ASN Wikibase Occurrence # 268426
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| Date: | Friday 8 October 2021 |
| Time: | c 17:10 LT |
| Type: |  SNCAN SV-4B |
| Owner/operator: | Private |
| Registration: | G-AIYG |
| MSN: | 21 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Westerschelde off Ossenisse, Zeeland -
 Netherlands
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Antwerpen-Deurne Airport (ANR/EBAW) |
| Midden Zeeland Airfield (EHMZ) | |
| Investigating agency: | Dutch Safety Board |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot conducted a flight from Antwerp (Belgium) to Midden Zeeland airport (the Netherlands). The aircraft was refuelled before the flight with 44 liters of Avgas.
Above the Westerschelde, after 25 minutes in flight at an altitude of approximately 1,000 feet, the engine failed.
The pilot made a forced landing on the water, where the aircraft overturned. The pilot was unharmed and was rescued shortly after the emergency landing by a ship of the Ministry of Infrastructure and Water Management.
The aircraft was salvaged by the Aviation Police, with assistance from the Ministry of Infrastructure and Water Management.
The aircraft was equipped with a Bristol-Siddeley Gipsy Major 10 MK I engine. No defects were found on the fuel system and fuel was present in the carburettor.
The engine could be rotated and the cylinders had compression. The magneto ignition system was largely in good condition, however the left magneto did not rotate when the engine was turned.
The Dutch Safety Board has conducted a further investigation assisted by a ground engineer who has detailed knowledge of the engine type and magneto concerned. The flexible coupling of the left magnet was damaged and the material appeared softer than a new coupling. It was found that the left magneto was hard to turn. The left magneto was then disassembled and it was found that the insulation of the rotor had touched the pole shoes housing. The rotor insulation has most probably been swollen due to aging and centrifugal forces, causing an increase of the rotor diameter. The swollen insulation resulted in rotational resistance which damaged the flexible coupling of the magneto.The rotational resistance in combination with the damaged teeth of the flexible coupling, created the possibility that the left magneto in relation to the drive could change position.
During flight, the damaged flexible coupling most likely resulted in a change of the ignition timing of the left magneto. Due to the difference in ignition timing of the two magnetos, the engine will malfunction. The severity of the malfunction depends on the magnitude of the difference in ignition timing between the two magnetos.
By switching off the magneto whose ignition time is no longer correct, the engine will in principle function normally again, albeit with slightly less power. To make the diagnosis, the magnets must be turned off alternately.
There is a chance that the properly functioning magnet will be switched off first. It must then be switched on again and the faulty magnet switched off. The pilot indicated that he was concentrating on the water landing and did not have enough time available for the diagnosis process.
During a maintenance inspection in June 2021, the ignition timing was checked. The magneto itself was inspected in May 2018.After this inspection, the aircraft had accumulated approximately 80 hours. The inspection scheme of the magneto is every 500 hours or 10 years.
The aircraft was deemed not repairable due to the damage and salt water immersion.
Note: The aircraft was manufactured under license by SNCAN in France as an SV-4C model. The Renault-engine was later replaced by a Gipsy Major engine, which was common in the SV-4B model. The aircraft was subsequently registered as an SV-4B.
Sources:
https://www.onderzoeksraad.nl/nl/media/inline/2022/9/7/quarterly_aviation_report_q2_2022.pdf
https://www.pzc.nl/zeeuws-vlaanderen/vliegtuigje-stort-in-westerschelde-piloot-ongedeerd~a5b7db2e
https://www.omroepzeeland.nl/media/61970/Gecrashte-sportvliegtuig-uit-elkaar-gehaald-Hij-is-niet-meer-te-redden
https://www.omroepzeeland.nl/nieuws/130407/Piloot-gecrasht-sportvliegtuig-ongedeerd-toestel-niet-meer-te-redden
http://www.stampe.be/UK/The_Collection_SV4-G-AIYG.html
Media:
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 08-Oct-2021 18:42 | harro | Added |
| 08-Oct-2021 18:46 | harro | Updated [Embed code, Category] |
| 08-Oct-2021 19:48 | harro | Updated [Location] |
| 09-Oct-2021 18:30 | RobertMB | Updated [Source, Damage, Narrative] |
| 09-Oct-2021 19:40 | harro | Updated [Source, Narrative] |
| 20-Oct-2021 08:49 | harro | Updated [Aircraft type, Source, Narrative] |
| 21-Jun-2022 20:29 | Ron Averes | Updated [Location] |
| 08-Sep-2022 08:36 | harro | Updated [Source, Narrative] |
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