THE GERMAN Federal Aviation Office (LBA) is resisting calls from the air-accidents investigation authority (FUS) to ground all Robinson R44 light piston-engined helicopters in Germany.

The row has been inflamed by the German R44 accident near Riesa, Saxony, in May, in which all four occupants of the helicopter were killed. According to the FUS, the reason for the latest accident is mast-bumping, which causes the helicopter to break up in mid-air.

Four R44s have crashed, causing eight deaths, since the helicopter's certification in Germany in early 1994. Three of these accidents - all of which took place within 13 months - have been attributed to mast-bumping. The FUS says that there are 20 R44s registered in Germany.

After consultations with the US Federal Aviation Administration, however, as well as with Robinson Helicopter owner and founder Frank Robinson, the LBA has concluded that grounding the helicopters would be "an over-reaction".

While the causes of the mast-bumping incidents remain unclear, the LBA says that there is no reason to believe that the accidents were caused by any technical or design fault in the helicopter. Robinson says that, among 165 registered R44s worldwide, no mast-bumping incidents have been recorded outside Germany.

A similar row, following a spate of fatal accidents in the USA, led the FAA to resisting grounding recommendations from the US National Transportation Safety Board to introduce in March strict new training rules for pilots of the R44 and the two-seat R22, (Flight International, 8-14 March).

Source: Flight International