EH101 demonstrates its maturity

June 12th, 1999

The two Anglo-Italian EH101 aircraft involved in the intensive flight operations programme (IFOP) in Aberdeen are clocking up the hours. Between them PP8 and PP9, the civil pre-production aircraft, have completed more than 3,500 hours of the 6,000 flying hour programme.

The IFOP began in 1996 and is designed to prove the reliability and maintainability of the EH101and the time between overhauls of major components. Flown by commercial pilots provided under contract by Bristow Helicopters, each aircraft will typically fly two, three hour sorties per day, six days a week, the sorties being simulated civil and military mission profiles. At peak flying rates the aircraft have logged as many as ten flying hours in a day.

A major milestone was reached in April when PP9s main gearbox and accessory and tail gearboxes were taken out for their 1,500 hour inspection. The results, said Flight Trials Manager Harold Cunningham, were excellent. "Everything was in first class working order. The gearboxes were reassembled and put back into the aircraft without the need for any replacement parts."

EH101 PP8 and PP9 over Aberdeen

With PP8s flying hours already well over 1,900, the 2,000 hour gearbox inspection will be undertaken in the next few weeks.

Another key milestone reached in the past few weeks was the successful meeting of the mean time between attributable failures (MTBAF) requirement. Under GKN Westland's contract with the UK Ministry of Defence, the EH101 had to complete 500 hours flying in which there was less than one attributable failure of any sort in every four hours. This target was comfortably achieved and the aircraft completed the last 70 hours of the programme with no recorded faults of any description.

The IFOP programme is planned to conclude in summer 2000, by which time the pre-production fleet will have logged a total of more than 10,000 flying hours. With twelve EH101 Merlin Mk1 aircraft already delivered to the British Royal Navy the production fleet is also clocking up the hours. Over 1,000 hours have been completed to date bringing the total flying hours for all EH101 aircraft to more than 9,500.

Both IFOP aircraft took time out in recent weeks to undertake demonstration tours. PP8 spent a week in south west England calling at a number of airports and undertaking proving flights from Penzance to the Isles of Scilly and from Cardiff to Battersea Heliport in London. PP9 attended the Finnish Air Show in Lappeenranta, Eastern Finland, with visits to bases in Sweden and Denmark en route.

Between them, the two aircraft undertook over 65 individual flights and logged some 90 flying hours during their tours. Both achieved 100% availability throughout, in spite of the unusual and demanding flying patterns involved.

You can contact GKN Westland Helicopters at info@gkn-whl.co.uk
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