Hundreds of Soviet-registered aircraft in service within the European Union fleet have been effectively grounded on the advice of European aviation safety regulator EASA.

European legislation dating back to 2003 had exempted - albeit temporarily - certain aircraft registered in member states from securing European airworthiness certificates, although it did specify that EASA determine the design approval necessary to issue them in the meantime.

But EASA now says that it has only received applications from the designers of the Antonov An-26 and the Kamov Ka-32A and Ka-32A11BC , together accounting for 39 aircraft - the equivalent of 15% of qualifying aircraft operated or owned by EU airlines mainly from ex-Soviet states.

These applications have been accepted, thus allowing the continued operation of the aircraft, and EASA will now work with the Interstates Aviation Committee of the CIS and the Ukrainian CAA for the An-26, and the Interstates Aviation Committee of the CIS for the Ka-32 to help them demonstrate compliance.

EASA reckons the certification processes involved could be concluded within an extension period of 18 months to September 2009.

Those operators of the remaining 213 Russian and CIS-built aircraft whose designers have failed to meet the 28 March deadline to at least start the process will however face the scrutiny of their national CAAs.

On 15 March EASA said: "These aircraft are likely to be grounded on 28 March 2008 unless urgent measures are taken by their owners/operators to obtain the necessary design approvals".

It added that the aircraft concerned included large commercial air transport such as the Antonov An-24, An-72 and An-74, the Tupolev Tu-154 and the Yakolev Yak-40.

A large number of general aviation aircraft as well as helicopters also fall within this scope.

EASA adds that the best option would be to apply to obtain a design approval in the form of a specific airworthiness specification.

Any commercial use would require an exemption from EU-OPS rules which enter into force on 16 July.