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ASN Wikibase Occurrence # 30905
Last updated: 16 December 2020
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Date:23-FEB-1989
Time:23:50
Type:Silhouette image of generic SW3 model; specific model in this crash may look slightly different
Swearingen SA226-T Merlin III
Owner/operator:Predator
Registration: N26RT
C/n / msn: T-216
Fatalities:Fatalities: 7 / Occupants: 8
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:near Helsinki-Vantaa Airport -   Finland
Phase: Approach
Nature:Private
Departure airport:Southend Airport (EGMC)
Destination airport:Helsinki-Vantaa Airport
Narrative:
The a/c was on a private flight from Southampton, England with all seats occupied. The pilot and the person occupying the right hand seat had previously on the same journey been receiving type training in the US. The "F/O" had not passed his test, but the plane could be legally flown with a single pilot. However, the plane, being in the US registry only, could not be flown legally outside the US. The plane's instrumentation checks were lapsed 13 months ago for the ILS operation. The Board also found the general condition of the plane and the engines poor with regard to the operating hours reported for them.

The pilot was an experienced crop duster plane pilot, but had little twin engine plane or in particular fast twin plane experience. On the ILS approach to runway 22 the plane initially overshot the glide scope, and to the ATC comment the pilot replied: "we had excess speed or height here ... too much height". The conditions just before a winter midnight ware demanding with the cloud ceiling at about 100 meters.

Witnesses on a public road saw and heard the plane aligned with the general direction of the runway, about 2 kms from the threshold, but with a stream of metallic noises and hard bangs heard emanating from it. The plane struck trees 1,100 meters from the threshold, cut some approach lighting guy wires and ended up 200 meters later inverted and broken up. Everyone onboard was killed, save one passenger seated furthest back left, who escaped though a broken window unharmed and walked to meet the rescuers soon coming from the runway direction. The surroundings were doused all over with leaked kerosene, but no fire broke out at any stage.

The plane had no CVR or data recorders. Neither was the ATC radar image recorded. The investigation found that the spruce needles found in the engines had been charred differently, the ones in the left engine had been exposed to a temperature of 300C at the most, while those in the right engine were charred at over 800C.

From the damages to the both propellers it was found that the blade angles were driven into the reverse region while in flight. The limiters installed in the operating levers were found to be worn out, allowing an unintentional advancing of them into the reverse region. Similar findings were also made on the other similar plane the Board reviewed in Finland. The pilot had attempted to shut down the left engine and to feather the left propeller but the mechanism was already too damaged for the actual feathering to function. The trimming of the plane was also shifted towards single-engine operation. The right hand propeller shaft had survived the initial stress of the blade angle reversal. Continuing asymmetrical flight at that point however was not possible. The plane, with a full complement of passengers and luggage had been 1,000 lbs overweight at takeoff but was within weight limits at the time of the accident.



Sources:

https://www.turvallisuustutkinta.fi/material/attachments/otkes/tutkintaselostukset/fi/ilmailuonnettomuuksientutkinta/vanhemmattutkintaselostukset/xdWh6wv4h/1_1989L_Tutkintaselostus.pdf

Accident investigation:
cover
  
Investigating agency: 
Status: Investigation completed
Duration:
Download report: Final report


Revision history:

Date/timeContributorUpdates
27-Sep-2008 01:00 ASN archive Added
17-Oct-2010 15:13 TB Updated [Aircraft type, Cn, Other fatalities, Location, Phase, Destination airport, Source, Narrative]
17-Oct-2010 15:16 TB Updated [Narrative]
27-Aug-2019 05:56 anttiruo Updated [Time, Total fatalities, Narrative]
27-Aug-2019 06:00 harro Updated [Date, Total fatalities, Total occupants, Location, Departure airport, Destination airport, Source, Narrative]
27-Aug-2019 19:45 harro Updated [Departure airport, Accident report, ]
16-Dec-2020 20:18 itapirkanmaa Updated [Nature, Narrative, Accident report]

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