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ASN Wikibase Occurrence # 200391
Last updated: 14 February 2020
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Type:Silhouette image of generic C25M model; specific model in this crash may look slightly different
Cessna 525 Citation M2
Registration: I-FVAB
C/n / msn: 525-0916
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: None
Category:Serious incident
Location:nr Zürich-Kloten Airport (ZRH/LSZH) -   Switzerland
Phase: Initial climb
Departure airport:Zürich-Kloten Airport (ZRH/LSZH)
Destination airport:Venice-Marco Polo Airport (VCE/LIPZ)
Investigating agency: STSB Switzerland
On the evening of the 8th October 2017, the flight crew accepted I-FVAB from the maintenance company with the intention of flying the aircraft to Venice Airport (LIPZ). As the crew was aware that maintenance work had been carried out on the aircraft, they performed a particularly thorough outside-check of the aircraft. No irregularities were detected during this check, nor when preparing the cockpit. Preparation with engines running also presented nothing out of the ordinary.

Subsequently, the flight crew began take-off from runway 28. Both crew members noticed an unusual, yet subtle smell during the take-off run. Shortly after the aircraft had taken off and the landing gear had been retracted, a significant amount of smoke developed inside the aircraft. The smoke was white in colour and the smell was unfamiliar to both crew members. It could not be attributed to burning oil, nor to overheated plastic. The pilot, who was the pilot flying (PF) at the time, told the co-pilot to put on his oxygen mask, then handed control of the aircraft over to him, so that she could put on her own oxygen mask and begin checking for faults.
Neither pilot put on protective goggles because they did not perceive the smoke to be causing irritation to their eyes at the time. Both crew members were able to see everything in the cockpit and the smoke did not particularly restrict their activities. These initial steps correspond to the first points set out in the ‘Environmental System Smoke or Odour’ checklist from the emergency/abnormal procedures. The pilot began checking for faults using the checklist, not going through the checklist step by step. She decided to first of all set the air source selector to left (L), then right (R), then emergency (EMER) and finally to FRESH AIR. Switching the air source to FRESH AIR is listed as point 9 in the checklist. This setting causes the pressure regulating-shutoff valves to close and therefore no bleed air is supplied to the aircraft cabin.
The cabin cannot be pressurised in this setting because the air is now supplied directly into the cabin from outside. This action prevented further smoke from entering the cabin. The pilot then notified air traffic control that there was smoke in the cockpit and that an immediate return to Zurich was necessary.
Shortly afterwards, the smoke lessened and the pilot therefore decided to stop going through the checklist and to focus on landing the aircraft at Zurich Airport. Air traffic control then directed the aircraft towards runway 14 using radar vectors. The crew ensured that it was not passing through any clouds so that, should the situation worsen, it would still be possible to
execute a visual approach at any time.
The aircraft finally flew at an altitude of 5000 ft AMSL and was directed to the instrument landing system of runway 14 via a right downwind approach. Approx. 8 minutes after take-off, I-FVAB landed on runway 14 and taxied to its parking position without any further incident.

The engine manufacturer stipulates that the engines run in idle power for at least 2 minutes following a compressor wash. The maintenance company had run the engines in idle after the compressor wash, initially for around 10 minutes, and for a few minutes the next day at a power of 60-80% N1, which significantly exceeded the manufacturer’s specification. Despite this,
smoke developed shortly after take-off due to cleaning fluid residue in the engine. This shows that the manufacturer’s procedure for the engine test following a compressor wash is not always sufficient to prevent smoke from developing at take-off power or full throttle.


Accident investigation:
Investigating agency: STSB Switzerland
Status: Investigation completed
Duration: 1 year 1 month
Download report: Final report


Photo of I-FVAB courtesy

Helsinki - Vantaa (EFHK / HEL)
14 June 2017; (c) Pertti Sipilä

Revision history:

14-Oct-2017 17:53 harro Added
27-Nov-2018 19:15 harro Updated [Nature, Narrative, Accident report, ]

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