO cleared SWR73KU to perform a left turn towards VOR station Saronno. When the autopilot was engaged again at 06:44 UTC, HB-IZW was flying on a southerly heading. The crew then worked through together the checklist for the operating condition R ENG FAULT. An attempt to start the shut-down engine was delayed.
The commander then handed over control of the aircraft and handling of radio communications to the copilot. The commander contacted the flight attendant on the intercom and informed her about the technical problem. She informed the commander that she could not ascertain anything abnormal outside on the engine in question. He also informed her of his intention to divert to Milan-Malpensa Airport.
To prepare for the approach in Milan, the crew of SWR73KU requested to join the holding pattern over VOR Saronno. On the way there, the checklist for preparing for a landing with only one engine was also processed. After all these checklist items had been completed, the passengers were informed about the issue concerning the right engine. The flight crew then discussed whether an attempt to start the right engine could be considered. In view of the available information the crew decided to attempt a start in accordance with the checklist. This start had to be interrupted by the commander because the engine was unable to reach a stabilized condition after fuel injection.
When the crew of SWR73KU reported that they were ready for the approach in Milan, a corresponding clearance with radar vectoring was given. In the meantime, the commander had taken back control of the Saab 2000. The allocation of responsibilities was the same as on take-off from Lugano. For her part, the flight attendant prepared the cabin for landing. SWR73KU then landed at 07:13 UTC on runway 35R in Milan-Malpensa, without further occurrence.
After HB-IZW had reached its assigned parking position, the left engine was shut down.

Causes
The serious incident is attributable to the fact that the total failure of the beta feedback transducer (BFT) for measuring the propeller blade angle led to a loss of control of the right engine due to a loose connector, so the engine had to be shut down by the crew.

Sources:

http://www.sust.admin.ch/pdfs/AV-berichte/HB-IZW.pdf

Accident investigation:
cover
  
Investigating agency: STSB Switzerland
Status: Investigation completed
Duration: 4 years
Download report: Final report


Revision history:

Date/timeContributorUpdates
02-Dec-2013 18:33 harro Added
02-Dec-2013 18:33 harro Updated [Country]
17-Dec-2017 15:38 harro Updated [Time, Nature, Departure airport, Destination airport, Source, Damage, Narrative]

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