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ASN Wikibase Occurrence # 221294
Last updated: 13 November 2019
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Date:17-AUG-2018
Time:18:53 LT
Type:Cessna 525B CitationJet CJ3
Owner/operator:Morgran Management, LLC
Registration: N525L
C/n / msn: 525B-0051
Fatalities:Fatalities: 0 / Occupants: 3
Other fatalities:0
Aircraft damage: None
Category:Serious incident
Location:near Zürich -   Switzerland
Phase: En route
Nature:Test
Departure airport:Zürich-Kloten Airport (ZRH/LSZH)
Destination airport:Sion Aéroport (LSGS)
Investigating agency: STSB Switzerland
Narrative:
As strange noises in relation to the autopilot had been noticed coming from the control columns during operation of Cessna 525B CitationJet CJ3, registration N525L, and could not be reproduced on the ground, the maintenance company decided to carry out a test flight. During this flight, the mechanic was to sit in the righthand pilot’s seat in order to be able to pinpoint the noises in question.
Shortly before the flight, the mechanic was informed that a colleague of the pilot, who possessed a helicopter pilot licence, would also be on the flight to Sion. This meant that this pilot sat in the right-hand pilot’s seat and the mechanic took a seat in the cabin.
At 17:51 local time N525L was given clearance for takeoff from runway 28 at Zurich Airport. As per the clearance for departure, the aircraft was to take off along standard instrument departure (SID) route VEBIT 3W and climb to an altitude of 5000 ft QNH.
From the beginning of the flight, the pilot was unable to fly the aircraft safely along the stipulated flight path. He failed to follow the SID route both laterally and vertically. For example, he missed the D2.3 KLO turning point and exceeded the cleared altitude of 5000 ft QNH that he had correctly entered into the FMS.
As the flight continued, there were no noticeable improvements in the pilot’s overview and situational awareness. Throughout the flight, the pilot was concentrating almost exclusively on the autopilot and repeatedly tried to switch it on.
The course of the flight, which lacked structure and at several times came very close to a loss of control, can be attributed to inadequate knowledge of the aircraft systems and limited situational awareness. The resulting significant deviations from what air traffic control had authorised represented a considerable threat to other airspace users, in particular in the dense airspace around Zurich Airport.

The investigation did not find any indications of pre-existing technical defects which could have influenced the serious incident. There is therefore no technical evidence for faulty operation of the autopilot (AP).
For this reason, it must be concluded that the problems with the AP, which the pilot repeatedly noticed, can be attributed to the fact that he was not always aware whether the AP was engaged or not. Firstly, this resulted in the aircraft intermittently being flown neither by the pilot nor by the autopilot. This inevitably posed the risk of an uncontrolled flight attitude. Secondly, steering input from the pilot when the AP was engaged caused unwanted adjustment of the elevator trim. This resulted in sudden changes in flight attitude when the AP switched off, either intentionally or due to the aircraft’s systems, making it difficult to pilot the aircraft and maintain a specified flying altitude.

Sources:

https://www.sust.admin.ch/inhalte/AV-berichte/N525L_VB_D.pdf

Accident investigation:
cover
  
Investigating agency: STSB Switzerland
Status: Investigation completed
Duration: 6 months
Download report: Final report


Revision history:

Date/timeContributorUpdates
30-Jan-2019 09:56 harro Added
06-Mar-2019 18:31 harro Updated [Nature, Narrative, Accident report, ]

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