Conservative peer Lord Ballyedmond who was killed in a helicopter crash last night had recently raised safety concerns with the aircraft's manufacturers.
Lord Ballyedmond, who owned Corby Castle outside Carlisle, was chairman of Norbrook, the largest privately owned pharmaceutical company in the world.
His AgustaWestland AW139 helicopter came down in thick fog in a field in Gillingham, near Beccles, Norfolk, at 7.30pm yesterday killing him and three others.
It has now emerged that his company Haughey Air Ltd had lodged a writ against AgustaWestland over concerns about a helicopter supplied by them.
The case was lodged in September last year and is understood to have included concerns about in-flight mapping systems.
A spokesman for AgustaWestland said it could not comment on possible defects with Lord Ballyedmond's AW139 VIP helicopter but said it was investigating.
Speaking from the company's office in Italy, he said: "We cannot comment now because we need to make internal checks to establish exactly what the situation is.
"We cannot yet comment on this accident because there is an investigation pending and there could be many causes, be them technical or due to human error.
"Obviously we are very much regretful of what happened and will support the ongoing investigation in any possible way."