Kieran Daly/LONDON

THE INVESTIGATION of the fatal crash of the first and only Antonov An-70 prototype may be hampered by a lack of useable information from the flight-data recorder (FDR).

Sources close to the Antonov flight-test operation allege that pressure on staff to accelerate the flying programme led to the final flight being conducted without the FDR having been calibrated. Antonov has refused to comment on the allegations.

It is understood, however, that a video film exists of the aircraft's sudden departure from control, taken from the chase aircraft - now thought to have been an An-74 - which itself was nearly destroyed in the ensuing mid-air collision (Flight International, 22-28 February).

The sources - former Antonov flight-test engineering and piloting staff who remain closely connected with the Kiev-based operation - say that the An-70 suddenly veered sideways and the pilot was heard to transmit the words "yaw, yaw".

According to them, the flight-test staff were under intense pressure to put more hours on the aircraft, despite numerous technical snags which, they say, created a high risk of an accident. The aircraft crashed two months after its first flight.

They allege that the An-70 first officer, who was also a qualified captain, had just been told that, once the flight on which he subsequently died was over, he was to be relieved of his position because of his repeated questioning of the technical risks being taken.

The faults are understood to have afflicted the fly-by-wire flight-control system and the aircraft's novel contra-rotating prop-fans. Failures in either system could potentially lead to the observed aircraft behaviour, although there is no confirmed evidence that these systems were actually at fault on the day.

Antonov has been urged by the Ukrainian Government to hurry the much-delayed programme because of its potential earning power and, in particular, because the Russian rival Tupolev-Tu 330 is in advanced development.

The design bureau is understood to hope now to use a static-test fuselage as the basis for another flying An-70.

Source: Flight International